薄膜X射线应力分析

由于Ｘ射线薄膜衍射几何的特点，致使薄膜Ｘ射线应力分析的精度很骓达到常规应力分析水平。本文采用真空充阑、内标校正的途径来提高薄膜Ｘ射线应力分析的精度。     

陶瓷—金属连接残余应力X射线衍射测试方法

用大功率的ＭＸＰ１８－ＨＦ Ｘ射线衍射仪测量了金属与陶瓷连接处的残余应力分布。实验表明，该衍射仪Ｘ射线强度高，光斑细，适用于材料残余应力分布的精确测量。通过用它对金属－陶瓷界面应力梯度的测量，为残余应力的缓解提供了依据。     

自增强反应管残余应力的测试

介绍一种用Ｘ射线法测试自增强反应管残余应力的方法，并将试验结果与常用的镗削法加以比较，结果表明Ｘ射线法可以用于自增强管体的残余应力测试。     

浦东国际机场钢层架上弦主梁的残余应力测定与分析

利用Ｘ射线应力测定技术对浦东国际机场钢屋架眩弦主梁的残余应力进行现场测定。简要阐明了造成不同焊缝应力分布的原因及火工校弯成形工艺对构件残余应力分布的影响。     

金属基复合材料残余应力测定

分析了金属基复合中热残余应力的形成机理及表现特点，并对几种常用的测定金属基复合材料残余应力的方法进行了分析比较，普通Ｘ射线法虽然简便、经济、但穿透能力有限，所测值仅反映试样表面的残余应力状态；中子衍射的区域较大，测出的仅是残余应力平均值。Ｘ射线能量衍射法虽然穿透能力较强，能测出试样内部较深范围的残余应力，但由于产生衍射法穿透力强，分辩率高，能测出复合材料内部的残余应力场梯度，是测定金属基复合材料残     

碳化硅晶须增强铝基复合材料热残余应力的宏观特征

采用Ｘ射线宏观应力测试方法，测量ＳｉＣｗ／ＬＤ２复合材料的热残余应力，应用盲孔及电阻应变片技术，研究热残余应力对宏观应变释放的影响。结果表明，热残余应力在材料表面呈三向拉应力状态，且不能引进宏观应变释放，是伪宏残余应力。冷处理可降低复合材料的热残余应力。     

高密度聚乙烯在应力作用下结构研究

本文使用广角Ｘ射线衍射仪研究了高密度聚乙烯在应力作用下晶体结构变化。我峰分离程序对样品的Ｘ射线衍射谱图进行后续数字化处理，通过ＭＰＳ处理后的谱图可以将力化学加工过程出现的单斜相与原有的正交相和非晶相彼此重叠的ＸＲＤ谱图完全分离，计算了三相的相对含量以及结晶度和各相的微晶尺寸。     

残余应力对储罐泄漏的影响

本文应用Ｘ射线法对不储槽及输送管道的残余应力进行了检测与分析。对焊缝、热影响区、母材等典型部位进行了重点测试，对热处理的效果进行了检测与评价，找出了储槽泄漏的原因。     

SiCp／6061Al复合材料基体相及增强相的实际外载应力

采用Ｘ射线应力分析技术测定ＳｉＣ颗粒体积分数为２０％的ＳｉＣｐ／６０６１Ａｌ复合材料由外加载荷作用而产生的基体铝合金相的实际外载应力，据此计算增强相的实际外载应力，结果表明，基体铝合金的相的实际外载应力为平均外载应力的７５．９％，而增强相的实际外载应力为平均外载应力的１９６．６％，两相性模量的差异是造成这种现象的主要原因。     

MSF—2M型X射线应力仪的微机控制系统开发研究

对ＭＳＦ－２Ｍ型Ｘ射线应力仪开发的微机控制系统，有效地拓宽了仪器的测量分析功能。系统可用多种扫描控制方式进行测量，实现了测量过程中动态图形跟踪、自动数据采集、应力分析计算和图形结果打印等功能。本文着重介绍系统的详细结构、微机与仪器之间的通讯命令体系以及实现控制的工作全过程。     

改进的复合材料斜接结构胶层应力半解析法

引入微分概念和复合材料铺层刚度分配原则,形成一种改进的求解复合材料斜面对接结构胶层应力的半解析方法 MAM(Modified semi-Analytical Method)。首先,针对铺层角度及铺层数不一致的情况,采用有限元法(FEM)平面应变模型对MAM进行验证;然后,分别用平均剪应力法、FEM及MAM预测了复合材料斜接结构的承载能力并与试验值进行对比;最后,利用MAM分析工程应用问题,考虑了被粘结体刚度不匹配及胶层厚度的变化。研究结果表明:MAM适于设计复合材料斜接结构;采用MAM能得到胶层应力的尖峰值,且应力分布与FEM计算一致。     

渐开线齿轮的接触分析

以Hertz应力表达式为基础,将单齿啮合的渐开线齿轮等效为相互挤压的两个圆柱体,推导了齿轮接触应力的理论表达式．建立一套单齿对啮合的有限元分析方法,包括引入渐开线和齿根过渡曲线方程及对应的自变量区间,建立参数化齿廓;模型轮缘厚度取3倍的模数,周向宽度取3倍的齿厚;在接触面上进行网格细化处理;在对应的主、从动齿轮内缘分别施加均匀切向力和固定约束等．计算结果显示,有限元解和理论解吻合较好,最大偏差不超过5%,该方法适用于不同的啮合轮齿参数．由有限元方法得到的渐开线轮齿的接触应力符合Hertz理论中的半椭圆分布规律,Mises应力和剪应力分布也符合接触力学理论,但应力分布的对称中心存在偏离或者偏斜现象,分析认为,是由于轮齿弯曲变形造成的．     

Heat transfer and thermal stress analysis in grooved tubes

Heat transfer and thermal stresses, induced by temperature differences in the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was applied from the external surface of the tube. Energy and governing flow equations were solved using finite difference scheme. Finite element method (FEM) was used to compute the thermal stress fields. Grooving effects on the thermal stress ratio have been discussed. As a result, maximum thermal stress occurs in the case ofp =d for all water inlet velocities. The maximum thermal stress ratio positions inside the tube have been indicated as MX for all investigated cases. In the light of the thermal stress values, various designs can be applied to reduce thermal stress in grooved tubes.     

Thermomechanical Analysis of Preheat Effect on Grade P91 Steel During GTA Welding

Effect of preheat on the thermal cycles, residual stress, and distortion during autogenous GTA welding of Grade P91 steel has been analyzed using FEM. Phase transformation effect on the residual stresses is also analyzed. Thermomechanical analysis has shown that preheat reduced the peak temperatures, cooling rate, and the distortion values. The phase transformation involving martensite during cooling resulted in typical “M” shaped residual stress profile with a reduction in peak tensile residual stress value and a wider distribution of residual stress. There is good agreement between the predicted and measured thermal cycles, residual stresses, and distortion of the P91 steel weld joint.     

振弦式压力盒在刚性接触面应力

在阐述振弦式压力盒组成结构和测试原理的基础上，结合江阴大桥(封面)南锚碇基底应力监测实践，分析了振弦式压力盒在刚性接触面应力监测中的可行性和存在的问题，推导出压力盒率定系数的表达式，提出基于有限元模拟分析的压力盒实测资料修正方法，建立了修正系数与被测介质刚度的关系式。研究成果表明，在刚性接触面应力监测中，振弦式压力盒的实测值普遍明显偏小，甚至仅为理论值的十几分之一，其原因是压力盒的实际受力条件与率定受力条件有明确而明显的不同，被测介质刚度对压力盒测值有重要影响。     

高性能铜合金板带残余应力测量中的转动结构的应用和分析

利用转动结构对面内位移高度灵敏的特性提出了高性能铜合金板带残余应力测量的新方法,对转动结构作了有限元分析和结构优化。设计了实验装置模拟残余应力释放对转动结构变形的影响。实验与有限元分析结果取得良好一致。本研究表明转动结构具有较高的测量灵敏度和良好的线性,试样制作及数据测量方便,为高性能铜合金板带残余应力测量提供了一种新的检测手段。     

A quasi‐static crack growth simulation based on the singular ES‐FEM

In the edge‐based smoothed finite element method (ES‐FEM), one needs only the assumed displacement values (not the derivatives) on the boundary of the edge‐based smoothing domains to compute the stiffness matrix of the system. Adopting this important feature, a five‐node crack‐tip element is employed in this paper to produce a proper stress singularity near the crack tip based on a basic mesh of linear triangular elements that can be generated automatically for problems with complicated geometries. The singular ES‐FEM is then formulated and used to simulate the crack propagation in various settings, using a largely coarse mesh with a few layers of fine mesh near the crack tip. The results demonstrate that the singular ES‐FEM is much more accurate than X‐FEM and the existing FEM. Moreover, the excellent agreement between numerical results and the reference observations shows that the singular ES‐FEM offers an efficient and high‐quality solution for crack propagation problems. Copyright © 2011 John Wiley & Sons, Ltd.     

车载作用下大跨径缆索支承桥桥型对铺装层受力的影响研究

以润扬长江公路大桥为工程背景，通过有限元数值模拟技术，分析建立其北汊斜拉桥和南汊悬索桥的三维整桥模型，进行整桥力学分析，提出整体—局部分析方法，进而分析铺装层的受力特点；悬索桥的桥型对铺装层的受力影响较大，作者计算的铺装层拉应力明显大于以往模型；对于斜拉桥跨中位置，考虑整桥后铺装层的受力略大于局部模型，对于承受斜拉索水平分力挤压的主梁部分，其铺装的受力略小于局部模型。     

Finite element method and experimental investigation on the residual stress fields and fatigue performance of cold expansion hole

Cold expansion is an efficient way to improve the fatigue life of an open hole. The residual stress fields of cold expansion holes are vital for key components designing, manufacturing and fatigue properties assessment. In this paper, three finite element models have been established to study the residual stress fields of cold expansion hole, experiments were carried out to measure the residual stress of cold expansion hole and verify simulation results. Three groups of specimens with different cold expansion levels are examined by fatigue test. The fracture surfaces of specimens are observed by scanning electron microscope. The finite element method (FEM) results show, with interference values develop, the maximum values of circumferential residual compressive/tensile stresses increase in “infinite” and “finite” domain, and a higher positive stress values are obtained at the boundary of “finite” domain. The effects of the friction between the mandrel and the hole’s surface and two cold expansion techniques on the distribution of residual stress is local, which only affects the radial residual stress around the maximum value and the circumferential residual stress near the hole’s edge. Crack always initiates near entrance face and the crack propagation speed along transverse direction is faster than that along axial direction.     

深冷处理消除铝合金板材残余应力的建模与仿真

介绍了用(热)弹塑有限元技术对铝合金板材深冷处理过程进行建模与仿真的基本原理.基于实验研究探讨了深冷处理数值模拟所需的7075铝合金材料的物性参数.运用ABAQUS6.5有限元软件,对7075铝合金板材深冷处理过程瞬态温度场与应力场进行了数值模拟.数值模拟得到的残余应力值与已发表文献的实验结果比较一致.最后分析了不同厚度铝合金板材的深冷处理应力消除效果.