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901.
黄甫全 《机械工业高教研究》2011,(1):3-6,21
格物致知,是2000多年前儒家为人生理想提炼的一句箴言;而知识栖息地,则是2010年英国学者哈珀为大学伟大描绘的一个隐喻。山高水长,时空穿越,不灭的光亮正是格物致知这个永恒的教育理想。也许就是这个点燃智慧的光亮,引领每一个人、所有学校和整个人类,孜孜不倦地投身到格物致知那绵延不绝的追求行动之中。一种理想的格物致知教育生活便一直伴随着我们:人类在创造知识中进步,学校在传播知识中发展,个人在识知探求中升华。 相似文献
902.
考虑壁面粗糙度的双流体颗粒-壁面碰撞模型 总被引:3,自引:1,他引:3
提出了考虑壁面粗糙度的双流体颗粒-壁面碰撞模型,将轨道模型中颗粒碰壁模型考虑壁面粗糙度和双流体模型中用概率密度函数积分法处理颗粒与光滑壁面碰撞模型的优点结合起来,引入壁面粗糙度对碰壁颗粒湍流影响的机理。数值模拟结果表明,由于考虑了各方面雷诺应力之间的相互转化,雷诺应力从平均运动中得到能量,以及壁面对运动的衰减作用等因素,包括摩擦系数、恢复系统、壁面粗糙度等物理参数的颗粒-壁面碰撞模型作为边界条件时,得到的结果与实验符合得更好。 相似文献
903.
This paper presents an analytical model for the transient thermomechanical response in the sandwich tube subjected to internal shock pressure and thermal load. A sandwich model (3-layers model) and a multilayer model for predicting transient temperature are proposed, and the effective thermal conductivities in each layer are obtained by the analytical method based on the Fourier law of conduction. The analysis of dynamic response is conducted by using the high order sandwich shell models, considering the shear deformation and compressibility of the core. Moreover, several numerical simulations are carried out by finite element (FE) analysis, which are compared with the results obtained by using analytical models. The slight discrepancies between the numerical simulations and analytical results indicate that the sandwich model (3-layers model) can predict the transient temperature in the sandwich tube correctly, and the thermomechanical response obtained by the high order sandwich shell model is within acceptable accuracy. Thermal stresses are strongly dependent on temperature gradient in the sandwich wall. The dynamic resultant forces with large amplitudes will induce structural fatigue, which is harmful to the structural life and reliability. Therefore, the thermal stresses should be considered for the design of sandwich tubes or pipes subjected to thermomechanical load. 相似文献
904.
A higher order refined model with isoparametric elements is proposed to study the transient dynamic response of laminated arches/curved beams. The strain field is modeled through cubic axial, cubic transverse shear and linear transverse normal strain components. As the cross-sectional warping is accurately modeled by this theory, the shear correction factor is rendered redundant. The stress–strain relationship is derived from an orthotropic lamina in a three-dimensional state of stress, so that angle-ply laminates can be studied through one-dimensional elements. Consistent mass matrix is constituted for the equation of motion, which is solved by Newmark integration scheme. The higher order formulation is validated with available results and subsequently applied to arches with various curvatures, aspect ratios, boundary conditions, loadings and lamination schemes to evaluate its transient dynamic performance and suitable conclusions are drawn. 相似文献
905.
In this paper, the effect of random system properties on the post buckling load of geometrically nonlinear laminated composite cylindrical shell panel subjected to hygrothermomechanical loading is investigated. System parameters are assumed as independent random variables. The higher order shear deformation theory and von-Karman nonlinear kinematics are used for basic formulation. The elastic and hygrothermal properties of the composite material are considered to be dependent on temperature and moisture concentration using micromechanical approach. A direct iterative based C0 nonlinear finite element method in conjunction with first-order perturbation technique proposed by present author for the plate is extended for shell panel subjected to hygrothermomechanical loading to compute the second-order statistics (mean and variances) of laminated composite cylindrical shell panel. The effect of random system properties, plate geometry, stacking sequences, support conditions, fiber volume fractions and temperature and moisture distributions on hygrothermomechanical post-buckling load of the laminated cylindrical shell panel are presented. The performance of outlined stochastic approach has been validated by comparing the present results with those available in the literature and independent Monte Carlo simulation. 相似文献
906.
An algorithm based on the finite element method (FEM) has been developed to study the dynamic response of composite laminated beams subjected to the moving oscillator. The first order shear deformation theory (FSDT) is assumed for the beam model. The algorithm accounts for the complete dynamic interaction between the components of system. The proposed method can also be applied to the general moving mass and the simplified moving force problems. After deriving the governing equations of motion of beam and oscillator, the corresponding equations of motion are integrated by applying the Newmark’s time integration procedures to obtain the system responses in each time step. The numerical results of free vibration and moving force problems analysis of isotropic and composite laminated beams are presented and, whenever possible, compared to the available analytical solution and other numerical results in order to demonstrate the accuracy of the present method. In addition, parametric analysis is carried out over a wide range of velocities and mass, frequency and damping ratios of system components. 相似文献
907.
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910.
RLC二阶电路暂态过程的Multisim仿真 总被引:2,自引:1,他引:1
基于探索RLC二阶电路仿真实验技术的目的,采用Multisim仿真软件对RLC二阶电路暂态过程进行了仿真实验测试.给出了电路在过阻尼、临界阻尼、欠阻尼等情况下零输入响应及零状态响应的Multisim仿真方案,并介绍了不同工作条件下仿真时Multisim中信号源的选取及设置条件。结论是仿真实验可直观形象地描述RLC二阶电... 相似文献