Study of the effects of deformation rate and adhesive layer thickness under impact loading on parameters of adhesive joints in a vehicle

Abstract

BACKGROUND: At the present time, new technologies of joints adhesive joints are used more and more widely along with spot welding in domestic and foreign vehicles. Study of the joint strength and the influence of deformation rate and the adhesive layer thickness under impact loading on the parameters of the joint in a vehicle is a relevant technical task. AIMS: Study of the influence of deformation rate and the adhesive layer thickness on the adhesive joint parameters (strength, deformation, etc.) under impact loading as well as evaluation of the efficiency of the proposed modified calibration method for the adhesive layer model on the example of tubular structure, which is often used in the strength elements of a vehicle. METHODS: Experimental studies were carried out with impact loading at the speed of 6.66 m/s (the axial im-pact) and 6.87 m/s (the side impact) with the mass of 22.3 kg. Simulation of operating conditions was performed in the LS-Dyna software that made possible to study the stress-strain states (SSS) of adhesive-bonded tubular structures and to estimate the simulation error. RESULTS: Based on experimental and calculated results, the length of the adhesive layer failure under the impact loading in the steel structures bonded with the Henkel EP 5055 adhesive is shorter in the joints with the 0.5 mm thick adhesive layer than in the joints with the 1 mm thick adhesive layer. The total deformation of the bonded structure at the side impact loading for the 1 mm thick adhesive layer is less than for the 0.5 mm thick layer, as the adhesive layer absorbs some of the energy. For the axial impact loading, the differences are insignificant. Errors of adhesive joint simulation under impact loading have been reduced significantly (by 15%) with using the proposed modified method of calibrating the adhesive layer properties considering the influence of the deformation rate and the adhesive layer thickness in the finite element model. CONCLUSIONS: The practical value of the study lies in the proposed modified model, considering the influence of the deformation rate and the adhesive layer thickness under impact loading on the joint parameters and making possible to improve simulation accuracy, as well as in recommendations for the best value of adhesive joint properties in adhesive-bonded vehicle structures.