Development of spot weld failure parameters for full vehicle crash modelling

Abstract

A cost and time effective process was developed to create spot weld failure parameters for crash models implemented in LS-DYNA. The process includes a design of experiment (DOE) approach for coordinating data collection, welding and testing, finite element modelling, statistical analysis, validation, and implementation. The DOE approach was used to coordinate testing of a reduced set of samples over a large range of material strengths and gauges. This testing included crosstension, lap shea, and coach peel type evaluations. Computer models for each metal combination and sample geometry were developed to obtain normalised tensile, shear and bending stress at the incidence of weld failure. These normalised loads were then regressed to extend these results to all possible material combinations within the DOE space. These results were then used to estimate the spot weld failure parameters for all the stack-ups of interest. A set of multiweld Tsection samples were then welded, physically tested and computer modelled to validate the failure parameters developed from the small single weld tests.

Welding metallurgy of stainless steels during resistance spot welding Part II –heat affected zone and mechanical performance

“…martensite formation in FZ and HAZ and martensite tempering in HAZ) have been studied in reasonable details. [5][6][7][8][9][10][11][12][13] However, the welding metallurgy of stainless steels during RSW is yet to be addressed. There are limited works on the resistance spot weldability of stainless steels.…”

“…Vehicle crashworthiness, which is defined as the capability of a car structure to provide adequate protection to its passengers against injuries in the event of a crash, largely depends on the integrity and the mechanical performance of the spot welds. 1,[5][6][7] The energy absorption capability of the spot welds, which is an important parameter in vehicle crashworthiness, is controlled by weld physical attributes [especially fusion zone (FZ) size and electrode indentation size] and weld metallurgical attributes [microstructure of the base metal (BM), FZ and heat affected zone (HAZ)]. [4][5][6][7][8][9][10] The failure mode of spot welds (i.e.…”

Welding metallurgy of stainless steels during resistance spot welding Part I: fusion zone

“…Vehicle crashworthiness, which is defined as the capability of a car structure to provide adequate protection to its passengers against injuries in the event of a crash, largely depends on the integrity and the mechanical performance of the spot welds. [7][8][9] Therefore, study of welding metallurgy of stainless steel sheets is a prerequisite for their use in automotive structural parts. Mechanical performance of resistance spot welds is significantly affected by: 7,[10][11][12][13][14][15] (i) weld physical attributes, particularly the fusion zone (FZ) size: the weld nugget size is controlled by heat generation and heat dissipation, which in turn are governed by electrical resistivity and thermal conductivity of the metal sheets being welded respectively.…”

An ICME Approach for Optimizing Thin-Welded Structure Design

“…An ICME implementation framework (Figure 1) for developing a product involving manufacturing processes such as welding was developed by generalizing the framework for automotive, aerospace, and maritime in [4]. This framework has been successfully used in designing automotive spot-weld structures [6] [7], repairing aeroengine blades [8], and designing composite-to-steel adhesive joined ship structures [9].…”

“…The critical value D c can be determined by experimental testing and modeling [17]. Daimler Chrysler failure model, as shown in Equation 4, has been used to predict resistance spot weld failure [7]. It is a stress-based failure model considering tension stress, bending stress, and shearing stress.…”