基于ADAMS的顶装式波轮洗衣机平衡环的研究与仿真

为研究平衡环参数的变化对振动特性的影响,利用ADAMS仿真软件,对实际洗衣机桶体脱水阶段的动态特性进行了仿真,合理地解释了平衡环的作用机理。在分析过程中虚拟力的提出对洗衣机的开发和动态优化设计具有重要的参考价值,为平衡环的实验研究提供了理论基础。     

单侧带平衡环的滚筒洗衣机抑振机理的研究

采用平衡环抑制脱水振动已成为滚筒洗衣机新的研究热点。为此,建立了单侧带有平衡环的滚筒洗衣机振动模型,进而在数值仿真的基础上,讨论了平衡环的抑振机理。改进了悬挂系统阻尼器的布局,以克服传统平面悬挂结构无法抑制平衡环瞬态冲击的缺陷;分析了筒体轴线的运动轨迹,指出脱水稳态阶段筒体轴线沿一圆锥面运动,且圆锥的顶点位于平衡环一侧;分析了稳态阶段系统离心力的平衡,指出筒体结构具有与平面圆盘转子类似的环绕质心旋转的现象;讨论了系统质心位置对筒体摆角的影响,指出通过将洗涤/脱水单元质心向电机一侧移动可减小筒体的摆角。最后,通过试验定性验证了筒体轴线锥形运动轨迹的结论。     

带球体平衡环的滚筒洗衣机平面模型稳定性分析

应用平衡环技术抑制滚筒洗衣机脱水振动已成为发展趋势。但由于轴线水平,重力的作用使得球体相对脱水桶周期振荡,且模型本身难以转为合适的自治形式。为分析带有球体平衡环的滚筒洗衣机振动稳定性,建立了滚筒洗衣机平面振动模型,开发了适合周期解稳定性分析的伪弧长单参数延拓算法与分岔点的双参数追踪算法。应用该算法求解发现了系统周期解的倍周期、半周期、环面与叉形分岔现象,并指出了低速区的3个失稳区域。通过数值仿真验证了分岔结论的正确性。     

基于MSC.ADAMS的滚筒洗衣机动态特性研究

滚筒洗衣机的核心部分--内外筒合成体(吊装体)运动的不平衡,是洗衣机噪声和振动发生的振源.文中将其作为研究对象,首先应用Pro/E和MSC.ADAMs建立了洗衣机吊装体的参数化样机模型,并给出了虚拟样机的仿真设计方案.通过对样机工作过程的仿真,分析研究其振动机理,确定了吊装体中影响振动的关键因素,从而为滚筒洗衣机的优化设计提供了一种新思路.     

双环道液体平衡环减振性能研究

针对波轮洗衣机在脱水过程中存在的悬挂系统偏心振动剧烈的问题,对作为减小波轮洗衣机悬挂系统偏心振动重要部件的液体平衡环的结构和工作原理进行了研究,提出并设计了一种双环道液体平衡环。使用Fluent软件对其双环道液体平衡环和传统液体平衡环的内部流场进行了数值模拟,对模拟结果进行了对比分析;借助悬挂系统多体动力学测试平台,分别对搭载两种液体平衡环的悬挂系统进行了脱水过程的偏心位移测试,并分析了试验结果。研究结果表明:与传统液体平衡环相比,搭载双环道液体平衡环的悬挂系统偏心位移减小,平衡环减振性能提高;双环道平衡环内部液体对壁面压力变小,使用寿命增加。     

滚筒洗衣机悬挂系统动力学建模与实验

考虑上配重对洗衣机悬挂系统振动的影响,基于拉格朗日方程,对该系统进行动力学建模。进行了多工况下的洗衣机筒体振动测量实验,以实验得到的筒体振幅随转速变化的关系曲线为目标,对数学模型进行了参数修正。通过数值仿真与实验结果的对比分析,验证了动力学模型的正确性。     

一种振动颗粒康复仪的噪声分析与降噪设计

对新开发的振动颗粒康复仪的振动噪声控制策略进行了研究。首先,通过对原样机的声强测试分析,确认实施按摩作业的薄壁圆柱桶与颗粒层为主要噪声源;其次,基于有限元方法,对圆柱桶进行了模态分析与振动响应分析,得到了圆柱桶场点处声压级频率响应曲线,构建了对圆柱桶噪声分析的数值仿真模型;最后,进行了试验验证。对现有不锈钢材质圆柱桶的振动传递路径进行了隔振处理分析,变桶底连接为法兰连接,并在法兰与振动平台间增加隔振层。数值仿真结果表明,与原样机相比,场点处声压级降低了约16.7dB。若当筒体材料选用阻尼大、比重小、壁厚大的有机玻璃材料时,基频的提高使结构的固有频率更远离激振频率,仿真发现与原样机相比,场点处声压级有望降低约28.2dB。搭建了改为有机玻璃桶且增加隔振层的试验样机,噪声试验表明:与原样机相比,空桶工作时,噪声降低了约15.2dB(A);加入按摩颗粒后,噪声降低约3.5dB(A)。     

基于虚拟样机的倾斜轴滚筒洗衣机动力学仿真分析

以某型号倾斜轴滚筒洗衣机为研究对象建立其三维模型,结合ANSYS有限元分析软件,在ADAMS/View环境下,依据刚柔混合建模方法建立了滚筒洗衣机的虚拟样机模型。基于此模型对其脱水工况进行仿真分析,研究其振动机理,确定悬挂系统各关键参数对洗衣机振动噪声的影响。     

双压力角非对称齿廓渐开线齿轮的振动分析

基于非对称渐开线圆柱齿轮传动时的啮合机理和齿轮系统动力学。同时考虑到齿轮系统时变啮合刚度和静态传递误差的影响，建立了齿轮动力学模型，利用数值积分和数值仿真方法对其进行了非线性振动研究。比较了标准齿轮与非对称齿轮的振动特性，分析了齿轮系统各参数对系统动态特性的影响。仿真结果对考虑动载荷情况下的油膜厚度计算提供了基础数据，为进一步研究非对称渐开线的各种特性提供了理论依据。     

基于CFD的液体平衡环流动特性仿真研究

液体平衡环是波轮洗衣机减振的重要部件,针对波轮洗衣机脱水过程中的振动问题,通过优化液体平衡环结构参数的方法改善其减振性能。利用模拟软件FLUENT 14.5对平衡环内部流场进行数值模拟,探究了凸筋数量、凸筋开孔尺寸、环道宽度比、容积比等对平衡环减振性能的影响规律。模拟结果表明,凸筋数量增加会提高平衡环启动阶段减振性能,但是稳定阶段反之;凸筋开孔有助于提高其减振性能和使用寿命;双环道平衡环在宽度比为50%时减振性能最佳;容积比为55%时平衡环减振性能最好。     

Dynamic modeling and analysis of drum-type washing machine

In this study, dynamic analysis of a drum-type washing machine has been conducted using a simplified dynamic model considering gyroscopic effects. Its mathematical model has 6-degree of freedom in the complex coordinate space into which is transformed real coordinate space to understand the whirling motion easily. Dynamic analysis is performed using MATLAB. For the purpose of numerical verification, the results for unbalance response are presented and compared with the experimental vibration test. The mathematical model proves quite good accuracy in predicting dynamic characteristics which could be changed by the parameters of design variable and can reduce design cycle shortly. Dynamic characteristics of a washing machine are shown through shape and directivity index (SDI), whirling orbits, rigid and flexible mode of a drum type washing machine during drum run-up. In designing drum type of washing machine, it is efficient than finite element method to analyze behaviors of drum and tub.     

立铣铣削加工参数和铣刀几何参数的计算机辅助设计

在立铣加工过程动态铣削力非线性数学模型的基础上 ,采用变步长数值积分算法和递推算法建立起动态立铣加工过程的计算机仿真模型。通过输入不同的立铣加工参数和铣刀的几何参数 ,在时域内利用计算机来仿真机床的铣削振动。以刀具—工件系统的相对振动位移振幅最小为目标 ,完成铣削加工参数和铣刀几何参数的设计。     

A method for vibration isolation of a vertical axis automatic washing machine with a hydraulic balancer

This paper discusses a method for vibration isolation of a vertical axis automatic washing machine with a hydraulic balancer. First, a way to isolate vibration through a small amplitude of the suspension rod’s axial force is proposed, and a base circle of a cone along which the lower joint of a suspension rod moves is discussed. Based on the circle, a geometric constraint involving the slant angle of the suspension rod, the deflection angle of the washing/spinning assembly, the suspension radius of the tub and the eccentricity of the system at the steady state is derived. Considering that the trace along which the suspension rod moves is also affected by the dynamics of the system, a governing equation satisfying the equilibrium conditions of the centrifugal forces and torques is obtained. Combing the geometric constraint and governing equation together achieves a general governing equation for vibration isolation of the system. Finally, the general governing equation is proven by simulations, and the relations between the optimal installing height and several parameters are discussed.     

A dynamic model and numerical study on the liquid balancer used in an automatic washing machine

The rotational system of an automatic washing machine has two major technical difficulties. One is the collision of the tub against the frame at the beginning of its early spinning stage. A factor that causes such instability of the rotational object can be attributed to the deflection of the liquid inside the liquid balancer due to the unbalance mass. This study proposes the installation of a middle plate to avoid the deflection of the liquid and a CFD method is used to verify its effectiveness. The other is the whirling vibration occurred during the high speed rotation of the basket and it shakes the center of its rotational axis. This is because the balancer cannot generate enough restoration forces during its high speed rotation. It is necessary to employ the multi-race in the balancer in order to increase restoration forces. The analysis for the configuration has been performed using a dynamic model.     

RV减速器传动系统动力学特性分析

为深入研究工业机器人用RV减速器动力学特性,采用集中参数法,综合考虑啮合阻尼、时变啮合刚度以及综合啮合误差,建立了RV传动耦合扭转动力学模型,通过数值解法对建立的动力学方程进行求解,得到其振动位移、振动角速度响应及各齿轮副动态啮合力。基于UG与ADAMS建立RV减速器动力学模型,进行仿真分析实验,验证动力学模型的正确性。通过改变啮合刚度分析了啮合力的变化,随着啮合刚度的增加,在一定范围内,传动过程中的啮合力更加稳定,为RV减速器的故障诊断和优化设计奠定基础。     

高速平面并联机器人动态分析与实验

基于弹性动力学和实验对高速轻型平面并联机器人的动态响应进行研究。首先,根据机构的几何和惯性非线性建立机构运动微分方程组,对机构的两个典型位形的动态响应进行分析;其次,建立了由3-RRR轻型并联机构和控制系统组成的实验装置,对理论分析进行了验证。结果表明,在位形2,理论分析和实验一致,即机构的残余振动很快衰减;在位形1,理论分析与实验两者不同,实验测量的动态响应为自激振动,而数值仿真得到衰减的残余振动。同时,结果也表明机构在不同位形有不同的动态响应。     

行星齿轮内齿圈的多柔体动力学分析

以多柔体动力学理论为基础,研究了行星齿轮内齿圈在啮合过程中的动力学行为.构建了基于UG的虚拟样机模型.对系统进行了分析、计算及数值仿真,求解得到轮缘厚度系数与内齿圈应力/应变的定量关系及动应力沿内齿圈的分布规律,并对内齿圈进行了结构优化.结果表明,适当降低内齿圈的轮缘厚度系数,可有效降低振动、冲击与噪声,从而提高机构的疲劳寿命.     

导弹滑行出箱过程中颤动现象的建模与分析

为了深入研究导弹在发射箱内滑行产生的颤动现象,建立了基于Stribeck摩擦模型的质量块-传输带干摩擦动力学模型,利用静、动摩擦转换时摩擦力降落引起的负阻尼力激发系统的自激颤动现象。通过对运动方程进行稳定性分析,得到平衡点失去渐进稳定特性并产生自激颤动的临界速度。利用数值方法求解常微分方程得到相平面内的相轨迹,仿真证明系统存在稳定的极限环、发生了自激颤动。通过试验曲线与仿真曲线的对比,阐明了导弹发动机燃气喷流、发射箱内燃气绕流和发射车底盘振动等强干扰因素对不稳定周期运动的影响。最后,给出了工程上切实可行的摩擦控制、颤动抑制的方法,这对地面箱/轨式发射导弹具有较大的参考价值。     

Effects of dynamic transmission errors and vibration stability in helical gears

Transmission error is an important reason for instability in helical gears. A six-degree-of-freedom dynamic model coupled flexional, torsional and axial motion of a helical gear transmission system, which includes time varying mesh stiffness, bearing supporting stiffness, mesh damping and backlash, is developed, after taking into account the dynamic characteristics and vibration responses of helical gear in three dimensions. Influences of involute contact ratio, bearing supporting stiffness, mesh damping and backlash on the dynamic transmission errors and vibration stability of the helical gear system are investigated using numerical simulation technique. The effects on dynamic transmission errors and stabilities by contact ratio, supporting stiffness and mesh damping as well as gear backlash are analyzed. The intrinsic relationship between above parameters and dynamic transmission errors and stabilities for helical gear system are presented. The stable and unstable regions under different parameters are given. The results in this paper can be helpful to the dynamic and stable design of a helical gear transmission system.