Abstract
This paper reports on the application of a special purpose finite element analysis tool that combines augmented finite element methodologies (AFEM) and cohesive zone model (CZM) methods to simulate initiation and propagation of both cohesive and adhesive cracks. The constitutive behaviour of an aluminium/silicon carbide metal matrix composite was predicted and compared with experimental data as an example of a material system controlled by cohesive cracks. The simulation allowed to determine the strain level, at which particle fracture was initiated and illustrates how the overall material response is dominated by particle fracture beyond that strain level. The effects of silica filler particles on the lifetime of polyurethane matrix aircraft coating systems were investigated in a second example in which adhesive cracks at the filler/matrix interface are a dominant failure mechanism. The influence of particle volume fraction and particle/matrix interface adhesion strength on coating lifetime predictions were investigated and the results show that low filler particle volume fraction and high interface adhesion strength improve coating durability. In general, the paper demonstrates the potential of combined AFEM and CZM micromechanical damage simulation to gain improved understanding of damage mechanisms in heterogeneous materials and to support analysis and design of advanced material systems. Key words: Augmented finite element method, phantom node method, cohesive zone modelling, metal matrix composite, aircraft coatings.
Highlights
Many modern design solutions include the application of advanced materials such as polymer, metal or ceramic matrix composites, because conventional homogeneous materials cannot meet all performance requirements
This paper reports on the application of a special purpose Finite element (FE) implementation that incorporates augmented finite element methodologies (AFEM) and cohesive zone model (CZM) formulations to investigate the damage initiation and evolution in two inhomogeneous materials with very different failure modes
Incorporating particle cracking in the small model resulted in predictions that were lower than the experimental data, since cracking of a single, brittle particle released a substantial amount of the totally stored strain energy and made the simulated metal matrix composite (MMC) too soft for the small representative volume element (RVE) model
Summary
Many modern design solutions include the application of advanced materials such as polymer, metal or ceramic matrix composites, because conventional homogeneous materials cannot meet all performance requirements. The possibility to evaluate the in-service growth of damage is essential to guarantee the safe performance of safety-critical components during their lifetime These are the reasons why substantial efforts were made over the last two decades to develop virtual testing methodologies and tools (LLorca et al, 2011; Yang et al, 2011; De Rosis et al, 2014). One promising technique to model weak as well as strong discontinuities in heterogeneous materials is the augmented finite element (AFEM) or phantom node method (PNM), (Fang et al, 2011; Hansbo and Hansbo, 2004; Wells, 2001). This paper reports on the application of a special purpose FE implementation that incorporates AFEM and CZM formulations to investigate the damage initiation and evolution in two inhomogeneous materials with very different failure modes.
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