Applied Mechanics and Materials Vol. 607

Abstract: The design, manufacture and installation of a practical and cost-effective anechoic chamber for aero-acoustic measurements are presented in this paper. The work was undertaken with a view to measure the aerodynamically generated noise of wind turbines under laboratory conditions. The chamber was designed to be used in conjunction with a wind tunnel. Tests were carried out to compare the reduction of noise levels from external sources with and without the chamber. The results obtained suggest a clear reduction of noise levels with different wind speeds, and as expected, resulted with higher reductions at higher wind tunnel speeds.

Abstract: Appropriate selection of methods of manufacture and materials of test models are essential components physical experimentations using wind tunnels. The present paper is written with a view to highlight some of the aspects that need careful considerations in formulating cost-effective test program and gathering of accurate test data for successful outcome of such wind tunnel experiments.

Abstract: Poor indoor air quality is a major threat towards workers since the office or office-like environment is now the workplace for the majority of the workforce in Malaysia. Workers in office buildings frequently have unexplained work-related symptoms or combinations of symptoms but evidence suggests that microbial contamination plays a part. Ultraviolet germicidal irradiation lights with high efficiency particulate air filter (UV-HEPA) are recognized for eradicating biological contaminants and capturing particles in indoor environments. Here, the effectiveness of UV-HEPA purification unit was obtained in two selected workplaces i.e. laboratory of conservation and laboratory of natural resources. Results show that there exist significance difference (P<0.05) on indoor air quality between pre-installation and post-installations of UV-HEPA filter in both selected room. Furthermore, it shows that UV-HEPA filter is effective in removing indoor air pollutants and improves the air quality. The use of UVGI lights with HEPA filter resulted in significant reduction in the concentration of microbes and respirable particulates within the ventilation systems. Keywords: indoor air quality, microbes, respirable particulates, UV-HEPA purification unit

Abstract: Based on the experimental study of response of the gravel cushion under the horizontal vibration loads, analyzed internal shear modulus changes process in the granular layer , which are the changing characteristics caused by the self-organization, particles movement and compacting degree. We simulated the response process of shear modulus in the granular layer by using the Poisson process, discussed the development of shear modulus after several vibration and established the model.

Abstract: In this paper, ANSYS-LSDYNA simulation software is used to build the three-dimensional finite element model of the ball bond and to get the Von Mises stress. The change of stress about the bump is researched which base on the model in different bonding pressure, bonding power and bonding time. The result show that: The stress increase with bonding pressure increase within a certain bonding pressure range, and then the stress will maintain a table number, however, the stress will continue to increase when the bonding pressure reach a certain value; increasing the bonding power, the area of lager stress will grow; prolonging the bonding time, the stress of the pad will increase with time, but when time increase to a certain value, the stress of the pad will not increase over time.

Abstract: It’s significant and necessary to assess the safety of the in-service pressure vessels containing crack defects, and there are so many methods that can do, for example, the finite element method and probabilistic fracture mechanics assessment method. However, knowing the safety of the pressure vessels containing crack defects is not enough. For the residual lifetime reason, we are eager to get the safety margin of the pressure vessels. That is how secure they are. Aiming at this problem, we put forward the concept of failure path based on the Failure Assessment Diagram (FAD) and fracture mechanics to help to characterize safety margin. Facts proved that this method was original and useful which can provide a new way in solving the residual lifetime assessment problem of the in-service pressure vessels containing crack defects.

Abstract: A module similarity measure method of the mechanical and electrical products is studied in this paper. First this paper proposes the module assembly type coding method and network modeling method, and establishes its weighted network model by taking typical module as an example; then it studies the assembly relationship similarity, node similarity and network similarity; finally it provides the module similarity measure method based on the assembly relationship.

Abstract: Power spectrum analysis is one of the important part of digital signal processing, various characteristics of the main signal in the frequency domain, is designed based on the limited data and extract the useful signal is submerged in the noise in the frequency domain. In this paper, the VB language to realize the power spectrum analysis can extract the useful signal was drowned in noise in frequency domain based on power spectrum, frequency structure and physical meaning analysis reflected the more obvious, monitoring and diagnosis in rotating machinery fault, power spectrum analysis is very wide.

Abstract: In present paper, deflection and stress of laminated composite plates are analyzed by a meshless local collocation method based on inverse multiquadrics radial basis function. This method approximates the governing equations based on first-order shear deformation theory using the nodes in the support domain of any data center. Transverse displacement, normal stresses, and shear stresses of the simply supported laminated composite plates under sinusoidal load are computed by the present method. The convergence characteristics are studied by several numerical examples. The present results are compared with available published results which demonstrate the accuracy and efficiency of present method.

Abstract: The seismic response analysis of project soil site is important to obtain the ground motion parameters for seismic design of upper structures. First, a simplified solving method is introduced, in which, the horizontal seismic loadings are expanded into Fourier series in the circumferential direction, using the orthogonality between the normal and tangential direction on the circumference, the three-dimensional problem is reduced to a series of two-dimensional problems. Then, the simplified method is used for seismic response analysis of a practical large-scale soil site with large diameter circular diaphragm wall. The influence of wall to the site is obtained through two field conditions, which are wall field and free field (without wall). Compare with the results of the site without wall, the peak acceleration of the pit bottom is increased owing to the confinement effect of wall, and the influence to ground surface far from the wall is very little.