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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
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高压气瓶工艺残余应力测试和分析 总被引:3,自引:0,他引:3
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。 相似文献
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用盲孔释放法测残余应力的基本理论导出在任意钻孔偏心下应变释放系数 A、B 的精确公式.同时通过用偏心公式和不偏心公式计算得到的残余应力值的比较,说明钻孔偏心量对残余应力值影响很大. 相似文献
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无损残余应力测量及其新技术 总被引:1,自引:0,他引:1
简述及比较了主要的残余应力无损测量技术,重点为磁力法,并介绍一台新的磁力仪MAPS,且对MAPS及传统磁力仪作了比较,同时以X射线及中子衍射得到的结果验证了MAPS的可靠性,也介绍了文献上较少见的火车钢轨残余应力分布图。 相似文献
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缺口根部和裂纹尖端残余应力的X射线法测定 总被引:1,自引:0,他引:1
X射线法用于缺口根部和裂纹尖端等徽区的残余应力测试的先决条件是解决缩小光束直径、提高衍射束的强度和准确设置试样等技术问题.在X射线衍射仪上借助于自行设计制造的限束对光装置和侧倾对中附件,成功地测定了缺口根部半径为1mm的喷丸残余应力场和板形试样压-压周期载荷下裂纹尖端的残余拉应力场. 相似文献
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本文分析了含有界面相纤维增强复合材料热残余应力的空间分布。针对材料实际微结构几何特点,建立含有界面相的三维三相单丝模型,用均匀和梯度函数描述界面相模量随空间变化规律,由轴对称体弹性力学理论得到单丝热残余应力分布,结果表明梯度界面降低了残余应力。通过碳纤维电阻法测出T300/环氧树脂单丝体系固化后的纤维轴向应变,与梯度界面的分析结果基本一致。用叠加方法得到密排六方结构代表性体积元(RVE)中纤维间相互偶合的应力场,同时应用有限元法分析RVE中纤维间的残余应力分布,两者结果相互验证。 相似文献
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用钻孔应变释放法测残余应力的基本理论导出在任意钻孔偏心下应变释放系数[A],[B]的精确公式.揭示了各传统近似方法(丝栅中心应变法、纵向线积分平均应变法及有效面积上积分平均应变法)的应变释放系数随r_м/а的变化规律。并采用数值逼近法求解了钻孔偏心时的应变释放系数及残余应力.结果表明,偏心对残余应力影响很大。 相似文献
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Stress Monitoring of Post-processed MEMS Silicon Microbridge Structures Using Raman Spectroscopy 总被引:1,自引:0,他引:1
Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated Micro-Electro-Mechanical Systems (MEMS) devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not well controlled during deposition. The residual stress; for example, tends to vary significantly for different deposition methods. Currently, few nondestructive techniques are available to measure residual stress in MEMS devices prior to the final release etch. In this research, micro-Raman spectroscopy is used to measure the residual stresses in polysilicon MEMS microbridge devices. This measurement technique was selected since it is nondestructive, fast, and provides the potential for in-situ stress monitoring. Raman spectroscopy residual stress profiles on unreleased and released MEMS microbridge beams are compared to analytical and FEM models to assess the viability of micro-Raman spectroscopy as an in-situ stress measurement technique. Raman spectroscopy was used during post-processing phosphorus ion implants on unreleased MEMS devices to investigate and monitor residual stress levels at key points during the post-processing sequences. As observed through Raman stress profiles and verified using on-chip test structures, the post-processing implants and accompanying anneals resulted in residual stress relaxation of over 90%. 相似文献
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Bi-axial compressive stress induced as a result of mechanical confinement within a zirconium diboride-silicon carbide (ZrB2-SiC) ceramic composite has been quantified using micro Raman spectroscopy and then validated using two independent experimental methods. First a relationship relating the Raman peak-shift on a confined silicon carbide (SiC) particle to magnitude of imposed confinement stress was developed by utilizing phonon deformation potentials for 3C-SiC diamond and zinc-blende crystal structures. ZrB2-5wt%SiC samples, prepared using spark plasma sintering were subjected to different confinement pressure on the lateral surface by thermal shrink fitting metallic sleeves. The relationship between Raman peak-shift and confinement stress was then verified by comparing the measured stress in this method with that calculated from analytical expressions readily available for thick walled cylinders. The relationship was further validated independently using digital image correlation (DIC) by measuring the displacements for unknown levels of progressively increasing confinement stress induced by a shaft-collar ring on similar specimens. The Raman peak-shift relation derived for SiC phase also correctly predicted process-induced residual stresses due to a mismatch in coefficient of thermal expansion between the matrix phase and SiC particles. The derived Raman peak-shift relationship can also be generalized and can be a valuable tool to experimentally determine unknown bi-axial stress in a Raman active structure. 相似文献
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L. Reis P.M. Amaral B. Li M. de Freitas L. Guerra Rosa 《Theoretical and Applied Fracture Mechanics》2008,49(2):226-231
The sintering process of diamond–metal matrix hot-pressed tools, usually used for cutting hard materials (e.g., stone cutting) originates residual stresses, which should be taken into account in the performance of the tool. The work concerns the use of finite element simulation for modelling of thermal residual stresses generated during the sintering process of metal matrix diamond tools normally employed by the industry. Stress distribution fields were determined for two different diamond shapes (modelled with 2D axisymmetric elements, with the sphere shape generated from the revolution of one circle and the octahedron shape generated from the revolution of one octagon, respectively) using an 8-node biquadratic axisymmetric quadrilateral, reduced integration element type CAX8. The thermal residual stress field in the nearby region of a diamond particle with the shape generated from the octagon is examined by using three different matrix materials, each one sintered at different temperatures. The analyses have demonstrated how much the residual stresses are sensitive to the stress–strain behaviour of the metal matrices. 相似文献
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S. J. Lewis S. Hossain J. D. Booker C. E. Truman U. Stuhr 《Experimental Mechanics》2009,49(5):637-651
Shear stresses along the shaft/hub interface in shrink-fit components, generated by torsional loads, can drive premature failure
through fretting mechanisms. It is difficult to numerically predict these shear stresses, and the associated circumferential
slip along the shaft/hub interface, due to uncertainties in frictional behaviour and the presence of steep stress gradients
which can cause meshing problems. This paper attempts to provide validation of a numerical modelling methodology, based on
finite element analysis, so the procedure may be used with confidence in fitness-for-purpose cases. Very few experimental
techniques offer the potential to make measurements of stress and residual stress interior to metallic components. Even fewer
techniques provide the possibility of measuring shear stresses. This paper reports the results of neutron diffraction measurements
of shear stress and residual shear stress in a bespoke test specimen containing a shrink-fit. One set of measurements was
made with a torsional load ‘locked-in’. A second set of measurements was made to determine the residual shear stress when
the torsional load had been applied and removed. Overall, measurement results were consistent with numerical models, but the
necessity for a small test specimen to allow penetration of the neutron beam to the measurement locations meant the magnitude
of shear stresses was at the limits of what could be measured experimentally. 相似文献
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P. Pagliaro M. B. Prime J.S. Robinson B. Clausen H. Swenson M. Steinzig B. Zuccarello 《Experimental Mechanics》2011,51(7):1123-1134
The traditional contour method maps a single component of residual stress by cutting a body carefully in two and measuring
the contour of the cut surface. The cut also exposes previously inaccessible regions of the body to residual stress measurement
using a variety of other techniques, but the stresses have been changed by the relaxation after cutting. In this paper, it
is shown that superposition of stresses measured post-cutting with results from the contour method analysis can determine
the original (pre-cut) residual stresses. The general superposition theory using Bueckner’s principle is developed and limitations
are discussed. The procedure is experimentally demonstrated by determining the triaxial residual stress state on a cross section
plane. The 2024-T351 aluminum alloy test specimen was a disk plastically indented to produce multiaxial residual stresses.
After cutting the disk in half, the stresses on the cut surface of one half were determined with X-ray diffraction and with
hole drilling on the other half. To determine the original residual stresses, the measured surface stresses were superimposed
with the change stress calculated by the contour method. Within uncertainty, the results agreed with neutron diffraction measurements
taken on an uncut disk. 相似文献
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Measurement of Applied Stresses and Residual Stresses on a Residual Stress Model by Applying Two Different Loads 总被引:1,自引:0,他引:1
T. Kihara 《Experimental Mechanics》2011,51(8):1275-1283
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. 相似文献
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Pipelines usually operate under bending and axial stresses, caused by external loads, combined with residual stress distributions (manufacturing stresses), which affect the mechanical behavior of the pipe. Despite its semi-destructive nature, the hole drilling technique and digital speckle pattern interferometry (DSPI) can be applied to determine combined stresses along a cross-section. To achieve this, a set of equally-spaced angular points spread along the cross-section perimeter are measured. For non-uniform stress computations the hole drilling technique frequently gives a detailed stress distribution which is related to the external layer (1 mm) of the pipeline. In order to obtain a representative and unique value for the stress acting at each point, a novel approach can be used to evaluate a weighted average stress from each available stress distribution and to identify possible outlier measured points. In accordance with this approach, weighting coefficients are calculated using some particular features found in the residual stress profiles of pipelines. A reference bending test bench was used to evaluate the proposed methodology and it verified good agreement between the reference and computed stresses. 相似文献
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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. 相似文献
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Wei Qiu Cui-Li Cheng Ren-Rong Liang Chun-Wang Zhao Zhen-Kun Lei Yu-Cheng Zhao Lu-Lu Ma Jun Xu Hua-Jun Fang Yi-Lan Kang 《Acta Mechanica Sinica》2016,32(5):805-812
Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in com-petition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy (SEM), micro-Raman spectroscopy (MRS), and transmission electron microscopy (TEM) were applied to measure the geometric parameters of the multi-layer structure. The relationship between the Raman spec-trum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and cross-section residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was suc-cessfully obtained. 相似文献