A Progressive Damage Model for Mechanically Fastened Joints in Composite Laminates

TLDR

The study develops a 3‑D finite‑element model to predict damage progression and ultimate strength of mechanically fastened carbon‑fiber‑reinforced plastic joints in bearing, tension, and shear‑out failure modes. The model couples a 3‑D failure criterion and a damage‑dependent constitutive law, using internal state variables for each damage type, and applies a global failure criterion to estimate joint strength. Experimental tests of damage evolution, stiffness, and strength show good agreement with the numerical predictions.

Abstract

A three-dimensional finite element model is developed to predict damage progression and strength of mechanically fastened joints in carbon fibre-reinforced plastics that fail in the bearing, tension and shear-out modes. The model is based on a three-dimensional finite element model, on a three-dimensional failure criterion and on a constitutive equation that takes into account the effects of damage on the material elastic properties. This is accomplished using internal state variables that are functions of the type of damage. This formulation is used together with a global failure criterion to predict the ultimate strength of the joint. Experimental results concerning damage progression, joint stiffness and strength are obtained and compared with the predictions. A good agreement between experimental results and numerical predictions is obtained.