机身与起落架连接接头疲劳强度分析方法研究
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摘要
为了对机身与起落架连接接头进行疲劳强度分析,在建立其细节有限元模型时,采用在接头筋条边缘和开口边缘引入"虚元",进行多工况细节应力分析的方法,提取"虚元"应力,进行组谱分析及雨流计数处理,进而确定接头不同部位地-空-地最大应力及其对应的载荷状态,给出一种接头危险载荷状态以及危险部位应力谱的确定方法;在此基础上,使用DFR法进行疲劳分析;采用Nasgro方程对疲劳最薄弱部位进行损伤容限分析,给出检查间隔。文中针对主接头结构形成的一套分析流程可以推广到其他复杂接头疲劳强度评估中。
In order to carry out the fatigue and damage tolerance analysis of the joint connecting fuselage and landing gear structure,a kind of rod element with very small stiffness is laid on the edge of stiffener and cut-outs when the detail finite element model of main joint is built. By using this method,the stress distribution of many different load cases can be obtained. Next spectrum of the special rod elements are edited and rain-flow counting is carried out. The load case which the maximum stress is related to is obtained,a method of obtaining fatigue weak case and fatigue weak sites is proposed. On this basis,DFR method is used to carry out the fatigue analysis,and Nasgro equation is adopted to carry out the damage tolerance analysis. The process can provide the theoretical instruction for fatigue strength assessment of other complex joint structure.
In order to carry out the fatigue and damage tolerance analysis of the joint connecting fuselage and landing gear structure,a kind of rod element with very small stiffness is laid on the edge of stiffener and cut-outs when the detail finite element model of main joint is built. By using this method,the stress distribution of many different load cases can be obtained. Next spectrum of the special rod elements are edited and rain-flow counting is carried out. The load case which the maximum stress is related to is obtained,a method of obtaining fatigue weak case and fatigue weak sites is proposed. On this basis,DFR method is used to carry out the fatigue analysis,and Nasgro equation is adopted to carry out the damage tolerance analysis. The process can provide the theoretical instruction for fatigue strength assessment of other complex joint structure.
引文
[1]中国民用航空局.中国民用航空规章第25部:运输类飞机适航规章:CCAR-25-R4[S].北京:中国民用航空局,2011:56-58.
[2]李宴宾,董登科,弓云昭.在斜向载荷作用下耳片疲劳寿命分析的等效载荷法[J].机械强度,2017,39(3):719-722.
[3]RIGBY R,ALIABADI M H. Stress intensity factors for cracks at attachment lugs[J]. Engineering Failure Analysis,1997,4(2):133-146.
[4]梁尚清,黄其青,殷之平,陈建设.计算应力强度因子的无网格—直接位移法[J].机械强度,2006,28(3):383-386.
[5]MESHII T,WATANABE K. Stress intensity factor evaluation of a circumferential crack in a finite length thin-walled cylinder for arbitrarily distributed stress on crack surface by weight function method[J]. Nuclear Engineering and Design,2001,206(1):13-20.
[6]Southwest Research Institute. NASGRO Reference Manual[M].[S. l.]:Southwest Research Institute,2015:7-19.
[7]《民机结构耐久性与损伤容限设计手册》编委会.民机结构耐久性与损伤容限设计手册(上册)疲劳设计与分析[M].北京:航空工业出版社,2003:273-275.
[2]李宴宾,董登科,弓云昭.在斜向载荷作用下耳片疲劳寿命分析的等效载荷法[J].机械强度,2017,39(3):719-722.
[3]RIGBY R,ALIABADI M H. Stress intensity factors for cracks at attachment lugs[J]. Engineering Failure Analysis,1997,4(2):133-146.
[4]梁尚清,黄其青,殷之平,陈建设.计算应力强度因子的无网格—直接位移法[J].机械强度,2006,28(3):383-386.
[5]MESHII T,WATANABE K. Stress intensity factor evaluation of a circumferential crack in a finite length thin-walled cylinder for arbitrarily distributed stress on crack surface by weight function method[J]. Nuclear Engineering and Design,2001,206(1):13-20.
[6]Southwest Research Institute. NASGRO Reference Manual[M].[S. l.]:Southwest Research Institute,2015:7-19.
[7]《民机结构耐久性与损伤容限设计手册》编委会.民机结构耐久性与损伤容限设计手册(上册)疲劳设计与分析[M].北京:航空工业出版社,2003:273-275.