Effect of the curing process on the transverse tensile strength of fiber-reinforced polymer matrix lamina using micromechanics computations

Abstract

The effect of the curing process on the mechanical response of fiber-reinforced polymer matrix composites is studied using a computational model. Computations are performed using the finite element (FE) method at the microscale where representative volume elements (RVEs) are analyzed with periodic boundary conditions (PBCs). The commercially available finite element (FE) package ABAQUS is used as the solver, supplemented by user-written subroutines. The transition from a continuum to damage/failure is effected by using the Bažant-Oh crack band model, which preserves mesh objectivity. Results are presented for a hexagonally packed RVE whose matrix portion is first subjected to curing and subsequently to mechanical loading. The effect of the fiber packing randomness on the microstructure is analyzed by considering multi-fiber RVEs where fiber volume fraction is held constant but with random packing of fibers. The possibility of failure is accommodated throughout the analysis-failure can take place during the curing process prior to the application of in-service mechanical loads. The analysis shows the differences in both the cured RVE strength and stiffness, when cure-induced damage has and has not been taken into account.

Effect of Manufacturing on the Transverse Response of Polymer Matrix Composites

“…Internal defects such as voids and microcracks may also occur [ 11 , 12 , 13 , 14 , 15 ]. Such defects can degrade the in situ matrix properties significantly and therefore, affect the composite mechanical response during subsequent load applications [ 16 , 17 , 18 , 19 , 20 , 21 ]. Despite these significant research contributions, a knowledge gap exists on the evolution of these process-induced uncertainties and their influence on the composite mechanical response such as transverse tensile [ 17 , 18 , 19 , 20 , 22 , 23 ] and compressive response [ 17 , 24 ].…”

“…Computational micromechanics is an emerging field that leverages the advances in finite element methods (FEM) and the ever-increasing computing capabilities to accurately predict the microscale response of composite representative volume elements (RVEs) when subjected to various thermo-mechanical boundary conditions [ 16 , 17 , 18 , 19 , 20 , 21 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Within this framework, process-induced residual stress generation and damage accumulation can be obtained, and their influence on the bulk composite properties can be investigated by means of virtual curing and mechanical loading simulations of RVEs.…”

“…Additionally, the prediction of the stress and strain microfields throughout the microstructure allow precise estimations of stress concentration, damage initiation, and propagation during curing and subsequent mechanical loading. Several numerical studies have been performed to characterize the generation of process-induced residual stresses and evaluate their effect on the processed composite performance [ 16 , 17 , 18 , 19 , 20 , 21 , 23 , 24 , 25 , 26 , 27 , 29 ]. These studies most commonly utilize the phenomenological cure kinetic model, introduced by Kamal [ 30 ], along with the Fourier’s heat transfer law to define the progression of cure, heat generation, and heat conduction in the PMCs during cure.…”

“…These studies most commonly utilize the phenomenological cure kinetic model, introduced by Kamal [ 30 ], along with the Fourier’s heat transfer law to define the progression of cure, heat generation, and heat conduction in the PMCs during cure. Coupled thermo-mechanical analysis with appropriate constitutive models have been used to predict residual stresses in composite microstructures including incremental elasticity model [ 31 , 32 ], linear mixing rule based on composite laminate plate theory [ 33 ], instantaneous linear elastic models [ 16 , 17 , 18 ], CHILE model [ 24 ], linear and nonlinear visco-elastic models [ 34 , 35 , 36 , 37 , 38 ], elasto-plastic model [ 23 , 26 ], network-based model [ 19 , 20 , 22 , 39 , 40 ], columnar model [ 29 ], and analytical models [ 41 ]. Some studies have investigated the effect of process-induced residual stresses on the bulk composite response under different loading scenarios.…”

Virtual manufacturing of composite aerostructures

“…These processes lead to the generation of self-equilibrating internal stresses in the matrix and evolution of matrix stiffness. The stress evolution is modelled through a network model as described in Mei (40) , Mei et al (41) , Heinrich et al (42) and D’Mello et al (43) . The degree of cure (φ) of the matrix is defined as φ = H ( t )/ H r , where H ( t ) is the heat generated up to time t , and H r is the total heat of reaction at the end of the cure cycle.…”