基于载荷—强度关系的失效率离散建模方法及模型  

DISCRETE FAILURE RATE MODELLING APPROACH AND LOAD-STRENGTH INTERFERENCE ANALYSIS BASED MODEL

作　　者：谢里阳[1] 林文强[1] 

机构地区：[1]东北大学机械工程与自动化学院,沈阳110004

出　　处：《机械强度》2010年第4期570-575,共6页Journal of Mechanical Strength

基　　金：国家自然科学基金(50775030);国家863(2007AA04Z428)资助项目~~

摘　　要：传统方法借助于寿命分布构造失效率函数,没能将失效率与载荷、强度等可靠性基本控制变量直接联系起来。因而,传统上对失效率函数的变化规律或失效率曲线形态的认识还只能是唯象的和定性的。尽管失效率是可靠性工程中经常用到的指标,由于没有"失效率—载荷分布—强度分布"关系模型,对产品失效率的变化规律及其影响因素的解释难免片面,更无法预测。根据机械零部件及机械装备的载荷特点及失效机理,采用离散的广义"时间"物理量,用载荷作用次数代替传统的连续时间量,定义"离散失效率",阐述"离散失效率"与失效概率之间的关系,显示通过载荷—强度干涉关系建立失效率模型的可行性。基于能反映强度退化效应、能反映载荷历史统计效应的动态载荷—残余强度干涉关系,建立失效率—载荷作用次数关系方程,呈现典型的失效率浴盆曲线。从载荷分布与强度分布及其之间相互作用的角度,阐释产品服役过程中失效率的变化规律及主要影响因素,揭示强度退化规律、载荷分散性、强度分散性等因素对失效率曲线形状的影响。Failure rate model was conventionally constructed with life distribution function, failing to relate failure rate to the basic controlling variables such as load and strength. Without a failure mechanism based model, the traditional interpretation on the variation of failure rate with operation time was only qualitatively. In view of the load characteristic and typical failure mechanism of mechanical product, discrete time variable, i.e. load action number n is used to replace the continuous calendar time t. Besides, a new concept of ＂discrete failure rate＂ is defined, and the equality between the ＂discrete failure rate＂ and failure probability is illustrated. Thus the feasibility is proven to model failure rate through general load-strength interference analysis. Furthermore, a ＂failure rate-load action num- ber＂ equation was developed by means of the discrete time parameter （i. e. nutuber of load action） and dynamic （i. e. load history dependent） load-strength interference principle. The equation can present typical bathtub shaped failure rate curve. Moreover, failure rate variation over operation time was interpreted from load-strength interaction, and the effects of load uncertainty, strength tmcertainty, as well as the strength degradation mode on the shape of failure rate-number of load action curve, i.e. the bathtub curve, was highlighted.

关 键 词：离散失效率 载荷统计量分布 残余强度 分广义载荷-强度干涉分析 

分 类 号：O346.1[理学—固体力学] TB114.3[理学—力学]