小型混匀仪关键部件振动件的设计与仿真分析研究

小型混匀仪作为核酸提取仪的主要组件,需要具有较高的稳定性和耐疲劳性。目前,国内市场上大部分混匀仪的振动件都不够稳定且容易损坏。为解决上述问题,设计一种回转式结构的振动件。该振动件在高频振动位置开有相应槽口,并在重要振动位置原有材料的基础上内衬了高性能弹簧钢60Si_(2)Mn。对该结构进行受力分析、疲劳分析以及仿真分析,验证了设计的振动件能够满足高强度、稳定性以及耐久性的要求。

车身板件振动声学贡献的计算机模拟

本文讨论车身板件振动声学贡献的计算机模拟研究方法。以桑塔那2000型轿车为实例建立无吸声材料和有吸声材料的结构-声学模型,使用ANSYS有限元分析软件计算车身板件在给定频率下振动引起的车内声压,进而求得板件的声学贡献。

多功能铁氧体和磁流变液结合的新型声学与振动控制器件

简要报道了一种由多功能铁氧体Ba6-xR2x(Nb1-xFe2+x)O3等和磁流变液(magnetorheologicalfluid)结合的新型声学与振动控制器件(模型)的初步研究情况。同时,也指出了它们多方面的重要应用及需要进一步研究的问题。

非线性包装系统中关键部件振动可靠度分析

研究非线性包装件中关键部件在真实的具有一定谱特征的随机振动激励下的振动可靠度。考虑到实测随机振动PSD曲线的多峰值特征,采用多阶Kanai-Tajimi模型模拟随机振动的功率谱密度,将真实随机振动在标准正态随机变量空间中离散化表达。考虑包装件中的关键部件,将包装件建模为二自由度非线性支座激励系统,应用模型修正因子法,将非线性包装件等效表示为一个线性化系统,应用一阶可靠度方法分析包装系统中关键部件的首次穿越损坏概率。应用数值分析的方法分析包装件中各参数变化对损坏概率的影响。该研究对于计算包装件损坏概率、优化包装件参数以提高振动可靠度,具有重要的指导意义。

声子晶体在空腔板件振动控制中的应用研究

建立了局域共振声子晶体板状结构,在266.1~528.8 Hz频率范围内获得了最大幅值为35 dB的减振特性。对不同布置形式的声子晶体板进行了仿真和试验分析,二者结论基本一致。构建了局域共振声子晶体结构空腔,并结合有限元方法对空腔结构进行模态分析、带隙机理和共振带隙特性分析。得出声子晶体单元的不同布置位置和形式对声子晶体结构空腔的振动固有频率的影响。

M26HD可控震源振动器密封件破损原因及解决办法

密封件概述 可控震源在野外勘探中,由于工区自然条件恶劣,以及设备长时间大负荷工作,故障率很高,对于整体液压系统来说,可控震源振动器密封组件的损坏不但影响生产而且维修困难,还带来许多其他问题。因此,摆在修理人员面前的就不仅仅是正确更换密封组件的问题,更应该设法延长密封件的使用寿命。

基于激光技术的振动定位器质量调态的研究

精密加工制作的振动定位器,是现代武器系统中定位、定向的关键器件,其质量调态是球型振动件加工的重要步骤。对基于激光技术的振动定位器质量调态进行了研究,系统地介绍了激光束调态的原理,振动件加工缺陷层的分布、形式和理论构成,去除缺陷的计算以及激光束工作时间的确定等问题。对应用激光束进行质量调态前后的缺陷情况的对比分析得出,机械加工后的球型振动件的振动分裂频差在0.5 Hz以上,而应用激光束进行质量调态的分裂频差为0.004 Hz,表明该方法是有效的。

基于单自由度参数激励模型的车辆随机振动分析

包装件振动可靠性的分析和优化需要构建高效准确的车辆随机振动载荷分析模型。该研究将车辆建模为单自由度参数激励系统,分析车辆在平稳载荷下的加速度响应。基于Mathieu方程分析车辆动态响应特性,结果表明,车辆响应中出现少量的大幅振动响应的原因是参数激励系统中随机过程β(t)的波动引起了系统的失稳。分别构建车辆在稳态、失稳和衰减条件下的响应分析方法,建立了车辆加速度响应的概率密度函数分析方法,构建了根据记录的试验数据识别系统参数的方法。分析结果表明,该研究建立的车辆随机振动分析方法能够高效准确地再现车辆非平稳随机振动的时域特征及概率密度函数(probability density function,PDF),为研究包装件振动可靠性提供了高效准确的分析基础。

GH4169高温合金材料薄壁件模态分析

利用ABAQUS对GH4169高温合金薄壁板的固有频率和振型进行仿真分析,研究试件厚度、高度以及不同约束条件对振动特性的影响。结果表明:同一阶模态时,固有频率随高度的增加而下降,随厚度的增加而上升;相较于薄壁件高度的影响,薄壁板的厚度对固有频率的影响更大;在不同的约束条件下对同一阶模态,四边约束固有频率最高,单边约束固有频率最低;约束条件对试件的振型影响很大。研究结果有利于GH4169高温合金材料的切削加工用量选择。

VIBRATION IN HIGH-SPEED MILLING OF THIN-WALLED COMPONENTS

To investigate the vibration principle in machining thin-walled components, a dynamic model for end milling of flexible structures is built based on considering the variations in the dynamic chip thickness and the differences between up-milling and down-milling. Two milling experiments verify the model. Experimental results show that the model can predict the milling force and displacements simultaneously in the dynamic milling process.

Effect of cooling condition on microstructure of semi-solid AZ91 slurry produced via ultrasonic vibration process

The effects of cooling conditions on the microstructure of semi-solid AZ91 slurry produced via ultrasonic vibration process were investigated. AZ91 melts were subjected to ultrasonic vibration in different temperature ranges under different cooling rates. The results show that fine and spherical α-Mg particles are obtained under ultrasonic vibration at the nucleation stage, which is mainly attributed to the cavitation and acoustic streaming induced by the ultrasonic vibration. The reduction of lower limit of ultrasonic vibration temperature between the liquidus and solidus increases the solid volume fraction and average particle size. Increasing cooling rate increases the solid volume fraction and reduces the average shape factor of particles. The appropriate temperature range for ultrasonic vibration is from 605 °C to 595 °C or 590 °C, and the suitable cooling rate is 2-3 °C/min.

车辆座椅减振系统中可控磁流液阻尼器的性能测试研究

半主动可控磁流液阻尼器是国际上新近研发的新一代智能振动抑制驱动器件,本文主要介绍对其进行性能测试研究的MTS实验系统及有关研究成果。该实验系统由液压反馈激振器、数据采集和处理计算机单元、传感器等软硬件组成,能实时在线显示阻尼器运动的相对位移、速度和所产生的阻尼力等时间响应信号,以及表征阻尼器基本特性的阻尼力对相对速度关系曲线。实验结果表明该智能驱动器件表现出典型的滞回非线性特性,并通过对大范围控制电流和大范围频率和幅度单谐波信号激励下的实验数据的分析,系统地描述了该新一代半主动可控智能驱动器件的主要性能特点。

SYSTEM IDENTIFICATION OF ADAPTIVE TRUSS STRUCTURES USING PIEZOELECTRIC ACTIVE MEMBERS

Adaptive truss structures are a new kind of structures with integrated active members,whose dynamic characteristies can be beneficially modified to meet mission requirements.Active members containing actuating and sensing units are the major components of adaptive truss structures.Modeling of adaptive truss structures is a key step to analyze the structural dynamic characteristics.A new experimental modal analysis approach,in which active members are used as excitatiDn sources for modal test,has been proposed in this paper.The excitation forces generated by the active members, which are different from the excitation forces exerted on structures in the conventional modal test,are internal forces for the truss structures.The relation between internal excitation forces and external forces is revealed such that the traditional identification method can be adopted to obtain modal parameters of adaptive structures.Placement problem of the active member in adaptive truss structures is also discussed in this work. Modal test and analysis are conducted with a planar adaptive truss structure by using piezoelectric active members in order to verify the feasibility and effectiveness of the proposed method.

Torsional vibration analysis of lathe spindle system with unbalanced workpiece

For the purpose of analyzing the torsional vibration caused by the gravitational unbalance torque arisen in a spindle system when it is machining heavy work piece,a 10-DOF lumped parameter model was made for the machine tool spindle system with geared transmission.By using the elementary method and Runge-Kutta method in Matlab,the eigenvalue problem was solved and the pure torsional vibration responses were obtained and examined.The results show that the spindle system cannot operate in the desired constant rotating speed as far as the gravitational unbalance torque is engaged,so it may cause bad effect on machining accuracy.And the torsional vibration increases infinitely near the resonant frequencies,so the spindle system cannot operate normally during these spindle speed ranges.

OBSERVATION OF A SHALLOW WATER INTERNAL OSCILLATION EVENT

At a shallow water station (6 m in depth), an internal oscillation event which consisted of one or two wave-like features, with a period of 3 h and a height of 1.5 m, was observed. The velocities within the water column were modified by the event during the flood phase of the tide; a multi-layered velocity structure and intense shear were generated. Further investigations are required to understand fully the mechanism for the formation of such an event.

Oscillations in Systems of Linear Neutral Differential Equations

Algebraic sufficient conditions are obtained for all nontrivial solutions of the linear system d d t[x(t)+cx(t-τ)]+A(t)x(t-σ(t))=0to be oscillatory.

Analyzing and exemplify the phenomenon of lossing control in vibration experiment

With science and technology development,vibration testing as the most important item in reliability test is becoming more and more important,at the same time,vibrate condition becoming more and more complicated,the phenomenon increases that the output of controller goes beyond controlling range so that destroy the specimen. In this paper,some skills such as how to set the parameters of force controller,where to place the sensor,which material to be chosen and which skills to be used while making jigs were introduced to avoid the just matter. At last,some examples were given to prove the validity of the method proposed.

Experimental Noise Analysis of Reed Switch Sensor Signal under Environmental Vibration

The chattering noise problem of reed switch sensor signal for Automatic Meter Reading system was analyzed experimentally under various types of external vibrations and shocks. The external vibration level amplitude was measured with an accelerometer. To apply for water flow measurement devices, the reed switch sensors should keep high reliability. But the measured digital meter data are occurred difference or errors by chattering noise. The reed switch contains chattering error by itself at the force equivalent position. The vibrations such as passing vehicle near to the reed switch installed location causes chattering. In order to reduce chattering error, most system uses just software methods, for example using digital filter algorithm and also statistical calibration methods. However software approaches were implemented for reducing chattering error, there has still generated chattering error due to external mechanical vibrations and magnetic field. The chattering errors can be reduced by changing leaf spring structure using mechanical hysteresis characteristics.

Remarks on Oscillation for Systems of High Order Partial Differential Equations of Neutral Type

In this paper, some sufficient conditions are obtained for the oscillation for solutions of systems of high order partial differential equations of neutral type.

Study on LQR control algorithm using superelement model

The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of freedom(DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element(FE) model for structure. In proposed model, the Craig-Bampton(C-B) method, which is one of the component mode syntheses(CMS), is used to establish superelement modeling to reduce structure's DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures.