Advanced Materials Research Vols. 652-654

Abstract: In this work, the indentation size effect (ISE) in Vickers hardness tests of steel with selected heat treatments (annealed or tempered) has been investigated and analysed. Systematical hardness tests were performed within a commonly used micro-load range. The experimental data was analysed according to the Meyer power-law and the proportional specimen resistance (PSR) models and the link between ISE and material properties was discussed. The results showed that the experimental data fitted well with the Mayers power-law (P = A.dⁿ) and the PSR (P/d = a_l + a₂d) models. The ISE index (n) showed a good correlation with the hardness-elastic modulus ratio (H/E), which potentially could be used to predict the relative contributions of the elastic and plastic deformation contact area under indentation load and to normalize the hardness values for inverse material properties .

Abstract: This paper do the research of molding process, experimental study, numerical simulation for carbon fiber reinforced polymer (CFRP) sandwich structure under an aircraft ditching model. The model is simultaneous restricted to the weight and strength requirements. Choosing three types of expandable polystyrene (EPS) foam, testing their properties in different kinds of conditions: density, thickness of the core, layer. By the experiment to verify the design, we can gain the optimized layer, thickness of the core and parameters. This project can provide the basis to the design of manufacturing, process parameters and weight control for CFRP sandwich structure on aircraft ditching model.

Abstract: Reinforcement corrosion is one of the main causes for the deterioration of reinforcement concrete structure. And it seriously affected mechanical properties of anchor structure system of underground engineering under complicated erosion environment. Based on elastic theory and assumption of maximum tensile-stress failure criterion, together with construction process of anchor structure and rust expansion critical process, reinforcement rust expansion mechanical model of anchor structure system was simplified. Elastic criterion of different initial cracking mode was rewarded under different stress ratios. According to analysis of critical cracking mode of different medium, cracking order of mortar and surrounding rock depended on their material parameters, in-situ stress and thickness of mortar cover. Critical cracking conditions of different medium without effect of in-situ stress was rewarded. The result provides a useful reference for analysis of mechanical deterioration mechanism of anchor structure and design of support structure of underground engineering.

Abstract: Young's modulus is one of the basic mechanical properties of materials, so its accurate measurement has great engineering significance. Electrometric method is one of the commonly used method. Proceeding from experimental techniques, this paper studies the key factors which affect the result of the experimental measurement, including the influence of the uneven load, the pre-stretching, the hardening time of the strain gauge binder, and sticking quality of strain gauge; comprehensively provides the experimental measures to improve the measurement accuracy. Then through the uncertainty evaluations of the results with different measures, this paper from a point of quantitative view proves that taking these measures can reduce the dispersion of the measurement results and significantly improve the accuracy of experimental results.

Abstract: Thermal stress, as one of the most important stress of the arch dam during construction period, strongly influences the sliding stability of the arch dam. To analyze this kind of impact on arch dam sliding stability, numerical modeling of a typical slope dam section from 300-meter-high levels arch dam during construction period was conducted. Based on the rigid body limit equilibrium method, results of the case considering thermal stress as well as those without thermal stress were presented. Detailed comparison with the results of multiple monoliths was also made. In addition, the relevant sliding stability coefficient with the consideration of thermal stress was suggested.

Abstract: Intelligent inspection is wildly used in the integrity management of transmitting pipeline in service. Recently, the intelligent inspection data of one natural gas transmitting pipeline showed that lots of the blistering was found in the pipe inner surface. In this paper, the methods of OM, SEM and EDS et al were carried out to study the reasons of the blistering failure and proposed the safety countermeasures. The results show that the blistering failure of pipeline was mainly related to the hydrogen blistering and the manufacturing technology of the pipe. The sulfide stress corrosion (SSCC) and the manufacturing damage accelerated the blistering failure of the pipe.

Abstract: Recently, the intelligent inspection data of one natural gas transmitting pipeline showed that lots of the blistering was found in the pipe inner surface. In this paper, the method of finite element analysis was carried out to simulate and calculate the effect of blistering to the pipe strength. The results show that the max vonmises stress of the pipe with blistering was close to the yield strength and the max vonmises stress of the pipe increased with the increase of the press in the blistering. The minimum safety factor in the pipe with blistering was 0.99 which was reduced by the blistering. The sulfide stress corrosion (SSCC) and the manufacturing technology of hot rolling compound accelerated the growth of the blistering in the pipe.

Abstract: To improve the comfort performances of Mongolian clothing, five Mongolian clothing fabrics were selected. According to the natural environments of Mongolian Plateau in China, their structure parameters and comfort performances were analysed. The most primary characteristics of Mongolian clothing fabrics were concluded in this research, which must be valuable to the evironment adaptability research of human to Mongolian Plateau.

Abstract: The application of ultrasonic phased array has been increasingly common in nondestructive testing and evaluation of composite components. An advanced post-processing imaging algorithm of ultrasonic array, termed total focusing method, is introduced to improve imaging quality and detection ability. Then, the experiment system is developed to capture and store the time domain signals from every transmitter-receiver pair. This imaging algorithm is implemented to detect standard phased array sample and shown to offer increased sensitivity to small defects and greater inspection coverage. Finally, experiments are carried out for composite components. The results show this approach has significant performance advantages for nondestructive testing of composite components.

Abstract: The load of C80B gondola freight car body is analyzed in railway. Measured load spectra of fatigue key parts of the freight car body are got. According to the measured load spectra, combined with the load-strain transfer coefficient, the fatigue damage of freight car body is calculated. Then fatigue life of C80B freight car body is predicted by using fatigue cumulative damage theory.