摘要
高周疲劳中的应力梯度与尺寸效应研究的目的有两个,第一,拓展经典的高周疲劳(HCF)准则(如Crossland, Dang Van,Papadopoulos,et al),进而考虑到这些疲劳准则在介观长度lg下的空间应力变化;第二,通过疲劳试验对比来了解扩展的准则对于这种效应的准确性。在引出由Luu等人提出的基本疲劳标准综述和他们的基于梯度效应的扩展后,专注于针对Crossland准则,同时考虑到应力幅和最大静水应力的梯度,一种更实用和简单的表达式被提出。在实验室环境下通过两种典型加载模式测试:简支梁弯曲测试和悬臂旋转弯曲测试,得到了理论值和数值模拟之间的差别,之后使用更为复杂的弯曲扭转试验来检验新准则的准确性。该方法对于其他多轴疲劳标准的推广在Papadopoulos 2001年的论文中有过详细阐述。最后,本研究提出了一种考虑梯度效应的多轴高周疲劳(HCF)准则扩展方法。在这项工作中仅强调梯度效应对于疲劳寿命的增益效果。
The objective of the work is firstly to extend some classic high cycle fatigue(HCF)criteria(as Crossland,Dang Van,Papadopoulos,et al)to take into account a sensitivity of the criteria to stress spatial variations occurring at length scale l_g,and secondly to compare the performances of the extensions through numerical simulations of experimental fatigue tests.After an introduction of the basic criteria and their gradient based extensions proposed by Luu et al.,we focus on the Crossland criterion to propose a more practical and simple expression taking into account the gradient of the stress amplitude and the maximum hydrostatic stress.The proposition is then tested and applied to different simple situations:4-point bending and cantilever rotative bending.The relative errors between the exact solutions and the numerical simulations are estimated.Biaxial bending-torsion tests are also simulated to demonstrate the capabilities of the approach.The generalization of the approach to other multiaxial fatigue criteria is briefly shown through the case of Papadopoulos 2001 proposal.Finally,the present study develops a simple formulation of gradient multi-axial fatigue criteria extending the classical HCF criteria.In this work only stress gradient with a beneficial effect on fatigue have been considered.
作者
马泽鹏
刘思宏
梁吉鹏
崔高伟
黄佳
MA Ze-peng;LIU Si-hong;LIANG Ji-peng;CUI Gao-wei;HUANG Jia(Beijing Institute of Structure and Environment Engineering,Beijing 100076,China)
出处
《强度与环境》
CSCD
2020年第5期7-12,共6页
Structure & Environment Engineering
基金
国家自然科学基金(12002055)。
关键词
高周疲劳
应力梯度
多轴
长度尺度
High cycle fatigue
gradient
multi-axial
length scale
