@article{ziaei_wu_fitch_elbadry_zikry_2019, title={Channel Cracking and Interfacial Delamination of Indium Tin Oxide (ITO) Nano-Sized Films on Polyethylene Terephthalate (PET) Substrates: Experiments and Modeling}, volume={59}, ISSN={["1741-2765"]}, url={http://dx.doi.org/10.1007/s11340-019-00534-y}, DOI={10.1007/s11340-019-00534-y}, abstractNote={Our research objective was to obtain a fundamental understanding of how ITO thin films layered on flexible polyethylene terephthalate (PET) substrates fail due to tensile, shear, and bending loading conditions. In our approach, we employed a nonlinear finite-element (FE) approach coupled with dislocation-density crystalline and hypoelastic material models and fracture approaches tailored for channel (film) cracking and interfacial delamination. These predictions were validated with mechanical experiments and characterization at different physical scales. Failure to strain and fracture predictions were used to account for interrelated mechanisms, such as channel and interfacial cracking nucleation and propagation along cleavage planes, interfaces, and within layers. Our predictions indicate that interfacial delamination occurred when channel cracks transitioned to interfacial cracks at the ITO/PET interface for tensile loading conditions. Furthermore, the thin film system, when subjected to three-point bending and shear loading conditions was more resistant to failure in comparison to systems subjected to tensile loading conditions.}, number={5}, journal={EXPERIMENTAL MECHANICS}, publisher={Springer Science and Business Media LLC}, author={Ziaei, S. and Wu, Q. and Fitch, J. and Elbadry, M. and Zikry, M. A.}, year={2019}, month={Jun}, pages={703–712} }
 @article{khanikar_wu_zikry_2016, title={Dynamic Fracture of Aluminum-Bonded Composites}, volume={138}, ISSN={["1528-8889"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84971467668&partnerID=MN8TOARS}, DOI={10.1115/1.4033036}, abstractNote={A dislocation density-based crystal plasticity framework, a nonlinear computational finite-element methodology adapted for nucleation of crack on cleavage planes, and rational crystallographic orientation relations were used to predict the failure modes associated with the high strain rate behavior of aluminum-bonded composites. A bonded aluminum composite, suitable for high strain-rate damage resistance application, was modeled with different microstructures representing precipitates, dispersed particles, and grain boundary (GB) distributions. The dynamic fracture approach is used to investigate crack nucleation and growth as a function of the different microstructural characteristics of each alloy in bonded composites with and without pre-existing cracks. The nonplanar and irregular nature of the crack paths were mainly due to the microstructural features, such as precipitates and dispersed particles distributions and orientations, ahead of the crack front. The evolution of dislocation density and the subsequent formation of localized plastic slip contributed to the blunting of the propagating crack(s). Extensive geometrical and thermal softening resulted in localized plastic slip and had a significant effect on crack path orientations and directions along cleavage planes.}, number={3}, journal={JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME}, author={Khanikar, Prasenjit and Wu, Qifeng and Zikry, M. A.}, year={2016}, month={Jul} }
 @article{wu_zikry_2016, title={Microstructural modeling of transgranular and intergranular fracture in crystalline materials with coincident site lattice grain-boundaries: Sigma 3 and Sigma 17b bicrystals}, volume={661}, ISSN={["1873-4936"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84960079801&partnerID=MN8TOARS}, DOI={10.1016/j.msea.2016.02.039}, abstractNote={The competing microstructural failure mechanisms of transgranular (TG) and intergranular (IG) fracture, in martensitic steel bicrystals with coincident site lattice (CSL) boundaries of Σ3 and Σ17b, have been investigated, using a dislocation-density-based crystalline plasticity formulation and a recently developed overlapping fracture method. A dislocation-density grain boundary (GB) interaction scheme was coupled within a dislocation-density based crystal plasticity formulation to investigate how different types of CSL GBs affect dislocation-density evolution, plastic deformation, dislocation pile-up formation, TG and IG fracture, and fracture toughness. The computational predictions indicate that the bicrystal, with a Σ3 boundary, transitioned from IG to TG fracture, with large dislocation density generation and plastic deformation on the TG fracture planes. Bicrystals with the Σ17b boundary failed due to intergranular fracture and rupture, with much lower, in comparison with the Σ3 boundary case, dislocation density generation and plastic deformation. These predictions, which are consistent with experimental observations, indicate that Σ3 boundary is resistant to IG fracture with a higher fracture toughness than the Σ17b boundary case. More significantly, the computational framework can potentially be used as a guideline for GB engineering for failure-resistant materials.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Wu, Q. and Zikry, M. A.}, year={2016}, month={Apr}, pages={32–39} }
 @article{wu_zikry_2015, title={Dynamic fracture predictions of microstructural mechanisms and characteristics in martensitic steels}, volume={145}, ISSN={["1873-7315"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937031196&partnerID=MN8TOARS}, DOI={10.1016/j.engfracmech.2015.06.002}, abstractNote={A dislocation-density-based multiple-slip crystalline plasticity formulation, and an overlapping fracture method were used to investigate the effects of carbide precipitates, M23C6, and martensitic block size on dynamic fracture in martensitic steels. The interrelated effects of dislocation-density evolution, orientation relations (ORs), adiabatic heating, and heat conduction on fracture behavior were investigated. Precipitates interfaces are shown to be the sites of crack nucleation due to dislocation-density impedance. Dislocation-densities are also shown to relieve tensile stresses and blunt crack propagation. These predictions indicate that the size refinement of martensitic blocks increases crack deflection at block/packet boundaries, which can significantly improve fracture toughness.}, journal={ENGINEERING FRACTURE MECHANICS}, author={Wu, Q. and Zikry, M. A.}, year={2015}, month={Aug}, pages={54–66} }
 @article{ziaei_wu_zikry_2015, title={Orientation relationships between coherent interfaces in hcp-fcc systems subjected to high strain-rate deformation and fracture modes}, volume={30}, ISSN={["2044-5326"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84939515483&partnerID=MN8TOARS}, DOI={10.1557/jmr.2015.207}, abstractNote={Abstract}, number={15}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Ziaei, Shoayb and Wu, Qifeng and Zikry, Mohammed A.}, year={2015}, month={Aug}, pages={2348–2359} }
 @article{wu_zikry_2015, title={Prediction of diffusion assisted hydrogen embrittlement failure in high strength martensitic steels}, volume={85}, ISSN={["1873-4782"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84943403130&partnerID=MN8TOARS}, DOI={10.1016/j.jmps.2015.08.010}, abstractNote={A stress assisted hydrogen diffusion transport model, a dislocation-density-based multiple-slip crystalline plasticity formulation, and an overlapping fracture method were used to investigate hydrogen diffusion and embrittlement in lath martensitic steels with distributions of M23C6 carbide precipitates. The formulation accounts for variant morphologies based on orientation relationships (ORs) that are uniquely inherent to lath martensitic microstructures. The interrelated effects of martensitic block and packet boundaries and carbide precipitates on hydrogen diffusion, hydrogen assisted crack nucleation and growth, are analyzed to characterize the competition between cleavage fracture and hydrogen diffusion assisted fracture along preferential microstructural fracture planes. Stresses along the three cleavage planes and the six hydrogen embrittlement fracture planes are monitored, such that crack nucleation and growth can nucleate along energetically favorable planes. High pressure gradients result in the accumulation of hydrogen, which embrittles martensite, and results in crack nucleation and growth along {110} planes. Cleavage fracture occurs along {100} planes when there is no significant hydrogen diffusion. The predictions indicate that hydrogen diffusion can suppress the emission and accumulation of dislocation density, and lead to fracture with low plastic strains.}, journal={JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS}, author={Wu, Q. and Zikry, M. A.}, year={2015}, month={Dec}, pages={143–159} }
 @article{wu_zikry_2014, title={Microstructural modeling of crack nucleation and propagation in high strength martensitic steels}, volume={51}, ISSN={["1879-2146"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84923217972&partnerID=MN8TOARS}, DOI={10.1016/j.ijsolstr.2014.08.021}, abstractNote={A dislocation-density based multiple-slip crystalline plasticity formulation, a dislocation-density grain boundary (GB) interaction scheme, and an overlapping fracture method were used to investigate crack nucleation and propagation in martensitic steel with retained austenite for both quasi-static and dynamic loading conditions. The formulation accounts for variant morphologies, orientation relationships, and retained austenite that are uniquely inherent to lath martensitic microstructures. The interrelated effects of dislocation-density evolution ahead of crack front and the variant distribution of martensitic blocks on crack nucleation and propagation are investigated. It is shown that dislocation-density generation ahead of crack front can induce dislocation-density accumulations and plastic deformation that can blunt crack propagation. These predictions indicate that variant distribution of martensitic blocks can be optimized to mitigate and potentially inhibit material failure.}, number={25-26}, journal={INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, author={Wu, Q. and Zikry, M. A.}, year={2014}, month={Dec}, pages={4345–4356} }