Blade Strain Peak Localization Method With Single Transducer During Multimode Vibration

Abstract

The dynamic strain/stress measurement of blades provides an effective method to anticipate fatigue life and investigate of failure causes. Unlike the blade strain peak is fixed during singlemode, which can be measured by a single transducer, the strain peak distribution changes over time and space during multimode vibration situations. The existing method reconstructs the full-field strain to find the peak point with multiple transducers. In this work, a single transducer-based full-field dynamic strain reconstruction technique is presented to find the strain peak position on rotor blades. First, the mode response is obtained by separating the measured response from a single strain gauge based on Ensemble Empirical Mode Decomposition. Second, based on the strain mode shape from the finite element model, the reconstructed strain transmissibility matrix is created between a single measured location and the full field. Third, the dynamic strain of the blade can be reconstructed at any location and time by combining the separated mode response with the RST matrix. Finally, the strain peak localization is identified according to the distribution of full-field dynamic strain during multimode vibration. The above process is verified by experimental data from rotor blades with the maximum error of reconstructed strain below 12% and three explicitly recognized strain peak positions.