共查询到19条相似文献,搜索用时 171 毫秒
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传统残余应力破坏测量方法无法满足焊接结构服役状态下的应力测量,无法实现结构的无损应力测量.基于声弹性原理,超声波法可以无损测量出结构内部的残余应力.使用临界折射纵波进行薄壁结构件测量时,易激发Lamb波和Stonely波等特殊波形,将影响测量的准确度.开发了适用于薄壁结构件测量的新型超声波法焊接残余应力测量系统,对厚度为2mm的两种LY12薄壁焊接结构进行了测量,测量过程实时无损快速.用切割释放法和有限元模拟进行了验证.结果表明,该测量系统准确可靠,为航天器薄壁焊接结构服役状态在线可靠性评估奠定了基础. 相似文献
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焊接残余应力影响焊接结构可靠性.传统残余应力测量方法无法满足焊接结构服役状态下的应力测量,无法实现薄壁结构的应力测量.使用改进的超声波法焊接残余应力测量系统,对壁厚3.5 mm的薄壁高速列车车体残余应力实现了无损测量,测量过程实时无损快速.测量结果与有限元模拟和激光全息小孔法测量结果对比,超声波法测量结果可靠,且对试验结果进行了讨论分析.建立的超声波法应力无损测量系统为焊接结构服役状态在线可靠性评估奠定了基础. 相似文献
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基于声弹性原理,超声法可测出残余应力。现有超声法应力测量均基于“单发单收”的思想,单次测量只能测出一个方向上的力,须采用多探头组合或一个探头移动多次的方式实现多向应力测量,检测效率低且不能实现应力集中精确检测等问题。测试、获得更小尺度的工作应力、残余应力是精确进行寿命评估的基础。针对寿命评估、高应力场分辨率残余应力测量的要求,文中提出了基于阵列算法的焊接残余应力超声测量方法,采取分割搜索算法对应力测量值序列和应力计算值序列进行比较,求解出最优系数序列,得到最优应力分布曲线。
相似文献7.
陶瓷加工后表面残余应力的测量通常采用一维X射线衍射线探测法,该方法存在测量过程烦琐、效率低、成本高等问题,因此采用新型快速二维面探测X射线衍射残余应力测量方法,对碳化硅陶瓷表面的残余应力进行测量,实验中测量了3种不同品牌碳化硅工件的初始表面和抛光后表面的残余应力。结果表明:此新方法单次测量即可获得样品500点的衍射信息,特别适用于陶瓷材料的应力测量。同时还发现:对于被加工表面的残余压应力,抛光加工最高能够消除近80%的残余应力,但不能改变工件的残余应力分布。 相似文献
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球形封头在其直边段易发生折皱和开裂,残余应力过大是造成其缺陷的根本原因之一.针对无损X射线衍射法、有损全释放法这两种残余应力测试方法的检测原理、测试方法及应用特点等方面进行了分析介绍.以12Cr2Mol R(H)材料为例,采用两种方法分别测量了球形封头热冲压成形后的外壁残余应力值.揭示了封头外壁残余应力分布规律:封头外壁的残余应力值由底部开始逐渐增大,过渡段为应力值转折区域,进入直边段后,残余应力值达到最大.通过对比发现:两种测量方法测得的残余应力变化规律相似;全释放法测得的残余应力值较大;残余应力值在封头外壁直边段部分达到最大. 相似文献
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基于声弹性效应,超声波可以无损检测出结构内部应力.超声波法焊接残余应力测量克服了传统应力测量方法费时耗力、破坏、体积庞大等缺点,对多种焊接结构残余应力进行的测量已证明其准确和可靠.在残余应力场测量时发现了在低应力弹性区存在声弹性不稳定现象,利用声弹性模拟试验对声弹性不稳定现象进行了分析研究.根据焊接残余应力场弹性区临界折射纵波包络波峰声弹性效应随机分布呈双峰分布的试验现象,提出了弹性区声弹性主应力计算公式,可通过超声波法纵向残余应力测量结果计算出测量点的两个主应力及横向残余应力. 相似文献
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大型汽轮机、发电机转子残余应力测量新方法——环芯法及国外应用实例 总被引:1,自引:0,他引:1
介绍了汽轮机、发电机转子残余应力产生的主要原因及若干残余应力测量方法,以及环芯法测量残余应力的基本理论和国外在大型汽轮机、发电机转子上的应用实例。 相似文献
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为避免残余应力对焊接结构的不利影响,保证其可靠性,需要探究残余应力分布. 模态试验法因具有快速和无损的特点,逐渐应用于残余应力测试. 为实现模态试验法测试焊接残余应力,通过振动理论分析了模态试验法的机理,获得了薄板焊件中残余应力与固有频率的关系;薄板焊件中的残余拉应力使固有频率减小,残余压应力使固有频率增大. 在此基础上,将钻孔法和模态试验相结合,借助数据拟合的方法,估计了模态试验法测试6 mm 7A52铝合金试板 VPPA-MIG(variable polarity plasma arc-metal inert gas)复合焊接残余应力的模型参数,确立了固有频率与残余应力的数值关系. 依据确立的数值关系,测得了7A52铝合金试板在不同复合焊接参数下的纵向残余应力分布. 结果表明,接头各区域的残余应力分布特征与钻孔法测得的结果基本一致,偏差在4%范围之内,估计出的模型参数能够保证模态试验法测试结果的可靠性,实现了焊接残余应力的快速和无损测试. 相似文献
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In the present research work the determination of residual stress distribution in welded non-oriented electrical steel samples is discussed. Tungsten inert gas was used for the welding method. Residual stress was directly determined through deformation measurements and appropriate math calculations. Two methods were used: the magnetic, non-destructive method of Barkhausen noise and the semi-destructive method of X-ray diffraction. In order to evaluate the accuracy and reliability of the magnetic method applied, the steel samples were subjected to both compressive and tensile stresses and the magnetic noise values were correlated to residual stress values through an appropriate calibration curve. The results were then verified by the XRD method and were further evaluated by examining the microstructure and the mechanical properties of the as received and welded samples through scanning electron microscopy and hardness measurements, respectively. It was found that the deviation between the two methods was within acceptable limits, thus implying potential applicability of the MBN method in non-destructive testing of materials. 相似文献
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X射线法测量淬火铝合金厚板表面残余应力 总被引:1,自引:0,他引:1
采用无损X射线衍射技术测试了7075铝合金厚板淬火后表面残余应力水平与分布,得到了淬火铝合金厚板表面残余应力的分布区间和一般规律,分析了准直管对测试结果的影响,并与中心钻孔法得到的结果做了比较。结果表明,两种方法都能有效并正确测量构件的表面残余应力,但中心钻孔法不适合用于应力梯度大的场合,而X射线法在无应力或原始应力水平很低的场合效果欠佳。淬火铝板表面残余应力的测试结果呈正态分布,且淬火过程中边缘局部有应力释放,释放值可达40%,且此区域大小约为铝板的一个厚度。 相似文献
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Non-destructive determination of residual stress state in steel weldments by Magnetic Barkhausen Noise technique 总被引:2,自引:0,他引:2
The purpose of this study is non-destructive determination of residual stresses in the welded steel plates by Magnetic Barkhausen Noise (MBN) technique. A MBN-stress calibration set-up and a residual stress measurement system with scanning ability were developed. To control the accuracy and the effectiveness of the developed system and procedure, various MBN measurements were carried out. The MBN results were verified by the hole-drilling method. Microstructural investigation and hardness measurements were also conducted. It was concluded that if the calibration procedure including the effect of microstructure is appropriate then MBN is a very promising method for non-destructive, fast and accurate prediction of residual stresses in the welded plates. 相似文献
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《Science & Technology of Welding & Joining》2013,18(2):166-171
AbstractA methodology has been developed using a non-destructive ultrasonic technique for measuring surface/subsurface residual stresses in 7 mm thick AISI type 316LN stainless steel weld joints made by activated tungsten inert gas and multipass tungsten inert gas welding processes. Measurement of residual stresses using an ultrasonic technique is based on the effect of stresses on the propagation velocity of elastic waves. Critically refracted longitudinal L CR wave mode was employed and accurate transit time measurements were made across the weld joints. Quantitative values of the longitudinal residual stresses across the weld joints were estimated from the measured transit times and predetermined value of acoustoelastic constant for AISI type 316LN stainless steel. The nature of the residual stress profiles and their variations across the two types of weld joints were compared and interpreted. 相似文献
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Measurement of residual stress in steel using the magnetic Barkhausen noise technique 总被引:1,自引:0,他引:1
Surface residual stresses on a structural beam steel sample were evaluated using a non-destructive technique based on the measurement of surface magnetic Barkhausen noise (MBN). MBN measurements were performed using a high resolution probe consisting of a small magnetic read head mounted between the poles of a ferrite U-core magnet. Applied stress magnitudes were correlated to MBN energy levels for calibration purposes. MBN energy measurements were done at various locations on the steel sample. The magnitude of the residual stress component along the sample beam axis was evaluated across the width of the beam using these calibration curves. The range of sensitivity of the MBN signal to stress as defined by the calibration curves was limited by the direction of easy magnetization. The effect of stress on the MBN signal was interpreted in terms of the active 180° domain wall population. The validity of the residual stress results was confirmed experimentally using conventional methods: cutting and sectioning and hole drilling. Possible sources of residual stresses and their distribution on the structural steel specimen are discussed. 相似文献
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When measuring residual stress of coarse-grain aluminum alloy using X-ray diffraction method,the diffraction profile shows two peaks and position of measured 2d will be changed,which lead to an inaccurate measurement result.Hence,in this paper,some methods were employed to improve the measurement accuracy.During the measuring process,different parameters(diameter of irradiated area,Ψ-oscillation range and exposure time) were selected and profile peak shift method was utilized.Moreover,when the 20 of profiles was determined,different calculation methods were used to calculate the residual stress.The results show that diameter of irradiated area and Ψ-oscillation range have significant influence on the measuring result.For stress value calculated directly from the test equipment,cross correlation method is more accurate than the absolute peak.Furthermore,another two calculation methods of slope with 2θ- sin~2Ψ and e- sin~2 Ψ were used to calculate the stress based on parameters(2θ,ε) obtained from cross correlation method.It is concluded that 20- sin~2Ψ method can further improve the measurement accuracy. 相似文献
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轮廓法是一种基于截面解剖法的残余应力测量方法,可以获得目标平面法向的残余应力二维分布云图。经过20多年的发展与完善,轮廓法已经被广泛应用在航空航天、核电、高端装备制造等许多重要领域,尤其适用于焊接件、金属连接件和异型工件的残余应力测量。文中详细介绍了轮廓法测量的优势,分析了轮廓法测量的理论依据、测量步骤、误差修正、拓展应用、试验验证及研究热点,深入探究在一次切割轮廓法测量基础上发展起来的多次切割轮廓法、断裂轮廓法和X射线衍射法的叠加测量、近表面残余应力轮廓法测量等方法,这些方法克服了常规轮廓法测量断面应力、近表面应力方面的技术限制,可获得工程结构件的三维残余应力分布,针对不同的工程应用需求调整切割方法及测量方案以提供技术支持,拓展了轮廓法测量的应用范围。该文旨在为国内的同行提供参考,助力轮廓法在国内科学研究和工程应用方面的推广应用。创新点: (1)对比常用的工程残余应力测量方法,明晰轮廓法测量的技术优势及其适用范围。(2)分析轮廓法测量过程中可能引入的试验误差,提出相对应的解决方法。(3)拓展轮廓法的应用范围以满足三维应力测量需求。 相似文献