首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
基于大型炉体焊接残余应力测试的盲孔法研究   总被引:1,自引:0,他引:1  
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.  相似文献   

2.
焊接残余应力是引起应力腐蚀开裂的主要原因,准确地掌握残余应力的分布是对结构完整性评定的关键.为了探明反应堆压力容器顶盖控制棒驱动机构(control rod drive mechanism,CRDM)贯穿件J形焊缝残余应力的分布,本研究加工两个CRDM贯穿件实验模拟件,采用盲孔法测试两个J形接头的焊接残余应力.通过实验探明了CRDM贯穿件焊缝残余应力的分布规律,为反应堆压力容器结构完整性的研究提供必要参考.  相似文献   

3.
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.  相似文献   

4.
采用新型三维云纹干涉系统并结合盲孔释放的方法 ,研究了半导体装配底座内的残余应力 ,这种混合的方法不仅能真实测试试件因应力的释放而产生的三维变形信息 ,而且具有灵敏度高、条纹对比度好等特点。本文中 ,残余应力是通过盲孔释放获得 ,然后使用三维干涉系统来测试试件因残余应力的释放而发生的位移 ;利用有限元模拟的方法 ,精确计算了应力大小和分布情况 ,为实验研究提供了有力的支持和补充。结果表明 ,残余应力在F - 1C半导体内部分布不均匀 ,在两引脚之间的区域 ,应力比邻近区域的应力要大 ,存在一定的应力集中 ,对可伐管产生一定的挤压作用 ,这是造成半导体装配底座失效的一重要原因。  相似文献   

5.
相移云纹干涉法与盲孔法相结合检测复合材料的残余应力   总被引:1,自引:0,他引:1  
常红  姚河省  侯丽丽 《力学季刊》2006,27(3):511-514
本文应用相移云纹干涉法与盲孔法相结合检测纤维增强复合材料的残余应力。盲孔法是工程中被广泛应用的测定残余应力的方法之一,相移云纹干涉方法可得到孔边任意一点的位移信息。由于正交各向异性复合材料在弹性主方向不发生拉剪(或剪拉)耦合效应,所以通过适当读取孔边特殊点的位移,可方便地得到残余应力值。  相似文献   

6.
本文应用弹塑性理论研究了被测试样的屈服强度、应力场对钻孔法测量残余应力过程中钻孔附加应变的影响,使用简化的理论模型推导了低速旋转钻头钻孔产生附加应变的一般表达式.结果表明钻孔引入的附加应变与被测试样的原始残余应力状态有关,随应力水平增加而增大,在压应力减小到某一临界值σ时,钻孔附加应变为零。在 Ly12铝合金上的实验测量结果与理论结果一致。  相似文献   

7.
表面涂层材料的残余应力测量技术   总被引:2,自引:0,他引:2  
本文采用电测盲孔法测定表面涂层材料残余应力的测量技术,在试件和表面涂层结构上进行测试.大量试验表明,此方法可靠、有效,可在工程实际中使用,为解决表面涂层“爆裂”等问题,提供了有效的测定残余应力的手段  相似文献   

8.
本文介绍了改进的光弹性贴片盲孔法测残余应力的计算公式,并与西田正孝计算公式进行了对比。进行了单向均匀拉伸板模拟残余应力试验验证,以及对接焊板残余应力实测。  相似文献   

9.
焊接残余应力是引起应力腐蚀开裂的主要原因,准确地掌握残余应力的分布是对结构完整性评定的关键.为了探明反应堆压力容器顶盖控制棒驱动机构(control rod drive mechanism,CRDM)贯穿件J形焊缝残余应力的分布,本研究加工两个CRDM贯穿件实验模拟件,采用盲孔法测试两个J形接头的焊接残余应力.通过实验探明了CRDM贯穿件焊缝残余应力的分布规律,为反应堆压力容器结构完整性的研究提供必要参考.  相似文献   

10.
激光反射全息干涉法现场测量残余应力的实验研究   总被引:1,自引:0,他引:1  
本文根据激光反射干涉法的基本原理,采用钻盲孔释放残余应变的手段,提出一种新颖的残余应力激光全息现场测量的方法,推导出该光学测量方法3种计算公式.解决了激光全息干涉法不能进行现场实测的难题.  相似文献   

11.
Residual stress measurement is of critical significance to in-service security and the reliability of engineering components, and has been an active area of scientific interest. This paper offers a review o[ several prominent mechanical release methods for residual stress measurement and recent developments, focusing on the hole-drilling method combined with advanced optical sensing. Some promising trends for mechanical release methods are also analyzed.  相似文献   

12.
金鹏  李喜德 《实验力学》2017,(5):645-651
残余应力分析方法主要有衍射法、应力释放法和声、光、磁等方法。其中,X射线衍射法与应力释放中的钻孔技术与理论最为成熟,应用最广。在应力均匀且数值较小时,两者可以给出相互接近的结果。然而当样品微小且微观结构复杂时,两者给出的结果会有明显的差异。本文利用上述两种方法对同一纯铜样品表面的残余应力进行分析,对比分析结果并讨论了相关的影响因素。我们对X射线衍射法与环芯法的适用性进行了讨论:前者适用于晶体材料的无损检测,而后者更能反映当前应力水平。此外,对方法的选用需要考虑应力测试的目的。  相似文献   

13.
Smit  T.C.  Reid  R.G. 《Experimental Mechanics》2020,60(8):1135-1148

Background: Incremental hole-drilling with the integral method has been extensively used in composite laminates but is sensitive to small measurement errors. Error sensitivity can be reduced by limiting the number of depth increments used in the calculation procedure. This approach is limited if a rapidly varying residual stress distribution exists since the calculated stress in each incremental depth is considered constant. Distortion of stress results can consequently occur due to averaging effects if the depth increments become too large. Tikhonov regularization is usually applied in isotropic materials to smooth the resulting residual stress distribution and reduce stress uncertainties, but has only been applied to composite laminates using the slitting technique. Objective: The intention of this work is to extend the use of Tikhonov regularization to incremental hole-drilling of composite laminates using the integral method. Methods: Finite element modelling is used to calculate the necessary calibration coefficients for unit pulses of uniform stress. Monte Carlo simulation is used to the determine uncertainties in the calculated residual stress distributions. Tikhonov regularization is optimised to reduce the stress uncertainty, while ensuring that the stress solution is not distorted. Results: The method is demonstrated on a GFRP (Glass fibre reinforced plastic) laminate of [02/902]s construction and the calculated residual stress field is compared with those obtained by the standard integral method and series expansion. Conclusions: It is found that Tikhonov regularization significantly improves the accuracy of the standard integral method in composite laminates and shows good agreement with the series expansion method.

  相似文献   

14.
The absence of expansion joints in Continuous Welded Rail has created the need for the railroad industry to determine the in-situ thermal stress levels for rail buckling and breakage prevention. This paper explores the hole-drilling method as a possible solution to this problem. A new set of calibration coefficients to compute the stress field relieved by fine hole depth increments required by the high strength steel was determined. The new calibration coefficients were experimentally validated on an aluminum plate subjected to a known uniaxial load. The thermal stress levels of constrained rails were estimated after compensation for the residual stress components, based on statistical relationships developed experimentally between the longitudinal and the vertical residual stresses. The results showed that the hole-drilling procedure, with appropriate calibration coefficients and residual stress compensation, can estimate the in-situ rail thermal stresses with an expected accuracy that is within the industry acceptable levels.  相似文献   

15.
The incremental hole-drilling method is widely used in residual stress depth distribution analysis. However, two specific difficulties with the generalization of the incremental method exist, including the consideration of the sample thickness and residual stress states close to the local material’s yield strength. The stress concentration effect of the hole can lead to plastic deformation in the vicinity of the hole, which results in an overestimation of residual stresses. Typically, the effect of the component’s thickness and the plasticity effects are analyzed separately and correction approaches are proposed. In the current paper, we analyze the combined effects of plasticity and thickness on residual stress analysis using the incremental hole-drilling method. A systematic study was performed on steel samples with (i) isotropic and (ii) anisotropic elastic and elasto-plastic material behavior with varying thicknesses ranging between 1 mm and 4 mm. Electronic speckle pattern interferometry (ESPI) hole-drilling experiments were conducted on beam samples loaded using a 4-point bending fixture. Finite element simulations were conducted to gain insight into the effects of incremental hole-drilling. The results indicate that reducing the component’s thickness increases the plastic deformation in the vicinity of the hole and results in significant stress deviations. Thin components bend during hole-drilling as a result of the loss of stiffness, which amplifies the plasticity effect.  相似文献   

16.
Residual stress estimation is an important question for structural integrity. Since residual stresses are self-balanced stress fields, a classical way to obtain information on them is to remove a part of the structure, and observe the structure displacement field arising from the stress redistribution. The hole-drilling method is such an approach. In some cases, as for the present one concerning a painted panel of cultural heritage, the hole-drilling method is not suited (a structure with a complex geometry, few tests allowed) but one can take advantage of structural modifications if they are monitored (here, a restoration act). We therefore describe in this article a model updating approach, focusing on the residual stress estimation and not on the material parameter identification.This study couples an optical non-invasive shape measurement (digital image correlation, using a projected speckle pattern on the painted panel, with luminance compensation) and a numerical approach (3D finite elements) for the model updating. The 3D stereo-correlation is used to measure a partial displacement field between three different states of the structure (at three different times of the restoration act). The numerical part concerns stress evaluation, once the model and the experiments are compared using a geometric mapping and a spatial projection of discrete fields. Using modeling and identification, the simulation is used to obtain the residual stresses in the panel, before and after the restoration.  相似文献   

17.
The Integral Method for determining residual stresses involves making surface deformation measurements within a sequence of small increments of material removal depth. Typically, the associated matrix equation for solving the residual stresses within each depth increment is ill-conditioned. The resulting error sensitivity of the residual stress evaluation makes it essential that data measurement errors are minimized and that the residual stress solution method be as stable as possible. These two issues are addressed in this paper. The proposed method involves using incremental deformation data instead of the total deformation data that are conventionally used. The technique is illustrated using an example ESPI hole-drilling measurement.  相似文献   

18.
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。  相似文献   

19.
Hole-drilling method is one of the most convenient methods for engineering residual stress measurement. Combined with moiré interferometry to obtain the relaxed whole-field displacement data, hole-drilling technique can be used to solve non-uniform residual stress problems, both in-depth and in-plane. In this paper, the theory of moiré interferometry and incremental hole-drilling (MIIHD) for non-uniform residual stress measurement is introduced. Three dimensional finite element model is constructed by ABAQUS to obtain the coefficients for the residual stress calculation. An experimental system including real-time measurement, automatic data processing and residual stresses calculation is established. Two applications for non-uniform in-depth residual stress of surface nanocrystalline material and non-uniform in-plane residual stress of friction stir welding are presented. Experimental results show that MIIHD is effective for both non-uniform in-depth and in-plane residual stress measurements. The project supported by the FRAMATOME ANP  相似文献   

20.
Residual stress measurements by hole-drilling have developed greatly in both sophistication and scope since the pioneering work of Mathar in the 1930s. Advances have been made in measurement technology to give measured data superior in both quality and quantity, and in analytical capability to give detailed residual stress results from those data. On the technology side, the use of multiple strain gauges, Moiré, Holographic Interferometry and Digital Image Correlation all provide prolific sources of high quality data. In addition, modern analytical techniques using inverse methods provide effective ways of extracting reliable residual stress results from the mass of available data. This paper describes recent advances in both the measurement and analytical areas, and indicates some promising directions for future developments.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号