Dissimilar material joints are of significant interest in automotive applications. An investigation was carried out to determine the peculiarities of an adhesively bonded Mg-steel system for lap shear configuration. Both experimental approach and computational method (FEA) were utilized to evaluate and analyze the Mg-steel bond. The adhesive used was Betamate 1480 — an epoxy based adhesive. The tests were done according to ASTM D 1002-99 method using MTS machine at room temperature. For computational analysis, finite element modeling techniques using ABAQUS processor was utilized. Failure modes were studied for different systems. Results were compared with Mg-Mg and steel-steel systems. It is observed that Mg-Mg balanced system (system with equal adherend or substrate thickness) failed either at interface (adhesive failure) or at substrate and system is flexible with lower failure load. While steel- -steel balanced system failed only at substrate and system is rigid with higher load and lower displacement. Mg-steel system provides flexibility in between them and only adherend failure (either out of plane Magnesium failure or steel-betamate in plane substrate failure) observed. Cohesive failure was not observed in any of the systems. For Mg-Mg, the shear stress distribution in the adhesive is poor (stress distribution is steeper) while for steel-betamate-steel it is much better. The FEA models were compared and rationale was forwarded to assess the failure modes observed in each case.
Copyright © 2004 by ASME
Available at: http://works.bepress.com/ahsan-mian/5/
Paper presented at the ASME 2004 International Mechanical Engineering Congress and Exposition Design Engineering,Anaheim, California, USA, November 13 – 19, 2004.