聚晶金刚石复合片热残余应力分布规律实验研究

利用改进的应力释放法、X射线衍射法以及Raman光谱,对平面界面结构金刚石复合片表面热残余应力分别进行了实验研究,得到了金刚石层表面热残余应力值及其分布规律,同时得到了基体厚度与热残余应力的相关关系.研究结果表明,采用应力释放法、X射线衍射法及Raman光谱法测试PDC表面热残余应力,其测试结果均与有限元分析结果相吻合,证明了这三种方法的有效性.其中,X射线衍射法测试结果的误差最大,应力释放法其次,Raman光谱法最为精确.由于应力释放法应变片尺寸及X射线衍射法光斑照射范围的限制,无法在试样表面上取较多的测试点,因此难以得到理想的热残余应力分布曲线.而Raman光谱法中所采用的激光光斑仅5μm,可以取更多的测试点,因此其结果更能真实的反映金刚石层表面热残余应力的分布规律.本文的研究结果为精确测试PDC热残余应力,从而为优化PDC界面结构、提高PDC使用性能提供了理论和实验依据.     

U型钢板桩的X射线法表面残余应力研究

由于对尺寸要求较为严格,因此钢板桩内部的残余应力会对其产品总体质量产生较大影响.采用X射线方法对U型钢板桩二分之一长度和四分之一长度位置的表面残余应力进行了测试.详细说明了X射线残余应力测试原理,试验设备和测试过程,给出了钢板桩应力分布状况.采用全释放法测试了对应点位的残余应力值,比较了X射线法和释放法之间的差距.结果表明X射线方法和全释放法所测数值较为接近,两个位置上的应力分布状态基本一致,钢板桩中部腹板位置呈现压应力,而两边板应力较小.     

膨胀管残余应力测试

膨胀管残余应力是影响膨胀管抗外挤、内压强度的重要因素之一。确定膨胀管的残余应力,测试方法至关重要。在常用测试方法中,机械测量法中的盲孔法体现出测试的优越性。应用盲孔法测试J55、K55两种规格膨胀管的残余应力,并根据实际测试的应力水平和实验误差,采用应变释放系数分级法对试验结果进行修正,以提高测试结果的精度。实验结果表明,膨胀管膨胀后存在环向、轴向的残余应力,且外表面总是压残余应力。将实验结果与仿真结果对比,误差满足工程要求,说明盲孔法测试膨胀管残余应力方便、快捷、准确、有效。     

高压气瓶工艺残余应力测试和分析

用X射线及磁记忆两种方法对压缩天然气的高压气瓶应力状态进行了系统分析,对一个气瓶整体制造工艺中的残余应力变化用X射线法进行了跟踪检测。考察了气瓶锻造后、淬火后及回火后外表面的残余应力状况,对相同测点进行了三次应力测试。为准确找到测点位置并寻求两种方法之间关系,在每次应力测试之前,均用金属磁记忆方法进行了先期检测。结果表明:锻造后应力水平不高,但磁记忆曲线有小幅波动,显示应力不均匀;淬火后表面具有较大压应力,最大达到0.86σS,且磁场亦有较大变化,个别点有明显应力集中;回火处理有效地消除了淬火残余应力,最大值小于0.17σS,应力均匀化,磁记忆曲线几乎无波动,效果良好。而从定量角度,残余应力和磁记忆两者之间没有明确的对应关系。对于磁记忆所显示的磁场强度变化处,用X射线法进行残余应力测试,结果并没有显示出较高的应力水平。说明两种方法不可互相替代,但以其各自的特点和优势可做互相补充。     

整体化复合材料结构残余应力实验研究

通过钻孔法测试了T型整体化复合材料结构件在不同固化工艺方案下的残余应力,并研究了多墙类加筋壁板的腹板和蒙皮的残余应力分布,以及不同钻孔深度对结构件内部残余应力测试结果的影响。研究结果表明:共固化方式下产生的残余应力要小于胶结共固化方式下的残余应力。     

15万立米气柜残余应力及工作应力测试分析

报导了１５万立米大型煤气气柜挂圈走台的残余应力及气柜升降时工作应力的测试结果。该气柜服役十余年后发生煤气泄漏，为分析其原因，进行了残余应力及气柜修复前后的工作应力测试，结果表明：修复前残余应力及工作应力均达到很高水平，气柜升起时伴有严重侧偏现象，修复后应力状态有明显好转。     

2000m~3在役压力容器应力状况分析

本文报道了钢制 2 0 0 0 m3球罐实际运行一年后的应力状况 ,对球罐的残余应力及工作应力进行了现场测试 ,发现球罐虽经过整体热处理 ,但局部残余应力仍较高等问题 ,并进行了对比分析 .     

2000m^3在役压力容器应力状况分析

本文报道了钢制2000m^3球罐实际运行一年后的应力状况,对球罐的残余应力及工作应力进行了现场测试,发现球罐虽经过整体热处理,但局部残余应力仍较高等问题,并进行了对比分析。     

高压聚乙烯装置用G4345V钢厚壁管冷弯残余应力检测

本文对某厂聚乙烯装置用Ｇ４３４５Ｖ钢厚壁管冷弯残余应力进行了检测．为寻求较适用的降低残余应力的方法，对弯管进行两种处理以后的效果进行了检验，二种处理工艺为热处理（３７０℃）及喷丸．最后在现场对喷丸前后的残余应力用磁各向异性探头进行了检测，证明该方法有很大的发展前途     

基于大型炉体焊接残余应力测试的盲孔法研究

为提高炉体焊接残余应力测试精度,对传统的盲孔法进行改进,即在测点打孔后多次扩孔并增加孔深;通过对SM400ZL钢焊接残余应力测试时的应变释放系数A,B进行实验标定,得出多组应变释放系数值,计算可得残余应力的估算值,并对不同状况下的残余应力值进行比较.通过大拉力标定试验得出SM400ZL钢盲孔的孔边塑性变形对测量精度的影响和塑性修正公式.结果表明,改进的盲孔法能够更准确地测得焊接残余应力值,测量结果经塑性修正,最大误差减小到2%以下.测试方法和结果可直接在相关的工程实际中应用.     

Residual stress prediction and determination in 7010 aluminum alloy forgings

Precipitation-hardened aluminum alloys gain their high strength through heat treatment involving a severe quenching operation, which can have the adverse effect of introducing residual stresses. The finite element code ABAQUS is used to simulate the quenching of aluminum alloy 7010 in an attempt to predict the residual stress distribution that develops in simple shapes. The rate of heat transfer from the material is determined using the finite element method to predict the heat transfer coefficient from surface cooling curves achieved experimentally. The flow stress of the material is assumed to be strain rate dependent and to behave in a perfectly plastic manner. The predicted residual stress magnitudes and directions are compared to values determined using the holedrilling strain gage method and the X-ray diffraction technique.     

A study on the relief of residual stresses in weldments with explosive treatment

Explosive treatment is an efficient and economical technique in reducing welding residual stresses. The whole course of residual stress reduction is investigated both numerically and experimentally, in order to discover the mechanism of the explosive treatment and optimizing the technique. It is proved that the reflection and superposition of stress waves aroused by explosive loading lead to redistribution and remarkable reduction of welding residual stresses. Moreover, the optimum working conditions, such as detonator shape, width, location, explosive loading and velocities, are also discussed. The numerical results and the experimental ones are in reasonable agreement with each other.     

爆炸处理消除大型柱壳结构环焊缝残余应力实验研究

为探讨大型耐压柱壳结构对接环焊缝焊接残余应力消除方法,根据耐压柱壳结构环焊缝焊接工艺,设计并制作了大型耐压柱壳结构对接环焊缝模拟焊接模型,并采用沿焊缝条状布药,分别进行了单、双面布药爆炸处理消除大型耐压柱壳结构对接环焊缝焊接残余应力模型实验。结果表明:大型耐压柱壳结构对接环焊缝存在较大的焊接残余应力;单、双面爆炸处理均能有效调整、消除焊接残余应力,残余应力分布明显均匀化;焊后残余应力越大,爆炸处理效果越明显,当焊接残余应力大于0.5s时,单面爆炸处理后残余应力m下降幅度在40%以上,双面爆炸处理后残余应力m下降幅度在60%以上;采用沿焊缝条状布药,爆炸处理能有效消除沿焊缝的纵向残余应力;双面爆炸处理效果优于单面爆炸处理效果。     

汽轮机轮盘热处理残余应力分析

百万核电汽轮机红套低压转子工作环境的蒸汽参数较低,各级轮盘均处于湿度较大的工作区域,易产生应力腐蚀,引起裂纹萌生和扩展．为提高轮盘的抗腐蚀能力,降低工作应力是一个有效的方法．通过热处理方法,在轮盘表面形成预压应力以抵消部分旋转拉应力是可行的方法,而产生适当深度和大小的预压应力则需对热处理过程进行谨慎的设计．本文以汽轮机轮盘为研究对象,建立轴对称有限元模型,通过对ABAQUS软件的二次开发,实现对轮盘热处理过程的温度场及应力场进行数值模拟．计算综合考虑了非线性的材料热物性参数、力学性能参数、表面换热系数及不同材料组织转变的相变潜热、热物性参数和力学参数,通过对不同热处理方法得到的残余应力场的比较,获得了较合理的水冷方式,为热处理工艺确定提供参考．     

X射线法测试1500m^3乙烯球罐焊接残余应力的现场应用

本文应用Ｘ射线应力仪对ＣＦ－６２钢制乙烯球罐焊接残余应力进行了现场测量，解决了大型球罐的残余应力现场测试过程中的技术问题，结果表明焊后残余应力水平较高而热处理效果良好     

Measurement of Applied Stresses and Residual Stresses on a Residual Stress Model by Applying Two Different Loads

Applied stresses on a residual stress model have previously been obtained by measuring the residual stresses and the resultant stresses generated by applying a load. The present paper reports that the applied stresses and the residual stresses on the residual stress model can be obtained by measuring two resultant stresses generated by applying loads of two different magnitudes. In the proposed method, the residual stresses need not be obtained from the residual stress model before applying a load. The residual stress model used to test the proposed method is a circular disk with frozen stresses that is subjected to a diametral compressive load at a certain angle. The applied stresses and the residual stresses on a residual stress model were experimentally and precisely obtained by digital photoelasticity using linearly polarized light.     

钻孔法测量残余应力过程中钻孔附加应变

本文叙述了钻孔法测量残余应力过程中的附加应变.研究应力水平对附加应变的影响是在单向应力条件下进行的,结果表明,钻孔条件、材料状态以及残余应力达到一定值时,附加应变为零.     

聚合物注塑残余应力的研究进展

综述了聚合物注塑残余应力的研究进展,详细介绍计算残余应力所用的理论模型及其基本概念．注塑制品残余应力由两部分组成,并且有不同的测试方法,这些应力是造成制品翘曲变形的原因．对于残余流动应力,重点分析本构模型的发展和注塑控制方程的建立;对于残余热应力,则讨论了冷却过程中的相交问题,以及热粘弹性模型在应力分析中的应用;最后介绍测量残余应力的几种实验方法．      

Measurement and Prediction of Machining Induced Redistribution of Residual Stress in the Aluminium Alloy 7449

The residual stress distributions in two 7449 aluminium alloy rectilinear blocks have been determined using neutron diffraction. Heat treatment included cold water immersion quenching and a period of precipitation hardening. Quenching induced very high magnitude residual stresses into the two blocks. One block was measured in this condition while the other was incrementally machined by milling to half thickness. Neutron diffraction measurements were made on the milled half thickness block at equivalent locations to the unmachined block. This permitted through thickness measurements from both blocks to be compared, revealing the redistribution of residual stresses induced by machining. A square cross section post in the centre of the machined face was left to act as a stress free reference sample. The distortions arising on the face opposite to that being milled were measured using a co-ordinate measuring machine. The residual stresses and distortion arising in the blocks have been compared to finite element analysis prediction and found to generally agree. Material removal only caused distortion and the residual stresses to redistribute; there was no stress relaxation evident.