Methods for predicting flow-induced vibrations in bellows expansion joints

Bellows expansion joints are a specialty corrugated pipe fixture that serve critical purposes in aeronautics, space, defense and industrial applications. Their corrugated design makes bellows joints susceptible to a high-amplitude, flow-induced vibration phenomenon that can compromise the structural integrity of the joint. The current empirically-based method used by NASA to assess flow-induced vibration in bellows joints was developed in the early 1980s. This historical method is discussed here with a new nondimensional analysis that provides a simpler way to apply the model and examine its output. Presently, new bellows designs are beyond the empirical basis of this historical method, underscoring the need for more modern methods that are computationally efficient and physically insightful. To this end, a physics based, coupled oscillator model of bellows flow-induced vibration is developed. A comparison of the model output to experimental bellows response is presented and discussed.