A damage sequence interaction model for predicting the mechanical property of in-service aluminium alloy 6005A-T6

Abstract

In the long-term service process, materials and structures will bear fatigue, ageing, and other degradation behaviours under environmental factors such as temperature, vibration, and radiation. Service damage makes materials and structures gradually deviate from the original design expectations. In this study, the material is decoupled into a two-phase system consisting of matrix and void phases. The different mechanical behaviours of material by the evolution of the void phase are analysed under the premise of the constitutive uniqueness of the matrix phase. Different characterisation methods of damage are discussed, and a finite element analysis–test combination method is proposed to identify the damage evolution function and the undamaged hardening, avoiding the influence of the necking effect and the accuracy of the test apparatus. A damage interaction model associated with the physical mechanism of microstructure evolution is constructed based on the ductile damage evolution function, discussing the influence of different damage definitions on the sequence interaction. The aluminium alloy 6005A-T6 commonly used in car body structures of rail vehicles is studied. The damage evolution function and undamaged hardening are established by testing undamaged specimens and verified by testing service-damaged specimens that bore a certain service loading. Then the damage interaction mode was determined. The proposed damage sequence interaction model provides an effective non-destructive testing method to obtain the hardening behaviour of in-service engineering materials. It can also extend to various existing constitutive equations.