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金属纤维材料吸声特性的试验研究 总被引:11,自引:0,他引:11
用驻波管法对新型吸声材料金属纤维的吸声特性进行了系统全面的研究。通过对金属纤维在不同厚度、容重、空气层厚度、含水量和不同频段吸声系数的测量 ,发现增加材料的厚度、容重及空气层厚度都有利于吸声性能的提高 ,含水量对吸声性能的影响非常小。说明金属纤维不但是一种性能优良的吸声材料 ,而且抗恶劣工作条件能力强。实验结果将为这种新材料的进一步开发、利用提供帮助。 相似文献
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研究了插入软管的赫姆霍兹共振器的声学原理,推导了声阻抗公式,进而研究了将插入软管的赫姆霍兹共振器用于旁支管的消声性能,并进行仿真计算.结果表明:插入软管可以有效降低吸声频率,明显改善赫姆霍兹共振器的吸声性能,满足实际工程需要. 相似文献
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微穿孔复合材料夹层板吸声性能测试研究 总被引:5,自引:0,他引:5
设计并研制了一种微穿孔玻璃短纤维聚酯树酯 /聚氨酯泡沫夹层复合材料吸声板结构 ,并用双通道驻波管法对吸声结构的吸声性能进行了实验研究 ,分析了吸声板结构参数和材料参数对吸声效率的影响 ,结果表明 :该复合材料吸声结构具有优良的吸声能力和较高的性能价格比 相似文献
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采用等效流体模拟吸声材料,建立外部流场作用下填充吸声材料夹层板结构与封闭空间声场的声振耦合模型,应用波动分析方法研究结构的声透射性能,分析入射声波入射角和方位角、流场流速和流向、夹层板几何尺寸和声腔深度等参数对填充吸声材料夹层板结构声振耦合特性的影响。计算分析表明吸声材料提高了结构的隔声性能;结构的隔声性能随着面板厚度和夹层厚度的增加而提高,且"板-等效流体-板"共振频率向低频移动;随着入射角、方位角、马赫数和空腔深度的变化改变了结构的隔声性能,驻波衰减频率和驻波共振频率随入射角和方位角的增大向高频移动,随空腔深度的增加向低频移动,顺流入射时随马赫数的增加向低频移动,而逆流入射时则移向高频。 相似文献
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压缩率和密度对泡沫铝吸声性能的影响 总被引:9,自引:0,他引:9
研究了压缩率和密度对发泡法制备的泡沫铝样品吸声性能的影响,与报道的日本用发泡法制备的泡沫铝样品的研究结果进行了比较。结果表明:压缩率达40%时,可获得最佳吸声效果,随密度的减小泡沫铝吸声性能增大。它们对吸声性能的影响规律与日本的研究结果相似。 相似文献
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用熔体发泡法制备了碳化硅颗粒增强泡沫铝样品,分析了碳化硅增强泡沫铝在准静态压缩条件下的变形行为。用不锈钢圆管为面板,碳化硅颗粒增强泡沫铝为夹芯制备层合圆管,研究了层合圆管在准静态压缩条件下的变形行为和能量吸收性能。研究表明:碳化硅颗粒增强泡沫铝的屈服强度在5~12MPa之间,对泡沫铝材料的力学性能有明显的增强作用;层合圆管在保持泡沫铝轻质、高吸能效率的同时,大幅度提高了吸能能力;碳化硅增强泡沫铝层合圆管的压缩屈服应力达到45MPa,平台应力达到40MPa,具有优良的吸能性能。 相似文献
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介绍了三维封闭声场主动声学控制的基本理论及应用。在封闭的三维声场内,通 过优化人为施加的次级声源强度可使其声势能达到极小,实际应用中可利用有限个 离散点的声压平方和来逼近其声势能。应用这一理论成功地在一封闭房间内进行了 控制实验。 相似文献
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声腔-弹性板结构在不同激励下声辐射特性研究 总被引:1,自引:0,他引:1
以声腔-弹性板声振耦合模型为研究对象,对比分析该模型在点力激励和点声源激励下,激励位置、声腔厚度以及弹性边界等对弹性板声辐射功率、表面振速和腔内声压的影响及两种情况下的区别。弹性板的振动位移函数通过谱几何方法得到,并采用Hamliton原理,充分考虑了板的振动与板两侧声场之间的耦合。利用Rayleigh积分,可计算出弹性板的声辐射特性参数。结果表明,在简支约束情况时,点力和点声源两种激励下,激励位置、声腔厚度和弹性边界对板的声辐射功率、表面振速和腔内声压有不同的变化。在薄声腔时,点力激励下,声腔个别模态对板有明显影响。点声源激励下,模型耦合作用明显,弹性板的声辐射功率、表面振速和腔内声压主要受到耦合模态的影响,且点声源的耦合作用明显强于点力作用。相较于扭转刚度,直线刚度对声辐射的影响更大。 相似文献
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This work considers analysis of transient sound radiation from an impact-excited rectangular plate with viscoelastic boundary
supports based on the Modal Strain Energy (MSE) method. Vibration of the plate is approximated by double infinite series in
the spatial coordinates. Each term of the series is constructed with vibration modes of beams having the same boundary conditions
as the considered plate, multiplied by a time dependent function. Modal loss factor of each mode is obtained by the MSE method.
The sound pressure for impact excitations is obtained in the time and frequency domain by numerical integration of the Rayleigh
integral. Then effects of width of the viscoclastic boundary supports on the vibration response and the radiated sound pressure
are investigated. It is shown that there is an optimum width of the support. 相似文献
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Fan Zijie Dept of Automotive Eng. Qinghua University Kim Kwang Joon Dept of Mechanical Eng. KAIST Korea 《机械工程学报(英文版)》1999,12(4)
0 INTRODUCTIONViscoelasticsurfacedampingtreatmentshavebeenusedformanyyearstoreducevibrationandnoiseofstructuresespeciallyforbeamandplatelikestructures.Althoughsuchsurfacedampingtreatmentshavebeenshowntobeeffectiveinvibrationandnoisecontrol,however,… 相似文献
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Joongkuen Lee Jaehwan Kim Chae Cheon Cheong 《Journal of Mechanical Science and Technology》1999,13(6):451-458
The feasibility of piezoelectric smart structures for cabin noise problem is studied numerically and experimentally. A rectangular
enclosure, one side of which is a plate while the other sides are assumed to be rigid, is considered as a cabin. A disk-shaped
piezoelectric sensor and actuator are mounted on the plate structure and the sensor signal is returned to the actuator with
a negative gain. An optimal design of the piezoelectric structure for active noise control of the cabin is performed. The
design variables are the locations and sizes of the disk-shaped piezoelectric actuator and sensor and the actuator gain. To
model the enclosure structure, a finite element method based on a combination of three dimensional piezoelectric, flat shell
and transition elements is used. For the interior acoustic medium, the theoretical solution of a rectangular cavity in the
absence of any elastic structures is used and the coupling effect is included in the finite element equation. The design optimigation
is performed at resonance and off-resonance frequencies, with the results showing a remarkable noise reduction in the cavity.
An experimental verification of the optimally designed configuration confirms the feasibility of piezoelectric smart structures
in resolving cabin noise problems. 相似文献
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The context of the present paper is the wall treatment of flow ducts, notably aero-engine nacelle intakes and outlets. For this purpose, hybrid active/passive absorbers have been developed at the LMFA for about 15 years. A hybrid cell combines passive absorbent properties of a porous layer and active control at its rear face. Active control is mainly used to increase absorption at low frequencies by cancelling the imaginary part of the surface impedance presented by the absorber. However, the optimal impedance (i.e. the one that produces the highest noise reduction) of an absorber for flow duct applications is generally complex and frequency dependent. A new hybrid absorber intended to realise any of impedance has therefore been developed. The new cell uses one microphone on each side of a resistive cloth. Normal velocity can then be deduced by a simple pressure difference, which allows an estimation of the surface impedance of the absorber. In order to obtain an error signal related to a target impedance, the target impedance has to be reproduced in time domain. The design of a stable and causal filter is a difficult task, considering the kind of frequency response we seek. An alternative way of representing the impedance in time domain is therefore given. The new error signal is integrated into a feedback control structure. Fast convergence and good stability are observed for a wide range of target impedances. Typical optimal impedances with a positive increasing real part and a negative decreasing imaginary part have been successfully realised. Measurements in a grazing-incidence tube show that the new complex impedance absorber clearly outperforms the former active absorber. 相似文献
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In this paper, the sound absorptions of flexible curved micro-perforated panels that are backed by an air cavity are studied in detail. A theoretical model that is based on the classical plate equation coupled with an acoustic wave equation is developed for the prediction of sound absorption. This model considers both symmetrical and antisymmetrical structural acoustic responses. Using the electro-acoustic analogy approach, another model is developed that only considers single structural and acoustic modes. It is proposed to make use of panel and cavity resonances to widen the absorption bandwidth of a single/double perforated absorber. The absorption of a flexible micro-perforated panel can be further enhanced by adjusting its curvature to bring the resonant frequencies closer together. The effects of various parameters such as boundary condition, incidence angle, and curvature on the absorption are studied. Predicted results for the single and double layer absorbers show good agreement with measurements. 相似文献
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为研究不同结构参数对质量相同、强度不同的两种铝蜂窝夹芯板低速动态冲击响应的影响,建立了铝蜂窝夹芯板受半球型落锤低速冲击的数值模型,并将有限元计算结果与试验结果进行对比,检验了模型的可靠性。在此基础上,对比研究了不同上下铝板厚度和不同蜂窝芯壁厚对两种铝蜂窝夹芯板在低速冲击下吸能效果的影响。结果表明:在质量相同的情况下,强度小、高度大的夹芯板在低速冲击下力-位移曲线更易出现双峰模式,增加蜂窝芯壁厚或是上下铝板厚度都会使第一次的峰值力增加,第二次峰值力降低;强度小、高度大的夹芯板蜂窝芯在低速冲击中吸能占比更多,强度大、高度小的则是上层铝板吸收的能量更多,前者的质量、体积比吸能更高;铝蜂窝夹芯板质量比吸能和体积比吸能与壁厚边长比、板厚芯高比均呈幂次关系。 相似文献