摘要
大型结构部件通常包含多个可能发生疲劳失效的高应力点,是典型的多点损伤结构。由于材料及结构性能具有分散性,大型结构件相当于一个串联系统,其疲劳寿命(随机变量)是由各高应力部位的寿命(随机变量)共同决定的。由于试验设施限制及加速试验的要求,试验状态下的结构部件往往无法做到与真实服役部件的加载方式及全局应力分布完全一致。在设计大型结构件疲劳试验方案时,需要全面考虑应力较高的多个部位,以保证疲劳试验结果能够客观、真实地再现服役状态下的疲劳寿命。研究基于"大型结构部件寿命概率分布-高应力点数量及寿命概率分布关系"的大型结构部件疲劳试验载荷等效变换方法,研究平均应力修正方法在疲劳试验方案设计中的应用及相关问题,阐释了将大型结构件服役中承受的对称循环载荷转换为试验时易于加载的脉动循环载荷的寿命等效原理、方法及具体计算公式。这些结果表明:通过这样的载荷转换,可以实现寿命概率分布基本等效的同时,显著提高电液伺服系统的试验加载频率(从2 Hz提高到4 Hz),缩短试验时间。
Owing to the dispersion of material and structure property,the fatigue life of a structure part depends on all its high stress sites. A multi-site damage structure is a series system with many weak links( damage sites) in probability sense.Therefore,the fatigue life( a random variable) of a complex structure part with multiple damage sites will be less than the life of the weakest site on the part. Owing to test equipment and conditions,the loads and stress state of a test part cannot exactly reproduce the real structure part in service. The present paper analyzed fatigue life influence factors for a large-size structure part test,expressed the relationship between fatigue life and number of high stress sites,studied fatigue life equivalence method when changing the fully reversed cyclic load in service into pulsation cyclic load in test. Through damage site number based load level adjustment and mean stress modification,this paper provides a load equivalence method to simplify fatigue test of large size multisite-damage parts. The results indicate that through such load transformation,the loading frequency of the electric-hydraulic servo test system can be increase from 2 Hz to 4 Hz,while the fatigue life distribution of the tested part keeps nearly the same as that of the service part.
作者
田洪雷
孙维光
杨文超
谢里阳
TIAN HongLei;SUN WeiGuang;YANG WenChao;XIE LiYang(CRRC Sifang Co.,Ltd.,Qingdao 266111,China;College of Mechanical and Automobile Engineering,Qingdao University of Technology,Qingdao 266525,China;College of Mechanical Engineering and Automation,Northeastern University,Shenyang 110819,China)
出处
《机械强度》
CAS
CSCD
北大核心
2021年第2期434-441,共8页
Journal of Mechanical Strength
基金
国家自然科学联合基金项目(U1708255)资助。
关键词
多部位损伤
串联系统
疲劳试验
平均应力
寿命等效
Multi-site-damage
Serial system
Fatigue test
Mean stress effect
Fatigue life equivalence
