Mixed-mode loading tests for determining the mechanical properties of clinched joints with an additional rivet used in the assembly of thin-walled structures

Abstract

This publication presents the possibility of forming a clinched joint with the use of a deformable element such as a full rivet. An analysis of the joint load capacity was also performed for three values of the hardness of the rivet. The joints were formed in the same sheet with thickness t=1.5 [mm] made of DX51D+Z275 steel (which is commonly used for thin-walled structures). Additional rivets with hardness values 350HV1, 400HV1, and 420HV1 were used. The joints were made with a uniform punch and a die with movable elements. Load capacity tests were carried out in order to demonstrate the influence of the angle between the load force and the axis of the clinch riveted joint. H-shaped samples were made for load tests with the use of a modified Arcan test device. All joints were tested under the same static test conditions (the traverse speed of the testing machine was 10 mm/min). In addition, the characteristic geometric parameters of the interlock were measured on the joint cross-sections.In the case of connecting the sheets with a rivet of three different hardnesses: 350HV1, 400HV1, and 420HV1, the largest surface deviations of the sheets were observed for the connection with the 350HV1 rivet hardness. Increasing the hardness of the rivet from 350HV1 to 400HV1 and 420HV1 resulted in a reduction in sheet deviations. The deviations for the largest distance from the rivet axis in the case of the 400HV1 and 420HV1 rivet hardness were at a similar level. The highest value of the interlock parameter, which determines the joint load capacity, was obtained for the rivet with the highest hardness value (420HV1). The highest joint load capacity was obtained when using a rivet with a hardness of 420HV1 and the lowest for the rivet hardness of 350HV1.