Benchmarking Mixed Mode Matrix Failure in Progressive Damage and Failure Analysis Methods

Effects of characteristic element length on fracture energy dissipation in continuum damage mechanics models

“…At these bounding values of w, analyses with smaller elements predict slightly lower far-field failure stresses and agree better with the LEFM solution, consistent with the results in literature. 4,5 While wՇ15 , the cracks propagate along the mesh lines (e.g., Figures 10(c) through 12(c)), and the far-field failure stresses predicted with L c;ML are relatively constant and agree well with the LEFM solution. In this range, the far-field failure stresses predicted using L c;FD decrease with increasing w, underpredicting the LEFM solution.…”

“…A center notch tension (CNT) specimen comprising unidirectional fiber-reinforced material was selected for this study, based on the analyses described in literature. [3][4][5]10 The CNT problem configuration contains a central fiber-aligned matrix crack in a flat plate sized so that the crack tip stresses are unaffected by the boundary conditions. A closed-form LEFM solution is presented by Mabson et al 3 for the far-field stress r 1;c at which crack growth should occur in an infinite orthotropic plate with a center notch when loaded in tension:…”

“…These constraints are related to constitutive snapback 1,2 and matching linear elastic fracture mechanics (LEFM) predictions for long crack growth. [3][4][5] To satisfy these mesh size requirements, to promote the growth of matrix cracks along the fiber material direction, 6,7 and to avoid other potential mesh size and orientation dependency issues, analyses performed by the authors in support of the NASA Advanced Composites Project (ACP) utilized a highly refined ply-by-ply, fiber-aligned meshing strategy. 8,9 In this modeling approach, individual solid-element plies are separated by layers of zero-thickness cohesive elements and connected via tie constraints.…”