Advanced Materials Research Vol. 625

Abstract: The rocket launch tower’s movement involve opening and closing.During these two process,the tower shakes severely. This study using ADAMS to simulate the movement of the tower and finding that the material of the tower’s components showing a characteristic of flexibility, the material’s characteristic of flexibility of the tower is a main reason of the vibration. In oreder to establish the rocket launch tower’s model,using Pro/E and Mech/pro to create the model.Then ,with the use of mechanical system simulation software ADAMS and finite element analysis software, Patran / Nastran to simulate the rocket launch tower’s movement. The results showed that although the rocket launch tower’s material is steel,it’s main components still showing the flexible feature. And its various components’ influence of flexibility for the tower’s vibration are quite different from each other.

Abstract: A theoretical model of an added water mass representation for calculating the bending modal frequency of a simply supported beam in water medium is presented. To accomplish this, the explicit expressions for computing the hydrodynamic interaction pressure and forced transversal displacements are first derived, and the bending modal frequencies can be accurately obtained by searching the corresponding resonance frequencies. The validity of the analytical process is checked by the finite element method. As the complicated interaction between the structures and water can be approximated to added mass, if the beam is sufficiently slender. Using the added mass curves, a simple method for evaluating the bending modal frequency of an underwater simply supported beam is proposed, and an approximate formula is found subsequently. The comparisons between the analytical solution and the simple method show that the simple method is adequately accurate, with errors less than 1%, and both of the added mass curves and the approximate formula have nothing to do with different material attributes.

Abstract: The relationship between the kineticsof the movement and the role of an object on the object,the force,the kinetics of the basic of the theoretical basis of the whole dynamis is established on the basis of the movement of a large amount of observations and experiments. Dynamic problem is extensive, only common collision vibration in our lives--has the gap or motion constraints between mechanical components of a kinetic phenomenon that repeated exposure. It is widely present in the machinery, aviation, aerospace, military, traffic, and energy systems ,typical examples : gear Vice heat exchange pipes its support , stretch and docking components of the spatial structure, the movement of the robot joints mechanical tools, contain gap mechanical systems, print machinery, mechanical shock , impact shock absorber and cutting machinery utilization cycle force loaded collision Rub between static and dynamic components of the rotor system. Guns , railway wheel and rail with rear seat features motion constraints between mechanical systems , and so on . To help the readers grasp the basic concepts of good dynamics , the basic law , improve readers analyze prolems and problem-solving abilities , on the basis of summing up the experiece of many years practice . Kinetics basic proble summarizd summary . Take advantage of the esperience and understanding of the issure in the practical resaerch.

Abstract: In this paper, an analysis on nonlinear dynamics of a simply supported functionally graded material (FGM) cylindrical shell subjected to the different excitation in thermal environment. Material properties of cylindrical shell are assumed to be temperature-dependent. Based on the Reddy’s third-order plates and shells theory^[1], the nonlinear governing partial differential equations of motion for the FGM cylindrical shell are derived by using Hamilton’s principle. Galerkin’s method is utilized to transform the partial differential equations into a two-degree-of-freedom nonlinear system including the quadratic and cubic nonlinear terms under combined parametric and external excitation. The effects played by different excitation and system initial conditions on the nonlinear vibration of the cylindrical shell are studied. In addition, the Runge–Kutta method is used to find out the nonlinear dynamic responses of the FGM cylindrical shell.

Abstract: To accurately analyze the force and deformation of the transmission tower, it is necessary to study performance of bolted joint in the tower. In the paper single shear and double shear bolted joint with number of bolts changed is tested. Based on the actual data in test, nonlinear finite element model of bolted joint is established with ABAQUS, considering the bolt clearance and preload, and shows good agreement with test results, which is proved correct and applicable. Eventually, through a comparison of FEM and test results, the factors that affect bolt slip and the changing relationship of axial force of bolt and friction force is described.

Abstract: The stress inside and outside the traditional cross-section angle steel in transmission lines are uneven, resulting in the deviation of the actual carrying capacity and the theoretical design value. This paper proposes the use of improved splicing form of the cross-section angle steel to improve the structure’s mechanical properties. Two spliced forms of cross-section multiple angle steel are analyzed by finite element simulation analysis, so as to compare two different forms’ coordination of component displacement, uniform of force, and stress status on the maximum stress control section. It is pointed out that double angle splicing forms’ displacement compatibility and bearing capacity are better than single angle splicing forms. Especially for towers with different height legs, the maximum stress of the main members of the two splicing forms in the control section is respectively 4.7% and 13.7%.

Abstract: The paper presents a mechanical press driven by Switched Reluctance Motor (SRM) and researches on its tracking performance and operating noise. A position servo control system is proposed with a hybrid closed-loop structure to achieve flexible process of servo press. Based on the working bench, experiments are made to measure the tracking performance and operating noise of the press. Experimental results indicate the press driven by SRM has better tracking performance and lower working noise.

Abstract: The performance of proton exchange membrane fuel cell is greatly influenced by the presence, distribution and transport of liquid water in the gas diffusion layer (GDL). In this study, air-water flow in a 3D GDL microstructure along the in-plane direction is studied numerically by using the volume of fluid (VOF) method. The GDL microstructure is considered initially filled with water, air flows into the structure under the driving force of a set pressure drop and the flow is supported by the capillary pressure due to the hydrophobic nature of the GDL structure. It is found that water removal can be accelerated by improving pressure drop. Pressure drop has little influence on the state-steady water volume fraction when the pressure drop is over a critical value.

Abstract: The dynamic characteristics of turbo generator foundation have an important impact on safe operation of power plant. The study first used the vibration mode superposition method to solve the structural vibration response and sensitivity through establishing the dynamic equations and optimization model of the foundation, and then determined the optimization variables, constraints and objectives according to the process conditions, and at last undertook multivariate optimization research on a 1000MW turbo-generator foundation. Finally, an optimization scheme which reduces both the linear displacement of foundation vibration and the amount of concrete used was obtained. The analysis results showed that the optimization method adopted in this study had higher efficiency and could achieve better technical and economic benefits.