Applied Mechanics and Materials Vols. 52-54

Abstract: In this paper, static-pressure strength, toughness index (TI) and thermal-toughness index (TTI) of each sample have been analyzed on the basis of the experimental studies on the magnetic separation and heavy liquid separation of diamond abrasives. The results show that the magnetism of synthetic diamond abrasives has an obvious influence on their mechanical performances. With the increase of magnetism, synthetic diamond abrasive particles becomes darker and darker in appearance color, and have more bubbles, impurities and defects inside the particles, furthermore, their surface fineness observed under the microscope will be found worse. While, the static-pressure strength, the TI under the normal temperature and TTI all become lower and lower. But the influence on the static-pressure strength and the TI is smaller, however the influence on TTI is the greater. The specific gravity of synthetic diamond abrasives has little influence on their mechanical performances.

Abstract: Mg2Si particle reinforced in-situ Al-Si composite is prepared by melt superheating, and the microstructure and properties of the composite are researched. The results indicate that it is feasible that the melt superheating is applied to preparing Mg2Si particle reinforced in-situ Al-Si composite, and the suitable preparing parameters of melt superheating on the alloy are obtained. When the superheating temperature is 860°C and holding time is 25 min, the average size of Mg2Si particle in the alloy will be reduced to 11μm compared with 34μm without melt superheating, and the mechanical properties of the composite is obviously improved.

Abstract: Casting of clad strip, which was one of the composite alloys, was tried using a roll caster. A vertical tandem type twin roll casters for clad strip were designed and assembled to cast the clad strip. Three layers of clad strip could be cast. The interface between the base strip and overlay strip was clear. The as-cast clad strip could be cold rolled without peeling at the interface. The element of the each strip did not diffuse to another strip at the interface. The effects of the roll speed and melt temperature of the overlay strip on the cladding of the strip were investigated.

Abstract: A systematically approach for structure synthesis of parallel manipulator is based on position and orientation characteristic (POC) matrix, by which a detailed application is focused on the synthesis of 2-translation and 2-rotation parallel mechanisms. The result synthesized involves not only part known mechanisms, but also some novel mechanisms. This paper synthesizes SOC branches which include 2-translation and 2-rotation output, classifies synthesized parallel mechanisms based on SOC branches types, analyses and research this kind parallel mechanism.

Abstract: The Kalman filtering theory was applied for the back analysis of mechanical parameters of mass concrete on the first time. The time-spreading equation and the observation-correcting equation were deduced. After the coupling problem of extending Kalman filtering theory and FEM was solved, the Kalman-FEM formula were deduced and the corresponding back analysis procedures were given. The results indicate that the Kalman filtering method has good characteristics of convergence and stability. The broached method can be used in other research fields such as the back analysis of creeping parameters. Many more conclusions are tested and discussed through a classic example.

Abstract: The steel building system of residence project has more advantage in environment protection and project management than the traditional residence project construction. The main steel structure residence components can be manufactured in the green construction base as the manufacturing industry. The key issue to realize the green construction model of steel building system of residence project is to apply with a suitable model of green construction base. This paper introduced four types of green construction base which are different levels related with project, enterprise, industry and region to combine construction industry with manufacturing. The TOPSIS method was applied to evaluate and analyze to figure out the optimization model of green construction base in steel building system of residence project.

Abstract: Rock pile is a typical kind of adverse engineering geologic phenomenon in mountainous engineering construction. In this paper, according to the main factors influencing the engineering properties of rock pile, the classification of the rock pile are studied. Based on the physico- mechanical properties of rock pile, the multi-hierarchy classification method is proposed. The suitability of the process is verified by classifying the typical rock pile on the Shui-ma(from Shuifu to Maliu Bay) expressway. The relevant results can provide reference to other classification study of rock pile.

Abstract: Joint configuration reveals some nonlinearity under different conditions. In this paper, a bolted joint structure subjected to different preload and external excitation is designed to study the nonlinearity dynamic characteristics of assembled structure. At the same time, nature frequent and damping nonlinear characteristics of the bolted connection are analyzed based on energy dissipation theory. The urgency of discussing the nonlinear characteristics of the joint configuration is discussed, and the theoretical and experimental foundation was established.

Abstract: In this paper, a system of coupled oscillators with delays is investigated. Some sufficient conditions to guarantee the existence of oscillations for the model are obtained. Examples are provided to demonstrate the proposed results.

Abstract: The Ting Kau Bridge in Hong Kong is a cable-stayed bridge comprising two main spans and two side spans. The bridge deck is supported by three towers, an end pier and an abutment. Each of the three towers consists of a single reinforced concrete mast which reduces its section in steps, and it is strengthened by transverse cables and struts in the transverse vertical plane. The bridge deck is supported by four inclined planes of cables emanating from anchorages at the tower tops. In view of the heavy traffic on the bridge, and threats from typhoons and earthquakes originated in areas nearby, the dynamic behaviour of long-span cable-supported bridges in the region is always an important consideration both in their design and health monitoring. This paper describes the development of the 3D grid model for the structural health monitoring of the bridge. The 3D grid model is intended to form the backbone of subsequent multi-scale finite element models for bridge rating. The baseline model is built up and calibrated to match the bridge geometry and cable forces specified on the as-built drawings. The modelling of the concrete deck in the simplified grid model is an important issue as it has great effect on the lateral and torsional vibrations of the bridge. This paper examines in particular the shear lag effect on the modelling strategy.