Applied Mechanics and Materials Vols. 148-149

Abstract: In order to eliminate the temperature difference between center measurement points and surface temperature of the material samples with low thermal conductivity, this paper introduces a new hot airflow double-sided heating method for sample, and describes its principle, application, and the impact of the existing and novel methods on the measurement results of spectral emissivity. Also, we analyze and compare the results of two different samples obtained with these two heating methods. The new method for material samples with low thermal conductivity has outstanding advantages and potential applications.

Abstract: The influence of centrifugal prestress on the foreign object damage of engine blades was analyzed by numerical simulation. A nonlinear dynamic model for foreign object damage of blade with centrifugal prestress was established. And the dynamic relaxation method was used to obtain the initial stress and displacement field of blade in the beginning of the dynamic analysis of impact. Numerical simulations of foreign objects impacting on the leading edges of the blades under different centrifugal preloads were carried out. The results indicate that the local plastic deformation on the impact location of blade with centrifugal preload, which is produced at the moment of impact, is decreasing with the increase of the preload. The growth of crack produced on the lead edge of blade is accelerated with the preload increasing.

Abstract: Nickel coating was prepared on surface of Epoxy Resin plate by electroless plating process. Surface and section morphologies of the coatings were observed by scanning electron microscopy (SEM) and metallographic optic microscopy. Electromagnetic shielding effectiveness was evaluated via flanged coaxial electromagnetic shielding effectiveness tester. The results showed that the surface of the nickel coating prepared by electroless plating process was smooth, and its structure was fine and compact. The electroless deposition rate of the nickel coating reached at 12μm/h. In the frequency range of 300 kHz to 100MHz the electromagnetic shielding effectiveness of the nickel coating was above 60dB, and in the frequency range of 100MHz to 1.5GHz the electromagnetic shielding effectiveness of the nickel coating was above 44dB.

Abstract: Plates and shells are well used in structures. In order to study the nonlinear stability of plate, the total potential energy expression was deduced after analyzing the geometrical conditions of four ends simply supported rectangular plate on large deflection, the cusp catastrophic model of the rectangular plate was established based on catastrophe theory, and the bifurcation set that makes the system unstable was obtained to analyze the instability conditions of rectangular plate. The instability conditions of rectangular plate were analyzed based on this set, the critical inner stress is at the cusp point, the necessary condition of instability is σ>σ_cr , but the plate is stable when the movement path of control variables composed by inner stress and landscape load not across the bifurcation curves in the control space. Structures in some projects can be predigested to such a rectangular plate and this cusp catastrophic model can be used for analyzing its instability conditions for taking preventive measures.

Abstract: This paper focus on how to improve wireless transmission efficiency, reduce the quality and volume of TPMS to reduce impact of tire balance in a moving vehicle. A tire pressure monitoring transmitter based on high integrated wireless sensor MPXY8300 is described in this paper and the hardware structure is being put forward. Introduced the way to reduce energy consumption, and wireless circuit design. This system can monitor the inner practical pressure and temperature of each tire and the security accidents can be avoided effectively.

Abstract: To examine how the dissolved CH₄ in soil solution would affect the CH₄ emission from rice field, fluxes of CH₄ emission were measured by using a manually closed static chamber-gas chromatography method, and the dissolved CH₄ in soil solution was obtained through shaking soil solutions, which were extracted from different paddy soil layers by a soil solution sampler with suction and pressure. The results show that the CH₄ fluxes from rice fields and the concentration of dissolved CH₄ in soil solution are both reduced significantly under the water-saving irrigation as compared to the traditional flooded irrigation. Under the water-saving irrigation, naturally receding water-layer during the early stage leads to an earlier peak of CH₄ flux, but dramatically reduces the concentration of dissolved CH₄ in soil solution. The maximum concentration is shifted to about 20-cm depth soil layers, and the relationship between CH₄ emissions and dissolved CH₄ in soil solution can be estimated using an exponential function of dissolved CH₄ in soil solution at the depth of about 20 cm (R2＝0.89, p4 in soil solution plays a more dominant role in CH₄ emission under the water-saving irrigation than that under continuously flooded irrigation.

Abstract: The electrical power generation and distribution in power plant suffers from so many problems, such as instability of demand and generation. These lead to increase of generation cost. The system under consideration is consist of two steam turbines each of 30 MW with total of 60 MW (2*30). The excitation system of 30 MW generators has been chosen, due to the problems faced by operators in power station. These problems include aging of the control element, feeding back signal and loading increase/ decrease problems.

Abstract: In the paper, the concept of time-varying wires structure is proposed to avoid interference between wires and a mobile platform in a wire-driven parallel suspension system. A mathematical model, a kinematic notation model and a calculation model for interference between wires and the mobile platform have been built for it. When the mobile platform moves at a single degree of freedom pitch rotation, the motion equations of relevant hinge are deduced. The simulation results demonstrate that interference can be avoided in the wire-driven parallel manipulators with time-varying wires structure, and the workspace of the mobile platform may be enlarged. But different motions chosen for the hinge correspond to distinguishable sizes of workspace of the wire-driven parallel manipulators with time-varying wires structure. Therefore, according to the requirements to avoid interference, the motion of the hinge can be designed.

Abstract: In the present paper, we have investigated a negative Poisson’s ratio structure with regular re-entrant cell shape to study its structural response under crush by rigid wall. Firstly, we created the geometry of cellular material in HYPERMESH. The developed geometrical model is imported into LS-DYNA. Then we use commercially available nonlinear explicit finite element code LS-DYNA to simulate the NPR material under uniformly distributed load. The deformation modes and energy absorption characteristics of NPR material were analyzed. Numerical results indicate that this NPR material have good ability of energy absorption.

Abstract: Through we do some research on the key technology and implementation of the air product simulation resource model library, we propose a general system framework, the solid modeling method of the components and parts, the design of the parameter table and the model library integration and application. With these key technologies, we design and develop three-dimensional modeling library system, CATIA taken as a platform.