Assessment of structural integrity of thermoset composite parts subjected to accelerated cooling during the manufacturing process using Puck criteria for failure initiation

Abstract

For many applications, the production of large-scale lightweight parts using composite materials requires a curing stage at elevated temperatures with long cycles resulting from necessary heating and cooling steps. Here, an accelerated cooling stage after curing of the matrix can shorten process times and make it possible to demould the components in a hot state. In this paper, the impact of higher cooling rates on residual stresses and strains and the criticality for internal failures are investigated. A literature model using the pultrusion process including thick laminates and the interaction with a production tool was used for the implementation of a thermochemical calculation and an incremental linear-elastic mechanical model to calculate residual stresses induced during manufacturing stage. This way, the capability of flexible simulation environments for handling state of the art calculation schemes is investigated to allow the extension of the physics of those models. The model is implemented in both a representative environment for advanced structural analysis with highly customised element formulation such as Abaqus and a general-purpose FE package. Here, Comsol Multiphysics is used and extended by the calculation of the inter-fibre failure initiation. Using the proposed models applied to a plate geometry, stresses and strains induced in different cooling scenarios are investigated. The assumptions are validated by simulations including the whole curing process, by manufacturing trials on the coupon level and with mechanical tests.