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Vibration Sideband Modulations and Harmonics Separation of a Planetary Helicopter Gearbox with Two Different Configurations 行星直升机齿轮箱两种构型振动边带调制及谐波分离
Q2 Physics and Astronomy Pub Date : 2016-11-10 DOI: 10.1155/2016/9820768
N. Sawalhi
This paper examines the spectrum and cepstrum content of vibration signals taken from a helicopter gearbox with two different configurations (3 and 4 planets). It presents a signal processing algorithm to separate synchronous and nonsynchronous components for complete shafts’ harmonic extraction and removal. The spectrum and cepstrum of the vibration signal for two configurations are firstly analyzed and discussed. The effect of changing the number of planets on the fundamental gear mesh frequency (epicyclic mesh frequency) and its sidebands is discussed. The paper explains the differences between the two configurations and discusses, in particular, the asymmetry of the modulation sidebands about the epicyclic mesh frequency in the 4 planets arrangement. Finally a separation algorithm, which is based on resampling the order-tracked signal to have an integer number of samples per revolution for a specific shaft, is proposed for a complete removal of the shafts harmonics. The results obtained from the presented separation algorithms are compared to other separation schemes such as discrete random separation (DRS) and time synchronous averaging (TSA) with clear improvements and better results.
本文研究了直升机齿轮箱两种不同结构(3行星和4行星)振动信号的频谱和倒频谱含量。提出了一种分离同步和非同步分量的信号处理算法,用于全轴谐波提取和去除。首先对两种构型振动信号的频谱和倒谱进行了分析和讨论。讨论了行星数变化对基本齿轮啮合频率(周转啮合频率)及其边带的影响。本文解释了这两种构型的区别,并着重讨论了四行星排列中星圈网格频率调制边带的不对称性。最后,提出了一种分离算法,该算法基于对顺序跟踪信号进行重采样,使特定轴的每转采样数为整数,用于完全去除轴谐波。与离散随机分离(DRS)和时间同步平均(TSA)等分离方法进行了比较,得到了明显的改进和更好的结果。
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引用次数: 11
Mixed Skyhook and FxLMS Control of a Half-Car Model with Magnetorheological Dampers 带磁流变阻尼器的半车模型混合Skyhook和FxLMS控制
Q2 Physics and Astronomy Pub Date : 2016-10-25 DOI: 10.1155/2016/7428616
P. Krauze, J. Kasprzyk
The problem of vibration attenuation in a semiactive vehicle suspension is considered. The proposed solution is based on usage of the information about the road roughness coming from the sensor installed on the front axle of the vehicle. It does not need any preview sensor to measure the road roughness as other preview control strategies do. Here, the well-known Skyhook algorithm is used for control of the front magnetorheological (MR) damper. This algorithm is tuned to a quarter-car model of the front part of the vehicle. The rear MR damper is controlled by the FxLMS (Filtered-x LMS) taking advantage of the information about the motion of the front vehicle axle. The goal of this algorithm is to minimize pitch of the vehicle body. The strategy is applied for a four-degree-of-freedom (4-DOF) vehicle model equipped with magnetorheological dampers which were described using the Bouc-Wen model. The suspension model was subjected to the road-induced excitation in the form of a series of bumps within the frequency range 1.0–10 Hz. Different solutions are compared based on the transmissibility function and simulation results show the usefulness of the proposed solution.
研究了汽车半主动悬架的振动衰减问题。所提出的解决方案是基于安装在车辆前轴上的传感器所提供的路面粗糙度信息的使用。它不像其他的预览控制策略那样需要任何预览传感器来测量路面粗糙度。在这里,众所周知的Skyhook算法被用于控制前磁流变(MR)阻尼器。该算法被调整为车辆前部的四分之一汽车模型。后磁流变阻尼器由FxLMS (filter -x LMS)控制,利用车辆前轴的运动信息。该算法的目标是使车身俯仰最小。将该策略应用于一个采用Bouc-Wen模型描述的带有磁流变阻尼器的四自由度车辆模型。该悬架模型在1.0-10 Hz的频率范围内受到一系列颠簸形式的道路诱导激励。基于传递率函数对不同解进行了比较,仿真结果表明了所提解的有效性。
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引用次数: 8
Vibrational Interaction of Two Rotors with Friction Coupling 具有摩擦联轴器的两转子振动相互作用
Q2 Physics and Astronomy Pub Date : 2016-10-18 DOI: 10.1155/2016/9275147
H. Larsson, K. Farhang
A lumped parameter model is presented for studying the dynamic interaction between two disks in relative rotational motion and in friction contact. The contact elastic and dissipative characteristics are represented by equivalent stiffness and damping coefficient in the axial as well as torsional direction. The formulation accounts for the coupling between the axial and angular motions by viewing the contact normal force a result of axial behavior of the system. The model is used to investigate stick-slip behavior of a two-disk friction system. In this effort the friction coefficient is represented as an exponentially decaying function of relative angular velocity, varying from its static value at zero relative velocity to its kinetic value at very high velocities. This investigation results in the establishment of critical curve defining two-parameter regions: one in which stick-slip occurs and that in which stick-slip does not occur. Moreover, the onset and termination of stick-slip, when it occurs, are related to the highest component frequency in the system. It is found that stick-slip starts at a period nearly equal to that of the highest component frequency and terminates at a period almost three times that of the highest component frequency.
提出了一种集总参数模型,用于研究两盘相对旋转运动和摩擦接触时的动态相互作用。接触弹性和耗散特性由轴向和扭转方向的等效刚度和阻尼系数表示。该公式通过观察系统轴向行为的接触法向力来解释轴向运动和角运动之间的耦合。利用该模型研究了双盘摩擦系统的粘滑行为。在这项工作中,摩擦系数表示为相对角速度的指数衰减函数,从相对速度为零时的静态值到非常高的速度时的动态值。研究结果建立了临界曲线,定义了两个参数区域:一个发生粘滑,另一个不发生粘滑。此外,当粘滑发生时,粘滑的发生和终止与系统中最高分量频率有关。研究发现,粘滑开始的周期几乎等于最高分量频率的周期,结束的周期几乎是最高分量频率的三倍。
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引用次数: 1
Comparison of the Time Domain Windows Specified in the ISO 18431 Standards Used to Estimate Modal Parameters in Steel Plates 用于估计钢板模态参数的ISO 18431标准中指定的时域窗口的比较
Q2 Physics and Astronomy Pub Date : 2016-08-29 DOI: 10.1155/2016/3837971
Jhonatan Camacho-Navarro, R. Guzmán-López, S. Gómez, Marco Fidel Flórez
The procedures used to estimate structural modal parameters as natural frequency, damping ratios, and mode shapes are generally based on frequency methods. However, methods of time-frequency analysis are highly sensible to the parameters used to calculate the discrete Fourier transform: windowing, resolution, and preprocessing. Thus, the uncertainty of the modal parameters is increased if a proper parameter selection is not considered. In this work, the influence of three different time domain windows functions (Hanning, flat-top, and rectangular) used to estimate modal parameters are discussed in the framework of ISO 18431 standard. Experimental results are conducted over an AISI 1020 steel plate, which is excited by means of a hammer element. Vibration response is acquired by using acceleration records according to the ISO 7626-5 reference guides. The results are compared with a theoretical method and it is obtained that the flat-top window is the best function for experimental modal analysis.
用于估计结构固有频率、阻尼比和模态振型等模态参数的程序通常基于频率方法。然而,时频分析方法对用于计算离散傅里叶变换的参数非常敏感:窗口,分辨率和预处理。因此,如果不考虑适当的参数选择,则会增加模态参数的不确定性。本文在ISO 18431标准的框架下,讨论了用于估计模态参数的三种不同时域窗函数(汉宁窗函数、平顶窗函数和矩形窗函数)的影响。在aisi1020钢板上进行了锤击元件激励试验。根据ISO 7626-5参考指南,通过使用加速度记录获得振动响应。结果与理论方法进行了比较,得出平顶窗是试验模态分析的最佳函数。
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引用次数: 0
Development of an Experimental Model for a Magnetorheological Damper Using Artificial Neural Networks (Levenberg-Marquardt Algorithm) 利用人工神经网络(Levenberg-Marquardt算法)建立磁流变阻尼器实验模型
Q2 Physics and Astronomy Pub Date : 2016-08-18 DOI: 10.1155/2016/7027259
Ayush Raizada, P. Singru, V. Krishnakumar, Varun Raj
This paper is based on the experimental study for design and control of vibrations in automotive vehicles. The objective of this paper is to develop a model for the highly nonlinear magnetorheological (MR) damper to maximize passenger comfort in an automotive vehicle. The behavior of the MR damper is studied under different loading conditions and current values in the system. The input and output parameters of the system are used as a training data to develop a suitable model using Artificial Neural Networks. To generate the training data, a test rig similar to a quarter car model was fabricated to load the MR damper with a mechanical shaker to excite it externally. With the help of the test rig the input and output parameter data points are acquired by measuring the acceleration and force of the system at different points with the help of an impedance head and accelerometers. The model is validated by measuring the error for the testing and validation data points. The output of the model is the optimum current that is supplied to the MR damper, using a controller, to increase the passenger comfort by minimizing the amplitude of vibrations transmitted to the passenger. Besides using this model for cars, bikes, and other automotive vehicles it can also be modified by retraining the algorithm and used for civil structures to make them earthquake resistant.
本文是基于汽车振动设计与控制的实验研究。本文的目的是建立一个高度非线性磁流变阻尼器的模型,以最大限度地提高汽车乘客的舒适度。研究了磁流变阻尼器在不同加载条件和系统电流值下的性能。将系统的输入输出参数作为训练数据,利用人工神经网络建立合适的模型。为了生成训练数据,制作了一个类似于四分之一汽车模型的试验台,用机械激振器加载磁流变阻尼器,以从外部激励它。在试验台的帮助下,通过阻抗头和加速度计测量系统在不同点的加速度和力,获得输入和输出参数数据点。通过测量测试和验证数据点的误差来验证模型。该模型的输出是提供给磁流变阻尼器的最佳电流,使用控制器,通过最小化传递给乘客的振动幅度来增加乘客的舒适度。除了将该模型用于汽车、自行车和其他汽车之外,还可以通过重新训练算法对其进行修改,并将其用于土木结构,使其具有抗震能力。
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引用次数: 10
Working and Limitations of Cable Stiffening in Flexible Link Manipulators 柔性连杆机械臂缆索加强的工作及局限性
Q2 Physics and Astronomy Pub Date : 2016-08-16 DOI: 10.1155/2016/4503696
Rahul Dixit, R. P. Kumar
Rigid link manipulators (RLMs) are used in industry to move and manipulate objects in their workspaces. Flexible link manipulators (FLMs), which are much lighter and hence highly flexible compared to RLMs, have been proposed in the past as means to reduce energy consumption and increase the speed of operation. Unlike RLM, an FLM has infinite degrees of freedom actuated by finite number of actuators. Due to high flexibility affecting the precision of operation, special control algorithms are required to make them usable. Recently, a method to stiffen FLMs using cables, without adding significant inertia or adversely affecting the advantages of FLMs, has been proposed as a possible solution in a preliminary work by the authors. An FLM stiffened using cables can use existing control algorithms designed for RLMs. In this paper we discuss in detail the working principle and limitations of cable stiffening for flexible link manipulators through simulations and experiments. A systematic way of deciding the location of cable attachments to the FLM is also presented. The main result of this paper is to show the advantage of adding a second pair of cables in reducing overall link deflections.
刚性链接机械手(rlm)在工业中用于在其工作空间中移动和操作对象。柔性连杆机械臂(FLMs)是一种更轻、更灵活的机械臂,过去已被提出作为降低能耗和提高操作速度的手段。与RLM不同,FLM具有无限自由度,由有限数量的作动器驱动。由于其灵活性高,影响操作精度,需要特殊的控制算法才能使其可用。最近,作者在一项初步工作中提出了一种使用缆索加强flm的方法,该方法不会增加明显的惯性或对flm的优点产生不利影响。使用缆索加固的FLM可以使用为rlm设计的现有控制算法。本文通过仿真和实验,详细讨论了柔性连杆机械臂钢索加筋的工作原理和局限性。本文还提出了一种系统的确定FLM电缆附件位置的方法。本文的主要结果是显示了增加第二对电缆在减少整体连接挠度方面的优势。
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引用次数: 8
Forced Response of Polar Orthotropic Tapered Circular Plates Resting on Elastic Foundation 弹性基础上极坐标正交各向异性锥形圆板的受力响应
Q2 Physics and Astronomy Pub Date : 2016-08-03 DOI: 10.1155/2016/1492051
A. Ansari
Forced axisymmetric response of polar orthotropic circular plates of linearly varying thickness resting on Winkler type of elastic foundation has been studied on the basis of classical plate theory. An approximate solution of problem has been obtained by Rayleigh Ritz method, which employs functions based upon the static deflection of polar orthotropic circular plates. The effect of transverse loadings has been studied for orthotropic circular plate resting on elastic foundation. The transverse deflections and bending moments are presented for various values of taper parameter, rigidity ratio, foundation parameter, and flexibility parameter under different types of loadings. A comparison of results with those available in literature shows an excellent agreement.
在经典板理论的基础上,研究了温克勒型弹性地基上线性变厚的正交各向异性极板的强迫轴对称响应。利用基于极坐标正交各向异性圆板静挠度的函数,用瑞利-里兹法得到了问题的近似解。研究了横向荷载对弹性基础上正交各向异性圆板的影响。给出了不同锥度参数、刚度比、基础参数和柔度参数值在不同荷载作用下的横向挠度和弯矩。结果与文献中已有的结果相比较,显示出极好的一致性。
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引用次数: 3
Stability Analysis of a Flutter Panel with Axial Excitations 轴向激励下颤振板的稳定性分析
Q2 Physics and Astronomy Pub Date : 2016-07-31 DOI: 10.1155/2016/7194764
M. Peng, H. Desmidt
This paper investigates the parametric instability of a panel (beam) under high speed air flows and axial excitations. The idea is to affect out-of-plane vibrations and aerodynamic loads by in-plane excitations. The periodic axial excitation introduces time-varying items into the panel system. The numerical method based on Floquet theory and the perturbation method are utilized to solve the Mathieu-Hill equations. The system stability with respect to air/panel density ratio, dynamic pressure ratio, and excitation frequency are explored. The results indicate that panel flutter can be suppressed by the axial excitations with proper parameter combinations.
本文研究了高速气流和轴向激励作用下板(梁)的参数失稳问题。其思想是通过面内激励来影响面外振动和气动载荷。周期性轴向激励将时变项引入到面板系统中。采用基于Floquet理论的数值方法和微扰法求解了Mathieu-Hill方程。研究了空气/面板密度比、动压比和激励频率对系统稳定性的影响。结果表明,在适当的参数组合下,轴向激励可以抑制面板颤振。
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引用次数: 2
Generation of Hydroacoustic Waves by an Oscillating Ice Block in Arctic Zones 北极地区振荡冰块产生水声波
Q2 Physics and Astronomy Pub Date : 2016-07-28 DOI: 10.1155/2016/8076108
U. Kadri
The time harmonic problem of propagating hydroacoustic waves generated in the ocean by a vertically oscillating ice block in arctic zones is discussed. The generated acoustic modes can result in orbital displacements of fluid parcels sufficiently high that may contribute to deep ocean currents and circulation. This mechanism adds to current efforts for explaining ocean circulation from a snowball earth Neoproterozoic Era to greenhouse earth arctic conditions and raises a challenge as the extent of ice blocks shrinks towards an ice-free sea. Surprisingly, unlike the free-surface setting, here it is found that the higher acoustic modes exhibit a larger contribution.
讨论了北极地区垂直振荡海冰在海洋中传播水声的时谐问题。所产生的声模可导致足够高的流体包的轨道位移,这可能有助于形成深海洋流和环流。这一机制为解释从雪球地球新元古代到温室地球北极条件下的海洋环流增加了努力,并提出了一个挑战,因为冰块的范围缩小到无冰的海洋。令人惊讶的是,与自由表面设置不同,这里发现更高的声学模式表现出更大的贡献。
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引用次数: 11
Optimization of Automotive Suspension System by Design of Experiments: A Nonderivative Method 基于实验设计的汽车悬架系统优化:一种非导数方法
Q2 Physics and Astronomy Pub Date : 2016-07-27 DOI: 10.1155/2016/3259026
A. Mitra, Tanushri Soni, G. R. Kiranchand
A lot of health issues like low back pain, digestive disorders, and musculoskeletal disorders are caused as a result of the whole body vibrations induced by automobiles. This paper is concerned with the enhancement and optimization of suspension performance by using factorial methods of Design of Experiments, a nonderivative method. It focuses on the optimization of ride comfort and determining the parameters which affect the suspension behavior significantly as per the guidelines stated in ISO 2631-1:1997 standards. A quarter car test rig integrated with a LabVIEW based data acquisition system was developed to understand the real time behavior of a vehicle. In the pilot experiment, only three primary suspension parameters, that is, spring-stiffness, damping, and sprung mass, were considered and the full factorial method was implemented for the purpose of optimization. But the regression analysis of the data obtained rendered a very low goodness of fit which indicated that other parameters are likely to influence the response. Subsequently, steering geometry angles, camber and toe and tire pressure, were included in the design. Fractional factorial method with six factors was implemented to optimize ride comfort. The resultant optimum combination was then verified on the test rig with high correlation.
许多健康问题,如腰痛、消化系统紊乱和肌肉骨骼疾病,都是由汽车引起的全身振动引起的。本文研究了用非导数方法——试验设计中的阶乘法来提高和优化悬架性能。它侧重于乘坐舒适性的优化,并根据ISO 2631- 1:20 97标准规定的指导方针确定影响悬架性能的参数。开发了集成基于LabVIEW的数据采集系统的四分之一汽车试验台,以了解车辆的实时行为。在先导试验中,仅考虑悬架的三个主要参数,即弹簧刚度、阻尼和簧载质量,并采用全析因法进行优化。但是对得到的数据进行回归分析,拟合优度很低,这表明其他参数可能会影响响应。随后,转向几何角度,弧度和脚趾和轮胎压力,包括在设计中。采用六因子分数阶乘法对平顺性进行优化。然后在高相关性的试验台上验证了所得到的最佳组合。
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引用次数: 5
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Advances in Acoustics and Vibration
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