凸肩叶片抗共振的模糊可靠性评估方法

Fuzzy Reliability Assessment Method of Shrouded Blades for Avoiding Resonance

分析了凸肩叶片固有频率的模糊性,并提出一种确定模糊隶属函数的统计分析方法;利用截集理论,建立了凸肩叶片抗共振模糊可靠性模型,并分别以均匀分布和线性分布为截集分布,给出了模型计算的数值方法。同时通过分析指出:常规可靠性模型是模糊可靠性模型的特例,模糊可靠性模型是对常规可靠性模型的补充和延伸。最后应用文中模糊模型,对凸肩风扇叶片抗共振可靠度予以计算,结果表明:文中提出的模糊方法对固有频率中值估计值和各拟合参数都具有较好的稳定性;且考虑了固有频率的模糊性后,模糊方法的可靠度估计结果小于常规方法的估计结果。

The fuzziness of shrouded blades’ natural frequency was considered and a statistics analysis method was proposed to determine the fuzzy membership function. The fuzzy reliability model for avoiding resonance was also es-tablished based on the truncated subset theory in fuzzy mathematics. A numerical calculation method was then pro-posed by introducing uniform distribution and linear distribution into truncated subsets respectively. Meanwhile, it was pointed out that the conventional reliability model is a special case of the fuzzy reliability model, while the fuzzy reliability model is the improvement and extension of the conventional reliability model when the system has fuzzi-ness. Finally, the fuzzy model was applied to calculating the reliability of shrouded fan blades to avoid resonance. The results and their analysis show preliminarily that the proposed fuzzy method is stable for the mean estimation of natural frequency and the fitting parameters. It is also shown that the fuzzy estimations are smaller than the conven-tional estimation because the fuzziness of naturgl frequency was considered in the fuzzy model.