Advanced Materials Research Vols. 314-316

Abstract: The stress and strain condition of the corroded line pipe with single hemisphere bottom defect under deferent inner pressure were analyzed by the Finite Element Methods (FEM) in this paper; At the same time, the residual strength models for the corroded pipe were established based on both the Von Mises equivalent stress and the Von Mises equivalent strain of the finite unit on the defect local zone respectively, the residual strength was decreased with the defect size (d/t) linearly. This way, the residual strength for the corroded pipe with a given defect size (d/t) could be conducted by using the model properly, which could help the owner make a decision when happened to the same defect in the operation. The analysis results shown that the residual strength calculation should choose based on stress when the defect depth (d/t) was less than 0.5, or else choose based on the strain when defect depth (d/t) was exceeds 0.5.

Abstract: This paper describes a set of theoretical and experimental results based on thermoelastic effect measurement from Glass-Fiber-Reinforced-Polymer (GFRP) composite structure for full-filed stress analysis. The sum of the principle stress (The first stress invariant) can be measured by means of thermoelastic stress analysis (TSA), and this method is used to determine the stress concentration of the composite structure. A finite element analysis is proposed to predict the stress distribution for GFRP gluing structure. The lock-in thermography has been applied to measure the structure stress distribution by its high thermal resolution. The experiment was carried out with different GFRP composite structures by lock in thermography. The experimental results show the stress distribution can be measured and evaluated with good accuracies by using of lock-in thermography

Abstract: Until now, the most common way to obtain the stress-strain curves for a material is through axial tensile testing. However, in recent years there have been developments on alternative methods for material characterization. In this sense, the bending procedure has proved to be a powerful technique, which allows simultaneous determination of tension and compression stress behavior by the use of bending moment and strain data. The characterization of materials by means of bending data was presented for the first time in 1910 by the German engineer Herbert. Some years later Nadai and Marin developed some research on this procedure. More recently, several researchers (Mayville and Finnie, Laws and Urriolagoitia-Sosa, et.al.) have developed diverse bending methods for the simultaneous determination of tension and compression stress-strain curves. In this paper, three bending methods are analyzed and compared against axial tensile and compressive results. It was decided to apply each one of the bending procedures to bent rectangular cross sections beams made from 6063-T5 Aluminum alloy. The specimens were annealed to eliminate previous loading history and axially pulled to induce a controlled anisotropic behavior (strain hardening and Bauschinger effect). The results obtained by two of the three methods provided great confidence and have certified the application of this new technique to characterize material.

Abstract: The trbriological properties of FeS solid lubrication composite layer were carried out on the type MS-T4000 friction wear testing machine. Morphology and elements analysis of wear surfaces was carried out on ultra high resolution field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the friction process of FeS solid lubrication composite layer can be divided into three stages. The friction coefficient of FeS solid lubrication composite layer is about 0.16 in the first stage, the friction mainly occurred in the surface of FeS solid lubrication. The friction coefficient is about 0.20 to 0.25 and is about 0.40, in the second stage and the third stage, respectively. The wear surface of FeS solid lubrication composite layer was smooth without obvious furrow. On the wear surface, there were mainly granular and flatteners-like FeS films.

Abstract: The non-destructive ultrasound infrared lock-in thermography (ULT) testing method was used to detect metal specimens with defects of micro cracks. An experimental platform was built based on the analysis of the ULT principle. Experiments had been carried out to Q235 plates with different testing parameters. The testing effect of thermography, amplitude and phase images was analyzed, and the relations between amplitude difference, phase difference, signal-to-noise ratio and modulation frequency were discussed.

Abstract: This paper is mainly about the experiment research of oil monitoring for a kind of special heavy vehicle’s transmission system. The wear elements in lubrication oil of a heavy vehicle’s transmission system were analyzed by the spectroscopic analysis method, and gear’s wear status was studied. Probability density function and probability distribution function of wear information about the elements in lubricating oil were calculated by the maximum entropy theory. The running cut-off point is obtained for diagnostic criteria of the vehicle’s failure, which provided evidence for monitoring and judging the reliability of the vehicle’s wear.

Abstract: The radial supporting bearing of main thrust bearing is the key equipments of shafting on large-scale ships, whose working lubricating property has an important influence on the working condition of the shaft. By means of theoretical analysis and Matlab programming, investigations have done on the main working condition lubricating of the radial supporting bearings. And the distribution rules of oil film thickness and pressure under same vertical load and different rotate speed is given, which lays a foundation for the design of large marine’s thrust bearing.

Abstract: In order to find out the variation law of ink stickiness during the printing, the ink tack value under 9 different linear velocities of ink distributing roller was tested, and the relation equations between tack value and the roller linear velocity were built up. At the same time, the plastic viscosities of 8 offset inks and their tack values under 9 separation velocities were also tested. The study results showed that the higher the linear speed was, the larger the tack value was, and it would stay in a relatively high tack value (regarded as infinite tack value). Also, the printing ink having high viscosity may possess low tack value.

Abstract: The influence of humid environment on fatigue property of pre-corroded 7XXX aluminum alloy were investigated by means of fatigue and staircase experiments (Kt=1 and Kt=3). The results showed that humid environment significantly reduces both fatigue life and strength with the influence-factor of 0.7339(Kt=1), 0.8603(Kt=3) and 0.973(Kt=1), 0.971(Kt=3), respectively. The humid environment enlarges the dispersivity of fatigue life. As a consequence, an unconservative results on prediction of the fatigue life with high reliability of 99.9% will be obtained, based on the corrosion-influence-factor reached from eigenvalue or mean value .

Abstract: Layer removal method is executed by milling process, which may causes deformation and stress change of sample in aluminum alloy thick plate. Through error assessment about the experimental testing process involved milling, the milling stress layer is very thin and fail to change the whole stress dietribution of sample under some technique. Because many times of the loading - unloading operation will increase the deformation error of sample, per-depth of milling is should not be too small for the enhancement of accuracy of data fitting in stress measurement. Finaly, under the conditions of reasonable milling process and scientific experiments, influence of milling process on internal stress measurement can be ignored.