@article{velasco_seng_hodges_peters_pankow_schultz_2024, title={Dynamic measurement of ballistic impact using an optical fibre sensor}, volume={33}, ISSN={["1361-665X"]}, DOI={10.1088/1361-665X/ad27fd}, abstractNote={Abstract}, number={3}, journal={SMART MATERIALS AND STRUCTURES}, author={Velasco, Ivann and Seng, Frederick and Hodges, Greyson and Peters, Kara and Pankow, Mark and Schultz, Stephen}, year={2024}, month={Mar} }
 @article{pankow_riosbass_justusson_zhang_waas_yen_2023, title={Effect of fiber hybridization on tensile fracture of 3D woven textile composites}, volume={165}, ISSN={["1878-5840"]}, DOI={10.1016/j.compositesa.2022.107306}, abstractNote={3D Woven composites provide the ability to handle higher damage tolerance (Pankow et al., 2019). Hybridization of fibers is an additional method to provide improved damage tolerance (Pankow et al., 2014) . This work is the first time that the tensile response of “hybrid” 3D woven composites (H3DWC) is investigated. The hybridization showed an increase in modulus with increasing carbon fiber volume fraction ( > 30 % in general). While, the strength showed a decrease that was proportional to the carbon fiber volume fraction ( > 78% of the baseline glass). Although the carbon failed, the material remains intact as the glass fibers have not failed, maintaining 80% of the strength after failure in the warp direction. The unsymmetric samples, which have benefits for bending type loading, produced coupled behavior due to thermally induced shrinkage. Overall looking at the combination of factors from previous bending work with this new tensile work, it can clearly be seen that there is a clear tradeoff in the amount and way one would perform hybridization.}, journal={COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING}, author={Pankow, M. and Riosbass, M. and Justusson, B. and Zhang, D. and Waas, A. M. and Yen, C. F.}, year={2023}, month={Feb} }
 @article{mendoza_graham_matejunas_hodges_siviour_pankow_lamberson_2023, title={Evaluation of Low-Cycle Impact Fatigue Damage in CFRPs using the Virtual Fields Method}, ISSN={["2199-7454"]}, DOI={10.1007/s40870-023-00386-7}, journal={JOURNAL OF DYNAMIC BEHAVIOR OF MATERIALS}, author={Mendoza, I. and Graham, A. and Matejunas, A. and Hodges, G. and Siviour, C. and Pankow, M. and Lamberson, L.}, year={2023}, month={Aug} }
 @article{thomas_nisar_zhang_joglekar_pankow_boesl_agarwal_2023, title={High strain rate response and mechanical performance of tantalum carbide-hafnium carbide solid solution}, volume={49}, ISSN={["1873-3956"]}, DOI={10.1016/j.ceramint.2023.09.249}, abstractNote={Ultra-high temperature ceramics (UHTCs) based on the solid solution TaxHf1-xC have shown great promise as materials for extreme environments (>2500 °C) due to their improved thermo-mechanical properties. However, their dynamic response under high-impact loading remains unknown. In this study, we investigate the dynamic impact behavior and fracturing evolution of TaxHf1-xC samples (with x = 0, 0.2, 0.5, 0.8, and 1) at a strain rate > 103 s-1 using the Split Hopkinson Pressure Bar (SHPB) test. Among the different compositions, Ta0.5Hf0.5C exhibits the highest compressive strength of 1870 MPa, representing a 36% improvement over TaC and 54% over HfC. High frame rate videos and deformation analysis reveal that Ta0.5Hf0.5C, characterized by extensive Ta–Hf bonding, significantly reduces the crack propagation rate by approximately 1435% compared to TaC and 4050% compared to HfC. This effect is attributed to the dislocation pile-ups, nano-twin formation, inter grain twisting exhibited mostly along {111} plane as Hf substitutes Ta in TaxHf1-xC samples. Further, the surface energy is least for {111} plane eliciting the higher probability for bypassing crack propagation along this plane in TaxHf1-xC. The exceptional damage tolerance and improved mechanical properties of Ta0.5Hf0.5C, compared to other solid-solution TaxHf1-xC compositions, make it an extraordinary structural material for hypersonic applications. These findings provide valuable insights into the dynamic behavior of UHTCs and highlight the potential of Ta0.5Hf0.5C as a superior material for extreme environments requiring high-impact resistance.}, number={23}, journal={CERAMICS INTERNATIONAL}, author={Thomas, Tony and Nisar, Ambreen and Zhang, Cheng and Joglekar, Shreyas and Pankow, Mark and Boesl, Benjamin and Agarwal, Arvind}, year={2023}, month={Dec}, pages={39099–39106} }
 @article{timofeeva_pankow_peters_2023, title={High-speed polarization imaging for failure detection in fiber spinning}, volume={12488}, ISBN={["978-1-5106-6083-0"]}, ISSN={["1996-756X"]}, DOI={10.1117/12.2665277}, abstractNote={Current trends in polymer fiber production for nonwoven material applications focus on increasing production rates and decreasing the fiber thicknesses. The quality of the polymer fibers during the fiber spinning process is influenced by the processing parameters, such as the spinning speed, throughput, and the polymer material. Irregularities in the crystallization process during the extrusion of the fibers can lead to stress concentrations and defects in the fibers that could cause failure of fibers and potential failure of the nonwoven material that is manufactured from those fibers. The ability to recognize these irregularities in fibers using a non-destructive measurement method would reduce the downtimes for production lines as well as provide in-situ quantitative data that could be used for optimization of the production process parameters. In this study, we implemented a high-speed polarization imaging technique that is capable of non-destructive measurement of the internal stress fields as well as detection of defects within a post-fabricated fiber. This imaging technique has been combined with a motion tracking algorithm for accurate alignment of the images corresponding to the same segments of the fiber. The results show that the technique is capable of detecting stress concentration regions in fabricated fibers in static and dynamic testing conditions. The sensitivity of the system also allows to track the changes in the distribution of the internal stress fields in static and dynamic loading. Future studies will apply the technique to the fiber spinning process.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS XVII}, author={Timofeeva, Anastasia A. and Pankow, Mark R. and Peters, Kara J.}, year={2023} }
 @article{white_firth_pankow_2023, title={Impact of Joint Parameters on Performance of Self-Opening Dual-Matrix Composites}, ISSN={["1533-6794"]}, DOI={10.2514/1.A35383}, abstractNote={ Origami-based structures have expanded in recent years due to new mathematical formulations along with materials that can achieve the bending requirements, often in the form of composites. While current methods of manufacturing can produce complex structures, they lack the ability to scale efficiently. A novel manufacturing technique is discussed in this work that allows for a simpler and lower cost fabrication that can scale to larger structures through robotic deposition. Samples made from this technique are investigated to understand the mechanical bending performance and effect on the tensile properties. Results show an orientation-dependent response for the material with the 45° samples having a direct impact on the tensile response. However, their bending response proved to be stiffer compared to the [Formula: see text] samples, holding more consistent bend radii. Joint stacking was also investigated, where discrete layers were not bonded together and showed an increase in force required to bend compared to the completely bonded samples. The results provide insight into how integrated composite hinges can perform in complex structures. The advancement of composite origami technology additionally works to reduce the overall number or parts and fasteners that are needed to achieve detailed deployable structures. }, journal={JOURNAL OF SPACECRAFT AND ROCKETS}, author={White, Charles and Firth, Jordan and Pankow, Mark}, year={2023}, month={May} }
 @article{hodges_pankow_2023, title={Modeling Micrometeoroid and Orbital Debris Impact on Composite Truss Tubes}, ISBN={["978-3-031-17477-3", "978-3-031-17474-2"]}, ISSN={["2191-5652"]}, DOI={10.1007/978-3-031-17475-9_5}, abstractNote={The growing congestion of space with large satellite constellations and the growing capabilities of on-orbit servicing assembly and manufacturing (OSAM) pose new problems for designers. The effects of micrometeoroid and orbital debris (MMOD) on these structures need to be well understood to ensure longevity and safety of operation. Composite truss members provide the structural backbone for in-space assembled structures, one example being the in-space assembled telescope (iSAT). Limited research has been conducted on the effects MMOD impacts have on composite trusses and their residual strength, post impact. To study the effects of MMOD impacts on composite trusses and to quantify their reduction in strength, a meso-scale hybrid FEA/SPH model was created. Simulation results of MMOD impacts were compared to experimental tests to validate the model’s damage predicting capabilities. Results from the damage reduction simulations can be used to further study the effects of MMOD impacts on in-space assembled structures.}, journal={THERMOMECHANICS & INFRARED IMAGING, INVERSE PROBLEM METHODOLOGIES AND MECHANICS OF ADDITIVE & ADVANCED MANUFACTURED MATERIALS, VOL 6}, author={Hodges, Greyson and Pankow, Mark}, year={2023}, pages={35–38} }
 @article{baber_hall_justusson_ranatunga_schaefer_pankow_guven_2023, title={Objective determination of peridynamic material parameters for fiber-reinforced composites with shear nonlinearity - Part 2: Strength properties and strain rate dependence}, ISSN={["1537-6532"]}, DOI={10.1080/15376494.2023.2291186}, abstractNote={Formulation and implementation of peridynamic strength parameters and strain rate-dependent behavior of fiber-reinforced composite laminates are presented. This work builds on the earlier framework [Citation1] objectively determining elastic parameters for laminates exhibiting shear nonlinearity. The formulation of the strength parameters uses energy-based failure criteria, specifically addressing intralaminar and interlaminar behaviors. A novel implementation of strain rate effects includes conversion from local strain to nonlocal stretch rates. The current peridynamic approach with shear nonlinearity and strain rate dependence accurately captures multiple experimentally measured metrics, including force vs. time, force vs. displacement, energy vs. time, and damage and delamination extents.}, journal={MECHANICS OF ADVANCED MATERIALS AND STRUCTURES}, author={Baber, Forrest and Hall, Riley and Justusson, Brian and Ranatunga, Vipul and Schaefer, Joseph and Pankow, Mark and Guven, Ibrahim}, year={2023}, month={Dec} }
 @article{elamin_pankow_2023, title={Rate-dependent mechanical response of polypropylene nonwovens}, ISSN={["1097-4628"]}, DOI={10.1002/app.53776}, abstractNote={Abstract}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Elamin, Mohammed and Pankow, Mark}, year={2023}, month={Feb} }
 @article{hodges_noevere_velasco_hackney_seng_schultz_peters_pankow_2022, title={Ballistic loading and survivability of optical fiber sensing layers for soft body armor evaluation}, volume={73}, ISSN={["1095-9912"]}, DOI={10.1016/j.yofte.2022.103043}, abstractNote={• To survive impact the contact radius between the fiber and impactor must be increased. • Silicone was chosen due to its high strain to failure and elastic properties. • In situ silicone sensors have shown to minimally effect back face deformation depth. • Silicone sensing mats are able to protect optical fibers during impact. The authors previously demonstrated the use of FBG sensors in Kevlar mats behind body armor to measure the transient back face deformation (BFD) during ballistic testing. This paper presents a novel sensor system based on a Fiber Bragg Grating embedded in silicone mats to improve the survivability of the body armor in-situ strain sensing layers. Due to the large amount of deformation, a relative slip between the optical fibers and the supporting structure is needed to maintain the performance of the sensors and determine the relationship between the measured strain and deformation shape. Two silicone materials were tested, Smooth-Sil 950 and Sorta-Clear 40, in both 1 mm and 2 mm thicknesses to evaluate their survivability and impact on BFD. To enhance slipping between the fibers and surrounding silicone a thin layer of petroleum jelly was placed on the fibers prior to being cast in the silicone mats. The 1 mm Sorta-Clear 40 mats performed best in silicone survivability, FBG survivability and minimal impact on the BFD. The new system improves on key deficiencies that were found from inserting the fibers directly into the Kevlar with minimal to no impact on the back face deformation.}, journal={OPTICAL FIBER TECHNOLOGY}, author={Hodges, Greyson and Noevere, Alexander and Velasco, Ivann and Hackney, Drew and Seng, Frederick and Schultz, Stephen and Peters, Kara and Pankow, Mark}, year={2022}, month={Oct} }
 @article{wu_pankow_onuma_huang_peters_2022, title={Comparison of High-Speed Polarization Imaging Methods for Biological Tissues}, volume={22}, ISSN={["1424-8220"]}, url={https://www.mdpi.com/1424-8220/22/20/8000}, DOI={10.3390/s22208000}, abstractNote={We applied a polarization filter array and high-speed camera to the imaging of biological tissues during large, dynamic deformations at 7000 frames per second. The results are compared to previous measurements of similar specimens using a rotating polarizer imaging system. The polarization filter eliminates motion blur and temporal bias from the reconstructed collagen fiber alignment angle and retardation images. The polarization imaging configuration dose pose additional challenges due to the need for calibration of the polarization filter array for a given sample in the same lighting conditions as during the measurement.}, number={20}, journal={SENSORS}, author={Wu, Xianyu and Pankow, Mark and Onuma, Taka and Huang, Hsiao-Ying Shadow and Peters, Kara}, year={2022}, month={Oct} }
 @article{joignant_bai_guymon_garrard_pankow_muddiman_2022, title={Developing transmission mode for infrared matrix-assisted laser desorption electrospray ionization mass spectrometry imaging}, volume={36}, ISSN={["1097-0231"]}, DOI={10.1002/rcm.9386}, abstractNote={RationaleThe development and characterization of the novel NextGen infrared matrix‐assisted laser desorption electrospray ionization (IR‐MALDESI) source catalyzed new advancements in IR‐MALDESI instrumentation, including the development of a new analysis geometry.}, number={22}, journal={RAPID COMMUNICATIONS IN MASS SPECTROMETRY}, author={Joignant, Alena N. and Bai, Hongxia and Guymon, Jacob P. and Garrard, Kenneth P. and Pankow, Mark and Muddiman, David C.}, year={2022}, month={Nov} }
 @article{knizner_guymon_garrard_bouvree_manni_hauschild_strupat_fort_earley_wouters_et al._2022, title={Next-Generation Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Source for Mass Spectrometry Imaging and High-Throughput Screening}, volume={9}, ISSN={["1879-1123"]}, DOI={10.1021/jasms.2c00178}, abstractNote={Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is a hybrid, ambient ionization source that combines the advantages of electrospray ionization and matrix-assisted laser desorption/ionization, making it a versatile tool for both high-throughput screening (HTS) and mass spectrometry imaging (MSI) studies. To expand the capabilities of the IR-MALDESI source, an entirely new architecture was designed to overcome the key limitations of the previous source. This next-generation (NextGen) IR-MALDESI source features a vertically mounted IR-laser, a planar translation stage with computerized sample height control, an aluminum enclosure, and a novel mass spectrometer interface plate. The NextGen IR-MALDESI source has improved user-friendliness, improved overall versatility, and can be coupled to numerous Orbitrap mass spectrometers to accommodate more research laboratories. In this work, we highlight the benefits of the NextGen IR-MALDESI source as an improved platform for MSI and direct analysis. We also optimize the NextGen MALDESI source component geometries to increase target ion abundances over a wide m/z range. Finally, documentation is provided for each NextGen IR-MALDESI part so that it can be replicated and incorporated into any lab space.}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Knizner, Kevan T. and Guymon, Jacob P. and Garrard, Kenneth P. and Bouvree, Guy and Manni, Jeffrey and Hauschild, Jan-Peter and Strupat, Kerstin and Fort, Kyle L. and Earley, Lee and Wouters, Eloy R. and et al.}, year={2022}, month={Sep} }
 @article{islam_perera_black_phillips_chen_hodges_jackman_liu_kim_zikry_et al._2022, title={Template‐Free Scalable Fabrication of Linearly Periodic Microstructures by Controlling Ribbing Defects Phenomenon in Forward Roll Coating for Multifunctional Applications}, volume={9}, ISSN={2196-7350 2196-7350}, url={http://dx.doi.org/10.1002/admi.202201237}, DOI={10.1002/admi.202201237}, abstractNote={Abstract}, number={27}, journal={Advanced Materials Interfaces}, publisher={Wiley}, author={Islam, Md Didarul and Perera, Himendra and Black, Benjamin and Phillips, Matthew and Chen, Muh‐Jang and Hodges, Greyson and Jackman, Allyce and Liu, Yuxuan and Kim, Chang‐Jin and Zikry, Mohammed and et al.}, year={2022}, month={Aug}, pages={2201237} }
 @article{chadwell_rocco_pankow_2022, title={The Dynamic Response of Additively Manufactured Polymers Subjected to Tensile Loading}, ISSN={["2199-7454"]}, DOI={10.1007/s40870-022-00361-8}, journal={JOURNAL OF DYNAMIC BEHAVIOR OF MATERIALS}, author={Chadwell, C. and Rocco, A. and Pankow, M.}, year={2022}, month={Dec} }
 @article{garmabi_elamin_bradford_pankow_2022, title={Understanding the role of bond point strain in the mechanical response of nonwoven polypropylene materials}, ISSN={["1530-793X"]}, DOI={10.1177/00219983221087332}, abstractNote={ A method was developed to study micromechanics of a bond point in nonwoven polypropylene materials. The micromechanical behavior of the thermal bonded nonwovens was studied using the digital image correlation (DIC) technique to understand the bond points deformation during mechanical stretching. An electrospray technique was used as a fast and reliable method to create the speckle pattern on the nonwovens. Various parameters of the electrospraying and their influence on the pattern accuracy and repeatability was studied and the best pattern in terms of dot size and distribution was determined from experimentation. Plasma treatment also proved to be essential to enhance the uniform distribution and adherence of the particles on the surface. Unloaded DIC experiments were carried out and proved the accuracy of technique with errors of lower than 0.5% strain. An automated high-resolution tensile apparatus was built and loaded DIC experiments were carried out using the device. The fabric was tested in Machine Direction (MD) direction and Cross Direction (CD) directions, both showing good correlation with low errors. Average strain values in bond points were plotted against total strain in fabric and the results showed noticeable amounts of strains developed in the bond points, contradictory to most of the FEM models which consider no deformation in the bond points. Results also indicated that in MD direction deformation, bond points can experience more than 30% of the overall strain presented in the fabric. }, journal={JOURNAL OF COMPOSITE MATERIALS}, author={Garmabi, Alireza and Elamin, Mohamed A. and Bradford, Philip D. and Pankow, Mark}, year={2022}, month={Apr} }
 @article{seng_hackney_goode_noevere_hammond_velasco_peters_pankow_schultz_2021, title={Dynamic back face deformation measurement with a single optical fibre}, volume={150}, ISSN={["1879-3509"]}, DOI={10.1016/j.ijimpeng.2020.103800}, abstractNote={A single optical fibre sensor is used to measure the dynamics of an impact. The method consists of sewing the optical fibre onto a woven Kevlar layer and placing it between the shoot pack and backing material. The measurement is accomplished by using the friction between the layer and the optical fibre to relate the optical fibre strain to impact deformation. Tests are done using a backing material of Roma Plastilina No.1 clay, and transparent ballistics gel with independent high-speed imaging. A final calculated BFD average error of 7.75% is presented as well as a timing error of 15.5% between the imaged dynamic BFD and the dynamic BFD determined by the FBG. This method is also tested at the U.S. Army Aberdeen Test Center in Maryland with a final calculated error of 7%.}, journal={INTERNATIONAL JOURNAL OF IMPACT ENGINEERING}, author={Seng, Frederick and Hackney, Drew and Goode, Tyler and Noevere, Alexander and Hammond, Alec and Velasco, Ivann and Peters, Kara and Pankow, Mark and Schultz, Stephen}, year={2021}, month={Apr} }
 @article{rock_ledford_garcia-avila_west_miller_pankow_dehoff_horn_2021, title={The Influence of Powder Reuse on the Properties of Nickel Super Alloy ATI 718 (TM) in Laser Powder Bed Fusion Additive Manufacturing}, volume={52}, ISSN={["1543-1916"]}, DOI={10.1007/s11663-020-02040-2}, number={2}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE}, author={Rock, Christopher and Ledford, Christopher and Garcia-Avila, Matias and West, Harvey and Miller, Victoria M. and Pankow, Mark and Dehoff, Ryan and Horn, Tim}, year={2021}, month={Apr}, pages={676–688} }
 @article{mcelroy_andre_goode_costa_olsson_pankow_2021, title={Use of enriched shell elements compared to solid elements for modelling delamination growth during impact on composites}, volume={269}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2021.113945}, abstractNote={Simulation of damage in composite laminates using currently available three-dimensional finite element tools is computationally demanding often to the point that analysis is not practical. This paper presents an enriched shell element that can provide a computationally efficient means to simulate low-velocity impact damage in a composite. The enriched element uses the Floating Node Method and a damage algorithm based on the Virtual Crack Closure Technique that is capable of simulating progressive damage growth consisting of delamination and delamination-migrations from ply to ply during a dynamic impact load. This paper presents results from the shell model in a test-analysis correlation for impact testing of 7-ply and 56-ply laminates. Analysis results from a separate high-fidelity three-dimensional finite element analysis are included also for comparison in the case of the 7-ply laminate, but not in the case the 56-ply laminate due to excessive computational demand. This paper serves as the first application of both models in low-velocity impact simulation. The shell model is considerably more computationally efficient than the high-fidelity model by at least an order of magnitude and is shown to produce results, while not as accurate as the high-fidelity model, potentially sufficiently accurate for a wide range of engineering applications including structural design and rapid prototype assessments.}, journal={COMPOSITE STRUCTURES}, author={McElroy, Mark and Andre, Alann and Goode, Tyler and Costa, Sergio and Olsson, Robin and Pankow, Mark}, year={2021}, month={Aug} }
 @article{joglekar_ranatunga_pankow_2021, title={Validation of an efficient finite element analysis approach for simulation of low velocity impact and compression strength after impact response}, volume={255}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2020.112945}, abstractNote={An efficient computational approach to simulate the damage during an impact event and subsequently predict the remaining compression strength is presented in this paper. The two-step explicit finite element modeling scheme to simulate the damage as interlaminar delaminations during an impact event and the ensuing failure during a compression test is developed to eliminate the typical issues associated with manual transfer of damage details between an impact simulation and a quasi-static compression failure simulation. The residual strength after impact simulation is predicted based on the damage state predicted by the impact model. Experiments were performed to validate the numerical study for 24 and 32 ply quasi-isotropic laminates, generally used in aircraft structure, with two different boundary conditions to ensure that the model is capable enough to predict the behavior of an impact even under different boundary conditions. A strong correlation is found between the delamination damage observed experimentally and the model predictions. Furthermore, the finite element approach presented in this paper was able to accurately simulate the compression strength after impact.}, journal={COMPOSITE STRUCTURES}, author={Joglekar, S. and Ranatunga, V and Pankow, M.}, year={2021}, month={Jan} }
 @article{kuznetsov_pankow_peters_huang_2020, title={A structural-based computational model of tendon-bone insertion tissues}, volume={327}, ISSN={["1879-3134"]}, DOI={10.1016/j.mbs.2020.108411}, abstractNote={Tendon-to-bone insertion provides a gradual transition from soft tendon to hard bone tissue, functioning to alleviate stress concentrations at the junction of these tissues. Such macroscopic mechanical properties are achieved due to the internal structure in which collagen fibers and mineralization levels are key ingredients. We develop a structural-based model of tendon-to-bone insertion incorporating such details as fiber preferred orientation, fiber directional dispersion, mineralization level, and their inhomogeneous spatial distribution. A python script is developed to alter the tapered tendon–bone transition zone and to provide spatial grading of material properties, which may be rather complex as experiments suggest. A simple linear interpolation between tendon and bone material properties is first used to describe the graded property within the insertion region. Stress distributions are obtained and compared for spatially graded and various piece-wise materials properties. It is observed that spatial grading results in more smooth stress distributions and significantly reduces maximum stresses. The geometry of the tissue model is optimized by minimizing the peak stress to mimic in-vivo tissue remodeling. The in-silico elastic models constructed in this work are verified and modified by comparing to our in-situ biaxial mechanical testing results, thereby serving as translational tools for accurately predicting the material behavior of the tendon-to-bone insertions. This model will be useful for understanding how tendon-to-bone insertion develops during tissue remodeling, as well as for developing orthopedic implants.}, journal={MATHEMATICAL BIOSCIENCES}, author={Kuznetsov, Sergey and Pankow, Mark and Peters, Kara and Huang, Hsiao-Ying Shadow}, year={2020}, month={Sep} }
 @article{rock_vadlakonda_figurskey_ledford_west_miller_pankow_daniels_horn_2020, title={Analysis of Self-Organized Patterned Surface Oxide Spots on Ejected Spatter Produced during Laser Powder Bed Fusion}, volume={35}, ISBN={2214-7810}, url={http://dx.doi.org/10.1016/j.addma.2020.101320}, DOI={10.1016/j.addma.2020.101320}, abstractNote={Spatter particles ejected from the melt pool after melting of 316 L stainless steel by laser powder bed fusion additive manufacturing (LPBF), were found to contain morphologies not observed in as-atomized 316 L powder. This spatter consisted of large, spherical particles, highly dendritic surfaces, particles with caps of accreted liquid, and agglomerations of multiple individual particles fixed together by liquid ligaments prior to solidification. The focus of this study is on an additional, unique spatter morphology consisting of larger, spherical particles with surface oxide spots exhibiting a wide distribution of surface configurations, including organized patterning. Spatter particles with organized surface oxide patterns were characterized for surface and internal particle features using multiple imaging techniques. The following observations are made: 1) spots resided at the spatter particle surface and did not significantly penetrate the interior, 2) the spot(s) were amorphous and rich in Silicon (Si)-Manganese (Mn)-Oxygen (O), 3) a two-part Chromium (Cr)-O rich layer exists between the particle and spot, 4) Cr-O rich morphological features were present at the top surface of the spots, 5) the spatter particle composition was consistent with 316 L but appeared to decrease in Si content into the spatter particle away from a spot, and 6) small Si-rich spherical particles existed within the spatter particle interior.}, journal={Additive Manufacturing}, publisher={Elsevier BV}, author={Rock, Christopher and Vadlakonda, Rashmi and Figurskey, Sullivan and Ledford, Christopher and West, Harvey and Miller, Victoria and Pankow, Mark and Daniels, Karen E. and Horn, Tim}, year={2020}, month={Oct}, pages={101320} }
 @article{firth_pankow_2020, title={Minimal Unpowered Strain-Energy Deployment Mechanism for Rollable Spacecraft Booms: Ground Test}, volume={57}, ISSN={["1533-6794"]}, DOI={10.2514/1.A34565}, abstractNote={This paper describes development and ground testing of an unpowered mechanism intended to control deployment of a rollable spacecraft boom. The mechanism constrains the boom to a single deployment ...}, number={2}, journal={JOURNAL OF SPACECRAFT AND ROCKETS}, author={Firth, Jordan A. and Pankow, Mark R.}, year={2020}, pages={346–353} }
 @article{sridharan_pankow_2020, title={Performance evaluation of two progressive damage models for composite laminates under various speed impact loading}, volume={143}, ISSN={["1879-3509"]}, DOI={10.1016/j.ijimpeng.2020.103615}, abstractNote={The focus of this paper is to explore two different finite element modeling strategies to understand how well they can be used to characterize different types of impacts. In this paper, finite element numerical simulations of both low velocity and high velocity projectile impact on composite laminates have been carried out. Low velocity impact was based on 3 mm thick 24 ply unidirectional graphite epoxy laminates. High velocity impacts were performed on a laminated S2 Glass with SC-15 resin, since large amounts of material data, and experimental and computational results are available for validation. Two separate progressive material damage models were investigated in the commercial finite element codes Abaqus/CAE and LS-Dyna. The Abaqus/CAE models used a VUMAT subroutine while MAT 162 was chosen due to its wide adoption for impact problems in LS-Dyna. For high velocity projectile impact simulations MAT 162 captures the correct velocity but misses the spread of damage with localization. While the Abaqus/CAE model underperformed due to the lack of modeling the through thickness shear type failures. For Low velocity impact simulations the Abaqus/CAE model showed a good correlation with experimental data while MAT 162 struggled. The modeling limitation imposed by MAT 162 restricting the model to only reduced integration solid elements was found to induce a mesh instability making the model prone to hourglassing. This was specifically a challenge in modeling laminates with a greater number of plies or more representative of structures which might be subjected to impact, which was not an issue at the higher energy.}, journal={INTERNATIONAL JOURNAL OF IMPACT ENGINEERING}, author={Sridharan, Sriraghav and Pankow, Mark}, year={2020}, month={Sep} }
 @article{hackney_goode_seng_pankow_schultz_peters_2020, title={Survivability of integrated fiber Bragg grating sensors in ballistic protection fabrics for high velocity impact testing}, volume={60}, ISSN={["1095-9912"]}, DOI={10.1016/j.yofte.2020.102356}, abstractNote={This research demonstrates that fiber Bragg grating (FBG) strain sensors can survive and provide useful strain information when integrated into a woven fabric subjected to ballistic impact testing. In this work, FBGs were integrated into a single-layer, Kevlar® fabric, sensing mat, placed between a 30-layer Kevlar® fabric shoot pack and clay backing material, and then impacted with an 8.23 g, 12.69 mm diameter, steel ball bearing at velocities up to 285 m/s. Three different optical fiber types, with differing fiber coatings and fiber diameters, were tested. The FBG strain response was determined from the full-spectrum FBG response which was interrogated at 100 kHz throughout the impact event. The difference in FBG strain response for the different coatings and fiber diameters were compared. Additionally, the degradation of the coatings after repeated impacts were visually characterized, showing that smaller diameter fibers behaved better with a more elastic coating.}, journal={OPTICAL FIBER TECHNOLOGY}, author={Hackney, D. and Goode, T. and Seng, F. and Pankow, M. and Schultz, S. and Peters, K.}, year={2020}, month={Dec} }
 @article{firth_pankow_2019, title={Advanced Dual-Pull Mechanism for Deployable Spacecraft Booms}, volume={56}, ISSN={["1533-6794"]}, DOI={10.2514/1.A34243}, abstractNote={In this paper, a mechanism is developed to control deployment of a rollable carbon-fiber boom. The dual-pull mechanism keeps the coiled boom tightly wound at all times with a cowound tape. A novel ...}, number={2}, journal={JOURNAL OF SPACECRAFT AND ROCKETS}, author={Firth, Jordan A. and Pankow, Mark R.}, year={2019}, pages={569–576} }
 @article{guo_pankow_peters_2019, title={High-Speed Interrogation Approach for FBG Sensors Using a VCSEL Array Swept Source}, volume={19}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2019.2927901}, abstractNote={This paper presents a fiber Bragg grating (FBG) interrogator based on vertical surface cavity emitting lasers (VCSEL). A Fabry–Pérot filter technique is developed to directly calibrate the dynamic wavelength behavior of VCSELs at both low and high sweep rates. A broad bandwidth light source is constructed by multiplexing five VCSELs together to increase the number of FBGs that can be tracked. Scanning of the VCSEL-array is accomplished by a high-speed electronic switch circuit. The developed interrogator achieves a sweep bandwidth of 10 nm at a scanning rate of 4 kHz. Low-velocity impact testing of a composite plate with a surface mounted FBG sensor shows that the wavelength detection error was 2.7% when compared with the FBG strain obtained by a high-speed swept laser.}, number={21}, journal={IEEE SENSORS JOURNAL}, author={Guo, Guodong and Pankow, Mark and Peters, Kara}, year={2019}, month={Nov}, pages={9766–9774} }
 @article{guo_hackney_pankow_peters_2019, title={Shape reconstruction of woven fabrics using fiber bragg grating strain sensors}, volume={28}, ISSN={["1361-665X"]}, DOI={10.1088/1361-665X/ab4ba3}, abstractNote={In this paper we develop a methodology that uses in-plane strain measurements to determine out-of-plane deflection for woven fabrics using an optical fiber based sensor network. A multiplexed fiber Bragg grating (FBG) network is used to collect strain at discrete locations in the fabric. To simplify the problem a circularly shaped two-dimensional woven fabric material under a spherical indenter load is studied. A finite element (FE) model of the fabric behavior, derived from benchmark testing, was used to help develop reconstruction algorithms, some of which account for slipping of the fabric at the clamped boundaries. Due to the large deflections, complex material behavior of the fabric and slipping of the fabric at the outer boundaries, a modified empirical approximation approach was found to be the optimal choice for the deflection reconstruction. Experiments are performed to evaluate one of the algorithms on strain data from FBG sensors for two test cases: bonded to and woven into the fabric. Despite the complex strain on the FBGs bonded to the fabric, the empirical approach well predicts the out-of-plane deflection, except in the region under the indentor, where the fabric deformation was different than that modeled in the FE simulations. This result is promising for structural applications were direct observations of the out-of-plane deflections are not possible. To increase the maximum deflection of the fabric that could be measured, weaving of the FBGs into the fabric is also attempted. This method was less successful, due to the large amount of relative slipping between the optical fiber and the fabric, drastically reducing the strain measured by the FBGs.}, number={12}, journal={SMART MATERIALS AND STRUCTURES}, author={Guo, Guodong and Hackney, Drew and Pankow, Mark and Peters, Kara}, year={2019}, month={Dec} }
 @article{goode_shoemaker_schultz_peters_pankow_2019, title={Soft body armor time-dependent back face deformation (BFD) with ballistics gel backing}, volume={220}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2019.04.025}, abstractNote={This paper presents a method for obtaining time dependent back face deformation (BFD) data for body armor during ballistic impact using a clear ballistics gelatin backing and high-speed cameras to capture the deformation profile. Using this method, baseline fabric characterization data was obtained for samples comprised of varying layers of 467 g/m2 Kevlar K29 fabric impacted with 8.24 g steel ball projectile and backed with NATO standard 20% clear ballistics gelatin. For these tests, deformation depths were seen to increase with increasing impact energy and decreasing total areal density. A limited study of the various test parameters was performed by testing one additional fabric, projectile, and ballistics gelatin. From these comparisons, it was observed that 122 g/m2 Kevlar KM2+ fabric performs better per weight than 467 g/m2 Kevlar K29 fabric in terms of BFD, 9 mm FMJ projectiles produce deeper BFDs than 12.7 mm steel ball projectiles, and backing a sample with FBI standard 10% ballistics gel increases the BFD considerably over NATO standard 20% ballistics gel.}, journal={COMPOSITE STRUCTURES}, author={Goode, T. and Shoemaker, G. and Schultz, S. and Peters, K. and Pankow, M.}, year={2019}, month={Jul}, pages={687–698} }
 @article{kuznetsov_pankow_peters_huang_2019, title={Strain state dependent anisotropic viscoelasticity of tendon-to-bone insertion}, volume={308}, ISSN={0025-5564}, url={http://dx.doi.org/10.1016/j.mbs.2018.12.007}, DOI={10.1016/j.mbs.2018.12.007}, abstractNote={Tendon-to-bone insertion tissues may be considered as functionally-graded connective tissues, providing a gradual transition from soft tendon to hard bone tissue, and functioning to alleviate stress concentrations at the junction of these tissues. The tendon-to-bone insertion tissues demonstrate pronounced viscoelastic behavior, like many other biological tissues, and are designed by the nature to alleviate stress at physiological load rates and strains states. In this paper we present experimental data showing that under biaxial tension tendon-to-bone insertion demonstrates rate-dependent behavior and that stress-strain curves for the in-plane components of stress and strain become less steep when strain rate is increased, contrary to a typical viscoelastic behavior, where the opposite trend is observed. Such behavior may indicate the existence of a protective viscoelastic mechanism reducing stress and strain during a sudden increase in mechanical loading, known to exist in some biological tissues. The main purpose of the paper is to show that such viscoelastic stress reduction indeed possible and is thermodynamically consistent. We, therefore, propose an anisotropic viscoelasticity model for finite strain. We identify the range of parameters for this model which yield negative viscoelastic contribution into in-plane stress under biaxial state of strain and simultaneously satisfy requirements of thermodynamics. We also find optimal parameters maximizing the observed protective viscoelastic effect for this particular state of strain. This model will be useful for testing and describing viscoelastic materials and for developing interfaces for dissimilar materials, considering rate effect and multiaxial loadings.}, journal={Mathematical Biosciences}, publisher={Elsevier BV}, author={Kuznetsov, Sergey and Pankow, Mark and Peters, Kara and Huang, Hsiao-Ying Shadow}, year={2019}, month={Feb}, pages={1–7} }
 @article{midani_seyam_saleh_pankow_2019, title={The effect of the through-thickness yarn component on the in- and out-of-plane properties of composites from 3D orthogonal woven preforms}, volume={110}, ISSN={["1754-2340"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85047940577&partnerID=MN8TOARS}, DOI={10.1080/00405000.2018.1481722}, abstractNote={Abstract Development of three-dimensional (3D) weaving technology introduced new and enhanced features to the 2D weaving technology. 3D Orthogonal Woven (3DOW) preforms have a through-thickness yarn component that significantly enhances the out-of-plane properties and delamination resistance. In this study, a range of 3DOW E-glass preforms were woven using 3D weaving technology and then converted into composites, using vacuum assisted resin transfer molding technology. The composite samples had varying Z to Y-yarn/ layer ratio, the objective is to study the effect of changing the Z to Y-yarn/ layer ratio on the in-plane and out-of-plane mechanical properties. The study concludes that changing the amount of Z-yarn in the structure has negligible effect on the tensile (in-plane), yet, it has a significant effect on the drop weight impact properties (out-of-plane). Moreover, it had a strong effect on the failure mechanisms, and as the amount of Z-yarn is reduced, delamination became more significant.}, number={3}, journal={JOURNAL OF THE TEXTILE INSTITUTE}, author={Midani, Mohamad and Seyam, Abdel-Fattah and Saleh, Mohamed Nasr and Pankow, Mark}, year={2019}, month={Mar}, pages={317–327} }
 @article{midani_seyam_pankow_2018, title={A generalized analytical model for predicting the tensile behavior of 3D orthogonal woven composites using finite deformation approach}, volume={109}, ISSN={["1754-2340"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041129364&partnerID=MN8TOARS}, DOI={10.1080/00405000.2018.1425107}, abstractNote={Abstract Over the past few decades, there have been an increasing interest in woven preforms as a reinforcement for composites. The invention of 3D Orthogonal Weaving (3DOW) technology introduced new and enhanced features to the conventional 2D woven preforms. Modeling the tensile behavior of 3DOW composites is very useful to the industry, it helps in characterizing the composite material with minimal need for coupon testing. In this study, a generalized analytical model was developed to predict the entire load–extension curve of the 3DOW preforms and composites including the non-linear region, using the finite-deformation approach. The model relies on the geometry of the structure and the tensile properties of the constituent yarn and resin components as input parameters. The model was generalized to predict the properties of any 3DOW structure, made with spun or filament yarn, jammed and non-jammed, which have any weave architecture, including hybrid composites. The model was verified experimentally for a broad range of experimental composites, including hybrid ones. The results indicated that there was a general good agreement between the experimental and theoretical curves.}, number={11}, journal={JOURNAL OF THE TEXTILE INSTITUTE}, author={Midani, Mohamad and Seyam, Abdel-Fattah and Pankow, Mark}, year={2018}, month={Nov}, pages={1465–1476} }
 @article{justusson_waas_pankow_2018, title={Dynamic Characterization of Textile Composites Part I: Uniaxial Tension}, volume={4}, ISSN={2199-7446 2199-7454}, url={http://dx.doi.org/10.1007/S40870-018-0164-4}, DOI={10.1007/S40870-018-0164-4}, number={3}, journal={Journal of Dynamic Behavior of Materials}, publisher={Springer Science and Business Media LLC}, author={Justusson, B. and Waas, A. and Pankow, M.}, year={2018}, month={Aug}, pages={258–267} }
 @article{justusson_marek_waas_pankow_2018, title={Dynamic Characterization of Textile Composites Part II: Bi-axial Tension}, volume={4}, ISSN={2199-7446 2199-7454}, url={http://dx.doi.org/10.1007/S40870-018-0165-3}, DOI={10.1007/S40870-018-0165-3}, number={3}, journal={Journal of Dynamic Behavior of Materials}, publisher={Springer Science and Business Media LLC}, author={Justusson, Brain and Marek, Jaspar and Waas, Anthony and Pankow, Mark}, year={2018}, month={Aug}, pages={268–281} }
 @article{wu_pankow_huang_peters_2018, title={High-speed polarization imaging of dynamic collagen fiber realignment in tendon-to-bone insertion region}, volume={23}, ISSN={1083-3668}, url={http://dx.doi.org/10.1117/1.JBO.23.11.116002}, DOI={10.1117/1.JBO.23.11.116002}, abstractNote={Abstract. A high-speed polarization imaging instrument is demonstrated to be capable of measuring the collagen fiber alignment orientation and alignment strength during high-displacement rate dynamic loading at acquisition rates up to 10 kHz. The implementation of a high-speed rotating quarter wave plate and high-speed camera in the imaging system allows a minimum measurement acquisition time of 6 ms. Sliced tendon-to-bone insertion samples are loaded using a modified drop tower with an average maximum displacement rate of 1.25  m  /  s, and imaged using a high-speed polarization imaging instrument. The generated collagen fiber alignment angle and strength maps indicate the localized deformation and fiber realignment in tendon-to-bone samples during dynamic loading. The results demonstrate a viable experimental method to monitor collagen fiber realignment in biological tissue under high-displacement rate dynamic loading.}, number={11}, journal={Journal of Biomedical Optics}, publisher={SPIE-Intl Soc Optical Eng}, author={Wu, Xianyu and Pankow, Mark and Huang, Hsiao-Ying Shadow and Peters, Kara}, year={2018}, month={Nov}, pages={1} }
 @article{guo_hackney_pankow_peters_2017, title={A spectral profile multiplexed FBG sensor network with application to strain measurement in a Kevlar woven fabric}, volume={10168}, ISSN={["1996-756X"]}, DOI={10.1117/12.2260114}, abstractNote={A spectral profile division multiplexed fiber Bragg grating (FBG) sensor network is described in this paper. The unique spectral profile of each sensor in the network is identified as a distinct feature to be interrogated. Spectrum overlap is allowed under working conditions. Thus, a specific wavelength window does not need to be allocated to each sensor as in a wavelength division multiplexed (WDM) network. When the sensors are serially connected in the network, the spectrum output is expressed through a truncated series. To track the wavelength shift of each sensor, the identification problem is transformed to a nonlinear optimization problem, which is then solved by a modified dynamic multi-swarm particle swarm optimizer (DMS-PSO). To demonstrate the application of the developed network, a network consisting of four FBGs was integrated into a Kevlar woven fabric, which was under a quasi-static load imposed by an impactor head. Due to the substantial radial strain in the fabric, the spectrums of different FBGs were found to overlap during the loading process. With the developed interrogating method, the overlapped spectrum would be distinguished thus the wavelength shift of each sensor can be monitored.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2017}, author={Guo, Guodong and Hackney, Drew and Pankow, Mark and Peters, Kara}, year={2017} }
 @article{chandrasekaran_pankow_peters_huang_2017, title={Composition and structure of porcine digital flexor tendon-bone insertion tissues}, volume={105}, ISSN={1549-3296}, url={http://dx.doi.org/10.1002/jbm.a.36162}, DOI={10.1002/jbm.a.36162}, abstractNote={Abstract}, number={11}, journal={Journal of Biomedical Materials Research Part A}, publisher={Wiley}, author={Chandrasekaran, Sandhya and Pankow, Mark and Peters, Kara and Huang, Hsiao-Ying Shadow}, year={2017}, month={Aug}, pages={3050–3058} }
 @article{wu_huang_pankow_peters_2017, title={Dynamic Polarization Microscopy for In-Situ Measurements of Collagen Fiber Realignment During Impact}, ISBN={["978-3-319-41350-1"]}, ISSN={["2191-5652"]}, DOI={10.1007/978-3-319-41351-8_9}, abstractNote={The long term goal of this work is to better understand the tendon-to-bone insertion injury due to medium strain rate impact (e.g. sports activity). Specifically, we imaged collagen fiber realignment during impact, to investigate the ability of the tendon-to-bone insertion to these survive harsh dynamic events. A polarized light microscopy (PLM) setup was built in the lab and used to monitor the birefringence property changes of a known material under changing stress conditions. Initially polycarbonate dogbone specimens were tested quasi-statically to validate the setup and analysis algorithm. Polarized light retardation and alignment direction images are generated to quantitatively analyze the birefringence property change under different stress and compared to theoretical predictions. To perform dynamic experiments a drop weight tower was modified for medium strain rate testing (10–100 %/s) and the PLM setup is being incorporated for imaging. Several dynamic experiments have been conducted using this modified drop tower on porcine tendon specimens. A high-speed camera is used to record their dynamic response and deformation.}, journal={MECHANICS OF BIOLOGICAL SYSTEMS AND MATERIALS, VOL 6}, author={Wu, Xianyu and Huang, Hsiao-Ying Shadow and Pankow, Mark and Peters, Kara}, year={2017}, pages={61–66} }
 @article{joglekar_von hagel_pankow_ferguson_2017, title={Exploring how optimal composite design is influenced by model fidelity and multiple objectives}, volume={160}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2016.10.089}, abstractNote={This paper explores how optimal configuration of a composite panel is influenced by the choice of analysis model – analytic or computational – and the consideration of multiple objectives. While past research has explored aspects of this problem separately – composite ply orientation, multiple load scenarios, and multiple performance objectives – there has been limited work addressing the interactions between these factors. Three loading scenarios are considered in this work, and it is demonstrated that for certain scenarios an analytical model likely over-predicts composite performance. Further, for complex loading scenarios it is impossible to develop an analytical model. However, this work also demonstrates that the use of analytical models can be advantageous. Analytical models can provide similar estimates to computational models for some loading cases at significantly reduced computational expense. More importantly, it is also shown how solutions from the analytical model, which can be relatively cheap to find computationally, can be used to seed the initial designs of a Finite Element-based optimization. Run time reductions as large as 80% are demonstrated when these informed seeded designs are used, even when the designs were created for a different set of loading scenarios.}, journal={COMPOSITE STRUCTURES}, author={Joglekar, Shreyas and Von Hagel, Kayla and Pankow, Mark and Ferguson, Scott}, year={2017}, month={Jan}, pages={964–975} }
 @article{flores_mollenhauer_runatunga_beberniss_rapking_pankow_2017, title={High-speed 3D digital image correlation of low-velocity impacts on composite plates}, volume={131}, ISSN={["1879-1069"]}, DOI={10.1016/j.compositesb.2017.07.078}, journal={COMPOSITES PART B-ENGINEERING}, author={Flores, Mark and Mollenhauer, David and Runatunga, Vipul and Beberniss, Timothy and Rapking, Daniel and Pankow, Mark}, year={2017}, month={Dec}, pages={153–164} }
 @article{mcelroy_jackson_olsson_hellstrom_tsampas_pankow_2017, title={Interaction of delaminations and matrix cracks in a CFRP plate, Part I: A test method for model validation}, volume={103}, ISSN={["1878-5840"]}, DOI={10.1016/j.compositesa.2017.09.011}, abstractNote={Isolating and observing the damage mechanisms associated with low-velocity impact in composites using traditional experiments can be challenging, due to damage process complexity and high strain rates. In this work, a new test method is presented that provides a means to study, in detail, the interaction of common impact damage mechanisms, namely delamination, matrix cracking, and delamination-migration, in a context less challenging than a real impact event. Carbon fiber reinforced polymer specimens containing a thin insert in one region were loaded in a biaxial-bending state of deformation. As a result, three-dimensional damage processes, involving delaminations at no more than three different interfaces that interact with one another via transverse matrix cracks, were observed and documented using ultrasonic testing and X-ray computed tomography. The data generated by the test is intended for use in numerical model validation. Simulations of this test are included in Part II of this paper.}, journal={COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING}, author={McElroy, Mark and Jackson, Wade and Olsson, Robin and Hellstrom, Peter and Tsampas, Spyros and Pankow, Mark}, year={2017}, month={Dec}, pages={314–326} }
 @article{mcelroy_gutkin_pankow_2017, title={Interaction of delaminations and matrix cracks in a CFRP plate, Part II: Simulation using an enriched shell finite element model}, volume={103}, ISSN={["1878-5840"]}, DOI={10.1016/j.compositesa.2017.10.006}, abstractNote={Numerical simulations are presented of a recently developed test which creates multiple delaminations in a CFRP laminate specimen that grow and interact via transverse matrix cracks [1]. A novel shell element enriched with the Floating Node Method, and a damage algorithm based on the Virtual Crack Closure Technique, were used to successfully simulate the tests. Additionally, a 3D high mesh fidelity model based on cohesive zones and continuum damage mechanics was used to simulate the tests and act as a representative of other similar state-of-the-art high mesh fidelity modeling techniques to compare to the enriched shell element. The enriched shell and high mesh fidelity models had similar levels of accuracy and generally matched the experimental data. With runtimes of 36 min for the shell model and 55 h for the high mesh fidelity model, the shell model is 92 times faster than the high-fidelity simulation.}, journal={COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING}, author={McElroy, Mark W. and Gutkin, Renaud and Pankow, Mark}, year={2017}, month={Dec}, pages={252–262} }
 @article{guo_hackney_pankow_peters_2017, title={Interrogation of a spectral profile division multiplexed FBG sensor network using a modified particle swarm optimization method}, volume={28}, ISSN={["1361-6501"]}, DOI={10.1088/1361-6501/aa637f}, abstractNote={This paper applies the concept of spectral profile division multiplexing to track each Bragg wavelength shift in a serially multiplexed fiber Bragg grating (FBG) network. Each sensor in the network is uniquely characterized by its own reflected spectrum shape, thus spectral overlapping is allowed in the wavelength domain. In contrast to the previous literature, spectral distortion caused by multiple reflections and spectral shadowing between FBG sensors, that occur in serial topology sensor networks, are considered in the identification algorithm. To detect the Bragg wavelength shift of each FBG, a nonlinear optimization function based on the output spectrum is constructed and a modified dynamic multi-swarm particle swarm optimizer is employed. The multiplexing approach is experimentally demonstrated on data from multiplexed sensor networks with up to four sensors. The wavelength prediction results show that the method can efficiently interrogate the multiplexed network in these overlapped situations. Specifically, the maximum error in a fully overlapped situation in the specific four sensor network demonstrated here was only 110 pm. A more general analysis of the prediction error and guidelines to optimize the sensor network are the subject of future work.}, number={5}, journal={MEASUREMENT SCIENCE AND TECHNOLOGY}, author={Guo, Guodong and Hackney, Drew and Pankow, Mark and Peters, Kara}, year={2017}, month={May} }
 @article{joglekar_pankow_2017, title={Modeling of 3D woven composites using the digital element approach for accurate prediction of kinking under compressive loads}, volume={160}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2016.10.070}, abstractNote={Model definition accuracy dictates the reliability of a predictive analysis for 3D woven composites (3DWC). The traditional modeling approach is based on analysis of ideal geometry with user specified imperfections. In that case, co-relating the actual imperfections arising from manufacturing processes with that of the model becomes an iterative process. In this study, a digital element (DE) approach is implemented for creating the woven architecture of the composite. This technique simulates the individual fibers and their interactions allowing the user to create a reference unit cell with imperfect geometry induced during manufacturing stages of 3DWCs. Thus the response and strength analysis account for the unique weaving signature and provide better predictions without the necessity to run iterative analysis procedures required for idealized geometry models. X-ray CT images or detailed statistical data for variations in specimen geometry are not required which makes this approach more attractive in terms of cost and creation time. A representative model created using the DE approach is used for prediction of compressive failure of 3DWC without having to seed imperfections for failure initiation. The analysis also captures the formation of a kink band as observed in experimental tests. Results of this study are compared with the experimental results and simulation results of idealized geometry reported previously in literature.}, journal={COMPOSITE STRUCTURES}, author={Joglekar, Shreyas and Pankow, Mark}, year={2017}, month={Jan}, pages={547–559} }
 @inbook{mcwilliams_yu_pankow_2016, title={Dynamic Failure Mechanisms in Woven Ceramic Fabric Reinforced Metal Matrix Composites During Ballistic Impact}, ISBN={9783319217642 9783319217659}, ISSN={2191-5644 2191-5652}, url={http://dx.doi.org/10.1007/978-3-319-21765-9_20}, DOI={10.1007/978-3-319-21765-9_20}, abstractNote={The complex interaction of dynamic stress waves during ballistic impact provides the opportunity to simultaneously observe the high strain rate loading response under various triaxialities including tension, compression, and shear. In this work the dynamic failure mechanisms of woven ceramic fabric reinforced aluminum metal matrix composites (MMC) during ballistic impact are experimentally investigated. In addition to experimental characterization, an orthotropic elastic-plastic constitutive model with hydrostatic pressure dependent yield is implemented in an explicit finite element code to quantify the stress states present during the progressive damage and failure of the MMC during the penetration and perforation process.}, booktitle={Residual Stress, Thermomechanics & Infrared Imaging, Hybrid Techniques and Inverse Problems, Volume 9}, publisher={Springer International Publishing}, author={McWilliams, Brandon A. and Yu, Jian H. and Pankow, Mark}, year={2016}, pages={155–159} }
 @inproceedings{mcwilliams_yu_pankow_2016, title={Dynamic failure mechanisms in woven ceramic fabric reinforced metal matrix composites during ballistic impact}, booktitle={Residual stress, thermomechanics & infrared imaging, hybrid techniques and inverse problems, vol 9}, author={McWilliams, B. A. and Yu, J. H. and Pankow, M.}, year={2016}, pages={155–159} }
 @article{anderson_lacosse_pankow_2016, title={Point of impact: the effect of size and speed on puncture mechanics}, volume={6}, ISSN={["2042-8901"]}, DOI={10.1098/rsfs.2015.0111}, abstractNote={The use of high-speed puncture mechanics for prey capture has been documented across a wide range of organisms, including vertebrates, arthropods, molluscs and cnidarians. These examples span four phyla and seven orders of magnitude difference in size. The commonality of these puncture systems offers an opportunity to explore how organisms at different scales and with different materials, morphologies and kinematics perform the same basic function. However, there is currently no framework for combining kinematic performance with cutting mechanics in biological puncture systems. Our aim here is to establish this framework by examining the effects of size and velocity in a series of controlled ballistic puncture experiments. Arrows of identical shape but varying in mass and speed were shot into cubes of ballistic gelatine. Results from high-speed videography show that projectile velocity can alter how the target gel responds to cutting. Mixed models comparing kinematic variables and puncture patterns indicate that the kinetic energy of a projectile is a better predictor of penetration than either momentum or velocity. These results form a foundation for studying the effects of impact on biological puncture, opening the door for future work to explore the influence of morphology and material organization on high-speed cutting dynamics.}, number={3}, journal={INTERFACE FOCUS}, author={Anderson, P. S. L. and LaCosse, J. and Pankow, M.}, year={2016}, month={Jun} }
 @inbook{pankow_mcwilliams_2016, title={Simulation of High Rate Failure Mechanisms in Composites During Quasi-static Testing}, ISBN={9783319217611 9783319217628}, ISSN={2191-5644 2191-5652}, url={http://dx.doi.org/10.1007/978-3-319-21762-8_52}, DOI={10.1007/978-3-319-21762-8_52}, abstractNote={High Rate testing is often difficult to perform, requires specialized equipment and often had results that are difficult to interpret. Being able to simulate the same failure mechanisms at high rates would enable rapid material selection. In this experimental investigation, the mechanical response is determined of different hybrid composites materials. A modified through-the-thickness tests has been used to force a high order of failure mode that is similar to those seen in high speed impact. Failure is observed in the samples and stresses on the surface are determine to help with failure envelope measurements. The details of a comparison between 2D fabrics vs. 3D woven fabrics has been under taken and a comparison will be presented showing the similarities and differences in response. A discussion of the comparison between the high rate testing and the low-rate testing will be investigated and discussion on the applications of the testing will be examined for failure envelope prediction.}, booktitle={Conference Proceedings of the Society for Experimental Mechanics Series}, publisher={Springer International Publishing}, author={Pankow, Mark and McWilliams, Brandon A.}, year={2016}, pages={445–450} }
 @inproceedings{pankow_mcwilliams_2016, title={Simulation of high rate failure mechanisms in composites during quasi-static testing}, booktitle={Mechanics of composite and multifunctional materials, vol 7}, author={Pankow, M. and McWilliams, B. A.}, year={2016}, pages={445–450} }
 @article{seng_hackney_goode_shumway_hammond_shoemaker_pankow_peters_schultz_2016, title={Split Hopkinson bar measurement using high-speed full-spectrum fiber Bragg grating interrogation}, volume={55}, ISSN={["2155-3165"]}, DOI={10.1364/ao.55.007179}, abstractNote={The development and validation of a high-speed, full-spectrum measurement technique is described for fiber Bragg grating (FBG) sensors. A FBG is surface-mounted to a split-Hopkinson tensile bar specimen to induce high strain rates. The high strain gradients and large strains that indicate material failure are analyzed under high strain rates up to 500  s-1. The FBG is interrogated using a high-speed full-spectrum solid-state interrogator with a repetition rate of 100 kHz. The captured deformed spectra are analyzed for strain gradients using a default interior point algorithm in combination with the modified transfer matrix approach. This paper shows that by using high-speed full-spectrum interrogation of an FBG and the modified transfer matrix method, highly localized strain gradients and discontinuities can be measured without a direct line of sight.}, number={25}, journal={APPLIED OPTICS}, author={Seng, Frederick and Hackney, Drew and Goode, Tyler and Shumway, LeGrand and Hammond, Alec and Shoemaker, George and Pankow, Mark and Peters, Kara and Schultz, Stephen}, year={2016}, month={Sep}, pages={7179–7185} }
 @article{mcwilliams_yu_pankow_yen_2015, title={Ballistic impact behavior of woven ceramic fabric reinforced metal matrix composites}, volume={86}, ISSN={["1879-3509"]}, DOI={10.1016/j.ijimpeng.2015.07.005}, abstractNote={In this paper, the effect of weave architecture on the ballistic impact response of woven fabric metal matrix composites (MMC) is investigated. The ballistic limits, V50BL, of four different composites are experimentally determined and post impact characterization is used to investigate the damage mechanisms active during dynamic loading. Numerical modeling implementing an elastic–plastic orthotropic material model with hydrostatic pressure dependent yield surface is used to model the pressure dependent response of the MMC during impact to predict the ballistic limit, and to offer insight into the damage mechanisms occurring during dynamic loading of woven fabric reinforced MMC. The correlation between laterally constrained compression testing and ballistic performance is investigated for use as a screening tool to enable rapid evaluation of the relative ballistic performance of potential fabric MMC weave and composite designs as a potential alternative to full scale ballistic testing. It was found that the fabric architecture has significant effect on ballistic performance and through thickness shear strength of the MMCs. It was found that 3D woven MMC is 13% and 40% lower in terms of ballistic limit and through thickness shear strength respectively, than its 2D counterpart. Furthermore, the numerical results successfully predict the ballistic limit of a 2D fabric reinforced MMC within 6% of the experiment and are used to qualitatively elucidate the experimentally observed damage mechanisms.}, journal={INTERNATIONAL JOURNAL OF IMPACT ENGINEERING}, author={McWilliams, B. and Yu, J. and Pankow, M. and Yen, C. -F.}, year={2015}, month={Dec}, pages={57–66} }
 @inproceedings{ranatunga_joglekar_pankow_clay_2015, title={Characterization of delamination in translaminar reinforced composites due to low velocity impact}, booktitle={Proceedings of the American Society for Composites: Thirtieth Technical Conference}, author={Ranatunga, V. and Joglekar, S. and Pankow, M. and Clay, S.}, year={2015}, pages={381–392} }
 @inproceedings{flores_mollenhauer_runatunga_berbeniss_rapking_pankow_2015, title={High-speed 3D digital image correlation of low-velocity impacts on composite plates}, booktitle={Proceedings of the American Society for Composites: Thirtieth Technical Conference}, author={Flores, M. D. and Mollenhauer, D. and Runatunga, V. and Berbeniss, T. and Rapking, D. and Pankow, M.}, year={2015}, pages={2120–2135} }
 @inproceedings{joglekar_pankow_2015, title={Modeling of 3D woven composites with realistic geometry for accurate prediction of kinking under compressive loads}, booktitle={Proceedings of the American Society for Composites: Thirtieth Technical Conference}, author={Joglekar, S. and Pankow, M.}, year={2015}, pages={593–612} }
 @inproceedings{pochiraju_iarve_haque_pankow_2015, title={Student simulation challenge: A competition-based composites education opportunity}, booktitle={Proceedings of the American Society for Composites: Thirtieth Technical Conference}, author={Pochiraju, K. and Iarve, E. and Haque, B. and Pankow, M.}, year={2015}, pages={1160–1170} }
 @inproceedings{von hagel_joglekar_ferguson_pankow_2015, title={Top down design using Bayesian network classifiers for composite panels}, booktitle={Proceedings of the American Society for Composites: Thirtieth Technical Conference}, author={Von Hagel, K. and Joglekar, S. and Ferguson, S. and Pankow, M.}, year={2015}, pages={468–475} }
 @article{pankow_quabili_yen_2014, title={Hybrid Three-Dimensional (3-D) Woven Thick Composite Architectures in Bending}, volume={66}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-013-0825-7}, number={2}, journal={JOM}, author={Pankow, Mark and Quabili, Ashiq and Yen, Chian-Fong}, year={2014}, month={Feb}, pages={255–260} }
 @inproceedings{pankow_yen_waas_2013, title={Comparison of 2D and 3D composites to confined crush loading}, booktitle={Proceedings of the American Society for Composites}, author={Pankow, M. and Yen, C. F. and Waas, A. M.}, year={2013} }
 @article{justusson_pankow_heinrich_rudolph_waas_2013, title={Use of a shock tube to determine the bi-axial yield of an aluminum alloy under high rates}, volume={58}, ISSN={0734-743X}, url={http://dx.doi.org/10.1016/J.IJIMPENG.2013.01.012}, DOI={10.1016/J.IJIMPENG.2013.01.012}, abstractNote={This paper presents a method for extracting the bi-axial rate dependent mechanical properties of thin homogenous materials, using a shock tube, demonstrated here using an aluminum alloy sheet. Rate dependence determination techniques such as Split Hopkinson Pressure Bar (SHPB) have long been used for determining uniaxial properties. Recent advances have led to modification of the SHPB to include a bulge cell to develop a so called “dynamic bulge test”. Due to the relative fixed nature of the SHPB, it is difficult to obtain lower strain rate response without significantly modifying the test fixture. Using shock wave loading, and a flat, circular thin plate specimen, a state of biaxial tensile stress is created at the center of the crown during intermediate to high rates of loading. An inverse modeling technique in conjunction with a finite element (FE) simulation technique is used to determine the rate dependent constitutive properties of the plate material. This work demonstrates the applicability of the shock loading method for extracting rate dependent properties of materials available in thin sheet form by using commercial grade aluminum. A finite element model of the shock response is used to determine the strain rate dependent mechanical properties using an optimization algorithm and an inverse modeling method. The results were found to be in agreement with previous literature and good correlation between the model and experimental results are presented here.}, journal={International Journal of Impact Engineering}, publisher={Elsevier BV}, author={Justusson, B. and Pankow, M. and Heinrich, C. and Rudolph, M. and Waas, A.M.}, year={2013}, month={Aug}, pages={55–65} }
 @article{pankow_waas_yen_ghiorse_2012, title={Modeling the response, strength and degradation of 3D woven composites subjected to high rate loading}, volume={94}, ISSN={0263-8223}, url={http://dx.doi.org/10.1016/j.compstruct.2011.12.010}, DOI={10.1016/j.compstruct.2011.12.010}, abstractNote={Experimental results which were obtained using a split Hopkinson pressure bar (SHPB) apparatus to determine rate dependent effects, and reported by the authors in [1] are used as the basis to perform dynamic simulations of 3D woven composites (3DWCs) using representative unit cells (RUCs). The input material properties for the RUC simulations were determined from the concentric cylinder model (CCM) in conjunction with the geometry of the textile architecture, mechanical properties of pure epoxy samples and fiber mechanical properties. The RUC model incorporates rate dependent plasticity. Additionally, linear-eigen perturbations that correspond to buckling modes are used to seed imperfections in the RUC model to capture buckling and subsequent failure that was observed in experiments. The RUC model results showed good agreement with experiment and correctly captured the observed modes of failure while pointing to transitions in failure modes.}, number={5}, journal={Composite Structures}, publisher={Elsevier BV}, author={Pankow, M. and Waas, A.M. and Yen, C.F. and Ghiorse, S.}, year={2012}, month={Apr}, pages={1590–1604} }
 @article{pankow_waas_yen_ghiorse_2011, title={Resistance to delamination of 3D woven textile composites evaluated using End Notch Flexure (ENF) tests: Cohesive zone based computational results}, volume={42}, ISSN={1359-835X}, url={http://dx.doi.org/10.1016/j.compositesa.2011.07.028}, DOI={10.1016/j.compositesa.2011.07.028}, abstractNote={The flexural response of 3D woven textile composite panels containing an edge crack is evaluated using the End Notch Flexure (ENF) test. In doing so, the effectiveness of 3D reinforcement in increasing and/or eliminating delamination is demonstrated. A finite element model of the ENF configuration using the Discrete Cohesive Zone Model (DCZM) was used to evaluate the deformation response and fracture properties corresponding to the experimental results presented in Pankow et al. (2011) [1]. A modified trapezoidal traction law was used in the DCZM to computationally evaluate the ENF test results. Good agreement between experimental results and predictions are reported, up to the point at which the crack reaches under the loading roller and damage begins to occur locally under the roller.}, number={12}, journal={Composites Part A: Applied Science and Manufacturing}, publisher={Elsevier BV}, author={Pankow, M. and Waas, A.M. and Yen, C.F. and Ghiorse, S.}, year={2011}, month={Dec}, pages={1863–1872} }
 @article{pankow_salvi_waas_yen_ghiorse_2011, title={Resistance to delamination of 3D woven textile composites evaluated using End Notch Flexure (ENF) tests: Experimental results}, volume={42}, ISSN={1359-835X}, url={http://dx.doi.org/10.1016/j.compositesa.2011.06.013}, DOI={10.1016/j.compositesa.2011.06.013}, abstractNote={The flexural response of 3D woven textile composite panels containing an edge crack is evaluated using the End Notch Flexure (ENF) test. In doing so, the effectiveness of 3D reinforcement in increasing and/or eliminating delamination is demonstrated. Two types of textile architectures, referred to as Z-fiber reinforcement and a layer-to-layer architecture were examined. At quasi-static and low rate; 0.01 mm/Section (0.0004 in/s) and 50.8 mm/Section (2 in/s), results showed that the Z-fiber reinforcement provided a higher strength, although the layer-to-layer reinforcement provided more energy absorption and prevented mode II crack propagation, thus providing insight into eliminating the delamination mode of failure. At higher loading rates, using an instrumented drop tower at impactor velocities of 2.79 m/Section (110 in/s) and 3.96 m/Section (156 in/s), results suggested a rate dependent mode II strength of the material. Computational models to further explore the experimental results are presented in a follow-on paper in this issue of the journal [1].}, number={10}, journal={Composites Part A: Applied Science and Manufacturing}, publisher={Elsevier BV}, author={Pankow, M. and Salvi, A. and Waas, A.M. and Yen, C.F. and Ghiorse, S.}, year={2011}, month={Oct}, pages={1463–1476} }
 @article{pankow_waas_yen_ghiorse_2011, title={Shock loading of 3D woven composites: A validated finite element investigation}, volume={93}, ISSN={0263-8223}, url={http://dx.doi.org/10.1016/j.compstruct.2010.11.001}, DOI={10.1016/j.compstruct.2010.11.001}, abstractNote={In a companion paper in this issue (Pankow et al., 2010 [1]), experimental results for the deformation response of 3D glass fiber textile composites subjected to shock wave pulse pressure loading were presented. In this paper, finite element models are developed to simulate the deformation response and damage development observed in the experiments. Two levels of models are presented, with the first focused on a layered, homogenous orthotropic model that examined the bulk macroscopic deformation response. In the second model, each layer is represented to capture the interactions between fiber tows and matrix, taking into account the discrete non-homogeneous material distribution in each layer. Both models incorporated a user defined subroutine within the commercial software ABAQUS to capture matrix micro-cracking, which is responsible for damage development and growth. Results from the computational models correlated well with experimental results and observed locations of matrix micro-cracking.}, number={5}, journal={Composite Structures}, publisher={Elsevier BV}, author={Pankow, M. and Waas, A.M. and Yen, Chian-Fong and Ghiorse, Seth}, year={2011}, month={Apr}, pages={1347–1362} }
 @article{pankow_justusson_salvi_waas_yen_ghiorse_2011, title={Shock response of 3D woven composites: An experimental investigation}, volume={93}, ISSN={0263-8223}, url={http://dx.doi.org/10.1016/j.compstruct.2010.10.021}, DOI={10.1016/j.compstruct.2010.10.021}, abstractNote={A modified shock tube was used to determine the effect of shock wave loading on 3D woven composite panels. The shock wave, which produces a short duration steeply rising pressure pulse when impacting the panel, was used to load the panels. The out of plane deformation response was measured using a full field Digital Image Correlation (DIC) technique. The results allow for measurements of full field displacements and strains in the samples. Three distinct textile composite architectures, corresponding to different amounts of Z-fiber (fiber tows that bind the different textile layers together) were investigated. Two separate shock intensities were used. Matrix micro-cracking was observed to be the mechanism by which failure is initiated, and this micro-cracking was found to occur closest to the center of the panel where the outer-surface straining is highest. Fiber tow failure was absent in the shock strengths studied in the present work. The results suggest that the 6% Z-fiber architecture provided the largest panel stiffness and the least amount of damage. This result suggests that this may be the optimal architecture and density for orthogonally woven Z-fiber reinforced composites, however due to the complex nature of the problem the same architecture with a different tow (and fiber) volume fraction may yield different results.}, number={5}, journal={Composite Structures}, publisher={Elsevier BV}, author={Pankow, M. and Justusson, B. and Salvi, A. and Waas, A.M. and Yen, Chian-Fong and Ghiorse, Seth}, year={2011}, month={Apr}, pages={1337–1346} }
 @article{pankow_salvi_waas_yen_ghiorse_2011, title={Split Hopkinson pressure bar testing of 3D woven composites}, volume={71}, ISSN={0266-3538}, url={http://dx.doi.org/10.1016/j.compscitech.2011.03.017}, DOI={10.1016/j.compscitech.2011.03.017}, abstractNote={Results from a series of split Hopkinson pressure bar (SHPB) tests on 3D woven tetxile composites (3DWC) are presented. These tests were done to determine the rate dependent compression response of 3DWC. Three different configurations of the 3DWC, corresponding to compression response in the plane of the material and through-the-thickness direction (out-of-plane) were studied. The rate dependent responses were compared against quasi-static test results and it was found that 3DWC showed an increase in strength in all three directions studied, however, accompanied by a transition in the failure mechanism. The in-plane orientations showed the largest increase in (about 100%) strength at the elevated rates of loading. A follow-on paper provides finite element based results that correspond to the experimental results presented here.}, number={9}, journal={Composites Science and Technology}, publisher={Elsevier BV}, author={Pankow, M. and Salvi, A. and Waas, A.M. and Yen, C.F. and Ghiorse, S.}, year={2011}, month={Jun}, pages={1196–1208} }
 @article{pankow_waas_yen_ghiorse_2009, title={A new lamination theory for layered textile composites that account for manufacturing induced effects}, volume={40}, ISSN={1359-835X}, url={http://dx.doi.org/10.1016/j.compositesa.2009.08.021}, DOI={10.1016/j.compositesa.2009.08.021}, abstractNote={This paper is concerned with the development of a new lamination theory for layered textile composites that can account for manufacturing induced effects. The theory can be used for the calculation of the effective linear elastic extensional and bending stiffnesses of laminated textile composite panels. A representative unit cell (RUC) of the textile architecture is first identified along with its constituents. Tow geometry is represented analytically taking account of tow undulation. Each tow is modeled as a transversely isotropic linear elastic solid and the contribution from each tow to the RUC elastic bending stiffness is obtained by volume averaging, taking account of the volume fraction of each constituent. The formulation is amenable to the incorporation of geometric changes to the textile architecture that occurs through manufacturing induced consolidation. Predictions of the elastic bending stiffness are compared against experimental data, showing a strong correlation between the analytical model and the experimental results.}, number={12}, journal={Composites Part A: Applied Science and Manufacturing}, publisher={Elsevier BV}, author={Pankow, Mark and Waas, Anthony M. and Yen, Chian-Fong and Ghiorse, Seth}, year={2009}, month={Dec}, pages={1991–2003} }