Applied Mechanics and Materials Vols. 105-107

Abstract: With the increasing problems of fatigue failure of PCB in aeronautic and astronautic electronic chassis, the paper proposes a life prediction method of the solder connector based on physics of failure by simulation and physical test. The virtual modal and random vibration response of the box should be solved by finite element method in the ANSYS software, and these results have been verified by modal test and random vibration test. While the structure parameter and the environment stress of the box, the results of the simulation as the input of the vibration fatigue physics of failure model, the life of solder connector could be computed. There is a comparison between results from the CalcePWA software and it from physics of failure model and simulation.

Abstract: The purpose of this paper is to research on shock wave propagation law of internal gas explosion. The multi-material Eulerian and Lagrangian coupling algorithm was adopt. Using ANSYS/LS-DYNA dynamic analysis software to build frame structure, air and gas explosion models. Multiple ALE elements for simulating air and gas explosion material the analysis of blast shock wave propagation in a three-story steel frame structure and the characteristics of explosion pressure using fluid-structure coupling method are carried out. The conclusions show that fluid-structure coupling method can well simulated shock wave propagation of internal gas explosion, and the pressure peak of blast shock wave increased with the increasing of the blast air initial energy. Locality is the characteristic of explosion pressure in sealed space, and the pressure pass weakly when it propagates in solid.

Abstract: Based on vibration theory, simplified analytical methods for computing the first natural vibration frequency and mode of transmission steel tower are investigated, which has improved the currently applied method. The method for frequency includes parameters of lumped mass such as tower head or cross arm, and can show the influence of section of tower main leg. The method for mode considers tower height, root space and head width. Examples of some typical transmission steel towers show that the dynamic characteristics computed with the simplified analytical methods are close to those of the Finite Element Method. Then the methods given in this paper are superior to the present methods used in engineering and have a better generality, which are suitable to different tower type structures.

Abstract: Modal parameters are widely adopted to identify structural damages. This paper explores the mode jumping problems in damage identification for Beam string structure (BSS). The characteristics of structural mode are discussed firstly. It is found that the modal concentration is obvious for BSS, and this may cause modes after damage not in the same order as those corresponding ones before damage due to proper structural damages. The reasons for mode jumping are analyzed in detail. Based on the principle of relativity, the correspondence of the structural modes before damage and after damage can be determined by calculating the mode correlation coefficients. Numerical experiments show that this method is of higher precision, and can be applied successfully in structural damage identification for BSS.

Abstract: However three-body vibrating screen is widely used in engineering practice, many dynamics of it have not well been addressed. For studying three-body vibrating screen dynamics, the vibrating screen dynamic model and the virtual model were established. Through deriving the dynamic equations and simulating the vibrating screen start - running process, the analytical equations and the trajectories were obtained. Studies have shown that the VBVS vibration in the Z direction is complex and the X direction which perpendicular to the axis of exciters is the sensitive direction for the installation error. In addition, the SBD’s trajectories in the direction which does not exist exciting force are superimposed by the trajectories of USB and LSB.

Abstract: Considering that the functionally graded and magneto-electro-elastic materials are in the spherical coordinate system and not accounting the body weight, body electric charge and body electric current. By the motion equation, gradient equation the functionally graded and magneto-electro-elastic materials constructive equation, the steady-state solutions of variables such as stress, strain, displacement, electric displacement, electric field intensity, electric potential, magnetic intensity, magnetic potential under additional stimulations are deduced. There can provide good theoretical basement for the dynamic control of the functionally graded and magneto-electro-elastic materials in the space spherical symmetry.

Abstract: The vibrational power flow in a submerged infinite cylindrical shell with internal rings and bulkheads are studied analytically. The harmonic motion of the shell and the pressure field in the fluid is described by Flügge shell theory and Helmholtz equation, respectively. The coupling condition on the outer surface of the shell wall is introduced to obtain the vibrational equation of this coupled system. Both four kinds of forces (moments) between rings and shell and between bulkheads and shell are considered. The solution is obtained in series form by expanding the system responses in terms of the space harmonics of the spacing of both ring stiffeners and bulkheads. The vibrational power flow and radiated sound power are obtained and the influences of various complicating effects such as the ring, bulkhead and fluid loading on the results are analyzed. The analytic model is close to engineering practice, which will be valuable to the application on noise and vibration control of submarines and underwater pipes.

Abstract: It is much valuable to find a method for predicting the middle and high acoustic characteristics of big and complex structures such as ships and airplanes. Impact of the ring frequency and the damping on the vibration transmission is discussed firstly. Then the feasibility of the model simplification method for big and complex structures whose acoustic characteristics will be predicted is analyzed. At last, the simplification method was applied to predict the middle and high frequency sound radiation of the double complex cylindrical structures. Numerical results showed that the proposed method has the same accuracy as the conventional finite element method and boundary element method, and can be applied to deal with engineering problems.

Abstract: Malaysia is a country with very low seismic. Most of the buildings in our country may not consider seismic load during structure design, thus the level of safety for remains unknown. Recently, earthquake events have become more frequent. Therefore, engineers have to be alert and kept updated with the knowledge and behavior of earthquake trend in this area. It is vital to assess the precaution measures that can be taken and consider them in the future building design. Therefore, a decision making framework in designing earthquake resistant building especially for school building in Malaysia is needed to help engineers to consider earthquake risk in the building design. This framework employed NERA Program with the assistance of SAP2000 software for analysis of the performance of earthquake resistant building.

Abstract: Research of loss of coolant accident (LOCA) postulated on the nuclear reactor coolant system (RCS) was investigated with ANSYS program. Secondary development of ANSYS was performed to form the customized module for implementing effective and efficient RCS LOCA nonlinear analysis. A standard analysis procedure was established. It has following functions, such as parameters and modular system modeling, automatically set break, static pilot analysis, LOCA nonlinear dynamic calculation and automatic reports generation. Main pipes, Steam generator and reactor coolant pump models were molded by parameterized modular modeling method. Those models considered the nonlinear factors, such as material nonlinearities, gap and so on, constructed component model libraries of RCS. Comparing the results calculated by ANSYS and program-specific, it is showed that the results are generally consistent.