神经网络在电机振动控制中的应用

基于干扰对消原理,利用多层前向神经网络对电气传动系统中存在的电机非线性振动进行控制。计算机仿真结果表明了该控制方案的可行性和有效性。     

Influence of shear deformation and rotary inertia on nonlinear free vibration of a beam with pinned ends

The method of multiple scales is used to analyze the nonlinear vibrations of a beam with pinned ends. The formulation incorporates the effects of the transverse shear deformation as well as the rotary inertia on the large amplitude vibration behaviour. A uniformly valid higher second-order perturbation solution is obtained. The predictions of nonlinear frequencies at different beam parameters are given. The influences of shear and rotary inertia are significant in the case of moderately thick and short beams undergoing large amplitude vibrations.     

旋转轴系弯-扭振动耦合的数值分析

介绍了一种可以同时计算出旋转轴系的弯曲振动及扭转振动的瞬态响应的数值计算方法,该方法所依据的模型是一种分段的连续质量模型,具有比较好的计算精度,而与有限元方法比较,该方法的计算工作量及比较小。作者用该方法对旋转轴系弯曲振动与扭转振动的耦合问题进行了一些分析     

Tuned vibration control of overhead line conductors

Linear and non‐linear theoretical and numerical analysis of ultimate response of overhead line conductors is treated in present paper. Interactive linear and non‐linear conditions in ultimate response are considered. Numerical solution of non‐linear problems appearing is made using the updated Lagrangian formulation of motion. Each step of the iteration approaches the solution of linear problem and the feasibility of the parallel processing FETM technique with adaptive mesh refinement and substructuring for non‐linear ultimate wave propagation and ultimate transient dynamic analysis is established. Some numerical results demonstrating current applicabilities and efficiency of procedures suggested are submitted. Copyright © 2000 John Wiley & Sons, Ltd.     

Macrotexture influence on vibrational mechanisms of the tyre–road noise of an asphalt rubber pavement

The road surface is one of the most important factors that have influence on the current traffic noise. Usually, for dense surfaces, impacts of the tyre on the pavement generate vibrations which are the dominant mechanisms in the tyre–road noise. In this study, the effect of muffling these vibrations, by the incorporation of crumb rubber (CR) from wasted tyres into asphalt pavements, has been evaluated acoustically. Close proximity measurements have been carried out to register the sound emission generated in the contact zone between a reference tyre and an experimental asphalt pavement with CR. The analysis of the measurements indicates that the incorporation of CR as well as the air voids content has less influence than the macrotexture of the road surface on the acoustical behaviour of this experimental asphalt pavement.     

基于能量解耦法的操纵台悬置系统优化设计

针对某机车在4档运行时司机室的操纵台的异常振动问题,利用VTCL-DSP信号采集与分析系统对操纵台在机车加速和等速过程中的振动信号进行了测试与分析并采用了悬置刚度匹配法与能量解耦法对此系统进行了研究,认为橡胶隔振块刚度匹配不合理而引起的操纵台悬置系统的耦合共振是操纵台异常振动的主要原因,并对悬置系统提出了优化方案。通过在MATLAB中进行的仿真验证与改进方案的试验验证,确定操纵台的异常振动得到了有效的控制。     

Hybrid damper with stroke amplification for damping of offshore wind turbines

The magnitude of tower vibrations of offshore wind turbines is a key design driver for the feasibility of the monopile support structure. A novel control concept for the damping of these tower vibrations is proposed, where viscous‐type hybrid dampers are installed at the bottom of the wind turbine tower. The proposed hybrid damper consists of a passive viscous dashpot placed in series with a load cell and an active actuator. By integrated force feedback control of the actuator motion, the associated displacement amplitude over the viscous damper can be increased compared with the passive viscous case, hereby significantly increasing the feasibility of viscous dampers acting at the bottom of the wind turbine tower. To avoid drift in the actuator displacement, a filtered time integration of the measured force signal is introduced. Numerical examples demonstrate that the filtered time integration control leads to performance similar to that of passive viscous damping and substantial amplification of the damper deformation without actuator drift. Copyright © 2016 John Wiley & Sons, Ltd.     

Explicit solution for the natural frequency of structures with partial viscoelastic treatment

The free vibration characteristics of structures with viscoelastic treatment are represented by the complex-valued natural frequencies. The assumed single mode representation associated with the low-frequency stiffness of the viscoelastic treatment is modified by a correction term representing the influence from residual vibration modes. The correction term is eliminated in terms of the corresponding natural frequency associated with the high-frequency stiffness of the viscoelastic treatment, whereby an expression is obtained for the complex-valued natural frequency, which only requires the solution of two real-valued eigenvalue problems.     

热超声倒装键合换能系统多模态振动与有限元分析

研究了热超声倒装键合设备的核心执行机构——换能系统的动力学特性.利用激光多谱勒测振仪测试系统末端各方向的振动速度,发现系统以轴向振动为主,但受到其他非轴向振动的干扰.非轴向振动对芯片造成芯片倾斜、键合强度降低等负面影响.采用有限元方法对换能系统建模,仿真计算发现换能系统振动是各方向振动的耦合结果,且工作模态附近存在多种干扰模态.最后分析了系统多模态产生的根源并提出抑制方法.     

Modeling the mechanics and dynamics of arbitrary edge drills

This paper presents a new approach for modelling the cutting forces and chatter stability limits in drills with arbitrary lip geometry. The oblique cutting geometry at each point on the drill lip is modelled using parametric curve equations. The cutting force and process damping coefficients at different parts of the drill lip are identified empirically; the cutting force coefficients are identified from non-symmetric drilling tests, and the process damping coefficients are identified from chatter-free orthogonal turning tests. The presented approach provides a practical method for modelling the cutting forces and vibration stability without needing the detailed geometry of drill lips. The accuracy of presented model in predicting lateral and torsional-axial chatter stability limits is verified by conducting drilling tests using drills with various edge geometries.