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Static and Dynamic Stability Analysis of an Asymmetric Rotating Tapered Sandwich Beam Subjected to Pulsating Axial Load with Thermal Gradient 非对称旋转锥形夹层梁在热梯度脉动轴向载荷作用下的静动力稳定性分析
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41363
M. Pradhan, P. Dash
The static and dynamic stability of an asymmetric rotating tapered sandwich beam subjected to pulsating axial load in temperature environment is studied under two different boundary conditions. The non-dimensional equations of motion and the boundary conditions are derived by applying Hamilton’s energy principle. A coupled Hill’s equations with complex coefficients are derived from the non-dimensional equations of motion by the application of the generalized Galerkin method. By the application of the Saito-Otomi conditions, zones of instabilities are obtained and presented graphically. For the calculation of the Young’s module for the elastic layers, the effect of temperature has been taken in to consideration by means of a uniform thermal gradient along the longitudinal axes for both the upper and lower elastic layers. The effects of the taper parameter, core loss factor, thermal gradient, rotational speed, hub radius, and core density parameter on the static buckling loads and the regions of instability are investigated.
在两种不同的边界条件下,研究了温度环境下受轴向脉动载荷作用的非对称旋转锥形夹层梁的静、动稳定性。应用哈密顿能量原理导出了无量纲运动方程和边界条件。应用广义伽辽金方法,从无量纲运动方程推导出复系数耦合希尔方程。应用Saito-Otomi条件,得到了不稳定区域,并给出了图形。在计算弹性层的杨氏模时,考虑了温度的影响,采用上下弹性层沿纵轴均匀的热梯度计算。研究了锥度参数、堆芯损耗因子、热梯度、转速、轮毂半径和堆芯密度参数对静态屈曲载荷和失稳区域的影响。
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引用次数: 0
A Study of Contact Interface for an Anti-Rotation Rivet Using Ultrasonic Detection 抗旋转铆钉接触界面的超声检测研究
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41330
C. Yao, Hsueh Chih Cheng
This work measures the contact area between an anti-rotation rivet and an aluminum plate under different riveting loads based on the regional scanning of ultrasound. The contact image is a novel disclosure for the anti-rotation rivet contact. The 2D maps show an apparent change not only in area sizes but also in contact shapes under various normal forces applied. The 3D contact images also provide useful information to show the intensity of contact. The contact area between the anti-rotation rivet and the aluminum is calculated using an image analysis software package. The range of contact areas varies from 6.3 mm to 57.2 mm, depending on the applied forces and the definition of the contrast ratio. Furthermore, a calibration of data fitting is performed to provide a useful polynomial equation for contact area estimation. In addition, maps of both a reflection coefficient and a pressure contour distribution are presented. The range of peak contact pressure varies from 7.1 MPa to 11.2 MPa.
本工作基于超声波的区域扫描,测量了不同铆接载荷下防旋转铆钉与铝板之间的接触面积。接触图像是用于防旋转铆钉接触的新颖公开。2D图显示,在施加各种法向力的情况下,不仅在面积大小上,而且在接触形状上都有明显的变化。3D接触图像还提供有用的信息来显示接触的强度。使用图像分析软件包计算防旋转铆钉和铝之间的接触面积。接触面积的范围从6.3毫米到57.2毫米不等,这取决于所施加的力和对比度的定义。此外,执行数据拟合的校准以提供用于接触面积估计的有用多项式方程。此外,还给出了反射系数和压力等值线分布图。峰值接触压力的范围从7.1MPa到11.2MPa不等。
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引用次数: 0
Fault Feature Extraction and Degradation State Identification for Piezoelectric Ceramics Cracking in Ultrasonic Motor Based on Multi-Scale Morphological Gradient 基于多尺度形态梯度的超声电机压电陶瓷裂纹故障特征提取与退化状态识别
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41464
Guoqing An, Hong-ru Li, Baiyan Chen
Piezoelectric ceramics cracking is one of the main faults of the ultrasonic motor. According to the morphological mathematics and information entropy, a method based on multi-scale morphological gradient was proposed for ceramics fault feature extraction and degradation state identification. To solve the problem that traditional multi-scale morphology spectral (MMS) entropy cannot exactly describe the performance degradation of the piezoelectric ceramics, multi-scale morphology gradient difference (MMGD) entropy was proposed to improve the sensitivity to the fault. Furthermore, multi-scale morphology gradient singular (MMGS) entropy was presented to reduce the system noise interference to the useful fault information. The disturbance analysis of temperature, load, and noise for MMGD entropy and MMGS entropy was also given in this paper. Combining the advantages of the above two entropies, a standard degradation mode matrix was built to distinguish the degradation state via the grey correlation analysis. The analysis of actual test samples demonstrated that this method is feasible and effective to extract the fault feature and indicate the degradation of piezoelectric cracking in ultrasonic motor.
压电陶瓷裂纹是超声波电机的主要故障之一。根据形态数学和信息熵,提出了一种基于多尺度形态梯度的陶瓷故障特征提取和退化状态识别方法。为了解决传统的多尺度形态谱熵不能准确描述压电陶瓷性能退化的问题,提出了多尺度形态梯度差熵来提高对故障的敏感性。此外,提出了多尺度形态梯度奇异(MMGS)熵,以减少系统噪声对有用故障信息的干扰。文中还对MMGD熵和MMGS熵进行了温度、负载和噪声的扰动分析。结合上述两种熵的优点,建立了标准的退化模式矩阵,通过灰色关联分析来区分退化状态。通过对实际测试样品的分析,证明了该方法提取超声波电机压电裂纹的故障特征,指示压电裂纹退化是可行和有效的。
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引用次数: 0
Fluid Acoustic Properties of Improved Hydraulic Mufflers with Extended Necks 改进型长颈液压消声器的流体声学特性
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41327
Fan Yang, B. Deng
The acoustic properties of three improved hydraulic mufflers with extended necks are investigated theoretically and experimentally. The effect of length and slope of the conical tube, and the perforations on the extended tube is studied on the resonance frequency and the insertion loss. The plane wave approach is used for the constant and the variable area tubes, while Sullivan and Peat’s method is applied for the perforation tube unit. Theoretical predictions are compared with experiments for these three different hydraulic noise suppressors, which are fabricated. It is shown that the resonance frequency and the insertion loss characteristics may be controlled by the length and the slope of the conical tube and perforation porosity of the extended tube without changing the expansion chamber volume. Finally, the effect of the cross-sectional shape of the expansion chamber is investigated.
对三种改进型扩颈液压消声器的声学特性进行了理论和实验研究。研究了锥形管的长度、斜度以及扩管上的穿孔对谐振频率和插入损失的影响。平面波法适用于定面积管和变面积管,而Sullivan和Peat的方法适用于射孔管单元。对自制的三种不同的液压降噪装置进行了理论预测与实验比较。结果表明,在不改变膨胀腔体积的情况下,锥管的长度、斜率和扩管的射孔孔隙率可以控制扩管的谐振频率和插入损耗特性。最后,研究了膨胀室截面形状的影响。
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引用次数: 0
Field Test Research and Numerical Simulation on Aerodynamic Deloading Characteristics of V-Shaped Noise Barrier V型声屏障气动减载特性的现场试验研究与数值模拟
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41468
J. Zhao, Ning Zhi, Lü Ming
With the rapid development of the high-speed railway in China, the problems of the noise pollution induced by passing trains emerge. Theoretically, the V-shaped noise barrier is of pretty good performance of noise-reduction and load-shedding. To assess the practical aerodynamic deloading characteristics of the V-shaped noise barrier, a full-scale field test was carried out at three measuring-sections equipped with noise barriers of different heights. In order to quantify the research work, the impact strength and deloading rate were selected as indicators. The effects of train speeds, train types and barrier heights are studied. This study includes the variations of impact strength and deloading rate in vertical directions. Meanwhile, 2D numerical simulation research is conducted to analyze the experimental results from the angle of mechanism. It is observed that the aerodynamic load acting on the surface of the V-shaped noise barrier was weaker and more uniform compared with conventional barrier. The flow field distribution influenced the deloading characteristics of the V-shaped noise barrier significantly. Moreover, the load-shedding effect of V-shaped noise barrier, when CRH380AM passed by, was slightly better than CRH380A. The deloading rate improved with the increasing of the noise barrier height in general.
随着我国高速铁路的快速发展,过往列车的噪声污染问题日益突出。从理论上讲,V型声屏障具有良好的降噪和甩负荷性能。为了评估V形隔音屏障的实际空气动力学减载特性,在配备不同高度隔音屏障的三个测量段进行了全尺寸现场试验。为了量化研究工作,选择了冲击强度和减载率作为指标。研究了列车速度、列车类型和护栏高度的影响。本研究包括冲击强度和减载率在垂直方向上的变化。同时,从机构角度对实验结果进行了二维数值模拟研究。观察到,与传统屏障相比,作用在V形噪声屏障表面的气动载荷较弱且更均匀。流场分布对V型声屏障的减载特性有显著影响。此外,当CRH380AM经过时,V形噪声屏障的减载效果略好于CRH380A。减载率总体上随着噪声屏障高度的增加而提高。
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引用次数: 1
Numerical Investigation of Surface Acoustic Wave (SAW) Interacting with a Droplet for Point-of-Care Devices 表面声波(SAW)与护理点设备液滴相互作用的数值研究
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41312
Imran Shah, E. Uddin, A. Mubashar, M. Younis, Hudair Samad, K. Choi
A three-dimensional numerical simulation of the interaction of a surface acoustic wave (SAW) with a droplet of water is carried out. The mixing produced inside the droplet due to the incident with the SAW and the droplet is investigated by undertaking a parametric study, with parameters such as frequency, drop size, and the lateral position of the droplet on the surface of the substrate. The linear relationship between the input voltage and the mixing velocity inside the droplet is obtained with variation of the input voltage of the inter-digital transducer (IDT) of the SAW device within a 10–40 V range. With the variation in frequency, the maximum mixing velocity is observed at 20 MHz and it appears to be independent of the size of the droplet. Varying the substrate material with lead zirconate titanate and lithium niobate produces better mixing. Lithium niobate is preferred due to its availability and cost-effectiveness. A drop of 600 μm diameter produces better mixing. The different velocities inside the drop and the SAW device are obtained by changing the droplet position in the lateral direction (asymmetrical position) from the centre of the substrate. Cut planes parallel and perpendicular to the SAW at the core of a half-spherical droplet are observed to visualise the mixing effects inside the droplet during the interaction. To achieve the best mixing criteria, the droplet is moved in a lateral direction. An efficient parametric design for the mixing phenomena in micro-fluidic devices is presented for point-of-care devices.
对表面声波(SAW)与水滴的相互作用进行了三维数值模拟。通过进行参数研究,研究由于SAW和液滴的入射而在液滴内部产生的混合,参数包括频率、液滴尺寸和液滴在基板表面上的横向位置。输入电压和液滴内混合速度之间的线性关系是随着SAW器件的数字间换能器(IDT)的输入电压在10–40 V范围内的变化而获得的。随着频率的变化,在20MHz处观察到最大混合速度,并且它似乎与液滴的大小无关。用锆钛酸铅和铌酸锂改变基底材料可以产生更好的混合。铌酸锂是首选,因为它的可用性和成本效益。直径为600μm的液滴可产生更好的混合效果。液滴和SAW器件内部的不同速度是通过从衬底中心在横向方向(不对称位置)上改变液滴位置而获得的。在半球形液滴的核心观察平行和垂直于SAW的切割平面,以可视化相互作用过程中液滴内部的混合效应。为了达到最佳混合标准,液滴在横向方向上移动。针对护理点设备中的微流体设备中的混合现象,提出了一种有效的参数设计方法。
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引用次数: 2
Why Balloons Make a Loud Noise When They Pop 为什么气球弹出时会发出巨大的噪音
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41433
E. Ross, J. Panda, J. Ross, L. K. Kushner
Measurements of balloon loudness and pressure signatures are presented for a variety of balloon shapes. The loudness and recordings were made 3.2 meters from the popped balloons. The balloons were of 3 types: round, long, and extremely long (the same type that is used to make balloon animals), filled with 3 gases, and inflated to multiple sizes. The data indicates that all 3 types of latex balloons share similar peak frequencies and acoustic signatures in spite of differences in shape and diameter or length when inflated. The data also shows a correlation of loudness to the ratio of specific heats of the gas and inflated diameter of the balloons. The data does not support some of the common hypotheses of balloon popping noise generation. It appears that the sound is generated by the vibration of the balloon surface and the ruptured edge of the latex. This explanation is consistent with the current acoustic measurements and shadowgraph videos, and the hypothesis of Pätynen, et al.4
对各种气球形状的气球响度和压力特征进行了测量。响度和录音是在距离弹出的气球3.2米的地方进行的。气球有三种类型:圆形、长型和超长型(与制作气球动物的类型相同),充有三种气体,并膨胀成多种尺寸。数据表明,尽管充气时形状、直径或长度存在差异,但所有3种类型的乳胶气球都具有相似的峰值频率和声学特征。数据还显示了响度与气体比热和气球充气直径之比的相关性。这些数据并不支持气球爆裂噪音产生的一些常见假设。声音似乎是由气球表面和乳胶破裂边缘的振动产生的。这一解释与当前的声学测量和阴影图视频以及Pätynen等人的假设一致。4
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引用次数: 0
Maritime Airborne Noise: Ships and Harbours 海上空气噪音:船舶和港口
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.4e94
D. Borelli
The topic of ships as noise sources has been studied for decades, mainly as regards underwater sound emission and onboard noise. There are several reasons: (1) underwater noise is investigated for military purposes in terms of “acoustic signatures” — a combination of elements (mainly cavitation noise, machinery noise and hydrodynamic noise) that help identify and track a vessel or weapon, (2) short and longterm negative effects on marine fauna, in particular marine mammals and cephalopods and (3) continuous onboard noise that can have an adverse impact on human health for both passengers and crew. Considering this last reason, from a regulatory point of view, the International Convention for the Safety of Life at Sea (SOLAS) in its regulation II-1/3-12 requires ships to be compliant with the International Maritime Organization (IMO) resolution MSC.337(91) “Code on noise levels on-board ships”. This IMO resolution is nowadays mandatory for ships of 1,600 gross tonnage or more, which have to be constructed to protect workers from noise and to reduce shipboard noise.
船舶作为噪声源的研究已经进行了几十年,主要涉及水下声音发射和船上噪声。原因有几个:(1)水下噪声是根据“声学特征”(一种有助于识别和跟踪船只或武器的元素(主要是空化噪声、机械噪声和水动力噪声)的组合)为军事目的进行研究的;(2)对海洋动物的短期和长期负面影响,特别是海洋哺乳动物和头足类动物,以及(3)可能对乘客和机组人员的人类健康产生不利影响的持续船上噪音。考虑到最后一个原因,从监管角度来看,《国际海上人命安全公约》(SOLAS)在其第II-1/3-12号条例中要求船舶遵守国际海事组织(海事组织)MSC.337(91)号决议“船上噪声级准则”。如今,海事组织的这项决议对1600总吨位或以上的船舶是强制性的,这些船舶的建造必须保护工人免受噪音影响,并减少船上噪音。
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引用次数: 8
Stochastic Minimax Vibration Control for Uncertain Nonlinear Quasi-Hamiltonian Systems with Noisy Observations 具有噪声观测的不确定非线性拟哈密顿系统的随机极大极小振动控制
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41446
Z. Ying, R. Hu, R. Huan
A stochastic minimax control strategy for uncertain nonlinear quasi-Hamiltonian systems with noisy observations under random excitations is proposed based on the extended Kalman filter and minimax stochastic dynamical programming principle. A structure system with smart sensors and actuators is modeled as a controlled, excited and dissipative Hamiltonian system with noisy observations. The differential equations for the uncertain nonlinear quasi-Hamiltonian system with control and observation under random excitation are given first. The estimated nonlinear stochastic control system with uncertain parameters is obtained from the uncertain quasi-Hamiltonian system with noisy observation. In this case, the optimally estimated state is determined by the observation based on the extended Kalman filter. The dual dynamical programming equation for the estimated uncertain system is then obtained based on the minimax stochastic dynamical programming principle. The worst-case disturbances are determined for bounded uncertain parameters and the optimal control law is determined for the worst case by the programming equation. The proposed minimax control strategy is applied to two uncertain nonlinear stochastic systems with controls and noisy observations. The control effectiveness for the stochastic vibration response reductions of the systems is illustrated with numerical results. The proposed minimax control strategy is applicable to general uncertain nonlinear multi-degree-of-freedom structure systems with noisy observations under random excitations.
基于扩展卡尔曼滤波器和极大极小随机动力学规划原理,针对随机激励下具有噪声观测的不确定非线性拟哈密顿系统,提出了一种随机极小极大控制策略。将具有智能传感器和执行器的结构系统建模为具有噪声观测的受控、激励和耗散哈密顿系统。首先给出了随机激励下具有控制和观测的不确定非线性拟哈密顿系统的微分方程。从具有噪声观测的不确定拟哈密顿系统出发,得到了具有不确定参数的估计非线性随机控制系统。在这种情况下,通过基于扩展卡尔曼滤波器的观测来确定最佳估计状态。基于极大极小随机动态规划原理,得到了被估计不确定系统的对偶动态规划方程。针对有界不确定参数确定最坏情况下的扰动,并通过规划方程确定最坏情形下的最优控制律。将所提出的极小极大控制策略应用于两个具有控制和噪声观测的不确定非线性随机系统。数值结果说明了系统随机振动响应降低的控制有效性。所提出的极大极小控制策略适用于随机激励下具有噪声观测的一般不确定非线性多自由度结构系统。
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引用次数: 0
Oversampled Modal Approach of a Turbocharger Rotor from the Experimental Lateral Vibrations 涡轮增压器转子横向振动的过采样模态方法
IF 1 4区 工程技术 Q4 ACOUSTICS Pub Date : 2019-12-31 DOI: 10.20855/ijav.2019.24.41484
L. A. Montoya, E. E. Rodriguez, H. J. Zúñiga, I. Mejía
The elements of rotors have inherent characteristics as geometry and material composition, which causes natural vibrations at frequencies that, due to the rotor unbalance, may coincide with the harmonics of the shaft speed, increasing stress and the probability of fractures even in transient conditions. Therefore, in this work, a theoreticalexperimental hybrid method for calculating the natural frequencies and the mode shapes, at rest and non-supported conditions, of a turbocharger rotor is proposed. Firstly, a discrete model of low number of degrees of freedom is considered, and from an oversampled modal approach (OSMA) based on the axial oversampling, sectioning and coupling of the rotor, it is possible to use the oversampled mode shapes to increase the degrees of freedom of the system without major complications in the model. This spatial oversampling criterion is based on the NyquistShannon theorem, and it is used to reduce the error in the estimates of the natural frequencies and to get a first approximation of the mode shapes. The natural frequencies were estimated by the transfer matrix method (TMM) and finite element method (FEM) in order to compare the proposed model results with well-founded numerical methods.
转子的元件具有固有的几何特性和材料组成,这导致频率上的自然振动,由于转子不平衡,可能与轴转速的谐波相吻合,增加应力和即使在瞬态条件下断裂的可能性。因此,在这项工作中,提出了一种计算涡轮增压器转子在静止和无支撑条件下的固有频率和模态振型的理论和实验混合方法。首先,考虑了一个低自由度的离散模型,并从基于转子轴向过采样,切片和耦合的过采样模态方法(OSMA)中,可以使用过采样模态振型来增加系统的自由度,而不会在模型中产生重大复杂性。该空间过采样准则基于nyquist - shannon定理,用于减小固有频率估计的误差并得到模态振型的第一近似。利用传递矩阵法(TMM)和有限元法(FEM)估算了固有频率,并与已有的数值方法进行了比较。
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引用次数: 0
期刊
International Journal of Acoustics and Vibration
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