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

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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.