共查询到20条相似文献,搜索用时 171 毫秒
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徐亚苹 《西安航空技术高等专科学校学报》1982,(2)
现代科学技术的飞速发展,加快了新旧知识更换的速度,要适应现代化的工作环境,必须进一步学习。科学的学习方法,是取得良好学习效果的可靠保证。我们在校学习期间,必须有一套适应启己特点的科学的学习方法。下面,我谈一下自己在学习中遵循的一些方法,供同学们参考。 1.力求当堂弄懂所授内容。听课时思维要紧跟老师的思路,当老师提出一个结论时,应该问个为什么,并力求寻找答案。作到这一点,不仅可使注意力高度集中,而且能引起强烈的求知兴趣,听课的效果较好,且记的也牢固。在注意听课的同时,尽量做好笔记。对于老师补充的内容或自己认为新鲜的东西都须记下,对于书本上有的东西可以不做笔记,以便更好的听讲。笔记也可以记在书的行间里,便于保存和复习。对于老师讲的某些问题,如自己暂时不能理解,应该承认它,并用它解释后继内容,但必须记下来,课后再思考。 相似文献
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九月的申城,金风送爽,丹桂飘香。世界杯女足、特奥运动会,向世界播洒中国的微笑。九月的上海,精彩纷呈,盛事满堂。欢度国庆节,喜迎十七大,让历史翻开崭新的篇章。淮海路上,火树银花,流光溢彩,笑语欢声,激情飞扬。21辆绚丽花车已经集结,将展示浓郁的民族特色、异域风情;36个表演团体已整装待发,将搭建璀璨的和谐纽带、友谊彩虹。9月15日晚上,来自五湖四海的宾朋云集上海,欢聚淮海路,共同感受美好与欢乐。 相似文献
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The stress-strain state of thin-walled aircraft structures such as a wing or fuselage made of composite materials is determined
based on the beam theory. The laminated skin is orthotropic. The solution was obtained without using the centroidal principal
section axes and subdividing the problem in shear and torsion. A calculation variant with skin discretization along the section
contour was studied. 相似文献
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引言 随着复合材料愈来愈广泛的应用,各种各样的力学问题被提了出来。非保守结构系统的稳定性是航空航天工程中的重要问题,复合材料的应用在该领域尤为受到重视。因此,研究复合材料结构在非保守载荷作用下的稳定性已为设计部门所要求,值得引起人们重视。 相似文献
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The paper deals with the problem of lateral bending for the five-layer panel with the lightweight filler that is reduced to the bending problem of a beam fixed at the end sections. To solve the differential equations describing the beam bending, the Euler-Lagrange variational principle is used. 相似文献
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Robust Nonlinear Attitude Control of Flexible Spacecraft 总被引:1,自引:0,他引:1
This paper presents an approach to large-angle rotationalmaneuvers of a spacecraft-beam-tip body configuration based onnonlinear invertibility and linear feedback stabilization. A controllaw Ud is derived for the decoupled control of attitude angles, lateralelastic deflections, slopes due to bending and angular deflection dueto torsion at the tip of the beam using torquers and force actuators.For the stabilization of the elastic modes, a linear feedback controllaw us is obtained based on a linearized model augmented with aservocompensator. Simulation results are presented to show thatlarge slewing and elastic mode stabilization can be accomplished. 相似文献
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从理论上推导了层状球面弹性轴承各橡胶层的压缩刚度和扭转刚度计算公式,通过具体算例,将层状球面弹性轴承各橡胶层压缩刚度和扭转刚度的理论计算结果与仿真结果进行了对比分析.结果表明:各橡胶层压缩刚度的理论计算结果与仿真结果基本吻合,最大误差为3.98%.各橡胶层扭转刚度的仿真结果与理论计算结果存在一定偏差,从小接头开始的前半部分橡胶层扭转刚度的仿真结果大于理论计算结果,最大误差为33.3%;后半部分橡胶层扭转刚度仿真结果小于理论计算结果,最大误差为32.8%.压缩刚度对压力变化表现的非线性特性不明显,扭转刚度则随扭转角的增大,其非线性特性变得越显著.但通过理论方法、有限元仿真方法得到的层状球面弹性轴承等效压缩刚度和等效扭转刚度与试验结果吻合良好. 相似文献
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针对翼面和桨叶等升力面结构,以单闭室薄壁梁为典型结构模型,讨论自适应复合材料薄壁梁的弯曲和扭转,探讨控制结构形状的途径 相似文献
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本文讨论复合材料圆柱壳在非线性失稳下的几个基本问题,即失稳时几何非线性影响、初始缺陷影响、材料物理非线性影响、横向剪切变形影响以及前屈曲变形和各种边界条件的影响等。这些因素的交互作用对失稳性能是重要而且复杂的。本文是对于这些问题的一系列研究结果的一篇综合性分析报告。 相似文献
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复合材料层合板弯曲振动高阶理论及有限元模型 总被引:4,自引:0,他引:4
本文提出了一种新的复合材料层合板高阶弯曲位移模式,此位移模式既考虑横向剪切的影响,又考虑了法向正应力的分布,进而建立的相当于三维弹性理论解的二维有限元模型,具有精度高、计算量并不大的优点。 相似文献
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本文介绍了一种直升机无轴承尾桨柔性梁标定与解耦技术,该技术能有效地解决无轴承尾桨柔性梁在试验中挥舞弯矩与摆振弯矩的耦合问题,并能有效分离截面上各分项试验载荷,减少其试验误差。 相似文献
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Firstly, a multi-field coupling finite element formulation of composited beam laminated with the photostrictive actuators is developed in this paper. Moreover, an optimal fuzzy active control algorithm is also proposed on the basis of the combination of optimal control and fuzzy one.This method opens a new avenue to resolve the contradiction between the linear system control method and nonlinear actuating characteristics of photostrictive actuators. The desired control for suppressing multi-modal vibration of photoelectric laminated beam is firstly obtained through optimal control and then the fuzzy control is used to approach the desired mechanical strain induced by photostrictive actuators. Thus, the multi-mode vibration control of beam is realized.In the design process of optimal fuzzy controller, the design of fuzzy control is independent of optimal control. The simulation results demonstrate that the proposed control method can effectively realize multi-modal vibration control of photoelectric laminated beams, and the control effect of optimal fuzzy control is better than that of optimal state feedback control. 相似文献