Simple Tests as Critical Indicator of Intra-Ply Shear Locking

Abstract

Standard finite elements can exhibit the numerical artifact of intra-plyshear locking during forming simulations. The displacement fields of elementsare piecewise continuous and cannot correctly capturediscontinuities in the shear field. This shear locking is illustrated insimulations of bias-extension experiments with an unaligned mesh. Two simpletests were developed as a critical indicator of intra-ply shear locking intriangular elements. A single-element-test shows the origin of the locking anda pull-out test indicates locking caused by small misalignments of theelements.

Locking and Enrichment Strategies

“…This mismatch between physical realistic displacement field and the interpolation field of the element leads to locking, as stated above. This can be seen in the recently developed single-element test [6]. The interelement-continuity, on the other hand, is continuous.…”

“…Several solutions have been proposed for the tension locking in fiber reinforced materials, as discussed in [6]. Ten Thije et al [4] suggested SRI as well as MF elements as solutions to intra-ply shear or tension locking.…”

“…Yu et al showed in [1] that if the element edges coincide with the fiber directions, where the hinge lines would occur, locking is absent. Aligning the element edges with the fiber directions has indeed proven to be an accurate solution to the tension locking [1,[5][6]. However, aligning the element edges has several disadvantages: standard meshers cannot be used; mesh refinement is prohibited; and usually the exact geometry is not matched.…”