刺绣机横梁的模态分析及优化设计

以GY920A型电脑刺绣机的主横梁作为研究对象,分别运用实验测试和有限元模拟方法分析了电脑刺绣机横梁弯曲振动的固有频率,并将所得结果用于电脑刺绣机横梁结构的优化设计,提高了横梁的固有频率,达到减小断线率的目的。     

电脑刺绣机横梁的模态分析

以GY920A型电脑刺绣机的主横梁作为研究对象．分别运用实验测试和有限元模拟方法分析了电脑刺绣机横梁弯曲振动的固有频率，并将所得结果用于电脑刺绣机横梁结构的改进，提高了横梁的固有频率，达到减小断线率的目的。     

电脑刺绣机横梁弯曲振动固有频率研究

以2头电脑刺绣机横梁为研究对象，分别运用简单梁理论，ANSYS有限元模拟和实验测试三种方法计算分析了电脑刺绣机横梁弯曲振动的固有频率，所得结论可用于电脑刺绣机横梁长度、截面形状和固定方式的改进设计。     

电脑刺绣机横梁的有限元动态分析

研究电脑刺绣机横梁有限元模型的建立,重点研究其复杂约束在有限元分析中的简化,得到了与实际等效的有限元计算模型。     

单机头电脑刺绣机横梁模态分析及优化设计

以RF1201型电脑刺绣机的横梁作为研究对象,运用有限元分析的方法,对其施加满足实际工况的约束,在计算机容量允许的情况下,选择精度更高的单元和划分更细的网格密度,计算出横梁的模态频率以及模态振型。为了验证有限元法计算结果,又通过实地的振动试验,具体测出了横梁的共振频率,验证了有限元计算结果的正确性。利用经过验证的有限元模型,在计算机上作结构的优化设计,找到了横梁截面尺寸的合理组合,提高横梁的模态频率,使电脑刺绣机更不易发生共振。     

电脑刺绣机自动注油系统

随着电脑刺绣机的不断发展,刺绣机的主轴转速越来越高[1].高速运转会加剧机械的磨损,特别是机头和旋梭部分.有效降低机械磨损的方法是关键机械部分定期地进行清洁和注油.本文针对目前电脑刺绣机的应用情况设计了一种自动注油控制系统,可以实现容积式和阻尼式润滑系统,满足了电脑刺绣机的润滑要求.目前本系统已广泛使用于高速电脑刺绣机...     

DXJ—106型电脑刺绣机

由国营苏州二六七厂和苏州工艺美术研究所共同开发研制的第三代电脑刺绣机,在苏州通过鉴定,并投入生产。该电脑刺绣机是列入国家火炬计划的高新科技新产品。该电脑刺绣机,造型美观,性能可靠,操作方     

电脑刺绣机挑线刺布机构的创新设计

以电脑刺绣机挑线刺布机构为研究对象,详细推导了创新机构的设计理论方程,设计了一种新型的电脑刺绣机挑线刺布机构。计算分析了创新机构的挑线运动规律,画出了创新挑线机构的结构简图,所得结论可用于电脑刺绣机挑线刺布机构的创新设计。     

电脑刺绣机挑线凸轮设计与优化

以电脑刺绣机为研究对象,根据刺绣机的面线消耗量和刺绣的可缝性,分析了挑线机构的设计要求;利用五次多项式曲线对挑线凸轮进行了设计;并根据刺绣机的特殊要求,提出了刺绣机最优化设计方法.     

高性能多功能电脑刺绣机控制技术

分析总结了刺绣机控制的三个难点:刺绣机种类繁多、主轴和框架系统的时变负载特性和弹性框架问题.针对这些难点提出了相关解决方法,实现了面向时变系统的多功能数控系统在刺绣机中的应用.继刺绣机电控系统国产化之后,实现了国产电脑刺绣机功能性能的第二次飞跃.     

Spectral analysis of dynamic response of a thin beam subjected to a varying speed moving mass

A parametric survey was conducted to capture the dynamic response of a thin beam subjected to a varying speed moving mass. The existing literature lacks a comprehensive study on the beam dynamic behavior under a varying speed moving mass with arbitrary constant acceleration and mass ratio. The current work represents midpoint response spectra for a thin beam acted upon by a varying speed moving mass for a wide range of design parameters. Findings show that for a given mass ratio, higher response amplitudes are observed in decelerating motion compared to accelerating one. Moreover, increasing the mass ratio of the moving mass generally leads to higher beam dynamic response. Among the methods that can be utilized to calculate beam response, the Eigenfunction expansion method (EFM) and Orthonormal polynomial series expansion method (OPSEM) were used. Then an improvement technique was applied on both aforementioned methods and computational efficiency and convergence rate of all utilized methods was compared.     

移动质量激励下梁动态响应分析与试验研究

以移动质量激励下的梁为研究对象,建立了移动质量-简支梁和移动质量-悬臂梁耦合振动模型.考虑了移动质量的重力、Corilous加速度和惯性加速度对梁横向振动的影响,利用得到的级数解编制程序分析了移动质量参数变化对梁动态响应的影响.建立了移动质量激励下的梁动态响应试验平台,通过试验得到了各种规格质量块以不同运动速度激励作用下的梁动态响应曲线.试验结果表明了移动质量激励下梁动态响应模型的正确性.     

耦合梁中高频抖动的行波分析与主动控制

为研究中高频扰动下耦合梁结构的动力学响应与主动控制,基于Timoshenko梁理论,考虑梁中转动惯量和剪切变形的影响,采用行波方法分别建立梁结构纵向运动、弯曲运动的单元模型与结点散射模型,进而获得耦合梁的行波动力学模型及其精确的中高频抖动响应;引入“功率流”的分析思想,并以此为目标函数,优化得到了最优控制力的大小与相位,然后对结构施加最优控制力,实现耦合梁结构的功率流主动控制。在此基础上,进行数值仿真分析,并与Euler-Bernoulli梁理论计算结果进行对比。结果表明,采用行波方法计算耦合梁结构的动力学响应准确可靠;Timoshenko梁模型较Euler-Bernoulli梁模型在中、高频段更为精确,且更接近工程实际;功率流主动控制可以明显降低耦合梁结构全频域内的抖动,验证了基于行波方法功率流主动控制的正确性与有效性。     

Dynamic responses and fuzzy control of a simply-supported beam subjected to a moving mass

This paper deals with the active vibration control of a simply-supported beam traversed by a moving mass using fuzzy control. Governing equations for dynamic responses of a beam under a moving mass are derived by Galerkin’s mode summation method, and the effect of forces (gravity force, Coliolis force, inertia force caused by the slope of the beam, transverse inertia force of the beam) due to the moving mass on the dynamic response of a beam is discussed. For the active control of dynamic deflection and vibration of a beam under the moving mass, the controller based on fuzzy logic is used and the experiments are conducted by VCM (voice coil motor) actuator to suppress the vibration of a beam. Through the numerical and experimental studies, the following conclusions were obtained. With increasing mass ratioy at a fixed velocity of the moving mass under the critical velocity, the position of moving mass at the maximum dynamic deflection moves to the right end of the beam. With increasing velocity of the moving mass at a fixed mass ratioy, the position of moving mass at the maximum dynamic deflection moves to the right end of the beam too. The numerical predictions of dynamic deflection of the beam have a good agreement with the experimental results. With the fuzzy control, more than 50% reductions of dynamic deflection and residual vibration of the tested beam under the moving mass are obtained.     

Experimental study on dynamic characteristics of linear parametrically excited system

An electromagnetic device, acting like a spring with alternating stiffness, has been designed to parametrically excite the cantilever beam transversely in the laboratory. It showed good potential for the experimental investigation of linear parametric system. Therefore, experiments for the natural frequency, the response (both free and forced) spectra and frequency response characteristics of a cantilever beam under electromagnetic excitation, are, respectively, conducted to study the dynamic characteristics of linear parametrically excited system. The vibrational model of the cantilever beam system is established using the assumed mode method. Theoretical results, related to the natural frequency, response spectra and external resonant condition, are presented to verify the experimental results. It is shown that the dynamic characteristics of linear time-periodic system do have some typical features, which differ distinctly from that of the linear time-invariant system.     

Dynamic response analysis of a cantilevered beam due to an elastic impact

The beam structure models with impact or contact parts under impact forces have been applied to the design of mechanical and electronic accessories. Switches, pick-ups and sensors are the typical examples of the structure to be designed to colliding with other parts. The damping characteristics and stiffness of an impacter have a great effect on dynamic responses of structures subjected to impact forces. Since the response characteristics of structures have an effect on the generation of impact forces, both theoretical and experimental investigations for the dynamic relationships between the impacter and impact mechanism are required for the structural design to reduce impact forces or eliminate unwanted vibration modes. In this paper, in order to examine the relationship between the changes of the stiffness and damping of an impacter and the variations of the dynamic characteristics of the impact model of a cantilevered beam with an impacter, the impact force of the impacter and response characteristics of the cantilevered beam were analyzed by both numerical simulation and experiments. Since the stiffness and damping of the impacter are highly nonlinear, the contact model using revised Hertz-model was established by experiments. Also, the results of numerical analyses for the dynamic response and impact force of a cantilevered beam with an impacter have a good agreement with experimental results. It is believed that the mathematical model and the analytical method presented here can be used for the design analysis and the improvement of performances of the beam-shape switches and pickup devices.     

考虑附加质量的中心刚体-柔性悬臂梁系统的动力特性研究

对考虑附加质量的中心刚体-柔性悬臂梁系统的动力特性进行研究.首先采用Hamilton原理和有限元离散化方法,在计入柔性梁由于横向变形而引起的轴向变形的二阶耦合量的条件下,给出该系统的刚柔耦合动力学方程(即一次近似耦合模型),以及相应的非惯性系下的动力学模型,然后通过数值仿真对系统的动力特性进行研究.仿真结果显示,即使是小的附加质量也会对系统动力特性产生重要影响,附加质量使得梁的响应幅值变大和响应频率降低,且会影响柔性梁和中心刚体的终点位置.附加质量的影响随系统大范围运动的角速度的增大而变大.当系统大范围运动为低速时,传统的混合坐标模型仍然会导致较大误差;当系统大范围运动为高速时,传统的混合坐标模型存在失效的可能.     

便携式轨道衡动力学仿真分析

针对便携式轨道衡的动态称重过程,采用多体系统动力学仿真软件(ADAMS),对轨道衡主要零件———称重梁,进行动力学仿真分析,研究列车以确定速度通过轨道衡时称重梁对系统的响应,为便携式轨道衡的设计、试验和改进提供了参考依据。     

Dynamic strain response of an infinite beam and inverse calculation of impact force by numerical Laplace transform

A general method for determining the dynamic strain response of an infinite beam to impact force is presented. The method consists of formulating and solving the dynamic problem in the Laplace transform domain and obtaining the strain response by numerical inversion of the transformed solution. Also, an inverse method for estimating the impact force on an infinite beam is investigated. Once the strain is known, it is shown how the impact force can be reconstructed.     

水平定向钻机大梁的瞬态动力学分析

以某型水平定向钻机的关键部件大梁为研究对象,在其三维实体模型的基础上建立了有限元模型,运用ANSYS有限元软件对大梁进行了瞬态分析。通过求解,确定了大梁结构承受随时间变化载荷时的动力响应,为定向钻机结构的改进和动态特性的提高提供了设计依据。