光纤几何参数自动测量技术

介绍了一种光纤几何参数自动测量的新技术，利用图象扫描和脉冲计数方法获取光纤截面的边缘信息，用微机进行数据采集和处理，有效地提高了测量系统的分辨率和测量速度，实验结果表明：该测量系统的测量重复性达0.1um，分辨率可达0.05um，单个光纤试样的测量时间<1min。     

一种高效准确的疲劳裂纹几何尺寸自动测量方法

在进行常规疲劳试验时,人工测量疲劳裂纹尺寸工作效率低,失误概率高,数据无法进行数字化管理。利用影像测量仪进行裂纹形貌识别,并通过合理安排试样排列顺序和测量顺序,最终实现了疲劳裂纹几何尺寸的自动化大批量测量。实践证明:该自动测量方法可适用于大批量检测需求下的各种金属材料疲劳断裂试样的疲劳裂纹几何尺寸测量。     

用球面三角简化几何尺寸测量中的计算

我们在工作中,经常遇到与空间角度有关的计算。如图1零件需测量图示交点尺寸(A、B尺寸)。对A尺寸,可用样柱和正弦规,但对B尺寸,用一般方法测量十分困难,必须采用钢球测量。然而,采用立体几何的计算方法又十分复杂。本文根据球面三角定理,     

三坐标测量机空间几何尺寸仿真测量原理

传统的三坐标测量机空间几何尺寸的测量方法是将测量基准建立在被测量的工件上，但由于工件本身在制造过程中总会存在一定的制造误差，因而这些工件被作为基准的部分本身就有误差。若想对形状复杂、精度要求高的工件进行精确测量，用这种传统的测量方法就难以保证测量的精度，因此我们提出三坐标测量机的空间几何尺寸仿真测量法的思路。三坐标测量机空间几何尺寸仿真测量法的原理是：首先，在计算机中利用CAD并根据工件理论图纸建立理论的数学模型，由这一理论模型生成一个空间包容区，该包容区是由理论工件模型和公差带所形成的包容区。…     

空间几何尺寸测量方法的设计

空间几何尺寸的测量是几何量测量的重要组成部分 ,本文根据具体零件设计了一种空间几何尺寸的测量原理及方法 ,给出详细的测量调整方法及步骤 ,并通过对测量误差分析来验证其可行性。     

高端装备大型零部件几何尺寸测量技术现状及趋势

高端装备的大型零部件几何尺寸测量与控制是保证产品交付质量的基础,高端装备性能及产量的提升对几何尺寸测量提出了更高的精度与效率要求.本文结合大型零部件几何参数测量需求,介绍了大尺寸坐标测量、扫描测量、姿态测量、协同测量、组网测量、动态测量六种大尺寸测量技术的工作原理、典型仪器以及应用特点,分析了固定式测量系统和柔性测量系...     

几何量尺寸测量中最佳支点的选择

随着科学技术的飞速发展,测量显得越来越重要,对测量准确度的要求也越来越高,为了减少测量误差,保证测量值的准确可靠,测量被测件的几何尺寸(大于100mm)时,除考虑测量方法、测量设备、测量环境以及测量人员的要求外,还必须考虑被测件的支承情况.测量被测件几何尺寸时,理想的支承状态是工作台平面为理想平面,且与被测件长度相等,这样测量长度几何尺寸时,被测件自重对测量结果将不产生影响.在实际工作中,如果有标准平面如平板,而被测件长度未超出平板尺寸范围,就可以把被测件直接放在平板上测量;如果支承后再测量,由于支承点以及被测件自重的存在,被测件的几何形状将不可避免地发生变化,测量结果将受影响.     

手推式钢轨外形几何尺寸测量系统

研制了一种手推式钢轨外形几何尺寸测量系统。利用激光线光源投射于钢轨表面,钢轨外形轮廓的光截曲线成像在CCD上。经过灰度变换、边缘提取和中心线提取,获得截面处的钢轨外形曲线。将其标定后,与钢轨标准曲线进行比较,从而求得实测钢轨的磨损量。该系统具有体积小、重量轻、实时处理、操作方便等优点。     

无缝钢管直线度激光视觉在线测量

应用多个激光线结构光传感器对无缝钢管进行光切 ,求出各个光切面中心点的空间三维坐标 ,通过空间直线拟合和误差评定算法 ,由此确定钢管轴线的直线度。本文提出了无缝钢管直线度激光视觉在线测量方法 ,推导出数学模型 ,并进行实验研究 ,给出了实验结果。     

交点尺寸的测量

本文介绍了交点尺寸测量的方法.     

Japanese experience with steam oxidation of advanced heat-resistant steel tubes in power boilers

Abstract

Japanese experience of steam oxidation behavior of advanced heat-resistant steel tubes in power boilers is discussed. Severe scale separation, cracking, and exfoliation were observed in T91 pendant reheater tubing in a Japanese utility boiler after around 40,000 hours of operation. Separation occurred at the interface between the inner and outer layers of scale. A high-pressure steam oxidation test rig in which the steam conditions could be controlled in a similar manner to that of an actual boiler was developed and T91 steel samples were tested up to 10,269 hours. The scale separation behavior of T91 was reproduced in the steam oxidation test. The growth rate of T91 was lower than that for conventional 9Cr-1Mo steel reported by EPRI. The scale separation was related to void formation at the interface between the inner and outer layers of scale, as well as the transformation of magnetite into hematite in the outer layer. Field exposure testing was carried out for T23 and T122 for 80,000 hours, and the properties of steam oxidation scale were obtained.     

基于模态指标与数据融合的钢管混凝土拱桥损伤识别

为了提高大型结构的损伤诊断率,本文提出了一种基于模态指标和数据融合的结构损伤识别方法.根据结构振动响应,首先利用多种模态损伤指标,对钢管混凝土拱桥的损伤位置进行初步诊断,然后利用文中提出的加权平均法,对多种模态损伤指标进行融合计算,最后根据峰值方法得到拱桥的损伤位置。为了验证所提方法的可行性和有效性,对一双跨下承式钢管混凝土拱桥进行了单损伤和多损伤模拟,同时考虑了噪声等环境因素对识别结果的影响,并与单一损伤指标识别结果进行了比较。结果表明,本文所提出的损伤识别方法能够对钢管混凝土拱桥的损伤进行定位,它明显优于单一损伤指标的识别结果。     

Experimental study of perforation and cracking of water-filled aluminum tubes impacted by steel spheres

Water-filled aluminum tubes were subjected to impact by six steel spherical projectiles of different diameters at impact velocities of 40–200 m/s. The effects of the diameter of the steel projectiles and of the material properties of the tubes on cracking and perforation were discussed. Water decreased the wall strength of the aluminum alloy tubes, and the impact velocity at which a steel projectile first passes through the tube wall decreased with increasing diameter of the steel projectile. Using the velocity at which the steel projectile perforates the tube wall, empirical equations of the energies required to perforate the tube wall were derived. Also, the energy balance in the steel projectile during a collision is discussed referring to the pressure history in the filled water and the velocities of the steel projectile before and after collision.     

Automatic device for magnetization measurements on superconductors

A measuring system is described which is based on the amplification at low temperature of small dc voltages proportional to the derivative of the superconductive magnetization. The system provides full computer control of the magnetization process, the data acquisition and the evaluation of the magnetization curves.     

The deformation mechanics of interlock tubes

Interlock tubes are one of the key structural layers of most flexible pipes of composite construction for offshore oil and gas transmission and water injection applications. The design and manufacture of such a tube based on a good understanding of its deformation mechanics are undoubtedly of significance to the integrity and safety of flexible pipes and pipe systems. This paper describes a semi-empirical model for the evaluation of the deformations in the critical sections of the interlock tube as it responds to the overall pipe loading and configuration. Results of a finite element analysis and radiographic tests are incorporated to verify and supplement the model.     

电磁超声探伤仪在棒材检测中的应用

介绍了棒材电磁超声探伤仪的设备结构、功能和工作原理,并对棒材内部缺陷进行了识别分析。相比常规水浸式压电超声,电磁超声探伤仪具有调整简便、适应温度范围广等优点,在棒材自动无损检测领域逐渐占据了重要地位。     

基于广义倒频谱的无缝钢管在线高精度测厚技术

 为了满足无缝钢管在线高精度测厚的需求,开展了基于广义倒频谱测厚技术的研究.分析了传统测厚算法的缺点,提出一种基于广义倒频谱的无缝钢管在线测厚方法,此算法结合了相关分析和倒频谱的综合优势,处理后的波形峰值尖锐,提高了测厚精度;在此基础上对在线系统钢管旋转造成的声程误差进行了补偿.实验结果证明该方法测量精度高,实时性强,适用于工业无缝钢管在线高精度检测系统.     

The effect of alloying additions on the oxide morphologies of super-heater tubes at elevated temperatures

Abstract

This paper considers the oxidation of boiler tube alloys; viz. 321H which contains titanium, and E1250 which contains niobium and vanadium, at temperatures of 650 and 750°C, under laboratory conditions, for 720 hours. The resulting oxides have been characterised using advanced techniques including scanning electron microscopy, energy dispersive X-ray spectroscopy and site specific crosssections using focused ion beam milling.

The results have shown that small concentrations of titanium and vanadium have a pronounced effect on the morphologies of the oxide layers. Where titanium is present, as in alloy 321H, titanium rich nodules form leading to the development of “whisker” growths from the nodules. On the E1250 alloy, vanadium rich, gem like, crystals form on the surface of the chromium/manganese rich scale. Cross-sectional analysis has shown a possible relationship between the surface features and underlying niobium particles.     

圆钢管约束高强混凝土轴压短柱的试验研究与承载力分析

采用内置型钢短柱对钢管约束钢筋混凝土(STRC)柱节点进行增强。为明确该节点中内置非贯通型钢STRC柱的控制截面位置及压弯承载力,进行了内置不同长度型钢STRC柱及无型钢对比试件的拟静力试验及有限元模拟研究,分析了试件的受力机理及压弯承载力,探讨了型钢长度和钢管约束等因素的影响。研究结果表明：随着内置型钢长度增加,破坏截面有从型钢-混凝土过渡截面转移至柱根的趋势;增大钢管径厚比会削弱其抗弯贡献,从而减小过渡截面压弯承载力,影响破坏截面位置。基于试验及有限元分析结果,提出柱根及过渡截面压弯承载力计算模型,建立内置型钢临界长度的确定方法,研究结果为STRC柱的设计及节点中型钢的参数确定提供理论依据。     

Degradation of mechanical strength of pyrolysis furnace tubes by high-temperature carburization in a petrochemical plant

Pyrolysis furnace tubes made of HP45 heat-resistant steel casting to handle carbonaceous gases at about 850 °C in a petrochemical plant developed longitudinal cracks after less than one-third of the expected life. Detailed microstructural analysis showed that the cracks were developed by a ductile intergranular mode. This was correlated with high-temperature carburization attack leading to massive precipitation of intergranular carbides and a mixture of carbides and sigma phase within the matrix. Experimental results suggested that the highly reducing nature of the environment precluded the tube material from developing and maintaining a surface protective oxide scale, which facilitated the rapid inward diffusion of carbon.