基于推广疲劳-蠕变等效转换理论的高温条件载荷谱编制方法

Method for Load Spectrum Compiling Spectra under High Temperature Conditions Based on Generalized Equivalent Transformation Theory of Fatigue-Creep Load

关键词:  航空发动机  保载时间  雨流计数法  载荷谱  寿命预测

Key words:  Aero-engine  Holding time  Rainflow counting  Load spectrum  Life prediction

摘要:

针对现有载荷处理方法对高温条件下保载时间内损伤的忽略或考虑不足问题，对疲劳-蠕变转换理论进行了推广，给出普适的转换模型建立流程，以此修正雨流计数中的等值点压缩、小幅值剔除等数据压缩步骤，从而获得了能够量化全工况保载损伤的高温条件载荷谱编制方法。在航空发动机高压涡轮盘上的应用表明：本方法考虑了全工况等值及小幅值载荷贡献的疲劳-蠕变耦合损伤，其相当于纯疲劳循环（传统雨流法）的298.25%，比常规转换方法多236.91%；寿命预测误差为8.35%，较常规转换方法降低了95%，仅为传统雨流法的2.5%，证明了优化的高温条件载荷谱编制方法的应用价值。

Abstract:

Aiming at the problem of ignoring or insufficiently considering the holding time at elevated temperature through the existing methods， a common method to establish the fatigue-creep equivalent transformation model is offered based on the generalized transformation theory. Accordingly， the damage contributed by the holding time and massive small-amplitude cycles in load history are measured quantitatively with optimizing the related steps concluding equivalent compression and invalid amplitude elimination in the rainflow counting. The application on high-pressure turbine disc of an aero-engine shows that the method takes into account the fatigue-creep coupling damage in full work conditions， which is equivalent to 298.25% of the pure fatigue cycles （by traditional rainflow method） and 236.91% more than conventional transformation method. The life prediction error is 8.35%， which is 95% lower than the conventional method and is only 2.5% of the traditional method. The applicability for high temperature load spectrum compilation is confirmed.