1500m3液化石油气球罐的强度分析

通过对球罐的整体应力分析，指出将焊缝布置在高应力区域是造成焊缝裂纹的重要外部因素之一。进一步的焊缝应力集中系数研究表明，焊缝存在很大的应力集中系数。高的宏观应力和大的焊缝应力集中系数所引起的局部高应力水平在焊缝某些位置造成开裂或裂纹／类裂纹缺陷的扩展是可能的。     

基于LD的近红外农产品水分检测仪的设计

设计以半导体激光器为光源的农产品水分近红外检测仪,将光源与分光系统合二为一,摒弃一般光谱仪器中复杂的分光系统,提高仪器的稳定性;样品在积分球内采用体吸收工作模式,可以最大限度减少样品粒度造成的散射现象对检测精度的影响,经3种物料的水分检测试验证明检测结果具有较高的精度,能满足一般生产和流动行业对农产品和食品的水分快速检测的需要。     

34km传感长度的布里渊光时域反射计的设计与实现

布里渊分布式光纤传感器是目前最具应用前景的分布式光纤传感技术之一,其关键是如何检测布里渊散射光信号,布里渊光时域反射计是其中较好的检测方式。针对布里渊散射光信号特点,应用光相干技术来检测布里渊散射光信号。具体采用微波电光调制产生频率可调的参考光,和散射光进行相干检测,根据散射光频移特性,应用电信号处理技术取出布里渊散射光电信号,并采用偏振控制技术来抑制相干检测的偏振相干性,再经过数字信号累加和平均处理,最后得到分布式传感信号。采用光相干检测设计方案实现了布里渊时域反射计分布式光纤传感器,并进行了34km光纤的分布式应变传感实验。     

A high pressure cell for dynamic light scattering up to 2 kbars with conservation of plane of polarization

We report on a high pressure cell with six optical windows which can be used up to 2 kbars for laser light scattering applications at scattering angles of 45 degrees , 90 degrees , and 135 degrees of liquid samples in a temperature range between -20 and 150 degrees C. The pressure transmitting medium is compressed nitrogen. The window material used is SF57 NSK, a glass with an extremely low stress optical coefficient in the order of about 10(-5) which allows thus to maintain the plane of polarization even under the action of high pressure. In order to demonstrate the functioning of the cell we show Rayleigh-Brillouin spectra of poly(methylphenylsiloxane) at different polarizations and pressures.     

A technique for identifying the initial stage of the extension of low-temperature creep cracks

A technique that makes it possible to obtain the initial data for constructing growth diagrams for low-temperature creep cracks is proposed. This technique is based on the acoustic-emission method. It is shown that the application of this method makes it possible to efficiently reveal early stages in the extension of creep cracks in structural steels. Using the data of experiments performed with this technique, the value of the lower threshold stress-intensity factor was obtained for constructing the first region of the diagram.     

Investigation of constantly and transiently propagating cracks in functionally graded materials by dynamic photoelasticity

In this study, the stress intensity factors (SIFs) for steady and transient propagation of cracks in transparent homogeneous functionally graded materials were analyzed by using the photoelasticity technique. The fracture analysis was carried out for the cracks propagating from a region with high elasticity towards low elasticity, as well as the cracks propagating from a region with low elasticity towards high elasticity. The analysis includes cracks propagating (1) at an almost steady speed, and (2) with the rapid increase, followed by a decrease in speed. For cracks with almost constant velocity, the SIFs were greater when a crack started from a high elasticity region, as compared to the cracks which initiated from a low elasticity region. For cracks propagating with rapid acceleration and deceleration, when the strain energy accumulated in the material due to an increase in load or stress was released at the moment of crack propagation, the SIF was momentarily lowered by approximately 45 %–50 % of the static SIF(before crack initiation), which subsequently increases by approximately 30 % eventually, the crack acceleration approaches nearly zero; the SIF decreases and increases respectively as the crack propagates in a material with decreasing and increasing modulus of elasticity.

     

Particle development in apple juice determined by light scattering and electron microscopy

Light scattering was used to detect the kinetic development of particles in apple juices produced with and without oxidation and in procyanidin extracts prepared from these two juices. Particle size developed exponentially inboth oxidized and unoxidized juices, suggesting an enzymatic origin for the particle forming reactions. The procyanidin extract from oxidized juices produced particles which grew linearly, suggesting diffusion-controlled aggregation or coalescence of particles. Procyanidins from unoxidized juice showed no particle development over at least 60 days of storage. Electron microscopy showed particles similar to those seen previously and some newly described morphologies. The mechanism of haze particle development is discussed in the light of the light scattering and electron microscopic results.     

Imaging in the far-red with electronic light microscopy: Requirements and limitations

The acquisition of simultaneous dual confocal images with red and far-red light has both advantages (e.g. lower autofluorescence) and limitations. An understanding of these requisites is necessary to acquire high-quality images and to avoid the misinterpretation of experimental data. The poor detection of far-red light mandates a high optical transfer efficiency for the system, thus the transmittance of the objective lens and its axial and lateral chromatic aberration in the far-red are important factors for consideration. This technical note is an attempt to ‘demystify’ the process of filter set design for confocal microscopy by discussing the considerations that went into the construction of a filter set for use with the reagents cyanine 3.18 (Cy3) and cyanine 5.18 (Cy5), and thus to encourage users to look beyond the multi-purpose designs available commercially. The 568-nm laser line exciting Cy3 is at its emission maximum, which limits the collectable Cy3 fluorescence. High-transmission optical filters with sharp band pass cutoffs are thus desirable for maximum light throughput. Light path mirror efficiency rapidly degrades above 700 nm, but the loss of this portion of the Cy5 emission spectrum is acceptable since the fluorophore is very bright, and these very long wavelengths are also likely to introduce aberration. While resolution is decreased with far-red light, there is also greater penetration and less scattering, and it is thus possible to obtain high-quality images from deeper within the specimen. Although only one make and model of confocal microscope (the Bio-Rad MRC–600) is considered, similar considerations pertain to the design of filter sets for any confocal microscope that accommodates user-installed filters.     

Stray light analysis for the Thomson scattering diagnostic of the ETE Tokamak

Thomson scattering is a well-established diagnostic for measuring local electron temperature and density in fusion plasma, but this technique is particularly difficult to implement due to stray light that can easily mask the scattered signal from plasma. To mitigate this problem in the multipoint Thomson scattering system implemented at the ETE (Experimento Tokamak Esfe?rico) a detailed stray light analysis was performed. The diagnostic system was simulated in ZEMAX software and scattering profiles of the mechanical parts were measured in the laboratory in order to have near realistic results. From simulation, it was possible to identify the main points that contribute to the stray signals and changes in the dump were implemented reducing the stray light signals up to 60 times.     

Experimental and theoretical modal analysis of constructions with fatigue cracks

On the basis of experimental and theoretical modal analysis, the appearance of fatigue cracks with various depths within rotor systems is studied. For cracks with various depths, stress values in the place of occurrence of a defect are obtained. By means of obtained stresses, it is possible to reveal fatigue cracks with a depth of 15% of the cross-sectional area of a shaft.     

Laser nitriding of the surface of phosphor bronze

Phosphorous bronze finds applications in industry because of its resistance to fatigue and ease of heat dissipation due to its high thermal conductivity. Laser treatment of bronze surface improves the hardness of the surface through forming a dense layer in the surface region. Consequently, in the present study, laser treatment of a bronze surface is investigated. Thermal stress and temperature fields developed during the laser-treated region are modeled after considering the transient three-dimensional situation in line with the experimental conditions. An experiment is carried out, and the resulting surfaces treated by a laser beam are characterized using scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction. It is found that high rate of strain developed in the heated region, due to fast-cooling rates, results in high von Mises stress in the surface region. The laser-treated region is free from cracks, and surface hardness increases almost four times above the base material hardness after the laser treatment process.     

A study on observation and growth behavior of small surface cracks by remote measurement system

A new experimental system using remote measurement system (RMS) and image processing technique was applied for studying the growth behavior of small surface fatigue cracks in 1Cr ?1Mo?0.25V steel at room temperature. The system includes a long distance focusing microscope, a CCD camera, a light source, a 3-axis controller a monitor, a personal computer and a data translation card. The measurement error of the system appeared to be 0.8%. It is possible for this system to measure down to 30 μm of surface fatigue crack length. The length of surface fatigue crack could be successfully measured by the RMS during testing as well as after the test. The growth rate of small cracks on smooth specimens was represented in terms of stress intensity factor and J-integral. At equivalent elastic stress intensity factor levels, the growth rate of small surface cracks was not consistent and faster than that of long crack of CT specimen.     

应力场强法研究

本文中作者提出了一种高周疲劳设计的新的方法——应力场强法（ISF法）。作者认为决定疲劳裂纹萌生和扩展的宏观力学参量是最大峰值应力点周围的局部应力应变场,这个应力应变场有一确定的范围。文中,作者提出一个新的力学参量——有效应力场强σ (RD),它定量地代表了局部应力场的强度,并能用作估算高周疲劳寿命的宏观判据,因为它恰当地反映了峰值点应力σ及其周围不同方向上应力梯度dσ/dx I（I=1,2……n）的综合影响,并在一定程度上代表了这个区域内变形能的积累。     

高温过热器制造焊口裂纹的成因分析

高参数发电锅炉的高温过热器由于其工作压力、温度较高，采用的材料多数为高合金钢。高合金钢材料的强度及硬度较高，其焊接性能相对较差，制造过程控制不好容易产生裂纹。本文对一台电站锅炉高温过热器制造焊口裂纹产生的原因进行分析。     

Estimating the probability of the propagation of stress corrosion cracks in compressor station pipelines

The conditions for the nucleation of stress corrosion cracks in linear and compressor station gas pipeline sections were considered. The potential for the use of pipes with a smaller diameter and a thicker wall in compressor station pipelines to create favorable stressed state conditions that promote the arrest, etching, and stabilization of stress corrosion cracks was shown. The fractographic inspection of pipe fragments with stress corrosion cracks allowed us to reveal an overload that was unrelated to the increase in the internal pressure of the given gas pipeline section. This overload was a major cause of such events as the reinitiation and propagation of stress corrosion cracks to a depth of nearly 50% of the pipe wall thickness. The overload itself was presumably caused by a construction factor connected with the position of a pipe on a pipeline route and its possible deformation (pinching) owing to soil and thermal instabilities.     

残余应力对焊接接头CTOD设计曲线的影响

基于BISPD6493：1991初级评定，采用热弹塑性有限元分析方法，研究了残余应力和强度组配对横向裂纹平板对接接头CTOD设计曲线的影响规律。结果表明，强度组配和残余力对CTOD设计曲线具有明显的影响；残余应力对接头中的短裂纹影响较大，PD6493：1991初级评定不适用于接头中含有位于拉伸残余应力区内的短裂纹情形，随着裂纹尺寸的增大，残余应力的影响逐渐减弱；在应用PD6493：1991初级评定曲线对接头中的大裂纹情形进行评价时，将得出偏于保守的结果。     

A real-time vision system for defect inspection in cast extrusion manufacturing process

The cast extrusion manufacturing process is the initial step which enables the creation of the raw materials, such as clear polypropylene film, needed for the flexible packaging printing process. The current methodology of controlling extrusion-related defect occurrences is attempted by a combination of statistical sampling and human inspection. However, due to the fact that the defects are small in size and hard to visualise in a clear thin film 2 m in width moving at a speed of 50 m/min. This results in poor product quality and high return ratio from customers. To the best of our knowledge, there is no system available that can accurately detect such defects. This research investigates possible defect detection methodologies and has subsequently proposed a system that is capable of real-time monitoring of defects on the cast extrusion manufacturing process. The proposed system utilises the refraction of a collimated light source, which is referred to as Mie light scattering. A vision analysis system is subsequently used to perform a blob analysis to detect the contrasting dark regions of the defects. Two test rigs were constructed to test the feasibility of the system. The first test rig was created to test the theoretical Mie scattering principles and the performance of the image analysis software in practice. The second test rig was created to test the practicability of integrating the Mie scattering theory on the physical cast extrusion line. The results obtained from the tests indicated a success rate of 90% in identifying gels and a 100% success rate in correctly identifying all the die lines presented in the tested samples. It is also deduced that the software has a capability to detect gel granules with a diameter greater than 480 μm and die lines with a thickness greater than 320 μm amid complete repeatability, ensuring that the proposed system fully conforms to the standard industrial requirements.     

框架式电加热器在消除焊接残余应力中的应用

氧化铝厂有一部分压力容器盛装苛性碱液,使用过程中,由于焊接残余应力和使用应力的共同作用,短时期内,就产生碱脆裂纹,严重影响正常生产。原通过履带式加热器消除应力,效果不理想。现采用框架式电加热器,提高了残余应力的消除能力,从而延长了容器的使用周期。     

New Thomson scattering diagnostic on RFX-mod

This article describes the completely renovated Thomson scattering (TS) diagnostic employed in the modified Reversed Field eXperiment (RFX-mod) since it restarted operation in 2005. The system measures plasma electron temperature and density profiles along an equatorial diameter, measuring in 84 positions with 7 mm spatial resolution. The custom built Nd:YLF laser produces a burst of 10 pulses at 50 Hz with energy of 3 J, providing ten profile measurements in a plasma discharge of about 300 ms duration. An optical delay system accommodates three scattering volumes in each of the 28 interference filter spectrometers. Avalanche photodiodes detect the Thomson scattering signals and allow them to be recorded by means of waveform digitizers. Electron temperature is obtained using an alternative relative calibration method, based on the use of a supercontinuum light source. Rotational Raman scattering in nitrogen has supplied the absolute calibration for the electron density measurements. During RFX-mod experimental campaigns in 2005, the TS diagnostic has demonstrated its performance, routinely providing reliable high resolution profiles.