Considerations for Using a Linear Viscoelastic Model in the Simulation of Adhesively Bonded Joints

Finite Element Analysis (FEA) is ubiquitously used in engineering design at all stages of the design process and across many industries as a tool to evaluate design feasibility and robustness. Furthermore, adhesive joining techniques are increasingly used to replace or augment traditional mechanical joining methods like welds, rivets, or bolts. These techniques enable modern design and manufacturing trends such as light- weighting, composite and dissimilar material joining and increased automation in manufacturing. Because of this, there is a growing need for FEA analysts to understand the modelling of adhesive materials in FEA simulations. Adhesives are used in many bonding applications and can provide both good adhesion and damping performance. These materials are generally soft, and their mechanical response exhibits both rate and temperature-dependency. In fact, even small changes in temperature and rate can lead to drastically different mechanical responses for adhesives and polymeric materials. In order to accurately model the response of adhesively bonded constructions, an appropriate constitutive model for the adhesive must be selected, and the parameters associated with this constitutive model must be derived using experimental measurements. To help the FEA analysts we will discuss the experimental methods for measurement, the implementation of linear viscoelasticity in FEA codes and showcase an example test joint for a tape and a structural adhesive to discuss the capabilities and limitations of the viscoelastic models compared to a linear elastic model, which is the defacto material model in many industries for mechanical simulation.