变厚度圆柱壳的轴对称弯曲问题

本文详细地研究了厚度h=h_0ξ~的圆柱壳的轴对称弯曲问题.文中通过引入一个位移函数H(ξ),将该问题的方程组化成一个关于H(ξ)的6阶常微分方程,用广义超几何函数给出问题的精确解.     

热/机械载荷下功能梯度材料矩形厚板的弯曲行为

采用Reddy高阶剪切板理论，考虑材料物性参数随坐标和温度变化的特性，研究在均匀变化的温度场内功能梯度材料矩形板在面内与横向载荷共同作用下的横向弯曲问题，基于一维DQ法和Galerkin技术，给出了一对边固支，另对边任意约束时板弯曲问题的半解析解，以Si3N4/SUS304板为例考察了材料组份，温度场，面内载荷及边界约束条件等对功能梯度材料板弯曲行为的影响。     

Fracture of a rectangular piezoelectromagnetic body

The singular stress, electric fields and magnetic fields in a rectangular piezoelectromagnetic body containing a center Griffith crack under longitudinal shear are obtained. Fourier transforms and Fourier sine series are used to reduce the mixed boundary value problems of the crack, which is assumed to be impermeable, to dual integral equations. The solution of the dual integral equations is then expressed in terms of Fredholm integral equations of the second kind. Expressions for stresses, electric displacements and magnetic inductions in the vicinity of the crack tip are derived. Also obtained are the field intensity factors and the energy release rates. Numerical results obtained show that the geometry of the rectangular body have significant influence on the field intensity factors and the energy release rates.     

陶瓷阻力曲线测定的新方法——断裂栅法

将零厚度单向试件栅刻蚀工艺应用于晶须增韧氮化硅陶瓷基复合材料表面，通过记录试件所在桥路的输出电压值，可得到随载荷不断增大裂纹逐渐向前扩展过程中每一时刻的裂尖位置和裂纹长度，从而得到该种材料的阻力曲线。     

Variation of the stress intensity factor along the front of a 3-D rectangular crack subjected to mixed-mode load

Summary  The singular integral equation method is applied to the calculation of the stress intensity factor at the front of a rectangular crack subjected to mixed-mode load. The stress field induced by a body force doublet is used as a fundamental solution. The problem is formulated as a system of integral equations with r ⁻³-singularities. In solving the integral equations, unknown functions of body-force densities are approximated by the product of polynomial and fundamental densities. The fundamental densities are chosen to express two-dimensional cracks in an infinite body for the limiting cases of the aspect ratio of the rectangle. The present method yields rapidly converging numerical results and satisfies boundary conditions all over the crack boundary. A smooth distribution of the stress intensity factor along the crack front is presented for various crack shapes and different Poisson's ratio. Received 5 March 2002; accepted for publication 2 July 2002     

ELECTROELASTIC FIELD FOR AN IMPERMEABLE ANTI-PLANE SHEAR CRACK IN A PIEZOELECTRIC CERAMICS PLATE

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Shear Band Formation in Fe–Cr–Mo–V–B–Si Amorphous Alloy under Nanoindentation

The formation of shear bands in Fe–Cr–Mo–V–B–Si amorphous alloy under nanoindentation Is studied. The indentation process is considered against the background of shear band formation in the amorphous material.     

Global structural behaviour of thin and moderately thick monoclinic spherical shells using a mixed shear deformation model

Summary The static and dynamic responses of anisotropic spherical shells under a uniformly distributed transverse load are investigated. Analytical solutions using the mixed variational formulation are presented for spherical shells subjected to various boundary conditions. Numerical results of a refined mixed first-order shear deformation theory for natural frequencies, critical buckling, center deflections and stresses are compared with those obtained using the classical shell theory. A variety of simply-supported and clamped boundary conditions are considered and comparisons with the existing literature are made. The sample numerical results presented herein for global structural behaviour of monoclinic spherical shells should serve as references for future comparisons.     

EXPERIMENTAL ANALYSIS OF ACTIVE STEERING HARDWARE-IN-LOOP BASED ON SLIDING MODE CONTROL 1)

为了提高重型车辆在转向过程中的稳定性和安全性,本文提出了一种基于滑模变结构控制的主动前轮转向控制策略,基于这种策略设计了主动转向控制器,建立了三轴商用车的二自由度车辆动力学简化模型及整车模型,利用TruckSim--Simulink建立联合仿真平台以及进行硬件在环实验。在不同工况、不同车速下,分别对有无主动转向控制器的车辆进行了操纵稳定性分析,并在此基础上进行了滑模变结构控制的主动转向影响因素敏感性分析。实验结果表明,这种控制器策略在不同工况下具有较强的适应性。     

水坝在水流作用下动力响应的一种分析方法

以广东某水坝为研究对象,给出一种基于Fluent平台和Ansys平台进行结构动力响应分析的方法。首先采用基于YOUNGS界面重构技术的VOF模型,对流动进行数值模拟,成功捕捉了闸门开启过程中自由面的变化,比较了在三种落差情况下水坝的受力差异。计算表明,即使在上游平稳的入流条件下,水坝所受到的湍流水压力也会出现波动现象,水压力对坝体的冲击为低频作用,下游水位的升高会减缓水压力的波动,这些特点都与现场观察的相符。然后将水动力作为激励条件导入结构动力分析平台Ansys后,进一步对坝体结构进行动力分析。结构的模态分析结果与实测结果一致。因此,方法可以应用于实际。