A modeling of residual stress in stretched aluminum alloy plate

A mathematical model is developed to calculate the residual stress in stretched aluminum alloy thick plate. It is based on balance of stresses, two-dimensional plasticity and a conception of free size. The model is verified against the published experiments performed on 7075 aluminum plate. It is found that the computed residual stress basically express the stress level of the stretched plate under the given stretching ratio and that through-thickness inhomogeneity plays an important role in residual stress. The effect of various tension ratios on residual stress is presented and stress-relief mechanism investigated. Calculation shows that residual stress in the transverse direction is higher than that of the rolling direction when the tension ratio is relatively small and the latter is larger than the former when tension ratio reaches a certain level. Non-uniform plastic deformation caused by stretching is also studied. Plastic strain in the rolling direction of the inner part is larger than that of the outer part due to the fact that the free length of the former is shorter than that of the latter. Besides, analysis indicates that residual stress is increasing during aging process. (C) 2012 Elsevier B.V. All rights reserved.