Applied Mechanics And Mechanical Engineering

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Authors: Fei Li, Yuan Biao Zhang, Shan Shan Hu, Hai Rui Liang
Abstract: . In this paper, we provide a Sweet Spot Model for two problems: where the “Sweet Spot” is and how the bat affects the hitting-effect. Our model is very close to live. And we can find the exact position of Sweet Spot and see the relationship between the rebound velocity of the ball after hitting and the factors of hitting point, such as the speed of bat before hitting, the speed of the ball before hitting, Coefficient of Restitution (COR) (a constant determined by the bat material), the mass distribution of bat and so on. After that, we apply our model to corked bats and study the influence of “corking”.
Authors: Xue Hai Gao, Xiao Diao Huang, Hua Wang, Jie Chen
Abstract: An 8-point-contact slewing bearing is usually applied with strict requirements. The load distribution over raceways is the fundament to calculate both the static and dynamic capability of a slewing bearing. The paper discussed a method for calculating the load distribution in an 8-point-contact slewing bearing under general load conditions (turnover moment, axial load and radial load). Based on the method, some suggestions were proposed for optimization of the slewing bearing design.
Authors: Xiao Yan Xi, Zhian Yang, Li Li Meng, Chang Jian Zhu
Abstract: On base of the electro-magneto-elastic theory and the theory of the bending vibration of the electric beam, nonlinear vibration equation of current-carrying beam subjected to thermal-magneto-elasticity field is studied. The Lorentz force and thermal force on the beam are derived. According to the method of multiple scales for nonlinear vibrations the approximation solution of the primary resonance of the system is obtained. Numerical analysis results show that the amplitude changed with the system parameters. With the decrease of magnetic intensity, the amplitude increases rapidly. The response curve occurs bending phenomenon and soft features is increased gradually. Increasing current, the amplitudes increase. With the decrease of temperature, the peak of response curves decrease. With the increase of temperature, natural frequency decreased. It is useful in practical engineering.
Authors: Yong Sheng Ren, Xiang Hong Du
Abstract: A geometrically nonlinear model for thin-walled, single-cell composite beams is developed by using variational formulation and the variational-asympotical method. The structural modeling is split into two parts: a two-dimensional analysis over the cross section, and a geometrically nonlinear analysis of a beam along the beam span. The nonlinear model is based on the assumption of moderate beam deflection, accounting for the pitch angle and extends the linear analysis model for anisotropic thin-walled beams. By employing the Galerkin’s method, an nonlinear algebraic equations is derived and then solved by means of an incremental Newton-Raphson method. Numerical results are obtained for one cantilevered box beam: Circumferentially Uniform Stiffness(CUS), under external load to investigate the effect of geometric nonlinearity and the effects of the fiber orientation, laminate stacking sequence, are also addressed.
Authors: Yi Qing Zhou, Zhi Fang Liu, Shan Yuan Zhang
Abstract: The motion equation of nonlinear flexural wave in large-deflection beam is derived from Hamilton's variational principle using the coupling of flexural deformation and midplane stretching as key source of nonlinearity and taking into account transverse, axial and rotary inertia effects. The system has homoclinic or heteroclinic orbit under certain conditions, the exact periodic solutions of nonlinear wave equation are obtained by means of Jacobi elliptic function expansion. The solitary wave solution and shock wave solution is given when the modulus of Jacobi elliptic function in the degenerate case. It is easily thought that the introduction of damping and external load can result in break of homoclinic (or heteroclinic) orbit and appearance of transverse homoclinic point. The threshold condition of the existence of transverse homoclinic point is given by help of Melnikov function. It shows that the system has chaos property under Smale horseshoe meaning.
Authors: Yin Da Sun, Wen Qin Xu
Abstract: A new radial plunger pump is given which is installed with roller between plunger and stator, the roller is purely rolling on the inner face of stator, reducing the friction force and effectively avoiding the combustion of friction pair in working orde. When viscosity varies with pressure and temperature, hydraulic pressure and cutting flow caused by plunger moving in the plunger auxiliary of a new radial-plunger pump, the computing formula of annular gap is corrected here, which provide a theoretical support for developing a high efficient radial-plunger pump.
Authors: Wen Qin Xu, Bai Qing Zhou
Abstract: A new radial plunger pump is given here, which is installed with a roller between the plunger and the stator. When in working order, the roller is purely rolling on the inner face of the stator, reducing the friction force and effectively avoiding the combustion of friction pair. The force on the roller and the plunger of the static pressure supporting cylinder pair are studied here and some theoretical evidences are provided for developing new radial-plunger pumps of high speed, high efficiency, and long lifetime.
Authors: Xue Qian Chen, Qiang Du, Xiao Juan Chen
Abstract: The kinematic interface joints are widely used in reflector systems of the high-power solid-state laser facilities. In order to get better finite element(FE) analysis results of reflector systems, it is important to model the joints exactly. The accordant displacement method is used for modeling the joints according to the contact form of joints. The FE model of the reflector system is built subjected to the assuming, the modal analysis and the ambient vibration calculations are carried out. The computing results of inherent frequencies, measure points’ root mean square(RMS) displacements and the transfer characteristics of four kinematic interface positions are accordant with that of the test results. The compared results show that the method modeling the kinematic interface joints is feasible in the paper.
Authors: Lei Guo, Shu Sheng Zhang, Ya Qun Chen, Lin Cheng
Abstract: In this paper, the boiling phenomena of steam boiler under atmospheric pressure are simulated by using the UDF program of CFD software. Characteristics including pressure, temperature and vapor fraction respectively for bubble, slug and annular flow regimes are extracted as the input characteristic vectors of the BP neural network and Elman neural network for the purpose of identifying the boiling two-phase (vapor/liquid) flow regimes within wall tubes. It reveals that the rate of recognition accuracy of flow regimes with BP neural network is up to 95.24%, as well as 100% with Elman neural network within the groups taken into consider. By analyzing relations between flow regimes, wall temperature and wall heat transfer coefficient, it is found that changes in flow regimes will cause drastic variation in heat transfer coefficient of the wall surface, and the coefficient reduces rapidly as the wall temperature increases and eventually converge to a minimum. It is a very effective method of using numerical simulation to extract the signal under poor experimental conditions, and is good reference for the further research.

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