Study of the effect of finite element dimensions on the simulation accuracy of adhesive bonding in automotive structures

This article studies the effect of finite element dimensions on the accuracy of simulation of adhesive bond in automotive structures using the LS-Dyna software package. The simulation was carried out under quasi-static loading for an “overlapped” adhesive joint. The properties and destruction of the adhesive material in the direction of shear were evaluated. The characteristics of the adhesive layer were obtained from experiments using a hydraulic press and other devices according to international standards ASTM 638-03 and DIN 54451-11.1978 with different sliding speeds and adhesive layer thicknesses. It was revealed from experiments that the properties of the adhesive material strongly depend on the deformation rate and the thickness of the adhesive layer, so this had to be taken into account when modeling. To solve this problem, 12 variants of finite element models were solved and evaluated, including by comparing with the results of experiments for glued “overlapped” joints. As a result of the analysis of the stress-strain states of models of an adhesive joint under quasi-static loading in the LS-Dyna software package, the recommended size and number of layers of finite elements were obtained for modeling an adhesive joint in automotive structures. The rational size of the facets of a volumetric finite element is 2 × 2 mm2, taking into account the modeling errors and the cost of computer time for the calculation in relation to multivariate calculations of structures at the design stage. It was determined the recommended number of layers of finite elements in the finite element model by the thickness of the adhesive layer, that should be selected for a highly accurate description of the gluing properties and ensuring the efficiency of calculations. At the same time, it was revealed that an increase in the number of layers of finite elements insignificantly increases the accuracy of modeling and significantly increases the required computer time for the calculation.