The Influence of Mechanical and Laser Cutting on the Fatigue Strengths of Square Hollow-Section Welded T-Joints

T-joint connections are commonly encountered in many machine components and load carrying members. The T-joint connections can be fabricated using traditional cutting (machine or flame) or by laser cutting techniques. The present study investigates the feasibility of using laser cutting to produce welded square hollow-section T-joints with similar or higher fatigue strengths than their conventional mechanical cut counterparts. A total of 21 full-scale T-joint samples, typical of those found in the agricultural industry, were included in this study. Nineteen of these samples were examined with the intention of forming a fatigue crack of approximately 3.8 cm (1.5 in.es) in length, and two samples with strain gauges attached for strain measurements. The experimental results of the full-scale T-joints subjected to cyclic loads showed that the fatigue strength of the samples that were manufactured with laser cutting were higher than those fabricated with mechanical cutting. A finite element analysis (FEA) of the T-joints was also performed, and the FEA results were verified with the experimental strain measurements.