Experimental assessment of the low cycle fatigue of landing gear components using a strain based analysis approach

SPPCA Engineering目前观察到的疲劳分析遵循基于重复应力的方法，没有考虑塑性残余，被认为是对高周疲劳寿命的充分估计。这种方法通常被称为“应力寿命”，在低应变高周疲劳应用中会产生可接受的结果。然而，在高应变低循环应用中，对于起落架部件的准确疲劳分析，塑性和平均应力的影响没有得到充分的考虑。由于许多起落架部件在低周疲劳标准下运行，因此需要一种考虑重复应变的方法来准确预测这些部件的疲劳寿命。工业合作伙伴SPPCA目前正在积极开展研究工作，以开发基于应变的可靠方法来预测起落架部件的低周疲劳。这项正在进行的研究工作的范围包括利用应变寿命方法开发基本的疲劳分析程序，并将该程序与其他方法和测试数据进行基准比较，以准确预测起落架部件的疲劳。为了全面实施这种方法，建议与瑞尔森大学合作进行一项实验研究，以产生必要的基于应变的疲劳数据。特别是，这种合作将使SPPCA能够生成和分析应变寿命数据，重点关注塑性和平均应力的影响，并最终使用这些数据开发可用于设计目的的疲劳分析模型。测试计划将在瑞尔森的航空航天材料和工程结构(框架)研究设施进行。

The current fatigue analysis observed by SPPCA Engineering follows a methodology based on repeated stress without accounting for plastic residuals and is considered an adequate estimate of high cycle fatigue life. Generally this method is referred to as "stress life" and will produce acceptable results in low strain high cycle fatigue applications. However, in high strain low cycle applications, the effect of plasticity and mean stresses is not "adequately addressed" for accurate fatigue analysis of landing gear components. Since many landing gear components operate under low cycle fatigue criteria, a methodology that accounts for repeated strain is necessary to accurately predict the fatigue life of these components. The industrial partner, SPPCA, is currently actively pursuing research efforts to develop robust strain based methods for predicting the low cycle fatigue of landing gear components. The scope of this ongoing research effort encompasses the development of a basic fatigue analysis procedure utilizing a strain life approach and benchmarking the procedure against other methods and test data to accurately predict fatigue of landing gear components. In order to fully implement such a methodology, a partnership with Ryerson University is proposed to undertake an experimental study to generate the necessary strain based fatigue data. In particular, such a partnership will enable SPPCA to generate and analyze strain life data focusing on the effect of plasticity and mean stresses and ultimately use such data to develop fatigue analysis models that can be used for design purposes. The testing program will take place in Ryerson's Facility for Research on Aerospace Materials and Engineered Structures (FRAMES).