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

SPPCA Engineering观察到的当前疲劳分析遵循基于重复应力的方法，未考虑塑性残余，并被视为高循环疲劳寿命的充分估计。 通常，这种方法被称为“应力寿命”，并将在低应变高循环疲劳应用中产生可接受的结果。 然而，在高应变低循环应用中，塑性和平均应力的影响对于起落架部件的精确疲劳分析没有“充分地解决”。 由于许多起落架部件在低周疲劳标准下工作，因此需要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，用于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开发一个基本的疲劳分析程序，利用应变寿命的方法和基准程序对其他方法和测试数据，以准确地预测起落架部件的疲劳。 为了充分实施这种方法，建议与瑞尔森大学合作进行实验研究，以产生必要的应变疲劳数据。特别是，这样的伙伴关系将使SPPCA能够生成和分析应变寿命数据，重点是塑性和平均应力的影响，并最终使用这些数据来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航空航天材料和工程结构研究设施（FRAMES）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).