板料网格应变显微测量系统应用研究

综合分析了国内外网格应变测量的研究情况以及应变测量对于FLD的重要性及意义,设计了专门的网格应变用显微测量仪,并选择了合适的CCD和图像采集卡,构成了板料网格应变显微测量的桌面系统.针对不同形式的应变网格,分析了不同网格印制方法的特点,研究了不同的图像处理测量方法,完成网格应变显微测量系统软件的开发及应用研究.     

基于热转印技术的应变测量网格印制法

金属薄板网格印制是研究薄板微塑性成形性能的难点之一.本文基于热转印技术,提出一种适用于金属薄板的网格印制方法.通过热转印机,将热转印纸上打印好的网格转印到金属薄板表面.该方法简易、高效,印制的网格精度高,且不会破坏金属薄板表面质量和力学性能.     

板料应变视觉测量系统研究

介绍了板料应变视觉测量系统结构和基本原理。该系统运用立体视觉技术对板料成形物理模拟中的圆形坐标网格系统进行测量，获得变形板料的应变分布。实验结果表明，该系统可以较为迅速地完成各种成形工艺的板料件应变参数的测量与分析，并取得比较理想的精度。     

网格法用于大应变的确定

此文对网格法作了回顾总结，详细说明了网格法的基本原理，阐述了至今用于网格制作，记录和分析网格的各种实验技术和数据处理技术，简要介绍了近期国内外网格法研究和应用方面的新动向，并指出了一些研究方向。     

板料成形应变计算机视觉测量中的网格应变计算方法

本文介绍了几种常见应变测量用的网格及其应变计算方法 ,提出了适合板料成形应变计算机视觉测量的基于欧拉法和应变增量理论解析的方网格计算方法。该方法对网格按对角线划分三角形并按变形后的网格建立坐标系统 ,由拉形比和边长的关系直接计算出主应变的方向 ,进而求出真实应变、工程应变和等效应变。     

板料成形过程显微应变分析方法

提出一种通过测定板料变形前后晶粒外形轮廓尺寸来计算板料局部应变的方法，将这种显微应变分析法对经单向拉伸后的侧面带圆弧制品的板料的４个位置的主尖变量的测定结果，与网格分析法的结果进行了比较，分析了显微应变分析法的精度及其影响因素。     

数字图像分析法在薄板成形应变场测量中的应用

对薄板成形应变场的传统的测量方法进行了研究，指出其不中产误差的来源，并提出了数字图像分析法测量薄板成形中的应变场，对测量原理，新的测量方法对老方法的改进，以及如何降低误差进行了介绍，指出了这种方法的前景，同时提出了改进意见。     

便携式板料应变测量系统GMAS

本文介绍了自行研制的板料应变非接触网格测量系统GMAS,并对GMAS的工作原理和关键技术进行了探讨,通过与国际上流行的美国ASAME网格测量系统的比较,验证了GMAS系统在测量精度和操作简便快捷以及界面的美观方面都已达到国际先进水平,是研究板料成形过程中应变路径和变形分布的重要工具.     

金属材料拉伸试验中基于应变网格的非接触实时测量

在金属材料拉伸试验中,传统的基于接触式引伸计测量存在诸如不能测量较软质材料,不能应用于高温环境,并且由于接触夹持力的影响会引进实验误差等缺陷.本文利用椭圆拟合技术,建立了基于应变网格的非接触实时检测系统,实现了金属材料在加载过程中长度和宽度应变的实时测量.试验结果表明,该测量方法能够在一定程度上取代接触式引伸计检测方法,其测量精度达到±0.5%,能够满足实际应用的要求.     

基于应变非接触测量的裂纹拼接

使用基于图像处理的非接触网格应变测量法绘制板料成形极限图,通常选取裂纹边缘网格测量应变,测量值较理论值偏小,甚至相差较多。本文使用图像处理方法,分别建立了基于多目视觉和显微测量镜头的裂纹拼接算法,可对难变形件裂纹处网格进行拼接测量。试验结果表明,两种拼接算法均满足精度要求,前者误差为1.5%,后者为1%,对于改进成形极限图的测量方法、提高成形极限图的测量精度具有一定的参考作用。     

电火花线切割二维仿形加工的图像处理方法

针对线切割仿形加工的二维图像处理方法进行了研究，给出了一种图像细化和矢量化的具体算法，此方法还可以用于其他二维仿形加工。     

Comparison of different analysis models to measure plastic strains on sheet metal forming parts by digital image processing

The principal strains of sheet metals and their limitations while forming can be obtained by using a strain measurement system. A strain measurement may employ one of two different approaches: namely the total least square optimization method or the multiple regression analysis (MRA) method. With both methods plastic strains of deformed parts are calculated based on the non-deformed reference configuration designated by a circle and the deformed configuration, which is a curve-fitting ellipse. In the MRA method, the mathematical formula is simpler reducing the required computations than that of the total least square optimization method. While the formula has a greater margin of error, this margin proves less than significant in the practical application of the method’s results.Information from the results of a strain measurement system can be used to determine the sheet metal’s formability and strain path allowing engineers to determine at which point, the sheet metal will crack. They can then change the thickness and the material of the sheet metal, or modify its shape accordingly to maximize the metal’s efficiency. Strain measurement systems possess practical advantages in their actual application; they improve the quality of sheet metal being produced by minimizing defects in sheet metal during production. One industrial case study of fine stamping electronic part is discussed to demonstrate the proposed methodology.     

Morphological analysis and classification of types of surface corrosion damage by digital image processing

This paper examines a new concept of corrosion surface damage analysis by using the digital image processing. Corrosion phenomena are analyzed using a digital value for morphological surface damages instead of electrochemical methods. Initial images are characterized by three categories: color, texture and shape features. To calculate corrosion surface damages color we use the interpretation of HIS model. For the texture attributes, the method of co-occurrence matrix is used. Five types of corrosion damage are examined. Multidimensional scaling procedure is used to define the classification plane. This study suggests a probabilistic method of decision-making. This analysis develops a method for automated identification system of corrosion damages and is supposed to be more advantageous than that of electrochemical techniques.     

Study on porosity of plasma-sprayed coatings by digital image analysis method

The porosities of plasma-sprayed Al₂O₃, ZrO₂, and TiO₂ coatings deposited on 304 stainless steel plates were evaluated by the digital image analysis method. As the accuracy of this method depends significantly on metallographic preparation and metallography procedure for coating specimens, the effects of cross-surface roughness, magnification, and number of fields of view on the porosity were studied. The results indicate that the porosity value from polished specimen with cross-surface roughness no more than 0.1 μm is acceptable. The porosity value obtained at higher magnification is a little bit higher, especially when the real porosity is higher; more fields of view have to be considered in this case. Both experimental results and statistic analysis suggest that 15 fields of view at 1000× magnification can be implemented to evaluate porosity of plasma-sprayed coating considering both the domain size and the resolution at the same time. The original version of this paper was published as part of the DVS Proceedings: “Thermal Spray Solutions: Advances in Technology and Applications,” International Thermal Spray Conference, Osaka, Japan, 10–12 May 2004, CD-Rom, DVS-Verlag GmbH, Düsseldorf, Germany.     

图像处理技术在CO2焊自动跟踪中的应用

利用CCD(电荷耦合器件)摄像及计算机熔池图像直接视觉传感方法，设计了一套基于面阵CCD计算机图像处理方法的CO2焊自动跟踪系统，图像经均值滤波和增值处理，再采用形态学的方法提取熔池边缘，从而确定熔池中心，即焊枪中心，以确定焊枪中心与焊缝的偏差，整个图像的处理时间为25ms?     

Compact disc quality control using digital image processing

This paper describes a rapid computerized quality control procedure that can significantly increase the efficiency of compact disc production lines. Quality control of the two main stages in the production line can be monitored by the procedure described here: injection moulding and metallization. The developed procedure is capable of checking each disc in less than 4 s. The quality control procedure is based on the following steps: an image of the compact disc is acquired by a CCD video camera and digitized by a PC/AT computer equipped with an image grabber; the developed algorithm is applied to the digitized disc image and the results of the inspection are displayed and recorded.     

基于立体视觉的坐标网格分析法

坐标网格分析法作为一种物理模拟技术 ,已在金属塑性成形的生产中被广泛应用 ,但传统的手工测量方法存在工作量大和精度低的缺点。该文针对板料成形中常用的三维圆形坐标网格系统 ,提出一种新的基于图像处理和立体视觉技术的网格应变自动测量分析方法 ,并开发了相应软件 ,成功地测绘出变形工件的应变等值线图和板料成形极限图。实验结果表明 ,该方法可以使板料应变的测量速度和精度均得到提高     

数字图像相关法的板料成形极限研究与应用

为了克服现有板料成形极限测定方法的不足,采用XJTUDIC三维数字散斑应变测量系统,实现了一种基于数字图像相关法的板料成形极限测定新方法.首先,将测量系统架构在杯突试验机上,记录从试验过程初始到破裂的一系列图像,实现应变在线、全场测定.然后,通过对破裂前的最后一张图像进行截线,拟合数据,对颈缩区域插值得到极限应变,从而绘制成形极限曲线图.最后,通过对SPCC36型号碳钢材料板料件成形极限的测量,验证了本文方法的可行性和有效性.