DYNAMIC BEHAVIOR OF ELASTIC-PLASTIC SIMPLY SUPPORTED PIPES

Nonlinear responses of the dynamic behavior of simply supported pipes were analyzed using a nonlinear finite element program. In the first m odel, a 1 1/2-in. schedule 40 stainless steel pipe 48 in. long wasstud ied. Anelastic-plastic material was specified. The dynamic response of the pipe to a sinusoidal force input was calculated. There was no int ernal pressure and the magnitude of theforce input was held constant a s the frequency was varied. A total of 26 cases were studied starting with low frequencies that exhibited static behavior to twice the natur al frequency. In addition, a 1-in. straight piping system studied expe rimentally by Beaney (1985a, b) was modeled analytically. Calculations are compared to experiment. The response of the piping al input frequ encies of one-quarter and one-half of the natural frequency exhibited resonance behavior. At one forced frequency, an almost chaotic behavio r of the dynamic pipe response was observed. However, at all other spe cified excitation frequencies, the system reaches a steady-state respo nse. Output in the form of strain and displacement time histories and force displacement plots is developed. In addition, both work and equi valent viscous damping are calculated and presented.