Are the cohesive zone models necessary for delamination analysis?

Abstract

We develop a dual-purpose damage model (DPDM) that can simultaneously model intralayer damage (ply failure) and interlayer damage (delamination) as an alternative to conventional practices that models ply failure by continuum damage mechanics (CDM) and delamination by cohesive elements. From purely computational point of view, if successful, the proposed approach will significantly reduce computational cost by eliminating the need for having double nodes at ply interfaces. At the core, DPDM is based on the regularized continuum damage mechanics approach with vectorial representation of damage and ellipsoidal damage surface. Shear correction factors are introduced to match the mixed mode fracture toughness of an analytical cohesive zone model. A predictor-corrector local-nonlocal regularization scheme, which treats intralayer portion of damage as nonlocal and interlayer damage as local, is developed and verified. Two variants of the DPDM are studied: a single-and two-scale DPDM. For the two-scale DPDM, reduced-order-homogenization (ROH) framework is employed with matrix phase modeled by the DPDP while the inclusion phase modeled by the CDM. The proposed DPDM is verified on several multi-layer laminates with various ply orientations including double-cantilever beam (DCB), end-notch-flexure (ENF), mixed-mode-bending (MMB), and three-point-bending (TPB).

A Damage Model Reflecting the Interaction between Delamination and Intralaminar Crack for Failure Analysis of FRP Laminates

“…Many research works pointed out these problems in theoretical analysis or simulation results by using CDM and CZM together. To overcome the difficulties in the simulation of the interaction between failure mechanisms, researchers proposed fully-three-dimensional CDM models that represent the delamination, as well as intralaminar failure [15,49,56]. However, these approaches, for which delamination is considered to be same as a matrix cracking and is simulated by CDM, could not eliminate the influence of element size through-thickness on the numerical simulation result for delamination growth.…”

Computational certification under limited experiments

“…Microphases are assumed to be brittle and anisotropic. We adopt an anisotropic damage model described in the work of Yuan and Fish . The matrix phase is assumed to obey an isotropic damage law with trilinear evolution.…”

“…In the FOCH, anisotropy is introduced due to nonuniform damage of individual elements. In the ROH, on the other hand, the inelastic response is uniform throughout each phase, and thus, an orthotropic damage model is employed to introduce anisotropy in the matrix response …”

Material‐dependent crack‐tip enrichment functions in XFEM for modeling interfacial cracks in bimaterials

“…Generally speaking, these methods can be grouped into 2 families: linear elastic fracture mechanics (LEFM) approaches and cohesive zone models . Recently, Yuan and Fish developed a continuum damage mechanics‐based dual‐purpose model to simultaneously describe delamination as well as ply failure. However, since the main scope of this contribution lies within the framework of LEFM analysis of interface cracks in isotropic bimaterials, only developments in this category of methods will be reviewed hereinafter.…”