电机用气体冷却器模态动力特性有限元分析

简述了有限元分析理论中的ANSYS APDL参数化建模技术,并应用该技术对某型号气体冷却器进行参数化有限元建模与模态分析。结果表明,该方法可以实现气体冷却器模态分析的参数化与自动化。计算结果与试验结果进行对比分析表明,仿真结果在关键频率上与试验结果较为吻合,为提高气体冷却器结构模态动力特性前端设计提供了有效的参考依据。

两种5000 m直纹曲面混合缆索悬索桥的模态特性

研究目的:本文针对5000 m级超大跨径海峡悬索桥的需求,依据二次直纹曲面方程,提出单叶双曲面混合空间缆索悬索桥和双曲抛物面混合空间缆索悬索桥两种新桥型,开展空间混合缆索悬索桥的几何构形研究,建立ANSYS有限元分析模型,研讨空间缆索悬索桥的动力模态特性,探索空间缆索悬索桥结构的技术优势,解决超大跨径悬索桥颤振抗风稳定性的技术难题,为将来建造5000 m级超大跨径海峡悬索桥提供参考。研究结论:(1)混合空间缆索悬索桥中的钢丝缆索和碳纤维空间缆索协同工作,其扭转振型比平行悬索桥出现得晚得多,扭转频率和扭弯频率比有很大的提高,颤振临界风速有很大的提高;(2)平行悬索桥、单叶双曲面空间缆索悬索桥和双曲抛物面空间缆索悬索桥的第一阶正对称扭转频率分别为0.07988 Hz、0.19840 Hz和0.15578 Hz,扭弯比分别为1.22、2.88和2.35,颤振临界风速分别为:Vcr^p=20.83 m/s、Vcr^d=91.21 m/s、Vcr^s=71.18 m/s;(3)两种空间混合缆索结构体系具有良好的抗风稳定性,可为将来建造5000 m级超大跨径悬索桥开辟一条新的思路。

拱型中央扣对大跨径马鞍面空间索网悬索桥动力模态影响

在超大跨径马鞍面混合空间缆索悬索桥基础上,提出一种刚柔并济的提篮拱状钢管混凝土拱型中央扣结构方案,以提高超大跨径悬索桥结构的空间刚度。结合规划中的5000m级琼州海峡大桥,建立ANSYS有限元分析模型,开展提篮拱状钢管混凝土拱型中央扣对马鞍面空间索网悬索桥动力模态特性影响研究。研究表明:提篮拱状钢管混凝土拱型中央扣代替柔性中央扣,提高了超大跨径悬索桥的结构整体性,相比柔性中央扣,提篮拱状钢管混凝土拱型中央扣能够有效提高悬索桥的反对称振型频率。

轴流压缩机动叶片模态分析方法研究

基于某轴流压缩机第1级动叶片,在精确建立其几何模型的基础上,通过有限元仿真方法提取了前10阶固有频率及模态振型的计算值,然后通过试验测试方法对其进行了模态测试,得到了前10阶固有频率及模态振型的实测值,并将理论计算结果和实际测试结果进行了对比。

磁悬浮支承转子系统的动力学特点

介绍了采用主动磁悬浮支承的转子系统动力学特性,说明了与传统轴承转子系统动力学相比的异同点,给出了一种分析计算以主动磁悬浮支承的转子系统动力学特性的方法.该方法包括系统临界转速的计算以及对应的振动模态分析方法.最后给出了部分分析计算和实验的结果.

5000m级空间混合缆索悬索桥的构形研讨

本文针对5000m级超大跨径海峡悬索桥的设计,依据双曲抛物面的直纹曲面特性,提出双曲抛物面空间混合缆索悬索桥的新结构体系,改革传统平行缆索悬索桥结构,增加碳纤维双曲抛物面空间缆索网,平行钢丝缆索承担竖向荷载,双曲抛物面形碳纤维空间缆索提高海峡悬索桥的空间刚度,二组缆索混合使用,优势互补,协同工作。结合5000m海峡悬索桥的工程背景,开展双曲抛物面空间混合缆索悬索桥的构形研究,建立ANSYS有限元分析模型,进行结构内力及动力模态特性分析研究,研究表明:双曲抛物面空间混合缆索悬索桥具有良好的空间刚度及抗风稳定性,其扭转频率和扭弯频率比显著提高,大幅度提高了颤振临界风速,从根本上解决了5000m级大跨径海峡悬索桥抗风稳定性问题。

Dynamic Characteristics of Transmission System for the Internal Grinder

The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new ...

On the method of the automatic modeling in hydraulic pipe networks

In this paper the dynamic characteristics in pipes are analyzed with frequency method, and puts forward a simple and practical describing method. By establishing the model library beforehand, the modeling of the pipe net is completed automatically, and we can accurately calculate the impedance characteristics of the pipe network, achieve the reasonable configuration of the pipe network, so that to decrease the pressure pulsation.

Dynamic analysis and nonlinear identification of space deployable structure

The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.

Dynamic behaviors of pretensioned cable AERORail structure

The AERORail, a new aerial transport platform, was chosen as the object of this work. Following a review of the literature on static behaviors, model tests on the basic dynamic mechanical characteristics were conducted. A series of 90 tests were completed with different factors, including tension force, vehicle load and vehicle speed. With regard to the proper tension and vehicle load, at a certain speed range, the tension increments of the rail's cable were proved relatively small. It can be assumed that the change of tension is small and can be reasonably ignored when the tension of an entire span is under a dynamic load. When the tension reaches a certain range, the calculation of the cable track structure using classical cable theory is acceptable. The tests prove that the average maximum dynamic amplification factor of the deflection is small, generally no more than 1.2. However, when the vehicle speed reaches a certain value, the amplified factor will reach 2.0. If the moving loads increase, the dynamic amplification factor of dynamic deflection will also increase. The tension will change the rigidity of the structure and the vibration frequency; furthermore, the resonance speed will change at a certain tension. The vibration is noticeable when vehicles pass through at the resonance speed, and this negative impact on driving comfort requires the right velocity to avoid the resonance. The results demonstrate that more design details are required for the AERORail structure.

Identification of Suspension Bridge Parameters under Exploitational Conditions

The paper concerns a research into dynamic properties of the steel suspension bridge across Opolska Street in Krakow, Poland. Parameter identification was carried out with the application of the nonlinear system identification method on the basis of system responses to exploitational excitation resulting from pedestrian traffic. In order to verify obtained results, on the basis of the geometrical and material properties of the considered system, the FEM （finite elements model） was created. Created FEM model was updated through the comparison with the model determined by the use of experimental modal analysis method and then applied to analytical evaluation of the considered suspension bridge natural frequencies.

超大跨径直纹面缆索悬索桥的抗风稳定性分析

利用直纹曲面的几何特性,改革传统的平行缆索体系悬索桥,将粗重的集中缆索改为分散的空间钢丝缆索,多股钢丝缆索空间交叉布置,形成超大跨径单叶双曲面和双曲抛物面空间缆索悬索桥。结合某4000m级超大跨径海峡悬索桥,进行空间缆索悬索桥的动力模态分析和抗风稳定性分析研究。研究表明,空间悬索桥扭转振型比平行悬索桥出现得更晚,扭转频率和扭弯频率比有很大提高,颤振临界风速也有很大提高,空间缆索悬索桥具有良好的抗风稳定性。

Nonlinear dynamic characteristics of magneto-rheological visco-elastomers

The smart magneto-rheological visco-elastomer (MRVE) has a promising application to vibration control.Its dynamic characteristics are described by complex moduli which are applicable to linear dynamics.However,experimental results show remarkable nonlinear relations between force and deformation for certain large deformations,and the nonlinear dynamic modeling needs to be developed.The present study focuses on the nonlinear dynamic characteristics of MRVE.The MRVE was fabricated and specimens were tested to show nonlinear mechanical properties and dynamic behaviors.The nonlinear effect induced by applied magnetic fields was investigated.A phenomenological model for the dynamic behaviors of MRVE was proposed to describe the nonlinear elasticity,linear damping and hysteretic effect,and the corresponding equivalent linear model in the frequency domain was also given for small deformations.The proposed model is applicable to the dynamics and control analysis of composite structures with MRVE.

Structure and Dynamics of Ethanol Adsorbed on a Mica Surface

The structural and dynamic properties of nanoscale ethanol film on a mica surface are investigated via molecular dynamics simulations. We observe a dense, almost fiat ethanol bilayer formed in the vicinity of the mica surface, with the hydrophobic alkyl groups pointing outward from the surface. Remarkably, such ethanol bilayer is laterally well-ordered with patterned adsorption sites. Each ethanol molecule in the first layer donates one hydrogen bond to the surface basal oxygen atoms and accepts one hydrogen bond from that in the second layer. The ethanol molecules within the bilayer exhibit constrained lateral mobility and delayed dynamics as compared with bulk ethanol, whereas those on top of the bilayer have bulk-like characteristics.

Investigation on structure and dynamic property of liquid Pd-Cu-Ni-P alloys using ab initio molecular dynamics simulation

Based on the short-range order,it is found that the abundance of the P-centered P-transition-metal clusters are the common feature among the liquid Pd-Cu-Ni-P alloys,and hence this feature alone could not uncover the underlying mechanisms of the variation of glass forming ability among the liquid alloys.For the so called similar elements such as Cu and Ni,their behaviors are significantly different when interacting with Pd or P atoms.Cu has weak bonding with both Pd and P while Ni has very strong bonding with P but nearly no bonding with Pd.The different bonding characters thus underlie the phenomenon that in the best glass formers the ratio of the two similar elements often deviates from 1:1.Only if the parameters of chemical short-range order of Cu and Ni around P become closest to each other the best glass forming ability is reached.It is also illustrated that the calculated dynamic properties are very helpful to locate the composition of the best glass former.