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The purpose of this study is to examine the effect of spot weld spacing on the stiffness and natural frequency of a two-piece welded body structure. The variation in spot weld spacing may occur either by design or due to assembly mistakes. In this study, rectangular beam cross sections with six different weld flange orientations are first considered. Finite element analysis is performed to compare the fundamental frequencies of these sections in bending and torsion. Weld pitch and sheet thickness are varied on two of the sections considered, namely the L-shaped and the clamshell sections. The effects of spot weld spacing on the bending stiffness, torsional stiffness, frequency response and mode shapes of these two sections are determined. Comparisons are made with seam welded sections. It is shown that the torsional stiffness and first torsional frequency can be severely affected by weld pitch, but the effect on the bending performance is not as severe.

Through testing conducted by multiple facilities, it has been observed that the class of compact two-person vehicles designed exclusively for off-road operation known as Recreational Off-Highway Vehicles (ROVs) exhibit a range of steady-state handling characteristics - including both understeer and understeer transitioning to oversteer as measured in circle-turn tests similar to those set forth in SAEJ266. This handling characteristic is different from on-road passenger cars and light trucks which, under all but heavy loading conditions, exhibit linear range and limit understeer steady-state cornering behavior. Limit understeer is considered desirable for on-road vehicles because it provides a directionally stable and generally predictable control response. In the research presented in this paper, the handling qualities, including controllability, of a ROV which was modified to have different steady-state handling characteristics ranging from understeer to oversteer is examined.