A micromechanical finite element model for predicting the fatigue life of heterogenous adhesives

Adhesive bonding enables joining together thin and dissimilar materials with a negligible increase in weight, which are attractive features in the automotive and aerospace industries. One of the potential sources of failure in adhesive joints is the fatigue damage in the adhesive layer, which often has a complex heterogeneous microstructure. Characterizing the fatigue life of structural adhesives would be a challenging task via numerical techniques. Besides difficulties associated with modeling the adhesive complex heterostructure, the lack of proper micromechanical models to simulate the fatigue damage in this materials system constitutes the major challenge. In this work, we introduce two new high-cycle fatigue damage models, one for the matrix and the other for the particle-matrix interfaces, to predict the fatigue life of a structural adhesive used for automotive applications. High-fidelity finite element (FE) models of representative volume elements (RVEs) of this adhesive are generated using an automated computational framework, enabling the virtual reconstruction of the microstructure and mesh generation. These 3D FE models are used to calibrate the fatigue damage model parameters with fatigue test data under different loading conditions. The calibrated models are then employed to study the impact of micro-voids and particle-matrix interfacial bonding strength on the fatigue life of the adhesive.

Automated summary

Adhesive bonding is beneficial for joining thin and dissimilar materials, making it suitable for the automotive and aerospace industries. However, characterizing the fatigue life of structural adhesives using numerical techniques is challenging due to the complex heterogeneous microstructure and lack of proper models. This study introduces two new high-cycle fatigue damage models and validates them through finite element simulation and fatigue test data calibration.