【作者】 蒋刚；

【导师】 何闻；

【作者基本信息】 浙江大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 本论文结合国家自然科学基金资助项目“多维高频微观激振时效机理及相关技术的研究”(No．50305036)，采用理论仿真与实验相结合的方法，对高频振动时效消除焊接残余应力的效果进行了研究。第一章介绍论文的研究背景和意义。综述了残余应力和振动时效技术的国内外研究现状，具体介绍了现有残余应力测试与评估技术；在此基础上提出了论文的研究内容及研究方法。第二章研究了焊接残余应力的理论及数值仿真过程。首先，介绍了焊接残余应力的产生机理及分布。然后对焊接过程中的温度场及弹塑性应力应变关系的有限元模型进行了理论研究，分析了温度场、残余应力场的计算方法。最后在大型有限元分析软件ANSYS上实现了焊接残余应力的数值仿真，得到了焊接残余应力的分布规律。分析结果表明模型的最大拉伸残余应力出现在熔和区附近，随着离焊缝的距离增加，逐渐变为压应力，离焊缝更远的地方，压应力逐渐变为小。第三章研究了高频振动时效的机理及数值仿真过程。首先从金属的应力应变机制和细观力学角度分析了常规振动时效和高频振动时效，得出了振动时效动应力必须满足的力学表达式，并对比了它们的差异，然后建立了振动时效消除焊接残余应力的仿真模型，采用大型有限元软件ANSYS对其进行了数值仿真，并比对了高频振动时效与常规振动时效的仿真结果。仿真结果表明高频振动时效比常规振动时效具有更好的残余应力消除效果，特别是在焊缝处的残余应力峰值处，并且高频振动处理后相比于低频处理后的应力均化状况要好。第四章对高频振动时效进行了实验研究。介绍了盲孔法测量残余应力的原理，并利用振动时效装置对焊接钢板进行高频振动时效消除焊接残余应力实验，并对不同激振频率对振动时效的效果影响进行了分析研究。实验结果证明了高频振动时效消除焊接残余应力的可行性，且激振频率越高，焊缝处残余应力消减率越高。第五章对论文的研究成果做出总结，并对以后有待进一步研究的工作进行展望。更多还原

【Abstract】 This dissertation is composed based on the project of National Natural Science Foundation of China—"Research on mechanism and related technology of multi-dimensional, high frequency, microscopic viewed Vibration Stress Relief (VSR)" (No.50305036).In the way of both theoretical simulation and experimental study, the effect of reducing the welding residual stress by high frequency VSR has been deeply researched. This dissertation consists of five chapters as followingIn chapter 1,the background and significance of the research were introduced. Then the current research situations of residual stress and VSR technology both at home and abroad were summarized. Meanwhile, the technology of how to test residual stress were specifically introduced. Finally, the framework of contents and researching methods were proposed.In chapter 2, the theories of welding residual stress and its process of numerical simulation were researched. Firstly, the mechanism and distribution of welding residual stress was introduced. Then, the finite element models for the thermal field and the relation of elastic plastic stress-strain in the process of welding were theoretically analyzed, and the calculation method of thermal field and residual stress field was deduced. At last, the numeric simulation of welding residual stress by using FEM software ANSYS was achieved, and the distribution of welding residual stress was got. The results of analysis indicate that the maximum tensile residual stress is in the fusion zone; moreover, following the increase of the distance away from the weld, the stress turns into the compressive stress and with the distance increasing from the weld, the compressive stress is becoming smaller.In chapter 3, the mechanism of high frequency VSR and its numerical simulation were studied. Firstly, regular VSR and high frequency VSR were analyzed from the view of metal stress-strain mechanism and mesomechanics, and from which the mechanics expressions of the stress in VSR were obtained, then the regular VSR and high frequency VSR were contrasted to show their difference. Finally, the simulation model of VSR was established and its numerical simulation was implemented by FEM software ANSYS, following, the outcome of these two kinds of VSR was analyzed comparatively. The results of the simulation indicate that high frequency VSR has a better effect, especially in the peak value area of weld joints, on relieving residual stress than regular VSR. Furthermore, the homogenization condition of residual stress is better by using high frequency VSR than regular VSR.In chapter 4, a series of experiments about high frequency VSR were carried out. At first, the measurement technique of blind hole method was introduced. Then the experiment of releasing residual stress of welded specimens by VSR device was tested. We analyzed the test process and results systematically and compare the effects of VSR between different drive frequencies. The experimental outcome indicated the feasibility of releasing stress by high frequency VSR, and the higher the drive frequency is, the higher the depletion rate of residual stress is.In chapter 5, all achievements of the dissertation were summarized and the further research work, which will be done from now on, was put forward.更多还原