Effect of Tensile Speed on the Failure Load of Laser Welding under Combined Loading Conditions

This paper is concerned with the failure characteristics and the failure loads of laser welds in a SPRC340 1.2t steel sheet under combined normal and shear loading conditions. The quasi-static and dynamic failure tests were carried out under nine different combined normal and shear loads including a pure-normal load and a pure-shear load. Especially for the pure-shear condition, a testing fixture was newly designed in order to evaluate the strength of a laser-welded region fabricated by the same welding condition as a two-layered lap joint. The failure load and the failure behavior of laser welds were investigated in each loading condition. Dynamic effects on the failure load of laser welds, which are critical for structural crashworthiness, were also examined based on the experimental data. In order to evaluate the effect of the strain rate on the failure contour of laser welds under the combined normal and shear loads, the failure loads measured from the experiment were decomposed into two components along the normal and shear directions.