Proposal of physical model for damage simulation of composite structures produced by 3D printing

Abstract

The article focuses on proposal and analysis of the physical models suitable to stress simulation and limit state prediction of components made of composite structure on Onyx basis. The observed parameters are physical properties of matrix and reinforcement. The additive manufacturing technologies also allow the production of complex shape constructions with cavities. The cavities are regions characteristic of damage initiations, but a realization of experimental measurements on inner surfaces of them to predict failure is problematic. Therefore, the exploitation of appropriate physical models and subsequently mathematical models is a method for observing of material behaviour using selected physical quantities beyond surface layers. The modelling of composite structures is viable using physical models, which working principle is based on homogenization of structure, for instance, representative volume elements (RVE). The primary disadvantage of RVE models is a complicated analysis of physical properties at inhomogeneity places of reinforcement. The physical model proposed in this paper describes each fibre separately regarding authentic physical properties and precise determination of fibre deposition in the matrix. Implementation of FEM programs with a primary objective to perform formation and analysis of the physical models, provides solution of various multiphysical problems, such as nonlinear behaviour of material induced by contact, temperature variation or interaction with other environments (temperature, fluid, electromagnetic fields), and so on. The main aspect of the presented concept is the generation of computational models with a precise definition of fibre deposition in the composite structure. The numerical analysis of loading and limit state prediction was executed on models of the composite structure. The structure includes onyx as a thermoplastic matrix and carbon fibres. The fundamental physical criterions for damage initiation assessment were stress state and strain at critical locations of matrix and reinforcement.