Layer-wise structural theories for thermomechanical modeling of process-induced defects in CFRP parts

Layer-wise, 1D and 2D structural models can provide high-fidelity stress fields with reduced computational overheads compared to 3D finite elements for laminated structures. Very accurate through-the-thickness distributions of shear and peeling stresses are necessary in many cases, e.g., for predicting failure onset and propagation, free-edge effects, and impact analysis. This work presents results concerning the use of advanced structural theories to obtain residual strain and stress fields induced by the curing process of composite parts. Such induced fields may cause geometrical and mechanical defects undermining the quality of the structural component. The aim is to develop a virtual platform to detect such defects and use it to find specific lay-ups to minimize process-induced deformations such as spring-in angle and warpage. Structural models are derived according to the Carrera Unified Formulation (CUF) via higher-order expansions of the primary unknown variables and fundamental nuclei of the FE matrices and arrays. In addition, a cure-hardening instantaneously linear elastic (CHILE) constitutive model is adopted for numerical simulations.