Finite element limit analysis of anisotropic structures

The limit analysis problem, permitting the direct computation of the collapse load of perfectly plastic structures, is considered for anisotropic materials. To this end, the essential piece of information, so far available in a limited number of cases only, is the expression of the dissipation power associated to the anisotropic yield criterion as an explicit function of strain rates. Such expression is derived for conditions based on the Tsai–Wu’s tensor polynomial form for failure criteria, truncated to second order stress terms, but accounting for possible tensile to compressive strength differential. On this basis, numerical procedures successfully employed in the isotropic case can be extended with minor modifications to the anisotropic context, as some examples illustrate.