Applied Mechanics and Materials Vols. 423-426

Abstract: The structural system and seismic performance of the composite shear wall are analyzed based on the horizontal load model tests. The test models are three groups of combined shear walls with shear span of 1.5, including an ordinary shear wall, a shear wall with vertical steel plates and a shear wall with transverse steel plates. The finite element software ABAQUS is used to build the calculation model of the shear wall structure. And the analysis the influence of steel plates to bearing capacity, ductility, and stiffness of shear wall are carried out. The research results indicate that the combination shear wall has good seismic behaviors.

Abstract: The pre-stressed modal and random vibration of electron gun are calculated by finite element software ANSYS Workbench. The results show that electron gun under the excitation of radial load (X direction) can be in danger of disable structure. Some measures can be taken to avoid electron gun failure due to resonance, such as replacing the materials, changing the structure of weak links and changing TWT installation to make external incentives along the axial direction (Y direction). The analysis results can provide effective reference and guidance for TWT development.

Abstract: The characteristics of four-order elliptical gear is analyzed. The parameters of four-order elliptical gear are chosen and calculated. The three-dimensional solid modeling of four-order elliptical gear is achieved. The dynamic model of four-order elliptical gear is established by finite element method and modal analysis of four-order elliptical gear is investigated. The natural frequencies and major modes of the first six orders are clarified. The method and the result facilitate the dynamic design and dynamic response analysis of high-order elliptical gear.

Abstract: As the wind turbine blade is becoming larger and larger, the flutter of the wind turbine blade has been paid great attention by many fields. The flutter region of the wind turbine blade airfoil was focused on. The equation of motion for the flutter of blade airfoil was established, based on the simplified aerodynamic force and torque. The flutter analysis of wind turbine blade was carried out with the four-order Runge-Kutta methods, and so the flutter region of the blade airfoil can be obtained. The results show that, there are two critical tip speed ratios for the given blade airfoil. When the tip speed ratio is below the low critical speed ratio, the blade airfoil is convergent. At the low tip speed ratio, the blade airfoil system will become divergent from convergent condition. When the tip speed ratio is between the low critical tip speed ratio and the high one, the blade airfoil system will diverge. At the high tip speed ratio, the system will become convergent from divergent condition. When the tip speed ratio is above the high critical tip speed ratio, the blade airfoil system will converge again. In addition, the torsional angular displacement and velocity always keep convergent, the flap velocity is slightly divergent, because they are not sensible to the change of the tip speed ratio, and they are difficult to cause flutter, so the torsional motion will be more stable than flap motion for the given blade airfoil. It can provide one of references for the determination of the blade airfoil.

Abstract: In order to explore the modal characteristics of the wind turbine, this paper researches how these natural frequencies of the major structural components within the operation speed range to avoid coupled resonance phenomenon. Aiming at 1500kW variable speed variable pitch double-fed wind turbines which are the mature products in market, the whole wind turbine dynamic modal equations are established by Lagrange method, and then process on-site testing is carried out to obtain measured modal characteristic parameters. The results of both theoretical and measured dates show that deviation between theoretical data and measured data, how the subsystem boundary conditions simplified methods to influence the rotor system natural frequencies, how the subsystem boundary conditions simplified methods to change the cross point of the rotor system natural frequencies with rotor speed 3P, and solution for wind turbine pass the cross point. The results will provide a certain extent guidance for the wind turbine development, design and optimization.

Abstract: With the continuous development of the marine oil industry, risers have become necessary equipment in offshore drilling engineering. On the basis of mode-superposition response spectrum method which is used commonly in anti-seismic design, the seismic responses of the marine drilling riser is analyzed on the theoretical and the related anti-seismic calculation formulas of the discrete system are promoted to the continuous system. The earthquake force and the resultant internal forces when the earthquake happening are analyzed and calculated. The calculation formulas of shear force and bending moment for each cross section of a riser under the earthquake action are deduced, which can offers some theoretical reference for riser engineering design when considering earthquake action.

Abstract: According to the detonation wave collision theory, initiation from two ends of charge, the liner will close to the middle to form high velocity penetrator. To achieve better closed effect, the influence of axis curvature radius on a single Annular MEFP was studied. Axis curvature radius influence little collision pressure, but is the important factor affecting the formation. The results showed the presence of axis curvature radius can all reach the closure effect, but different greatly. The velocity and mass of penetrator increase as decrease of axis curvature radius, but it forms easily to be rod jet, when the radius is too small. The penetrator mass have bigger loss as increase of axis curvature radius.

Abstract: This paper based on the generalized probabilistic perturbation finite element method solves the random response analysis problem of vibration transfer path systems with translational and rotational motions. The effective random response analysis approaches are achieved using Kronecker algebra, matrix calculus, generalized second moment technique of vector-valued functions and matrix-valued functions. For the vibration transfer path system with multi-dimensional paths, the random response is described correctly and expressly in time domain as uncertain factors, which include mass, damping, stiffness and position, are considered. The mathematical expressions of the first order and second order moments for the random vibration response of vibration transfer path are obtained. According to the corresponding numerical example, the results of calculation are consistent with the results of Monte-Carlo simulation, which shows the method is feasible theoretically.

Abstract: Steel truss bridge is an important part of transportation hub and lifeline engineering, it recently has attracted more attention on dynamic performance of steel truss bridge. In this paper, the ANSYS software is used to perform the modal analysis of steel truss bridge, and we find that the main bridge are more sensitive to the vertical earthquake (i.e., Y direction). In the earthquake response spectrum analysis on Y direction, we find that the maximum deformation is at mid-span of steel truss bridge. In the transient analysis of seismic waves, under the action of horizontal and vertical earthquake accelerations, the structure displacement dynamic diagram and time-history displacement curve are obtained and some conclusions are drawn.

Abstract: With the development of aviation industry, more and more performance requirements are submitted to aero-engines, and structure response and safety problem of aero-engine is concerned. Overview is made of the recently years full engine vibration response due to blade-off. And summary about case containment and rotor dynamic response caused by sudden unbalance in blade-off situation is presented. Then the analysis technologies and modeling methodologies of full engine blade-off structure response are focused. According to the trend, the field of couple vibration analysis should be paid more attention to in the research of full engine dynamic response during blade-off.