框架结构主动控制最优时滞研究

在结构振动主动控制中,时滞的大小对结构控制能量和响应均产生影响。在允许时滞的范围内,把结构控制能量和响应作为目标函数,数值仿真发现目标函数随着时滞的变化呈现曲线状态,这说明存在最优时滞。在目标函数处理方面,考虑到控制能量和响应数量级不一致,本文采用了无量纲化处理。同时,考虑到地震波的随机性,本文还推导了含控制力的改进的随机Newmark方法。最后给出了一个计算实例。实例表明本文所提出的方法是有效的。     

二代高温超导带材耐高温性能研究

通过有限元软件对由20层高温超导带材所制成的超导叠带在覆铝时的温度分布进行模拟,模拟结果表明在覆铝过程中两侧带材均会经历420°C以上的高温.对几种高温超导带材在不同温度和持续时间下,对其ReBCO侧、哈氏合金侧和双侧分别加热进行高温实验,测试得出了各带材临界电流的退化情况.实验结果表明,高温对带材造成了性能退化,不同...     

APPLICATION OF PENALTY FUNCTION METHOD IN ISOPARAMETRIC HYBRID FINITE ELEMENT ANALYSIS

By the aid of the penalty function method, the equilibrium restriction conditions were introduced to the isoparametric hybrid finite element analysis, and the concrete application course of the penalty function method in three-dimensional isoparametric hybrid finite element was discussed.The separated penalty parameters method and the optimal hybrid element model with penalty balance were also presented. The penalty balance method can effectively refrain the parasitical stress on the premise of no additional degrees of freedom. The numeric experiment shows that the presented element not only is effective in improving greatly the numeric calculation precision of distorted grids but also has the universality.     

惩罚函数法在三维等参杂交元的应用

提出在等参杂交元中用惩罚函数法引入平衡约束条件,具体讨论了惩罚函数法在三维等参杂交元中的运用,并提出采用分项罚数的方法,建立最佳的罚平衡杂交元模型．罚平衡法可以在不增加自由度的前提下,有效地扼制寄生应力．数值实验表明,新建立的单元,可以有效地抑制单元畸变对计算精度的影响,从而大幅度提高畸变网格下的计算精度,方法带有普遍性．     

APPLICATION OF PENALTY FUNCTION METHOD IN ISOPARANIETRIC HYBRID FINITE ELEMENT ANALYSIS

IntroductionSince T.H.H.Pain firstly puts forward hybrid element method[1]in1964, the researchand application of hybrid element have got great development. T.H.H.Painet al.havemade important pioneer works in the domain of the research on incompatible displacementstructure hybrid elementstress pattern[2,3]in recentdecades. Reference [4] had provided theoptimizing design concept of hybrid element further and established standardization methodof incompatible displacement structure hybrid eleme…     

非线性基准建筑物振动的主动控制

非线性基准建筑物的振动方程属于非仿射系统,目前的非线性模型降阶方法不能采用．而直接采用非线性控制策略所设计的控制器阶数较高,难以用于实际场合．为此,开发了一种适合于非线性建筑结构的新的振动主动控制方法,该方法思路是识别线性化的结构模型,进而根据力作用原理把控制力施加到所识别的结构模型上．该方法所建模型可以通过经验Grammian矩阵进行平衡降阶,所以具有较好的实用性．最后给出了3层基准结构的计算实例,其结果表明所提出的方法对土木工程结构是可行的．     

Active vibration control of nonlinear benchmark buildings

The present nonlinear model reduction methods unfit the nonlinear benchmark buildings as their vibration equations belong to a non-affine system. Meanwhile, the controllers designed directly by the nonlinear control strategy have a high order, and they are difficult to be applied actually. Therefore, a new active vibration control way which fits the nonlinear buildings is proposed. The idea of the proposed way is based on the model identification and structural model linearization, and exerting the control force to the built model according to the force action principle. This proposed way has a better practicability as the built model can be reduced by the balance reduction method based on the empirical Grammian matrix. A three-story benchmark structure is presented and the simulation results illustrate that the proposed method is viable for the civil engineering structures.