Study of stress-strain states of bonded and welded vehicle structures under impact loads

In this article a comparative study of the properties of adhesive-bonded and welded joints in automobile structures under impact loads has been studied. The influence of the thickness of the adhesive-bonded joint on the stiffness of tubular car structures under the impact loading with the velocity of 6.66 m/s (under the axial impact) and 6.87 m/s (under the side impact) according to the results of the experiments with different thickness of the adhesive layer was estimated. For bonding samples was selected adhesive Henkel EP 5055, which is widely used for bonding structures of automobiles. In the conducted research measured and investigated zones of joint damage, total deformation of specimens and strain in them under lateral and axial impact loads. Modeling and calculation of the stress-strain states of models and the failure zone of adhesive bonds were performed using the LS-Dyna. The models took into account the influence of the thickness of the adhesive bond and the strain rate on the bond strength in tubular car structures under impact loads. To estimate the accuracy of calculations on the basis of created finite-element models of the adhesive-bonded connection of the vehicles structure, verification according to the results of the experiments was carried out. According to the results of the experiments and modeling the reliability of the connection of the welded structures under the impact load is higher than that of the structures with the adhesive-bonded, but the adhesive-bonded layer absorbs more impact energy than the weld spots according to the simulation results. On the basis of research results of calculations carried out using the proposed modified model, the recommended value of the adhesive-bonded layer thickness for bonding of car attachments was substantiated.