Applied Mechanics and Materials Vol. 525

Abstract: This paper deals with noise and mechanical vibration reduction by optimization and proper application of the hexagonal cell structure formed on the surface of oscillating bodies. This structure can be applied in a broad spectrum of products like home appliances, industrial machines and devices, drives etc. It stems from the knowledge of the area of human health protection against the negative effects of noise and vibrations as well as psychological comfort, performance and optimization of psychoacoustic perceptions. The authors present the design of a suitable parametric model which makes it possible to change the basic structure parameters and by means of numerical simulations approach the achievement of optimal structure parameters.

Abstract: A displacement function of a single pile among pile groups was proposed according to Mindlin solution. Using variational theory and principle of minimum potential energy and considering the relation between shear stress of soil around piles and displacement described in Randolph single pile displacement solution, the relation between soil and settlement in the tip of a pile was derived. Relation between load and displacement of a single pile among pile groups was obtained. It was compared with other examples after that. The result calculated by the method proposed here matchs closely with the result calculated by other methods.

Abstract: In order to discuss the road performance of desulfurized rubber asphalt and mixture, Swelling mechanism of desulfurized rubber asphalt was studied first, and then performance testing of KLMY90#, normal rubber asphalt and desulfurized rubber asphalt were taken, after that, penetration, shear strength and cohesive strength of desulfurized rubber asphalt mortar were test, road performance of desulfurized rubber asphalt mixture were test at last. The results of the study show that, there is no Rubber particle core, but lots of chemical reaction in desulfurized rubber asphalt; the performance of desulfurized rubber asphalt is better than normal rubber asphalt without high viscosity, easy isolation and poor high temperature storage stability; shear strength and cohesive strength of desulfurized rubber asphalt mortar is better; and desulfurized rubber asphalt mixture have good road performance.

Abstract: Aiming at the limitation of traditional constitutive theories which can not explain the decrease of inclination angle of shear bands correctly when confining pressure increases, a state-dependent critical state model is employed to analyze strain localization of Hostun sands. Firstly, the critical state formulation and model parameters are calibrated through available drained triaxial test results of Hostun sand. Then an analysis of strain localization is performed on the drained plane strain tests. The results show that the state-dependent critical state model is capable of simulating the effect of initial effective confining pressure on inclination angle of shear bands.

Abstract: The paper covers the results of studies of the alkali activated slag cement concretes from the cements prepared under all-in-one technology to meet the requirements for concretes for marine engineering application. The compressive strength, weather resistance, biodegradability, bonding strength with steel reinforcement bar, steel reinforcement bar protection, chlorine ions diffusion parameters and resistance to corrosive exposure of 5% Na₂SO₄ solution were tested, which exhibit that alkali activated slag cement and concretes are very suitable for marine engineering applications.

Abstract: Compound plates of stainless steel is used to weld under construction in the Southern links railway bridge for the first time in China, but there occurs weld warpage of the convex parts and roughness appears excessive on the overall composite plate and severe deformation in the early phase of construction and the quality of railway bridge is affected seriously. Reasons of the impacting weld quality are analyzed and specific measures are proposed, and the construction program is optimized,too. A good foundation for the compound plate welding is layed and the efficiency and quality of welding can be improved .All of these will be contribute to ensure the overall quality of the welding quality of railway bridge.

Abstract: A new composite strengthening method that the CFST short column was strengthened with concrete filled steel tube was presented. Through the finite element analysis of five specimens with strengthening circular concrete filled steel tube columns and a specimen without strengthening circular concrete filled steel tube to explore the impact of the outer layer of concrete strength grade, external pipe wall thickness for the ultimate bearing capacity of concrete filled steel tube columns. The results show that with the increase of the outer pipe wall thickness, double concrete filled steel tube column yield strength and ultimate strength have increased. As the outer concrete strength grade increased as the specimen bearing capacity increased. When the concrete strength grade greater than C40, the improvement of concrete strength for specimen ultimate bearing capacity is not great.

Abstract: It is studied the influence of triethanolamine (TEA), diethylenetriamine (DEA), Triisopropanolamine (TIPA), aminoethyl ethanolamine (AE), and polyvinyl alcohol ammonium phosphate (PAAP) at different dosages on the properties of fresh and hardened cement pastes and mortars prepared by Portland cement, including standard consistency water, setting time, the cement paste fluidity, and compressive and flexural strength. It is showed that the high polarity alcohol amine molecules exhibit strong chemical interactions with cement matrix, which are reflected in modified macroscopic properties of the cement system. All alcohol amine admixtures increased the standard consistency water and decreased cement paste fluidity of Portland cement. TEA significantly shortened the initial setting time and final setting time of Portland cement. On the other hand, TIPA, DEA, AE and PAAP extended the initial setting time of cement but shortened the cement final setting time. All alcohol amine admixtures except TIPA at 0.2 and 0.5 dosage increased the compressive and flexural strength of the Portland cement mortars at 3 days. Especially when the dosage of PAAP is 1, the compressive strength of the Portland cement mortars at 3 days is increased 10.5MPa. All alcohol amine admixtures except AE at 0.2 and 0.5 dosage increase the compressive and flexural strength of the Portland cement mortars at 28 days, Especially when the dosage of TIPA is 1, the compressive strength of the Portland cement mortars at 28 days is increased 8.8MPa.

Abstract: This paper presented a excitation liquid-cooled retarder control system based on a microprocessor MC9SXS128. In order to achieve the constant speed, It used PWM to adjust the output current of excitation liquid-cooled retarder. It analyzed and calculated the inductance value in PWM output circuit and also analyzed the excitation liquid-cooled retarder control systematical mathematical model . It divided the brake stalls based on the current flowing through the field coil. by adding the PID closed-loop control system, the retarder could quickly reach the set speed. It tested the PID control algorithm at the experiments in retarder drum test rig and the results show that the control algorithm has good control performance to meet the application requirements.

Abstract: Aim of the paper is to investigate the indoor thermal comfort of the buildings. This work is undertaken by the combination of the literature review and experimental measurement and analyses, on basis of the selected 12 public buildings in Dongguan City (Guangdong Province, China), located at the typical sub-tropic climatic region. It was found that when the air-conditioning system was turned off, the internal surface temperature of the insulation was above a control target of 30°C; when the air-conditioning system was turned on, the internal surface temperature of the insulation was below the control target of 30°C, meeting the requirement of the thermal comfort of human body in summer. These figures will be helpful in the determination of the quantitative control target to improve the indoor thermal comfort in the subtropical areas.