The Assess On Safety Life,Durability And Damage Tolerance Of Main Gear Strut Cylinder

From the view of safety life, durability and damage tolerance, the article mainly discuss the assess of key position of strut cylinder.Because there is no measured load spectrum, the article gives the typical task fatigue load spectrum of main landing gear of some aircraft based on <> GJB3099-97 and under the relational stipulation of the <> GJB67. 6-85. It is closer to the practicality than the method of purely designing spectrum.Fatigue safety life assesses use compare methods, which are, comparing of life test and life calculation of type A aircraft and type B aircraft main landing gear strut cylinder key danger position in group simulators. Using results of prototype aircraft (type A aircraft) main landing gear full-scale fatigue test, we can amend the S~N curve of slick test part to the S~N curve of component danger position by amending synthetically, and so that the conclusions of life calculation are more reliable.Improved crack sprout method is adopted in durability economy life analysis, which method is applied time after time to the economy life assess of domestic aircraft structure, and the result is reliable.During damage tolerance analysis, the probably crack types of key danger position are surface crack and edge angle crack in this article. Damage tolerance analysis model select generalized Willenborg model. To meet the residual strength requirement, it takes the stress intensity factor K1C/1. 2 as the termination condition in crack propagation calculation in the article.In the end, the article gives the conclusion as following: the main landing gear strut cylinder of type B aircraft first repairing period is 4000 landing and take-offs, examine interval is 1500 landing and take-offs and the total life is 6000 landing and take-offs.