Limit and shakedown analysis of double-layer tube considering different material properties

This paper is devoted to the maximum bearing capacity of double-layer tubes subjected to monotonic and cyclic loading, within the framework of static limit and shakedown analysis. The double-layer tube comprises inner and outer layers made of different materials, both obeying the von Mises criterion. The effects of different geometric dimensions (thickness and volume fraction) and material properties (elastic modulus, Poisson's ratio, and yield stress) on the effective mechanical behavior are studied analytically and numerically. The results indicate that the bearing capacity of the double-layer tube under monotonic load reaches its maximum value when both inner and outer layers reach their elastic or plastic limits simultaneously. The computation of plastic and shakedown limits are presented, divided into different cases by considering the volume fraction of the inner and outer layers. The double-layer structure under cyclic loads may fail due to fatigue and excessive deformation mechanisms of the inner or outer layers at the first cycle. Only when both layers fail due to fatigue simultaneously, the shakedown limit of the structure reaches its maximum value. Compared to a single-layer tube, the long-term strength of the double-layer tube can be significantly improved by applying appropriate geometric dimensions and materials in fabrication.