FINITE ELEMENT METHOD BASED MODELING OF RESISTANCE SPOT-WELDED MILD STEEL

Abstract

THIS PAPER DEALS WITH FINITE ELEMENT REFINED AND SIMPLIFIED MOD- ELS OF A MILD STEEL SPOT-WELDED SPECIMEN, DEVELOPED AND VALIDATED BASED ON QUASI-STATIC CROSS-TENSILE EXPERIMENTAL TESTS. THE FIRST MODEL WAS CONSTRUCTED WITH A FINE DISCRETIZATION OF THE METAL SHEET AND THE SPOT WELD WAS DEFINED AS A SPECIAL GEOMETRIC ZONE OF THE SPECIMEN. THIS MODEL PROVIDED, IN COMBINATION WITH EXPERIMENTAL TESTS, THE INPUT DATA FOR THE DEVELOPMENT OF THE SECOND MODEL, WHICH WAS CONSTRUCTED WITH RESPECT TO THE MESH SIZE USED IN THE COMPLETE CAR FINITE ELEMENT MODEL. THIS SIMPLIFIED MODEL WAS DEVELOPED WITH COARSE SHELL ELEMENTS AND A SPRING-TYPE BEAM ELE- MENT WAS USED TO MODEL THE SPOT WELD BEHAVIOR. THE GLOBAL ACCU- RACY OF THE TWO MODELS WAS CHECKED BY COMPARING SIMULATED AND EXPERIMENTAL LOAD-DISPLACEMENT CURVES AND BY STUDYING THE SPECI- MEN DEFORMED SHAPES AND THE PLASTIC DEFORMATION GROWTH IN THE METAL SHEETS. THE OBTAINED RESULTS SHOW THAT BOTH FINE AND COARSE FINITE ELEMENT MODELS PERMIT A GOOD PREDICTION OF THE EXPERIMENTAL TESTS.