含基体横向损伤的黏弹性板的蠕变后屈曲分析

基于Schapery三维黏弹性损伤本构关系,引入沈为和Kachanov损伤演化方程,建立了基体横向损伤的纤维单一方向铺设黏弹性板的损伤模型;应用von Karman板理论,导出了考虑损伤效应的具初始挠度的纤维单一方向铺设黏弹性矩形板的非线性压屈平衡方程. 对未知变量在空间上采用差分法离散,时间上采用增量算法和Newton-Cotes积分法离散,控制方程被迭代求解. 算例中讨论了损伤以及有关参数对黏弹性复合材料板后屈曲行为的影响,且与已有文献的结果进行了比较. 数值结果表明：随着外载荷或者初始挠度的增大,板后屈曲趋于稳定时的挠度就愈大,损伤的影响愈明显;而随着长宽比的增大,板后屈曲趋于稳定时的挠度愈小,损伤的影响却随之增大.     

Properties of Three Pseudo-Spins in Ferroelectric or Ferro-Antiferroelectric Materials Described by a Transverse Ising Model

Ferroelectric phase diagrams and the temperature dependence of polarization, dielectric properties of the three pseudo-spin in ferroelectric or ferro-antiferroelectric system described by a transverse Ising models are investigated on the basis of the effective-field theory with the differential operator technique. The effects of the transverse field and the coupling strength between the nearest-neighboring pseudo-spin on the physical properties are discussed in detail.     

Study of Depolarization Field Influence on Ferroelectric Films Within Transverse Ising Model

An improved transverse Ising model is proposed by taking the depolarization field effect into account. Within the framework of mean-field theory we investigate the behavior of the ferroelectric thin film. Our results show that the influence of the depolarization field is to flatten the spontaneous polarization profile and make the films more homogeneous, which is consistent with Ginzburg-Landau theory. This fact shows that this model can be taken as an effective model to deal with the ferroelectric film and can be further extended to refer to quantum effect. The competition between quantum effect and depolarization field induces some interesting phenomena on ferroelectric thin films.     

边缘转动受弹性限制矩形板横向振动固有频率的一个近似解法

本文给出了边缘转动受弹性限制矩形板横向振动固有频率的一个近似解法,不但公式简单易程序化,而且有着较高的精度,本文最后给出了一些算例,并与已有结果作了比较。     

曙光一号自由电子激光器(FEL)电子束发射度的分析

对曙光一号自由电子激光装置电子束发射度的测量值进行了深入的分析。严格地计算了不同发射度的束流在摇摆器内的传输,计算了发射度对激光功率的影响。由此得出,曙光一号自由电子激光器可以省去9米长的束流选择段。     

风电螺栓轴向应力超声测量标定实验研究

根据超声导波法测量螺栓轴向应力的基本原理,建立了简便有效的声速标定测试实验系统,通过实验分析了测试系统延时误差和温度误差对不同测试方法测量精度的影响.对10.9级42CrMoA风电螺栓轴向应力进行的实际测试表明,超声纵波实际测量误差不大于±2％,纵横波联合测量误差不大于±5％,完全能满足工程应用需求,为该技术在风电领域...     

Effects of hunting on the stability of ecosystems

In this present paper, we examine the effects of hunting on the stability of prey-predator systems and grazing systems. The theory of stability and singular perturbationmethod are applied for analysing.     

Phase Transition for a Mixed Spin-1/2 and Spin-sB System with a Transverse Crystal Field

The critical behaviors of a mixed spin-1/2 and spin-s_B Ising system with a transverse crystal field are studied by use of the effective-field theory with correlations. The effect of the transverse crystal field on transition temperatures is investigated numerically for the honeycomb (z=3) and square (z=4) lattices. The results show that there is no tricritical point for the system.