残余应力测试与校准方法研究现状与展望

简单介绍了残余应力产生的原因及其对材料性能的影响,分析了现阶段残余应力测试方法的基本原理、应用场合和优缺点等,尤其是对目前普遍使用的X射线衍射法、中子衍射法、纳米压痕法、钻孔法等残余应力测试方法进行了详细说明.针对残余应力准确测量需求,分析现阶段基于标样法和仪器性能校准的残余应力校准方法,并说明了校准对残余应力准确测量...     

7050和7075铝合金板材的淬火残余应力

铝合金板材的残余应力主要产生于淬火过程中,而残余应力是导致航空航天用铝合金板材机加工变形的主要原因。采用X射线衍射法、超声波法和盲孔法分别对7050铝合金板材水浸淬火试样的残余应力进行了测试,并对3种方法的测试结果进行了对比和分析;采用超声波法对7075铝合金板材喷淋淬火试样的残余应力进行了测试。结果表明:超声波法测得的7050铝合金板材水浸淬火试样的残余应力分布规律与X射线衍射法和盲孔法测得的具有较好的一致性,板材近表层处的残余应力随着测试深度的增加而减小;7075铝合金板材喷淋淬火试样的残余应力随着辊速和喷水量的增大而增大。     

两种残余应力测定方法的研究和比较

先用X射线衍射法再用盲孔法测定了同一试样的残余应力,对测试结果进行了分析比较。结果表明：对于残余应力分布不随深度改变的情况,两者结果一致;但对于其他情况,两种方法得到的结果不一致。通过测试残余应力沿试样深度的分布和从原理上比较两种测试方法的不同,得出盲孔法的测试结果受深层残余应力分布影响,而X射线衍射法的测试结果不受其影响。     

冷轧无取向硅钢冲裁边缘残余应力研究

针对武钢冷轧无取向硅钢,利用纳米压痕法研究了硅钢片冲压后的残余应力,采用Suresh理论模型恒定压深时的公式计算残余应力,测得硅钢残余应力分布,并结合X射线衍射法和冲裁仿真验证其准确性,最后利用有限元软件ABAQUS对压痕过程进行数值模拟和分析。结果表明,纳米压痕技术能有效测量硅钢片冲裁边缘的残余应力分布,硅钢片在冲裁后边缘的应力影响区宽度为0.4~0.5mm。     

X射线法测量淬火铝合金厚板表面残余应力

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。     

X射线衍射技术在薄膜残余应力测量中的应用

残余应力测量在薄膜材料研究中具有重要的意义,综述了薄膜残余应力X射线衍射技术测量的研究现状,其中介绍了强织构薄膜残余应力X射线衍射测量技术;同时对由于G(o)bel平行光镜、毛细管元件及二维探测器等X射线功能附件的发展,以及同步辐射源X射线的应用而带来残余应力分析的新进展进行了介绍.     

用X射线衍射法测定振动时效后水电站钢岔管中的残余应力

介绍了采用振动时效技术消减水电站钢岔管焊接残余应力,以及用X射线衍射法进行焊接残余应力测试来对振动时效效果进行定量评价。并举例说明X射线衍射测试焊接残余应力的应用情况。     

X射线衍射法测残余应力的“突变”现象与定峰技巧探讨

X射线衍射法（XRD）是一种常用的测试金属表面残余应力的无损检测法。依据X射线应力测试的原理,对试验中遇到的衍射强度“突变”现象进行了初步探讨,并对其产生的原因和定峰中的处理方法进行了具体分析,为进一步发展和完善铝合金焊接残余应力的X射线分析技术提供了参考。     

高强度钢丝残余应力的研究进展

回顾了近年来以珠光体钢丝为代表的高强度钢丝残余应力的数值模拟及其相关试验研究进展,主要介绍常规X射线衍射、中子衍射及同步辐射X射线衍射技术在钢丝残余应力分析中的应用,对残余应力的来源、测量原理及其结果进行了讨论;简述了残余应力对钢丝性能,如拉伸、应力松驰和环境促进断裂性能等指标的影响,同时对通过改变残余应力分布实现钢丝性能优化的主要工艺进行了介绍.     

残余应力检测与消除方法的研究现状及发展

残余应力的存在会严重影响工件的强度及相关性能,对残余应力的检测及消除方法的研究具有重要的理论意义及工程应用价值。从残余应力的概念及形成原因入手,介绍了钻孔法、X射线衍射法、磁测法、超声波检测法等测量残余应力的手段以及研究发展现状;同时阐述了热处理法、振动时效法、超声波冲击法等消除残余应力的方法。     

单传声器实现声场空间特性测量的研究

提出了一种测量室内声场空间特性的方法,测量系统由一个可重复发射的声源配合装置在缓慢转动平台上的接收传声器组成。阐述了借助此测量系统进行入射脉冲空间分布的测量方法及典型的实验结果。实验表明,根据测量需求选择适当的空间计权因子,能够实现各种指向性传声器的等价测量,从而进一步获得反映声场空间特性的各种客观参量。     

Mixed nitrogen source effect in the hydrothermal synthesis of cubic BN

Mixed nitrogen source effect was applied in the synthesis of boron nitride (BN) by hydrothermal method. The experimental results revealed that, compared to those obtained by using only two kinds of nitrogen sources, when three kinds of nitrogen sources were used during the synthesis of BN, it was more easier to obtain BN samples with cBN as the dominant phase. Furthermore, if this effect was applied together with the two-step reaction method, nearly pure cBN can be obtained. The results of X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), transmission electron microscopy (TEM), selective area electron diffraction (SAED), high-resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectroscopy (XPS) measurements proved that the major phases in the samples are cBN.     

Q235钢的污染海洋大气环境腐蚀寿命预测模型

采用周浸加速实验模拟Q235钢在我国青岛、万宁两种污染海洋大气环境的腐蚀行为,用失重法、X射线衍射(XRD)、扫描电子显微镜(SEM)等方法分析Q235钢在室内模拟大气环境的腐蚀形貌、腐蚀产物、腐蚀动力学。研究室内加速实验与室外暴晒实验的相关性。结果表明:周浸加速实验后Q235钢与实际污染海洋大气环境暴晒实验结果相关性较好。结合灰色关联法建立Q235钢在两种污染海洋大气环境下的腐蚀寿命预测模型:T_(QD)=137.002t~(1.093),T_(WN)=102.398t~(0.952)。     

静力荷载作用下结构参数识别及状态评估的统计分析

基于静态结构识别方法,提出了服役结构损伤探测及状态评估的概率分析方法。首先通过有限元法把结构离散成用基本参数及核心矩阵表示的分析模型,根据两种分析模型和实际结构间的误差定义,用 Gauss-Newton法推导了在不完全测量情况下两种参数识别方法。在设计的测量情况下,进一步采用 Monte Carlo 法模拟测量数据,详细分析和比较这两种算法在有测量误差时的有效性和稳定性问题。第一种算法中的敏感矩阵不受测量误差的影响而具有比较好的性能,在确定了其识别结果的概率特性后,引入假设试验,探测和评估损伤的位置及程度。数字模拟显示了这一方法的有效性和准确性。     

高吸水性聚合物吸液模型及性能测试方法评述

结合高吸水性聚合物平衡吸液模型及吸液动力学公式的分析，介绍和比较说明了各种测试高吸水性聚合物平衡吸液能力方法（如茶袋法，需湿法，比色分析法）等，及吸液动力学研究方法（如粘度法，漩涡观察法），并提出相关建议。     

Particle size measurement of standard reference particle candidates with improved size measurement devices

In order to prepare standard reference particles, experimental and theoretical studies have been conducted on particle size measurement of two kinds of spherical glass beads. The sheath flow- type electrical sensing zone method and the revised sedimentation balance method were used for the measurement. The data were compared with those obtained by the microscopic method with a sample size greater than 10 000. The particle size distributions obtained by use of the sheath flow- type electrical sensing zone method and microscopic method are nearly equal for the two kinds of glass beads. However, deviations of less than 5% were observed between the improved sedimentation balance and microscopic methods. The experimental data of the microscopic method are within the 95% reliability region of the sheath flow-type electrical sensing zone method.     

属性综合评价系统在岩爆发生和烈度分级中的应用

应用属性数学理论,建立了岩爆发生预测和烈度分级的属性识别模型。选取影响岩爆的主要因素:如最大切向应力σθ、单轴抗压强度σc、单轴抗拉强度σt以及弹性能量指数Wet,以σθ/σc、σc/σt以及Wet作为岩爆评价指标和烈度分级标准;构造了属性测度函数;定义了单指标属性测度和样本综合属性测度的计算方法。利用国内外一些重大岩石地下工程实例对模型进行了验证,由于评判结果与实际情况基本一致,并且与模糊综合评判法、物元可拓评判法等的评判结果有较好的一致性,从而验证了属性识别模型应用于岩爆预测预报的可行性和有效性。此外,利用该模型对某水电站工程和秦岭隧道工程的岩爆情况进行了评判,结果与人工神经网络法、距离判别法等的评判结果一致。     

铬镍奥氏体不锈钢焊缝铁素体含量的测定

分别应用定量金相法、wRC-1992组织图法和X射线衍射物相定量方法对铬镍奥氏体不锈钢的焊缝铁素体的含量进行测定。在定量金相法中,考虑了铁素体含量分布的均匀度;在X射线衍射物相定量方法中,分析了试样择优取向对测定结果的影响,考虑了测定结果的分散性。最后,对三种方法的测定结果进行了比较。结果表明：在一定条件下,应用类似于X射线衍射仪测定残余奥氏体含量的方法对焊缝铁素体含量进行测定,也能得到与金相法和WRC-1992组织图法比较一致的结果。     

Applicability of the Magnetic Barkhausen Noise Method for Nondestructive Measurement of Residual Stresses in the Carburized and Tempered 19CrNi5H Steels

There exist no materials and/or structures of technical importance without residual stresses. The residual stress management concept has gained importance in industrial applications aiming to improve service performance and useful life of the product. Thus, the industry requests rapid, reliable, and nondestructive methods to determine residual stress state. The aim of this article is to investigate the applicability of the Magnetic Barkhausen Noise (MBN) method to measurement of surface residual stresses in the carburized steels. To comprehend the differences in the surface residual stress state, 19CrNi5H steel samples were carburized at 900°C for 8 and 13 hours, and then, tempered in the range of 180°C and 600°C. The MBN measurement results were correlated with those obtained by the X-ray diffraction (XRD) measurements. Microstructural investigations and hardness measurements were also conducted. For this particular study, it was concluded that both techniques give similar qualitative results for monitoring of the residual stress variations in the carburized and tempered steels. Since the MBN method is much faster than the XRD method, from the industrial point of view it is a very strong candidate for qualitative monitoring of residual stress variations. With an appropriate pre-calibration by considering the effect of microstructure, the MBN method may give reliable quantitative results for residual stress.     

An extended complex Kalman filter for frequency measurement ofdistorted signals

The design of an extended complex Kalman filter for the measurement of power system frequency has been presented in this paper. The design principles and the validity of the model have been outlined. A complex model has been developed to track a distorted signal that belongs to a power system. The model inherently takes care of the frequency measurement along with the amplitude and phase of the signals. The theory has been applied to standard test signals representing the worst-case measurement and network conditions in a typical power system. The proposed algorithm is suitable for real-time applications where the measurement noise and other disturbances are high. The complex quantities can be conveniently handled using a floating point processor. Comparison of the results of the proposed method with those obtained from a real extended Kalman filter reveals the superior performance of the former method