Dual-function fixture design for dynamic testing of automotive bumper/crash-box case study utilizing friction stir welding
Handyside, Alan Bruce
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Recent advancements in friction stir welding (FSW) technology and pin (probe) tool design for aluminum have made FSW applications in aerospace and automotive structures quite attractive. FSW has the potential for better fit, form and function when compared to fusion welding. The aim of this research was to design, develop and fabricate a fixture to meet the requirement of a standard automotive impact test on an FSW bumper/crash-box assembly. A fusion welded bumper/crash-box design was provided to Wichita State University (WSU) by the General Motors Corporation (GM). For this case study, the bumper design was not changed, but the existing crash box was altered to satisfy two FSW assembly designs, incorporating unique lap and hybrid welds for the closeout area at each end of the bumper. Both designs use a common butt weld along a nested interface between the crash box and the bumper. The goal of this test fixture was to facilitate a dynamic vehicle test on FSW bumpers and compare the test results to that of fusion-welded bumpers. Functional use of FSW in bumper design was to be determined through this case study. Since the test fixture uses similar type welds as the bumper geometry, FSW was also incorporated into the test fixture design. Several design constraints related to vehicle testing, FSW and the University Impact Laboratory were met. Process simulation of dynamic forces on the bumper and test fixture welds, along with standard static analysis, were used for design verification. Parameter bounding and test coupons of FSW in aluminum were used to determine parent and weld material properties as well as optimum weld parameters for manufacturing the test fixture. Aluminum alloys 6063-T6, 6061-T6, 7050-T7451, concrete and structural fusion welded steel were selected for materials in the test fixture design. A linear bearing rail system was used to facilitate the gravity-fed drop tower and dynamically fed sled test functions
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.