【作者】 陆超；

【导师】 袁中凡； 杨战平；

【作者基本信息】 四川大学 ， 机械工程， 2003， 硕士

【摘要】 信号变换装置是飞行试验中状态测量和信号变换的重要设备。信号变换装置内安装有一块印制电路板，印制电路板上有电容、电阻、继电器和集成电路等电子元器件。在做随机振动试验时，有几个装在印制电路板上的继电器出现损坏现象，为提高产品可靠性，需要重新设计信号变换装置。振动可通过磨损、疲劳和过应力引起对产品的损坏，并且可能会导致产品在使用期间的过早损坏。几乎每一类机械都要经受某种类型的随机振动，确定系统能否经受这些载荷是分析人员要做的工作。动力载荷对微电子组件和装置能否可靠工作起关键作用。信号变换装置在飞行试验等试验中常常要经受随机振动。因此，对于信号变换装置来说，分析随机振动下关键器件的动力响应并进一步最小化不利影响是非常重要的。本文研究了基于虚拟环境的信号变换装置动态设计的方法。在虚拟环境中实现结构的动态设计和性能分析，可及时发现设计中的薄弱环节。有限元法已广泛地应用于研究、生产和设计单位，成为解决工程实践中各种复杂问题必不可少的工具。有限元法仍在发展和完善之中，未来的若干年对有限元分析来说是激动人心的。本文介绍了作者在结构动态设计方面的研究工作及其工程应用。首先研究了结构的最低阶固有频率的计算方法。一个典型结构可能有数百个振动模态，但通常我们只对少数低阶频率对应的模态感兴趣。探讨了有限元法的概念和原理。随着有限元分析建模技术的发展，基于模型的结构设计正取代传统的反复试验式设计。计算机辅助设计(CAD)和计算机辅助工程分析(CAE)已经被看作产品设计修改、分析、仿真、评价的有效工具。在设计规范和试验的基础上，用ANSYS软件建立了信号变换装置有限元分析模型，由有限元分析模犁得出的结构最低阶固有频率与试验测得的数据基本一致。深入研究了随机振动响应的谱分析法。响应谱分析是一个计算结构对基础激励(或地震)的统计最大响应的过程。每一个振动模态可以被假设为像一个单自由度系统一样单独地响应。已经确定了每个振动模态对激励的响应之后，可通过综合每个振动模态的响应效果来获得结构的响应。单自由度系统最大响应取决于系统的固有频率和阻尼比。一类重要的机械结构仿真是预测系统对随机振动的响应。本文最后对信号变换装置进行了随机振动响应分析，简要探讨了实验模态分析法，找出了装在印制电路板上的继电器在随机振动试验中被损坏的原因，也介绍了结构动力模型修正技术的发展。 在结构动态分析的基础上设计了新的信号变换装置。试验结果表明:新的信号变换装置在随机振动试验中工作性能良好。更多还原

【Abstract】 The signal transform device is an important states measuring and signal transforming facility in the flight experiments. In structure, it is an aluminum case that contains a printed circuit board with various attached electronic components such as capacitors, resistors, relays, and integrated circuits. Some relays on the printed circuit board were destroyed under random acceleration excitations. In order to improve the product reliability, the new signal transform device must be designed.Vibration can cause damage to products by abrasion, fatique and overstress and may contribute to early product failure during use. Almost every type of machinery undergoes some type of random vibration, and it is the job of the analyst to determine if the system can stand up to this loading. Dynamic loading plays a critical role in the functional performance and mechanical reliability of microelectronic components and devices. For the signal transform device, a commonly met dynamic loading is random vibration, as met in the flight experiments, etc. Therefore, analyzing the dynamic response of some key components under random vibration , and further minimizing its adverse consequences on the products is very important for the signal transform device designs. The method of dynamic design for the signal transform device based on the virtual environment is studied in the paper. The dynamic design and capability analysis for the structure can be carried out in the virtual environment, and the weakness of design can be found in time. The finite element method has been widely applied in the fields of research, construction and design and has become anecessary tool to solve complicated problems in engineering practice. Finite element method is still under development and improvement. It will be exciting for finite element analysis in future years.This study introduces the author’s research and engineering working on structural dynamic design. At first the method for calculating the fundamental natural frequency of structure is researched. There may be hundreds of potential vibration modes in a typical structure, but usually, it is only a small number of vibration modes with the lowest frequencies that are of interest. The general concept and principle of finite element method is discussed. With the advancement of finite element analysis (FFA) modeling, model-based design of mechanical structures in general is replacing the traditional trial-and-error approach. Computer-aided design (CAD), together with Computer-aided engineering (CAE), is already regarded as an effective tool for the generation modification, analysis, simulation, and evaluation of a product design. The FEA model of the signal transform device is established with the use of ANSYS based on design specifications and tests. The fundamental natural frequency predicted by the FEA model is consistent with it obtained by the tests. The spectrum analysis of random vibration response is deeply researched. Response spectrum analysis (RSA) is a procedure for computing the statistical maximum response of a structure to a base excitation (or earthquake). Each of the vibration modes that are considered may be assumed to respond independently as a single-degree-of-freedom system. Having determined the response of each vibration mode to the excitation, it is necessary to obtain the response of the structure by combining the effects of each vibration mode. The maximum response depends on the natural frequency of the single-degree-freedom system and the damping ratio of the system. One of the most important types of mechanical simulation is the prediction of a system’s behavior due to random vibration. Finally, the random vibration analysis of the signal transform device is presented. Experimental modal analysis is discussed briefly. The reasons why the relays on the printed circuit board were destroyed under random acceleration excitations are found out. The modifying technique of structure dynamic model is also introduced.On the bases of structural dynamic analysis, a new更多还原