改进的平均应力准则对钛合金断裂强度的评估(英文)

结构完整性方法通常用来论证工程零件载荷传递的合理性。损伤模型对含尖缺口的钛合金断裂强度的预测取决于材料的无缺口强度以及缺口损伤区前的临界长度。损伤区的临界长度通常取决于材料、试样以及尖缺口的尺寸。平均应力准则作为一种应力断裂准则,常用来对含尖缺口的钛合金抗拉强度进行精确预测。基于不同厚度的中心裂缝钛合金的断裂数据,对平均应力准则进行改进。缺口(断裂)强度的预估值与测试结果接近,表明改进的平均应力准则可以简便地预测缺口的抗拉强度。

基于结构完整性评定方法和有限元分析并考虑焊接残余应力的焊接缺陷评估(英文)

采用欧共体提出的结构完整性评定方法(SINTAP)与有限元分析(FEA)方法,结合焊接残余应力对存在横向贯穿裂纹的ASTMA36钢板和7075-T7351铝合金板对接焊接头的缺陷进行评估。由SINTAP方法、FEA或者实验得到焊接产生的纵向残余应力曲线。该残余应力曲线与SINTAP方法中得到的梯形残余应力拟合较好。计算了3种不同情况下的裂纹长度和残余应力强度因子(SIF),并与通过有限元分析得到的结果相比较,绘制了残余应力强度因子与裂纹长度的关系曲线。利用该图可以计算包括残余应力和力学载荷的总的SIF,比较了总的SIF与损伤容限分析法得到的材料断裂韧性。绘制了焊接态的、力学载荷的和存在残余应力情况下的不同裂纹尺寸的7075-T7351铝合金板的失效评估图,以确定在某特殊裂纹尺寸和力学载荷下的安全水平。

Influence of residual stresses on failure pressure of cylindrical pressure vessels

The utilization of pressure vessels in aerospace applications is manifold.In this work,fnite element analysis（FEA）has been carried out using ANSYS software package with 2D axisymmetric model to access the failure pressure of cylindrical pressure vessel made of ASTM A36 carbon steel having weld-induced residual stresses.To fnd out the effect of residual stresses on failure pressure,frst an elasto-plastic analysis is performed to fnd out the failure pressure of pressure vessel not having residual stresses.Then a thermo-mechanical fnite element analysis is performed to assess the residual stresses developed in the pressure vessel during welding.Finally one more elasto-plastic analysis is performed to assess the effect of residual stresses on failure pressure of the pressure vessel having residual stresses.This analysis indicates reduction in the failure pressure due to unfavorable residual stresses.