PARAMETRIC NONLINEAR FINITE-ELEMENT ANALYSIS OF STRAIN RATCHETING IN PRESSURIZED ELBOWS BASED ON RANDOM VIBRATION

The large strain ratcheting in cyclic plasticity of a typical pressuri zed pipe elbow in a realistic nuclear piping system was investigated i n a more quantitative manner than previously. The elbow was modeled us ing a fine mesh of shell elements that can provide the completed infor mation of detailed time varying strain distributions in the whole elbo w area. The nonlinear time history str ess analyses performed were bas ed on a pseudostatic concept using the vector-valued stochastic displa cement response time series loaded at the elbow ends. The response tim e series were synthesized using a simulation approach based on the ran dom vibration analyses of the piping system and its supporting buildin g. After a finite element mesh convergence study, parametric analyses were conducted that included the effects doe to the magnitude changes in excitation level, internal pressure, material yield stress, and mat erial strain hardening. (C) 1996 John Wiley & Sons, Inc.