@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{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{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{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} }
 @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{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{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} }