摘要
用有限元法计算了一种低合金高强钢缺口试样在非对称四点弯曲加载(Ⅰ+Ⅱ型复合加载)下缺口前端的变形和应力应变分布.研究结果表明:纯Ⅰ型加载时,缺口前端变形和塑性区形状对称分布.Ⅰ+Ⅱ型复合加载下缺口前端的变形为一侧钝化,另一侧锐化,塑性区顺时针旋转一个角度θ,且θ随Ⅱ型载荷比例的增加而增大.表征缺口前端变形程度的d/b0 值,随外加载荷P/Pgy的增加和Ⅱ型载荷比例的增加而增大.另外,对缺口前端最小塑性区路径上的最大切向正应力σθθ、三相应力度σm/ σ和等效塑性应变εp 的分布,以及它们随外加载荷P/Pgy和Ⅱ型载荷比例的变化规律也进行了分析,发现缺口试样的开裂遵循最大切应力判据.
The distribution of deformation,stress and strain in front of notches under symmetric four-point bending loading (mixed mode Ⅰ/Ⅱ loading) was calculated with finite element method for a HSLA steel.The results showed that,under pure mode Ⅰ loading,the deformation and shape of the plastic zone in front of the notch tips are symmetric.Under mixed mode Ⅰ/Ⅱ loading,the notch tip blunts on one side and sharpens on other side,and the plastic zone shifts an angle θ clockwise.With the increase of the portion of mode Ⅱ,the angle θ increases.With the increase of the applied loads P/P_(gy) and the portion of mode Ⅱ,the parameter d/b_0 which characters the deformation level of the notch tip,increases.In addition,the distribution of the maximum tangent normal stress σ_(θ θ),stress triaxiality σ_m/,and equivalent plastic strain ε_p along the path of minimum plastic zone as well as their changes with applied loads P/P_(gy) and the portion of mode Ⅱ were are also analyzed.The result showed that the behavior of the fracture of the notch sample are found to agree with a maximum tangential tensile stress under mixed modes I and Ⅱ.
出处
《兰州理工大学学报》
CAS
北大核心
2005年第2期16-20,共5页
Journal of Lanzhou University of Technology
基金
国家自然科学基金(50471109)
关键词
低合金钢
复合型加载
有限元
应力
应变
缺口
low alloy steel
mixed-mode loading
finite element analysis
stress
strain
notch
