求助：求西安交通大学机械学院 李伟的论文！
各位师兄师姐请帮帮我，由于做课题的需要，我现在很需要西安交通大学 李伟的《冲击减振理论的离散单元法研究及应用》（1997年）这篇学位论文，哪位能帮我下载到，或者提供能找到这篇文章的方式，小妹将不胜感激！！:'([ 本帖最后由 无水1324 于 2008-7-24 16:47 编辑 ] 大家帮帮忙吧，或者有谁知道到哪里找这些早年的论文呢？:handshake 此类90年代的论文只有找他们本学校的人才可以找到 作者 李 伟 著
题名 冲击减振理论的离散单元法研究及应用 [学位论文] / 李 伟著; 黄协清教授,胡选利教授指导
出版发行 西安 : 西安交通大学, 1997
馆藏地索书号处理状态
科技资料阅览室 Y165105 在架上
版本 复印本
载体形态 124页 : 图 ; 26cm
学位论文附注 博士论文:振动冲击噪声:1997
文摘 冲击减振是振动控制中常用的一种减振技术，尤其是柔性约束下的颗粒冲击阻尼技术，也称 BBD(Bean Bag Damping)技术的出现，更为冲击减振技术的工程应用提供了广阔的前景LD但目前对冲击减振的理论研究尚不完善，对BBD技术的研究更是处于起步阶段，本文根据传统冲击减振器和BBD技术的具体结构特点，建立了冲击减振分析的离散单元法(Discrete Element Method,简称DEM)模型，利用DEM的原理和方法对冲击减振的减振机理和减振特性进进了深入的理论研究LD主要工作是：Dl.在前人研究的基础上，全面系统地研究了球体元三维DEM的原理、算法和计算过程LD创造性地把DEM的原理和思想方法引入到冲击减振的分析中LD根据赫兹接触理论，合理地确定了各接触参数，提出和建立了球体元三维DEM的数据结构和编程方法LD根据本文的研究内容要求，首次提出了柔性约束的算法，建立了单冲体冲击减振器和豆包冲击阴尼减振器的离散单元分析法，并用C/C++语言成功地研制了相应的DEM程序LDDo.对本文提出的冲击减振分析的DEM进行了大量的实验验证LD表明冲击力波形和间隙比区间的DEM计算结果和实验结果有很好的一致性；振动响应的DEM计算结果和实验结果的误差均不超过13%；减振效率的DEM计算结果和实验结果的误差均不超过5%LD证明了本文提出的冲击减振分析的DEM的可靠性和正确性LD同时还证明了冲击减振分析的DEM在预估减振效率方面比前人脉冲响应叠加法具有更高的精度LDDd.首次用DEM对传统的冲击减振理论进行重新研究，研究结果揭示并证明了冲击减振现理是由于冲击体和主系统碰撞过程中，冲击力对主系统做负功，增加了主系统阻尼的结果，且动量交换在冲击减振中起主导作用LD同时研究了结构参数和振动条件参数的变化对传统的单冲体击减振器减振效果的影响规律，并提出单冲体冲击减振器在工程应用中的设计原则LDDth.首次用DEM对BBD进行了理论研究LD提出了BBD减振的新观点：BBD是一类特殊的冲击阻尼减振器，它的减振机理是BBD和主系统碰撞过程中碰撞力对主系统做负功的结果LDBBD的阻尼机理由冲击阻尼和颗粒阻尼两部分组成，其中颗粒阻尼对冲击阻尼起补充和调节作用LDDae.首次研究了BBD的阻尼特性LD研究表明：BBD的阻尼特性具有随振动幅值和振动频率呈非线性变化的性质LD振幅对BBD阻尼特性的影响有一临界值，当振幅大于此临界值时，BBD的阻尼性能迅速增大，而当振幅小于此临界值时，BBD的阻尼性能较小LD同时研究了各相关参数的变化对BBD阻尼特性和减振效果的影响规律，并提出了BBD技术工程应用的参数设计原则LDDoe.首次把DEM和模态分析相结合，建立了连续体冲击减振分析的DEMLD实验表明该方法在预估减振效率方面具有较高的精度LD对工程中常用的板结构进行了大量的BBD减振试验，得到了BBD的布置形式和布置位置对其减振效果的影响规律，为BBD的工程应用提供了可靠的依据LD{0}neural network are the sameas that used for generator-shed-ding, while the outputs are the maximum relative swing angle between genera-tors with no control action , the minimum dead-time of the valve for maintaining the first swing stability and the maximum dead-time determined by the sec-ond swing stability. Fast valving control requirement is determined by compar-ing the first output with a given crtical value and the dead-time is decided by averaging the second and the third output. It is also demonstrated that the mapping of the inputs to the outputs is approximately continuous. Simulation results of a 6-machine test system are given to illustrate the rationality of the proposed neural network structure and effectiveness of the method.(3) A new application of feedforward neural network to thecoordinating decision of generator-shedding requirements betweentwo power plants for transient stability augmentation in multi-machine power systems is further proposed. By adding the possible number of shedding units at the other power plant as an additional input to the neural network placed in one plant, the coordinating decision is then determined according to the principle that the lose of generation capacity should be a minimum. The method is still hold. Some satisfactory results of the New England test system are given.(4) To apply the above-mentioned methods to ...
Impact damping is a technique of vibration reduction often used in vibration control. The brilliant prospects for it opened up by the invention of impact damping with flexible constrained granular assemblies, so called "Bean Bag Damping (BBD)".Nevertheless, the theoretical studies about impact damping, esecially about BBD technique are still very few. The DEM's(Discrete Element Method)models of impact damping based on the structure features of traditional impact absorber and BBD are built up in this dissertation, then the deep and systematic theoretical studies about the mechanism and property of impact absorber are carriedout using DEM.The main work does as follows: 1.Based on the predecessors' studies, the principle, algorithm and process of calculation of three-dimensional spherical element DEM are systematically discussed and used for the analysis of impact damping. The contact parameters are determined reasonably by means of the Hertz's contact theory,and the data structure and programming method of three-dimensional DEM are developed.The flexible constrain algorithm is firstly presented, and the discrete element analysis methods for single-unit impact absorber and BBD impact damper are described, then appropriate DEM program using C/C++ language is successfully developed. 2. Lots of experiments are performed to verify the DEM's results of impact damping analysis. It shows that the DEM's results of wave-shape ofimpact force and interval of clearance ratio are in accord with those of experiment; the errors of vibration response and damping efficiency between DEM's results and experimental results are no more than 13% and 5%. The reliability and validity of DEM in the analysis of impact damping have been verified.Meanwhile, the result of DEM in prediction of damping efficiency has higher precision than that of impulse response superposition method.3.Traditional theory of impact damping is firstly studied anew using DEM, and the results verify the mechanism of impact damping which is that impact force apply negative work on the primary system in the process of collision to add the damping of the primary system. It is also found that the movement exchange dominates the level of vibration reduction. The effects of structure parameters of single-unit impact absorber and vibration condition parameters on the damping efficiency are also studied,and application principles of single-unit impact absorber in engineering are obtained.4. BBD is firstly studied using DEM too, the results show that BBD is a sort of special impact absorber, its mechanism of damping is the result of impact force applying negative work on the primary system in the process of collision between BBD and the primary system. BBD damping is composed of impact damping and granular damping, and granular damping is a complement and adjustement of impact damping.5. The damping feature of BBD is firstly studied, and the resuls show that BBD is such a damping structure of which the damping varies non-linearly with vibration amplitude and frequency. The amplitude has a critical value in its effect on BBD damping, when the amplitude is in excess of the critical value, the damping property of BBD is very good, otherwise, the damping property of BBd is poor. The effects of relative parameters on BBD damping property are also studied, and application principles of BBD in engineering are given.6. DEM being combined with modal analysis, the DEM of continuous body's impact damping analysis is developed, and the experiment results show that it is precise in predicting vibration reduction level. Many experiments of BBD on plate-like structure's vibration control are carried out, the effect laws of form and position of BBD on damping efficiency are obtained, which can be as an useful reference for application of BBD in engineering
Uncon Sub 减振器
冲击阴尼
颗粒阴尼
离散单元法
其它作者 黄协清 指导
胡选利 指导
并列题名 Research and Application of Theory of Impact Damping Using DEM
国际标准号码 精装 80.00元
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怎么在数据库里面找不到这样的论文呢？谢谢各位热心帮助！！
好久没来了，身体出了点状况。很感谢大家的热心帮助，不过告诉大家一个好消息，这个论文我已经找到了！！还有告诉大家我是在中国科技文献中心下载的，花钱了:'( 不过还好，弄到了
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