Estimation of Strain in a Rotating Shaft Using Deterministic–Stochastic Approach

Abstract

Strains in rotating shafts are used for various purposes, e.g., stress estimation, damage prediction, etc. Mostly, local strains are measured by strain gauges. The structures are usually very large in size, and hence, a large number of sensors are required to measure strains at different locations. Few sensors are available for direct strain measurements, and also, some locations are inaccessible. Thus, a model-based approach based on joint input-state estimation (JIS) technique is presented here to estimate strains in a rotating shaft using a limited number of vibration measurements. This technique can be used when input forces are unknown. Numerical simulations are presented for a single-disk rotor system. The state-space form of a modally reduced-order model and noisy acceleration/strain/displacement signals are used for strain estimation. Also, the effects of different vibration measurement on the performance of estimator are shown and discussed. The results are presented for different noise levels of measured signal and modeling errors.