A large number of cracks which develop in railroad tank car sheels form near the ends of skip wldis which are used to attach stiffeners to the tank. The development and growth of these cracks in fatigue are affected by the opresence of residual stresses induced locally in the shell plate by welding. Leaking and the potential for tank failure pose significant safety concerns, especially in the case of tank cars containing hazardous materials. Determination of the distribution and magnitude of these residual stresses is important in assuring the structural integrity of tank shells. A three-dimensional thermo-elastic-plastic finite element model (FEM) of a skip weld has been developed to explore the redidual stress distribution in the weld and the surrounding base material. The model geometry corresponds to that used in a series of experiments designed to measure residual stresses by means of X-ray and neutron diffraction. Model results are presented for characteristic skip wllds on base paltes of standard tank sheel material and comparisons are made between the model predictions and the laboratory measurements. Validation of the model will permit its use in evaluating residual stresses in the vicinity of different weld geometries used for other shell attachments.
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