分光光度计数据采集与处理系统的改造

为实现对传统分光光度计的改造,设计了一种基于声卡的分光光度计数据采集系统。利用普通PC机的声卡配合VB编写的软件构建数据采集系统,替代原记录仪,完成了对分光光度计检出数据的采集和处理。测试结果表明,该系统不仅可以准确地采集到原始信号,而且数据量小,可以实时地对原始信号分析处理并显示光谱信号曲线。     

光透法测定粉末颗粒粒度

论述了光透法测定粉末颗粒粒度的原理．并对其设备结构作了简要分析；研究了光透法测定粉末粒度的计算机数据采集及处理系统；并讨论了影响测试精度的因素及注意事项。     

光透法测定粉末颗粒粒度

论述了光透法测定粉末颗粒粒度的原理，并地其设备结构作了简要分析；研究了光透法测定粉末粒度的计算机数据采集及处理系统；并讨论了影响测试精度的因素及注意事项。     

管道共振监测分析方法研究

为减小管道共振对工业生产及管线使用寿命造成的危害,首次提出利用LabVIEW对管道共振进行在线监测分析研究,并利用SFPCI-6122数据采集卡和PC机自带声卡编程对系统的稳定性进行验证.采集卡采集管道内压力脉动和机械振动产生的电信号,并通过LabVIEW编程对振动信号进行时域分析、谱分析和小波分析,对数据进行保存分析,实现报警及事故追忆等功能.通过在线监测及时采取相应的减振措施,保障生产安全.硬件部分主要包括传感器、调理电路、数据采集卡和计算机;软件部分主要完成信号采集处理等功能.     

现场测试系统与远程测试系统的统一设计

分析了远程测试系统的必要性,给出一种现场测试系统软件结构,基于LabVIEW和LXI的远程测试系统,提出C/S模式下基于复用技术的现场测试系统与远程测试系统统一设计的方法和B/S模式下基于复用技术和ActiveX的远程测试系统复用设计方法。     

高校计算机一级考试评分系统的实现

讨论了用Visual Basic.net和SQL Server 2000实现高校计算机一级考试评分系统,阐述了考试评分系统的功能、结构及其应用情况.     

玻璃钢缠绕成型工艺的计算机辅助分析、设计和控制

本文综合分析了计算机辅助分析、辅助设计和控制在纤维缠绕成型工艺中的广泛应用，分析了系统的组成、结构、功能以及设计方法，并开了计算机软件和控制系统     

光纤光栅传感器在道路测试及工程应用的研究进展

路面结构内部温度、湿度、应力和应变等参数的测试一直是道路测试领域的重点和难点,随着光纤光栅传感技术的发展,为道路测试领域提供了新方法;为了论证光纤光栅传感技术在道路测试领域的可行性,介绍了光纤光栅传感系统的基本结构,从温度和应变传感器基本原理出发,综述了光纤光栅传感器的室内探索性研究和在实际路面温度和应变测试的成果.最后介绍了光纤光栅传感器在其他工程,包括桥梁、隧道及机场跑道中的应用情况,并分析了光纤光栅在道路测试工程中推广使用所面临的困难和发展方向.     

螺纹综合尺寸非接触光电测试系统

基于激光三角测量原理的激光传感器通过和特殊的机械结构结合,不仅可以直接测试新螺纹的精确几何参数,而且可以对有油腻、灰尘等物部分填充螺纹情况下进行测试,通过计算机处理后得到螺纹参数,可以判断螺纹的轴向损坏情况。系统的满量程线性度优于0. 1%,静态最高分辨力可达到1μm,静态定位测试重复性误差达±5μm,系统测试速度最大为4mm/s。内螺纹直径在30~300mm,长度0~100mm;外螺纹长度无限制。测试数据具有自动采集、统计、判断、存储等功能。     

金属材料高温测试系统的设计

设计了一种由计算机、高温加热装置、压力传感器、引伸计及数据采集卡等部分组成的金属材料高温测试系统。系统以C++Builder6.0软件为基础进行程序开发,由计算机和智能仪表控制,实现温度的采集并对采集数据进行实时、直观的显示,目的是改造老式试验机,使其完成高温拉伸试验,提高设备利用率和实现金属材料高温测试系统的综合性能。     

Grain-Size Dependence of Fracture Energy in Ceramics

A simple model incorporating thermal elastic anisotropy stresses is used to calculate the microcrack zone size around cracks in Al₂O₃. It is found that the ratio of microcrack zone size to grain size is almost constant for notched beam tests, but increases with grain size for double cantilever beam data. It is suggested that notched-beam ratios of fracture toughness are related to crack initiation, whereas double cantilever beam values are related to propagation and reflect R-curve behavior of the material.     

Re-evaluation of Adhesive Fracture Energy

A model to evaluate the Energy Release Rate (ERR) of adhesives using the Double Cantilever Beam (DCB) specimen is described. The model accounts for the adhesive bond thickness and its material properties. The analysis, considered as an improvement to the built-in cantilever beam model, treats the adherend as a finite beam which is partly free and partly supported by an elastic foundation and the adhesive bond as a thin strip under prescribed displacement. The results show significant effect of the adhesive parameters on the total ERR and that the built-in cantilever model underestimates the ERR. In general, the contribution of the adhesive bond to the ERR increases for softer adhesives, shorter cracks and thicker bonds.     

悬臂梁结构光纤光栅电流传感器的优化

针对电力系统对电流测量高精度的要求,设计了一种基于等强度悬臂梁结构的光纤光栅电流传感器。将两根光栅分别粘贴于等腰三角形结构的悬臂梁上下表面,末端永磁体材料振子置于两螺线圈中间。当螺线圈接通电流时,形成的磁场将会引起永磁体振子偏移,进而引起光栅中心波长的变化。采用差分方式建立电流大小与光栅波长变化之间的关系,在提高测量灵敏度的同时消除了温度对测量结果的影响。实验结果表明:在0~5A的范围内,利用光纤光栅波长变化可准确反演待测电流值,与理论计算值相比,误差小于1.2%。     

Experimental study of the Mode I adhesive fracture energy in DCB specimens bonded with a polyurethane adhesive

The Mode I fracture energy of a polyurethane adhesive with low Young’s modulus was investigated. Metal adherends in standardized double cantilever beam (DCB) tests are typically too stiff for soft adhesives, making it difficult to measure the fracture energy accurately. However, soft adhesives, such as a single-component polyurethane adhesive tested in this paper, are in high demand in the automobile industry. Thus, accurate measurement techniques must be established. Flexible substrates composed of spring steel were used for the DCB tests to accommodate the deformation of the adhesive layer. First, the applicability of the flexible substrates was discussed using specimens bonded with an epoxy adhesive. For soft adhesives, however, the deformation of the adhesive layer must be considered in the calculation methods of the fracture energy. Although the deformation effect on the DCB tests has been discussed with Winkler’s elastic foundation, the crack length must be measured along with the load and displacement. To overcome the difficulty of measuring the crack length, a calculation method based on Winkler’s elastic foundation was introduced applying the compliance-based beam method (CBBM). Finally, the fracture energy of the polyurethane adhesive was discussed by comparing the calculation methods with and without measuring the crack length.     

Measurement of Fracture Toughness of Plasma-Sprayed Al2O3 Coatings Using a Tapered Double Cantilever Beam Method

The fracture toughness of plasma-sprayed Al₂O₃ coatings in terms of the critical strain energy release rate G _Ic was measured using a tapered double cantilever beam (TDCB) approach. The fracture surfaces were examined using a scanning electron microscope (SEM). The measurement yielded the mean G _Ic values from 13 to 27 J/m² for the sprayed Al₂O₃ coatings at different spray distances. These values agree well with those obtained by the conventional double cantilever beam approach. The dependence of the observed G _Ic on spray distance is consistent with that for the lamellar bonding ratio. These results suggest that the TDCB test is a reliable approach for measuring the G _Ic of thermal-spray coatings without the crack-length measurement.     

Analysis of the cohesive zone and crack length correction in the adhesively bonded double cantilever beam specimen

The double cantilever beam specimen has been increasingly employed to enable the development of cohesive zone models for adhesive joints. Evaluation of the traction–separation law (TSL) requires elaborate experimental techniques and usually relies on data measured until the crack initiation point. Nonetheless, current standards stipulate fracture energy measurements under steady-state crack propagation. This paper investigated the influence of the cohesive zone on the commonly used corrected beam theory data reduction scheme. Analytical solutions for the elastic–perfectly plastic, bilinear, and trapezoidal laws were developed using a beam model. The role of the elastic traction decay zone was found to be significant for high strength moderately tough adhesives. Nevertheless, the results showed that the sensitivity of the crack length correction to the cohesive zone can be exploited to obtain approximate TSLs.     

Characterization of micro-mechanical properties of AlON ceramic by cantilever bending test

The AlON transparent ceramic cantilever beams containing twin and grain boundaries were fabricated by focused ion beam technique. The deformation behaviors were investigated by measurement of the load and displacement dependence of cantilever beams from micro bending tests. Young's modulus of AlON transparent ceramics was calculated from load and displacement curves, the results of which were consistent with results of previous works. Moreover, the bonding strengths of twin lamella boundary, twin boundary, and normal grain boundary in AlON transparent ceramics were 5.00, 5.05, and 4.81 GPa, respectively.     

A model for predicting fracture resistance of fiber reinforced concrete

A theoretical model is presented to predict the crack propagation resistance of fiber reinforced cement based composites. A crack in the matrix is divided into a traction free zone, fiber bridging zone and the matrix process zone. The crack closing pressure due to fibers depends on the (Mode I) crack opening displacement (COD). A method is suggested to estimate this relationship from the pull-out tests. Although calculations of COD are based on linear elastic fracture mechanics concepts, the energy absorbed in the fiber bridging zone is included in the analysis. Theoretical results are compared with the experimental data of notched beam and double cantilever beam specimens.     

Role of Crack-Bridging Ligaments in the Cyclic Fatigue Behavior of Alumina

The cyclic fatigue crack growth behavior in two aluminas with different grain sizes and purities has been investigated using tapered cantilever beam specimens. The curves of load–crack opening displacement revealed a hysteretic loss behavior, in both aluminas, produced by frictional forces generated in the crack wake. From measurements of the specimen complinces it is concluded that the fatigue cracks in these materials were strongly bridged by both "frictional" and "elastic" load-bearing ligaments. It is shown that the "elastic" contribution to the total crack-bridging force is far greater than that produced by fristional sliding ligaments. The results support the view that cyclic loads produce degradation of the strength of the bridging ligaments. The effect of grain size and compressive loads on the magnitude of the bridging forces is discussed.     

Fracture mechanics testing of the bond between composite overlays and a concrete substrate

This paper presents a methodology for assessing the bond strength of composite overlays to concrete utilizing a fracture toughness test. The principles and practices of existing ASTM standards for determining the fracture toughness of adhesive bonds between double cantilever beam (DCB) metallic and composite specimens (D 3433-93 and D 5528-94a) have been extended to cover the case of an elastic composite layer bonded to a rigid concrete/masonry substrate. In the theoretical section, the dominant loading conditions, relevant ASTM standards, and the development of energy release rate concepts for analyzing a disbonding composite layer modeled as an elastic cantilever beam are presented. The experimental section covers specimen fabrication and preparation, experimental setup, test procedures, post-test evaluation of the specimens, and data processing. The discussion of test results focuses on explaining the variability in measured strain energy release rate, and identifies trends between the measured strain energy release rate and the fraction of the fracture surface retaining cement paste after disbonding. It was found that good-quality composite-to-concrete bond is associated with high fracture toughness of the adhesive and location of the crack path in the concrete substrate. Strict enforcement of surface preparation and adhesive handling procedures was found to play an important role in promoting good bond strength and high fracture toughness. The fracture toughness test developed in this paper can be used for screening various composite-repair systems, to assess the effect of different environmental attacks, and as a quality control tool.