@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{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{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{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{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} }