Isogeometric analysis of nearly incompressible large strain plasticity

We study the behavior of NURBS-based Isogeometric Analysis on problems of large-deformation plasticity. We evaluate the performance of standard NURBS elements and elements based on the F ¯ formulation of Elguedj et al. (2008) [1]. Our experience shows that standard measures of evaluation employed in the literature, namely, displacements at selected locations and graphs of reaction forces versus displacements, are often misleading metrics in problems of plasticity. On the other hand, stress distributions, in the form of contour plots, are, in our experience,revealing measure of element performance. We also determine that the concept of “mesh locking”, which has dominated investigations of low-order elements, is not a relevant issue for higher-order NURBS elements for problems of large-deformation plasticity. However, standard higher-order NURBS elements of type Qk, of continuity class C k - 1 , k ⩾ 2 , typically exhibit spurious stress oscillations, whereas the F ¯ elements of type Qk/Qk-1 produce good results in all cases.