基于响应传递比的转子叶片动应变重构

Dynamic strain reconstruction of rotating blade based on response transmissibility

提出基于响应传递比的转子叶片动应变重构方法,从系统应变频响特性出发,在频域获得应变-应变响应传递比关于模态振型的解析表达式,建立叶片已知测点应变与不可测位置应变的映射关系;开展高速旋转叶片动应变测量实验,建立叶片有限元模型,并采用转子叶片前4阶固有频率的实验结果修正有限元模型;开展考虑转速影响的转子叶片模态分析,提取对应的应变模态振型,计算得到单模态振动下应变-应变响应传递比;综合应变响应传递比和实测动应变重构叶片不可测位置的动应变。实验结果表明:与应变片实测结果相比,基于响应传递比的转子叶片动应变重构结果相对误差小于10%。

A dynamic strain reconstruction method of rotating blades based on response transmissibility was proposed. Based on the characteristics of system strain frequency response,an analytical expression of the strain-strain response transmissibility with respect to the modal shape was obtained within the frequency domain,and the mapping between the measured and unmeasured strains on the blade was established. Experiments for the blade dynamic strain measurement were conducted under the high-speed rotating condition. Then,the finite element model of the blade was established and updated by using the first four natural frequencies from experiments. The modal analysis of the rotating blades was conducted considering the prestress of rotational speed. The blade strain mode shapes were extracted from the finite element model and the strain-strain response transmissibility on single-mode resonance was calculated. Experimental results showed that the relative errors between the measured dynamic strains measured by strain gauges and the reconstructed dynamic strains based on the response transmissibility were less than 10%.