Thermo-hygro-mechanical coupling model based on discrete element method to simulate hygrothermal-induced damage of PA6/GF30 material

The present contribution deals with a thermo-hygro-mechanical coupling model based on Discrete Element Method to numerically simulate hygrothermal transfers and their influence on the mechanical behaviour and interfacial damage of composite materials. For application purposes, we consider the context of a 30% glass fibre reinforced polyamide 6 material which is notably used in automotive industry due to its advantageous strength-to-weight ratio. Firstly, a coupled hygrothermal model based on boundary layer theory and the analogy between Fickian mass transfer and heat transfer by conduction is proposed. This is validated in terms of water concentration and water concentration gradient fields, by comparison with Finite Element Method calculations through the simulation of water absorption process in a PA6 material sample. Secondly, a swelling model is proposed to couple hygrothermal transfers to the mechanical behaviour of a material modelled using the hybrid lattice-particle approach. Finally, the hydric swelling-induced interfacial debonding of glass fibre reinforced polyamide 6 material is simulated. Results exhibit the pertinence of the proposed Discrete Element Method based thermo-hygro-mechanical model to reproduce such a process and yields stress and displacement fields with an acceptable level of precision.