Patent ID: 8069017

Claim:
An improved method of initializing bolt pretension independent of axial strain in a finite element analysis for simulating structural responses of a structure with bolted joints included therein, the method comprising: defining one or more bolts, each as a beam element in a finite element analysis model of the finite element analysis having a plurality of solution steps in time; defining at least one pretension-versus-time curve for specifying desired pretension of said each of the one or more bolts, wherein the at least one pretension-versus-time curve comprises a ramp portion, a desired pretension portion and an optional unloading portion; conducting a first series of quasi-static analyses at a first set of the solution steps covering the ramp portion of the pretension-versus-time curve; conducting a second series of quasi-static analyses at a second set of the solution steps covering the desired pretension portion of the pretension-versus-time curve, at each of said second set of the solution steps, incrementing current time in the finite element analysis by a time step (Δt), identifying a group of bolts to be excluded and performing one of said second series of quasi-static analyses without the group of bolts to be excluded until the current time exceeds the desired pretension portion's end time; and achieving of the initializing bolt pretension by terminating the second series of quasi-static analyses when either of first and second bolt pretension termination conditions has been detected and determined.