Lubricant effects on strain fields of seven wire strands subjected to tensile load

As a part of an extensive analysis on strand behaviour the lubricant effect in strain fields was examined. The strains were measured by using electrical resistance strain gauges. The results obtained, by loading the unlubricated and lubricated sample both statically and quasi-statically, showed relevant effects caused by different contact loads developed among the wires. By examining the strains measured during the severing of one helical wire the inapplicability to the strands of one Italian regulation relative to wire ropes, was also confirmed.     

Swelling behaviour of rubber vulcanizates: 2. Effects of tensile strain on swelling

The effects of tensile strain on the swelling behaviour of acrylonitrile-butadiene copolymer rubber vulcanizates were studied by real-time pulsed nuclear magnetic resonance (n.m.r.) measurements and volume swelling measurements at equilibrium. It was shown that tensile strain causes an increase of the initial swelling rate evaluated by n.m.r. measurements and of the swelling ratio of the rubber matrix at equilibrium. This behaviour was discussed qualitatively in terms of the molecular mobility of the network chains on the basis of Treloar's theory for swelling under deformation. It was suggested that the presence of reinforcing fillers in the rubber matrix exerts two noticeable effects on swelling under deformation: (1) a transient effect through some oriented structure induced by stretching, which restricts the increase of the swelling rate; (2) a strain amplification effect, which causes the increase of the average local strain in the rubber matrix and enhances the swelling ratio more remarkably proportional to the filler concentration as compared with that of the unfilled system.     

Time-Harmonic Analysis of Wave Propagation in Unbounded Layered Strata with Zigzag Boundaries

A frequency-domain consistent absorbing boundary for horizontally layered strata is derived for the cases of antiplane shear and plane strain. The boundary can be composed of nonvertical as well as vertical segments, thus enabling efficient modeling of unbounded media. While the nonvertical boundary, as long as not horizontal, can be inclined at an arbitrary angle, numerical instability is encountered as the boundary becomes nearly horizontal, leading to erroneous results. A modification of the formulation based on selective reduced integration is proposed to make the new boundary condition more robust. Application problems in foundation dynamics and dam–foundation–reservoir interaction are considered to demonstrate the computational efficiency provided by the new boundary.     

Distributed Measurement of Strain using Optical-fibre Backscatter Polarimetry

Abstract: Fully-distributed optical-fibre sensing (FDOFS) systems are developing rapidly and are offering significant advantages for measurement functions in a variety of structural applications, especially in the oil industry, the power supply industry, the aerospace industries and civil engineering construction.
Polarization techniques are well established in FDOFS, and in the analysis of polarization-mode dispersion (PMD) for optical-fibre telecommunications. However, a major problem has been that of determining, from one end of the fibre, the distribution of the full polarization properties of a monomode optical fibre, along its length, with some specific spatial resolution.
This paper will present a new technique for providing this full information, and thus for measuring the distribution of any parameter, external to the fibre, which can modify its polarization behaviour. As a result, for example, it becomes possible to measure simultaneously the distributions of temperature and of a strain field comprising, in the latter case, the longitudinal and the two transverse components of direct strain, plus the transverse shear strain.
The technique comprises an extension of polarization-optical time domain reflectometry (POTDR) [16], and necessitates on-line processing. Details of the physical principles, the algorithms and the polarimetry will be presented, together with results illustrating the measurement accuracies which can be achieved.     

Behavior of Oxide Scale on 9Cr–1Mo Steel Under Varying External Stresses

The effects of different external stresses on the oxidation behavior of9Cr–1Mo steel were investigated. Tensile specimens were subjected tostresses of 11, 20, 28, and 40 MPa and the oxidation behavior was studiedat a temperature of 973 K. The elongation of the specimen was determined byan extensometer. An acoustic-emission unit was employed to monitor theintegrity of the oxide scale. The oxide scale was found to undergo bucklingbefore spalling, in the case of unstressed specimens, and in the case ofthose specimens subjected to a stress up to 28 MPa. The specimen with 40 MPastress showed the development of cracks. The application of external stressup to 28 MPa (average strain rate for 28 MPa stress was1.2 x 10^-7 s^-1) had a beneficial effect with respectto the adherence of the oxide scale. The specimen with 40 MPa of stress(average strain rate of 5.2 x 10^-77 s^-1) showedsubstantial weight gain on oxidizing up to 140 hr. The unstressed specimenrevealed enhanced spallation when compared with the stressedones. Investigation by SEM revealed the spalling of the oxide scale when theduration of oxidation was higher than 70 hr at all stress levels employed inthe present investigation. Formation of cracks at 40 MPa exposed fresh areasto oxygen and caused accelerated oxidation. Analysis by energy-dispersiveX-ray spectrometry (EDS) revealed the segregation of chromium at the oxideridges. The segregation of silicon was also significant for the specimensubjected to a stress of 40 MPa. Analysis by XRD clearly revealed thepresence of oxides of chromium and iron (Cr₂O₃ andFe₂O₃) and spinel-type oxide (FeCr₂O₄).     

Micro-measurement using grating microscopy

In this paper, two quantitative methods to measure micro-deformation using grating microscopy are proposed, a grating diffraction method and a full-field grating phase-shift method. A compact optical transmitting microscope with white light source is reconstructed by developing a loading and recording system. For direct strain measurement, a grating diffraction method is presented. With the help of a Bertrand lens, the Fourier spectrum of the grating is formed on the CCD sensor plane with high image quality. Software for precise, fast and automatic determination of the diffraction spot centroids is developed. Local strains are thus measured with high resolution. For the deformation measurement, a phase-shifting grating microscope method with high sensitivity and spatial resolution is proposed. Phase-shifting is based on the slab refraction effect and is realized via a tilting compensator. The system possesses a high spatial resolution (1 μm), and a displacement precision of 0.1–0.03 μm. The combination of the grating diffraction method and the phase-shifting method in the same test provides simultaneous measurement of strain and displacement, thus demonstrating that the grating techniques are viable in the microscope environment.     

High temperature deformation of oxide scale

Samples of ultra low carbon steel were oxidized in a chamber designed to control the thickness of the scale layer prior to their deformation by plane strain compression. The specimens were reheated within the temperature range of 950-1150 °C for different periods of time to vary the scale thickness; compression was conducted at temperatures that vary from 650 to 1150 °C. Metallographic analyses were conducted on deformed and undeformed scales to evaluate the integrity of the oxide crust that is made almost exclusively of wustite. It was found that the integrity of the crust depends on the temperature at which deformation is carried out and on the amount of deformation imparted. It is concluded that thin scales exhibit a plastic behaviour when deformed at temperatures above 900 °C and a brittle behaviour at temperatures below 700 °C; mixed behaviour was observed within this temperature range, as the scale was found to resist limited amounts of deformation.     

体内治疗用鼠源性乙脑单克隆抗体细胞系的质量控制

分泌乙脑单克隆抗体（JEV－McAb）原始细胞株2H4、2F2复苏后，在克隆化阳性率达100％时，细胞体外长期传代6个月，观察分泌抗体的稳定性，并对冻存0、1、4、7年的细胞复苏，按常规制备腹水，作ELISA、中和、血凝抑制和体内保护试验进行抗体特异性检定。结果，细胞传代6个月仍能持续稳定分泌特异性抗体，培养上清和腹水抗体效价不降低。冻存0～7年细胞复苏后抗体特异性不变。支原体及鼠源性病毒检测均为阴性，与人体16种组织不发生交叉反应。表明原始细胞库及生产细胞库其稳定性与特异性均符合质控要求。     

A quantitative study of blister growth on lacquered food cans by scanning acoustic microscopy

Scanning acoustic microscopy was used to image blistering of samples from food cans, internally coated with an epoxy-modified polyester lacquer, during exposure to aerated brine. Results were subjected to quantitative image analysis and have been discussed in the light of different models of blistering. The samples were taken from the side wall of the can, which had been formed by the draw-redraw process from pre-lacquered electro-chrome-coated steel sheet, thus providing insights into the effects of lacquer deformation.     

大直径灌注桩质量检测方法探讨

分别讨论了低应变反射波法和超声波透射法的原理及其局限性;通过两种方法现场检测结果的分析比较,讨论了两种检测方法对大直径灌注桩质量判定的准确性。