中厚板屈曲的加权残值方法

用加权残值方法分析了矩形中厚板的屈曲问题。试函数和权函数依据短梁函数进行构造。结果良好。     

Numerical solution to the buckling problem for a sandwich plate under uniaxial compression

A thin rectangular sandwich plate with isotropic linear elastic layers is considered. The plate is in a plane-strain state under uniaxial compression. An exact statement of the buckling problem is given. Its approximate solution is found by the finite-difference method. The concept of base scheme is used to formulate discrete problems in explicit and compact form. As an example, the critical parameters of the plate are calculated using a computation optimization procedure. Its efficiency is demonstrated __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 9, pp. 98–105, September 2006.     

用曲线大窗口平滑散斑条纹图的方法研究

提出一种计算条纹方向的简单算法,以及通过条纹方向图获得沿条纹方向的曲线窗口并对散斑条纹图进行曲线大窗口滤波的方法．实验表明此方法较好地消除了散斑条纹图的噪声,同时尽量减小了对条纹结构的损害．为从单幅散斑条纹图中应用条纹中心线法或全灰度法进一步提取相位场的后处理,奠定了良好的基础．     

表面力仪的改进及超薄膜流变特性的实验研究

在对原表面力仪进行较大改进的基础上 ,以 5 0 0 SN基础油和十六烷为研究对象 ,进行了超薄膜流变特性的实验研究 .结果表明 :在超薄膜润滑条件下 ,5 0 0 SN和十六烷均表现出明显的非牛顿剪切响应 ,即剪切稀释现象 ;摩擦力幅值随剪切速度的增大急剧上升到最大值 ,然后下降至某一固定值附近并产生波动 ;剪切挤压下的临界膜厚小于静态挤压的临界膜厚 ,剪切运动对吸附层有序结构产生破坏作用     

桁架结构稳定分析的几何非线性欧拉稳定理论

目前,桁架结构稳定分析有两个理论:经典的特征值理论和几何非线性临界点理论。前者发展较早,在许多结构力学书中都有叙述。但是经过工程应用检验,它过高地估计了结构抗稳定的能力。后者是20年前提出的,提出者认为适用于所有的扁桁架。经过几年的研究,作者连续提出三个稳定理论:线性与非线性欧拉理论;非线性临界点-欧拉理论和两个计算方法,进行桁架结构的线性和非线性截面优化设计。经过理论研究和对前人文献中数值例题的计算和比较,发现特征值理论不符合实际,临界点理论只适用于大扁度的桁架,而不适用于一切扁桁架。研究结果提供了若干有用的结论,给出了各种稳定理论的适用范围,指出了国际文献中若干例题的正确和错误,补充了桁架结构的稳定分析理论,使之更为完整和实用了。     

双轴反复荷载作用下钢筋混凝土空间框架结构滞回全过程分析

实际地震中结构所承受的地震作用是多维的。结构的恢复力特性是反映其抗震性能的一个重要属性。对地震作用下钢筋混凝土柱、梁塑性铰区的计算模型进行了分析,给出了塑性铰区等效长度的简便计算公式;建立了“有限纤维”空间线性梁单元模型并推导出了其刚度矩阵;使用“弥散法”来考虑梁锚固钢筋在结点区的粘结滑移对结构整体变形的影响。最后使用空间杆系模型对一承受双向反复荷载的框架结构进行了计算分析。分析表明所建立的计算模型是精确有效的。     

水工混凝土S-N和P-S-N曲线特性研究

在已知混凝土静压强度分布的基础上使用S－N曲线模型推导出一种疲劳寿命满足的分布，并对水工混凝土做了大量的等幅抗压疲劳试验。通过分析发现，实验数据能较好地符合该分布，同时得出了该种混凝土的S－N曲线和P－S－N曲线。     

侧柱对串列双柱脉动压力的干扰

研究了串列双圆柱旁加上一个等直径的圆柱，组成一个等边三角形排列的三圆柱的脉动压力分布．着重研究侧柱对串列双圆柱脉动压力分布的影响．研究的结果表明，绕流等边三角形排列的三圆柱，受影响最严重的是后柱．脉动压力分布出现了严重的不对称，外侧的压力脉动极其强烈，内侧的压力脉动较弱，与时均压力分布，很好的对应关系．另外，侧柱对于串列双圆柱是否达到超过临界间距的绕流流态，有很大的影响     

Slip flow of non-plasticized PVC compounds

Measurements on seven rigid PVC compounds were carried out with a slit rheometer working in combination with an injection moulding machine. Plastication of the compounds occurred in the screw of the plastication unit, which also forced the melt through the die with a controlled forward velocity. The rectangular slit had a length of 90 mm and a widthB of 20 mm. The heightH could be varied between 0.8 and 3.3 mm. Pressures and temperatures were recorded at several positions in and before the die. Measurements were carried out at shear rates from 10 to 2000 s^–1.When the reduced volume output was plotted against the wall shear stress _W , only four compounds showed master curves independent ofH, which is indicative of wall adhesion. In the other cases this plot did not produce such a master curve, but the plot of the mean velocity against _W was independent ofH (slip curve). This indicated that slip flow prevailed with a slip velocityv _G When, in the case of wall slip, the smooth inner surfaces of the die were replaced by surfaces with grooves perpendicular to the direction of flow, slip flow was prevented and the flow curves were shifted to much higher values of _Wc Above a critical value of the wall shear stress ( _Wc ) at which slip flow began, the output became nearly independent of _W . From the measurements made below _Wc a vs. relation for the shear flow could be derived, which was used to calculate the superimposed shear flow . Exact values of the slip velocity were then given by . Wall slip only occurred for compounds with a high shear viscosity, which corresponds to a high molecular weight (K-value).Dedicated to Professor H. Janeschitz-Kriegl on the occasion of his 60th birthday.     

正交各向异性压磁电弹性矩形板的稳定问题

从压磁电弹性力学的三维平衡方程和本构关系出发,推导得到了正交各向异性压磁电弹性矩形板稳定问题的状态方程。求解状态方程并结合边界条件得到了稳定问题的屈曲方程。给出了临界应力的算例。