Study on residual stress in viscoelastic thin film using curvature measurement method

Using LSM (laser scanning method), the radius of curvature due to thermal deformation in polyimide film coated on Si substrate is measured. Since the polyimide film shows viscoelastic behavior, i.e., the modulus and deformation of the film vary with time and temperature, we estimate the relaxation modulus and the residual stresses of the polyimide film by measuring the radius of curvature and subsequently by performing viscoelastic analysis. The residual stresses relax by an amount of 10% at 100°C and 20% at 150°C for two hours.     

Influence of inclined holes in measurement of residual stress by the hole drilling method

The hole drilling method is widely used in measuring residual stress in surfaces. In this method, the inclination of holes is one of the sources of error. This paper presents a finite element analysis of the influence of inclined holes on the uniaxial residual stress field. The error in stress has been found to increase proportionally to the correct inclined angle of the hole. The correction equations by which one may easily obtain the residual stress, taking account of the inclined angle and direction, have been derived. The error of stress due to the inclined hole has been reduced to around 1% using the correction equations.     

FEM analysis of plasticity-induced error on measurement of welding residual stress by the contour method

The contour method relies on deformations that occur when a residually stressed component is cut along a plane. The method is based on the elastic superposition principle. When plasticity is involved in the relaxation process, stress error in the resulting measurement of residual stress would be caused. During the cutting the specimen is constrained at a location along the cut so that deformations are restrained as much as possible during cutting. With proper selection of the constraining location the plasticity effect can also be minimized. Typical patterns of longitudinal welding residual stress state were taken to assess the plasticity effect along with constraining locations.     

A new approach to improve the discharging capacity of sharp-crested triangular plan form weirs

Conventional weirs are inherited with afflux and submergence of area upstream of the weir. Various weirs of modified plan form have been suggested in the past to enhance their discharging capacity and to restrict the afflux. Presented in this paper are results of the experimental study carried out to investigate the discharging capacity of a sharp-crested triangular plan form weir under free flow conditions in a rectangular channel. The efficiency of the triangular plan form weirs is better than the normal weir and also high for low vertex angle and decreases with the increase of ratio of head over the crest of the weir and crest height due to interference of the water jets downstream. The computed discharge using the proposed equation is within ±5% of the observed ones. Sensitivity of the weir, i.e., change of discharge due to unit change in head is also carried out which indicates that the weir is more sensitive at the low head and low vertex angle.     

A novel approach to multi-path ultrasonic transit time flow meter based on measurement model analysis to improve accuracy

Ultrasonic transit time flow meter (UTTFM) is commonly used in a wide range of applications. It is commonly believed amongst researchers, industrialists, and standard committee members that due to nonuniform flow velocity distribution inside the pipe (flow velocity profile) the measured flow velocity using UTTFM needs to be corrected by the flow profile. Mathematical analysis of UTTFM measured quantity shows that UTTFM measures flow correctly when flow is fully developed or laminar. However, the measurement results using flow profile correction factor produces erroneous values. The UTTFM measurement model assessment shows, when flow is not fully developed, there are unknown quantities contributed by flow velocity in the axial and diametrical direction to measurement results. These unknown quantities lead to erroneous measurement results when it is simply corrected by flow profile. Assessment of the UTTFM error model shows that using multi-path UTTFM can significantly reduce the impact of the unaccounted quantities and improve accuracy. A novel approach to UTTFM design utilizing multiple acoustic paths (using different planes and transmitting angles) is proposed to reduce potential error for UTTFM. This approach is consistent with the general measurement modeling method with incomplete information recommended by JCGM GUM-6:2020.     

一种新型测量旋光色散的方法

提出了一种新的测量旋光色散的方法。该方法利用白光LED作为光源,经起偏棱镜、样品管和检偏棱镜后,复色偏振光经平面衍射光栅分光后,由线阵CCD进行采集,CCD的每个像元对应接收复色偏振光经分光后的某一波长的光信号,在检偏器旋转一周内,获得相应的光强数据,使用拟合算法,对每一个像元所采集的光强数据逐一进行处理,最终得出CCD像元所对应波长的旋光度,最后得到旋光色散数据。并利用标准石英管进行了实验研究,证明了这种测量方法的可行性。     

A new method for measurement of particle abrasivity

A modified micro-scale abrasive wear test has been used to study the abrasivity of a range of silica and calcium carbonate abrasives in aqueous slurries, against polymethylmethacrylate (PMMA) samples. The method involves the rotation of a cylindrical disc against the specimen surface in the presence of small abrasive particles, and generates a wear scar with an imposed geometry. It allows a wider range of particle sizes to be used than the more conventional ball–cratering method. For the abrasives used in these tests, differences in abrasivity by a factor of at least 16 were found. The main factor which influenced abrasivity was particle shape.     

一种新型的矿井井斜测量方法研究

井斜测量单元研究是基于捷联惯性导航原理,由三轴光纤陀螺和三轴加速度计构成惯性测量单元,通过数学平台实时地解算出载体的姿态角、位置和速度等参数.以煤矿勘测和开采为背景,采用捷联惯性导航系统替代传统的平台惯性导航系统,利用光纤陀螺和加速度计构成惯性敏感单元替代传统的磁通门和加速度计的结构,适用于具有磁场干扰的场合.初步完成井斜测量系统的静态测试,并对产生的测量误差进行了分析,姿态角可获得较高的测量精度,基本满足井斜测量的指标.利用Labview进行数据采集界面和姿态信息显示界面设计,具有良好的交互性和实时性的特点.     

A new approach for force measurement and workpiece clamping in micro-ultrasonic machining

Micro-ultrasonic machining (micro-USM) is a promising micromachining technique to meet the increasing demands of high accuracy in processing the micro-components of hard and brittle materials. Unlike the well-established conventional USM, micro-USM still lacks in its commercial viability. The major concerns in micro-USM process are the accuracy of the setup and dynamic behavior of the system associated with precise force monitoring and robust workpiece clamping. In this study, a new micro-USM system with regards to measurement and monitoring of static force as well as tooling and workpiece clamping is developed. A force measurement and control system is proposed which is well suited for machining conditions in micro-USM. Furthermore, a reliable and quick setup for the vacuum chuck is introduced, which is capable of consistently transmitting the ultrasonic vibration from horn to the workpiece. Measurement of acoustic characteristics as well as experimental investigations is carried out to validate the functionality of the proposed system.     

Failure analysis of rolling bearings by X-ray measurement of residual stress

Residual stress measurements were carried out for the failure analyses of rolling bearings. According to the survey of more than one hundred examples, some change in residual stress was observed in most cases.Compressive residual stresses peak below the surface and if present, represent the position of maximum shearing stress due to normal contact pressure. Unexpected overloading is confirmed by this method.However, bearings often fail without such overloading. Early failures were observed to be associated with the residual stress changes near the surface. The influences of sliding, vibration and surface roughness on residual stress changes are discussed.     

一种基于相位法的彩色三维形貌测量方法

基于相位法的三维形貌测量。提出了一种建立被测物体彩色三维形貌的方法。该方法采用主动光源投射一组光强呈余弦变化的光栅。并由一台黑白CCD工业摄像机对被测物体拍摄从而实现三维形貌的重建;然后对被测物体进行三色光投射。同时黑白工业摄像机拍摄被测物体,通过对所得图片进行分析。实现被测物体的色彩恢复。实验结果表明,该方法能够快速准确的获得被测物体的彩色三维形貌,色彩度误差小,可有效解决黑白工业相机无法进行色彩捕捉这一问题。     

A new emissive-probe method for electron temperature measurement in radio-frequency plasmas

A new method to measure electron temperature by an emissive probe has been proposed. The method is based on measurement of the functional relationship between the floating potential and the heating voltage of emissive probe. From the measured data of the floating potential change as a function of the heating voltage, the electron temperature could be determined by comparing with the theoretical curve obtained under the assumption of Maxwellian distribution. The overall characteristic of the floating potential change could be explained as a function of the heating voltage. The electron temperatures obtained by the present method were consistent with those measured by the rf-compensated Langmuir probe within the error. These experimental verifications were made in the electron density range of 2.6x10(11)-2.8x10(12) cm(-3). It was stressed that the present method is advantageous in that the probe is operated in a floating condition, hence applicable to plasmas produced in an insulated container.     

一种可提高皮带粘接强度的新工艺

通过对皮带粘接技术的研究制定一种全新皮带粘接工艺,从而强化粘接效果提高皮带粘强度,以延长皮带使用寿命减少材料,降低生产成本确保生产正常进行。     

焊接残余应力的小孔法测试

应用小孔释放法对系列手弧焊接接头的焊接残余应力分布进行测试，讨论了焊接残余应力的分布规律及其相关影响因素，对加载法消除焊接残余应力的效果进行了初步的验证。结果表明，焊接接头的应力不均匀性和不确定性是影响钢制压力容器安全性的关键，采用加载法可以有效地改善这种非均匀应力分布状况。     

A new method for heat measurement during high speed machining

The cutting temperature and temperature distribution along the rake face of cutting tool and work piece is an essential factor in study of machining processes due to its effect on surface quality, tool life, tolerances, metallurgical behavior and chip-removing rate. Several methods have been introduced to measure temperature during machining, such as the thermocouple technique, infrared camera and metallurgical methods. Each of these methods has some advantages and limitations. In this article, an infrared high-speed sensor with specially designed software has been used to measure the transferred heat to the work piece during high speed machining (HSM) of bronze alloys. The results revealed that this system enhances accuracy and reduces the number of tests required.     

A new digital measurement method for accurate curve grinding process

In this paper, an online measurement and error compensation system for curve grinding based on pattern recognition was presented and verified by experiments. The measurement system organization and its principle of operation were introduced in detail. The work piece and grinding wheel image were sampled at certain positions to avoid spark influence. In order to increase system resolution, images were sampled only at local areas of the work piece and grinding wheel. A discrimination technology based on a circular tolerance zone was proposed which can solve the problem of local image edge comparison. For image de-noising, a local threshold algorithm was applied to determine new wavelet coefficients. Furthermore, a two-step edge detection method was used to realize sub-pixel precision. Finally, a series of experiments were carried out to examine the detection precision of the image measurement system and its influencing factors. From experiments, it can be said that the proposed method in this paper is effective, and its detection precision is much better than traditional methods.     

高速加工技术研发的新进展

每个车间都希望在他们的机床配置中,能使用新开发软件去提高高速加工中的可靠性和加工性能。据Mikron Bostomatic公司（位于瑞士Mass省Holliston市）介绍,他们开发出的智能加工软件,能满足用户的这一要求。智能加工软件主要由两个关键系统组成,一是智能的温度控制系统,它可在加工中调整切削温度在一定范围,对由于高切削温度产生的零件的尺寸误差进行自动补偿。一个是先进的工艺系统,能对加工过程进行监控。     

提高微机控制配料系统配料精度的一种方法

介绍了一种微机配料系统,通过对金属镁微机配料系统工艺过程的分析,提出一种提高配料精度的方法,即采用静态与动态结合,增量称重和减量称重相结合的方式,且下料采用基于经验知识的两级振幅。     

管道焊缝残余应力超声环形组合测量方法

重点阐述基于临界折射纵波(LCR波)的超声环形组合探头管道焊缝残余应力的测量方法,该方法用于实际测量,可提高管道焊缝残余应力检测的效率。详细介绍了检测系统硬件和软件,并对残余应力与纵波声速的线性关系进行实验分析,通过切块分离法验证了该方法测量输送管道焊缝残余应力的可行性。