Patent ID: 7945432

Claim:
A method of determining spot weld failure in a time-marching simulation of a structure impact event for designing a structure with one or more spot welds contained therein, the method comprising: receiving one or more spot weld definitions in a structure, each of the spot weld definitions includes a spot weld along with first and second parts connected therewith; creating a finite element analysis model of the structure including a cluster of at least one solid element to represent the spot weld, a plurality of first shell elements to represent the first part, and a plurality of second shell elements to represent the second part, said cluster having first and second ends, the first end having a plurality of nodes each connecting to corresponding one of the first shell elements and the second end having a plurality of nodes each connecting to corresponding one of the second shell elements; determining an average axial stress sensitivity scale factor and an average shear stress sensitivity scale factor for each end of the first and second ends; determining an average location sensitivity scale factor of said each end of the first and second ends; calculating force and moment resultants at said each end in current solution cycle of the time-marching simulation; calculating an overall plastic strain rate at said each end using plastic strain calculated in the current solution cycle and stored plastic strain in previous solution cycle of the time-marching simulation; checking spot weld failure criterion at said each end in the current solution cycle, the spot weld failure criterion is a function of the calculated force and moment resultants, the plastic strain rate, and the average axial stress sensitivity scale factor, the average shear stress sensitivity scale factor and the average location sensitivity scale factor; and when the spot weld failure criterion indicates failure or rupture of the spot weld at either end of the first and second ends of the cluster, removing the cluster from the finite element analysis model for subsequent solution cycles of the time-marching simulation.