Damage evolution in aluminum alloys and composites under dynamic/shock loading

铝合金和铝基复合材料由于其高强度重量比，在国防、汽车和航空航天工业中得到了非常有用的应用。为了提高军事作战车辆的效率，铝合金作为装甲板的使用在军队中不断受到越来越多的关注。适当评估装甲板在极端载荷条件下的表现，如在弹道冲击或暴露于简易爆炸装置（IED）下的表现，正如加拿大武装部队目前所目睹的那样，是确保维持和平行动中军事人员安全的关键因素。飞机的铝合金框架还必须能够承受冲击载荷的威胁，例如在飞行过程中受到外来物体的冲击。与其他金属合金的情况一样，铝合金在冲击或冲击载荷下的破坏是由沿称为绝热剪切带的窄带的极端局部化变形引起的。高性能铝合金中绝热剪切带的出现降低了其在高速冲击中抗穿孔或开裂的能力。本研究项目系统研究了铝合金在冲击载荷作用下的损伤演化与绝热剪切带出现的关系，主要受合金成分、回火和加载条件以及陶瓷颗粒增强等因素的影响。优化微结构设计以增强在冲击载荷下承受绝热剪切破坏的能力是本研究的目的。将产生动态应力-应变数据，用于开发材料冲击响应的微结构敏感数值模拟。开发适用于铝合金和复合材料渐进损伤分析的增强本构模型，考虑材料的非线性和应变率效应，这些都与冲击载荷有关，是本研究项目的长期目标。这种方法将为如何调整铝合金的性能以改善其动态冲击性能提供信息。

Aluminum alloys and aluminum-based composites are finding very useful applications in the defense, automobile and aerospace industries as a result of their high strength-to-weight ratio. The use of aluminum alloys as armor plates has continued to attract increased attention in the military in order to improve the efficiency of military combat vehicles. A proper evaluation of how armor plates behave under extreme loading condition as in ballistic impact or exposure to improvised explosive devices (IED), as currently being witnessed by Canadian Armed forces, is a key factor to ensuring the safety of military personnel in peace keeping operations. The aluminum alloy frames of aircrafts must also be able to withstand the threat of exposure to shock loading as exemplified by impact from extraneous object during flight. As in the case of the other metallic alloys, failure of aluminum alloys under shock or impact loading is initiated by extreme localization of deformation along narrow bands called adiabatic shear bands. Occurrence of adiabatic shear bands in high performance aluminum alloys reduces their capacity to resist perforation or cracking during high velocity impact. This research program involves a systematic investigation of the damage evolution in aluminum alloys under shock loading in relation to the occurrence of adiabatic shear bands, as influenced by the alloy composition, temper and loading conditions, and ceramic particle reinforcement. Optimized microstructure design for an enhanced capacity to withstand adiabatic shear failure under impact loading is the aim of this study. The dynamic stress-strain data that will be used in developing microstructure-sensitive numerical simulation of the impact response of the materials will be generated. The development of enhanced constitutive models suitable for progressive damage analysis of aluminum alloys and composites that takes into account the materials' non-linearity and strain-rate effects, which are associated with shock loading is a long term goal of this research program. This approach will provide information on how to tailor aluminum alloy's properties in order to improve their dynamic impact behaviour.