Micromechanical Analysis of Mechanical Response for Unidirectional Fiber-Reinforced Plies

Abstract

Unidirectional fiber-reinforced composites are highly anisotropic and exhibit various damage modes at the microscale. In this study, micromechanical models for fiber, matrix and interface to study the complex behavior of unidirectional composite plies were proposed. A representative volume element (RVE) was constructed with the interface meshed as a separate layer. An orthotropic nonlinear bi-modulus model was used to capture the asymmetry mechanical behavior between tension and compression commonly observed in carbon fiber filaments. For the thermoset resin, which exhibits pressure-sensitive behavior, a Drucker–Prager elasto-plastic model is developed. An orthotropic failure model was proposed and implemented to capture the behavior of the interface. The material properties of fiber, matrix and interface were obtained by reverse engineering from experimental data or from the literature when needed. Compared results between simulation and experimental data show that one single micromechanical model can effectively capture the mechanical behavior and failure mode of the ply under different loading conditions. This is an important step toward leveraging such RVE models in a multi-scale constitutive modeling framework to predict the mechanical behavior of laminates and composite parts.