Vývoj metodiky testování lepených spojů pro automobilový průmysl

Abstract

This dissertation deals with the development of a methodology for testing bonded joints for the automotive industry. The thesis aimed to characterize the surface changes of EN AW 5754 alloy after exposure of a cleaning laser and also to investigate the effect of different cleaning laser parameters on the shear strength of the bonded joint. The objectives also included comparing the effect of laser surface pretreatment with the conventionally used chemical cleaning surface pretreatment method on the shear strength of the bonded joint. The progress of the bonded joint shear test was imaged using the DIC method. Experimental measurements revealed that the best properties are achieved in a bonded joint that is completely cleaned of contaminants by laser surface pretreatment and where the change in adherend topography results in a unique surface with a number of spattered drops of molten metal that contribute to the formation of mechanical interlocks and increase the strength of the bonded joint. The specimen with a maximum shear stress value of 24.77 MPa achieved the best results in tensile testing. The tensile test results investigated by the DIC method describe the rotation of the bonded specimen and the moment of peel associated with the onset of a crack in the bonded joint. The results obtained for the maximum stress of the bonded joint were compared with the stress applied to the bonded joint in a self-supporting battery box under conditions simulating real car use. The bonded specimen with laser pretreatment can transfer the load applied to the self-supporting battery box load simulating real car use.