Parametric Instability in Metallic Bellows Due to Internal Fluid Pressure Variation During Earthquake

This paper deals with the parametric instability of the metallic bellows filled with fluid and subjected to the earthquake excitation. The axial stiffness of the metallic bellows varies due to the internal fluid pressure variation, and this stiffness variation excites the parametric resonance in the metallic bellows. Finite element model about the metallic bellows that connected to the pipe is developed to examine that parametric resonance is excited in the metallic bellows by earthquake motion or not. Numerical simulations are carried out using past recorded earthquake motions. As the results, parametric resonance may be excited in the bellows when the pipe is close to resonance with the predominant frequency component of the earthquake though earthquake is not the harmonic motion.