共查询到19条相似文献,搜索用时 156 毫秒
1.
一维声子晶体振动带隙的带边模式研究 总被引:1,自引:0,他引:1
从一维声子晶体的波动方程出发,选用保持晶格对称性的原胞对声子晶体的能带结构进行解析分析.结果表明一维声子晶体带隙边缘的振动模式与其单个对称性原胞的固有振动模式完全一致,从而对一维声子晶体带隙特性的分析可以简化为对其单个对称性原胞固有模式的分析.研究表明,一维声子晶体中的振动模式是其各对称性原胞固有振动模式相互作用的耦合模式,在带隙边缘由于布拉格散射出现解耦效应,振动模式为解耦的驻波模式,从而与单个对称性原胞的固有振动模式一致.以有机玻璃及铝构成的声子晶体细直梁为例,采用振动试验对其振动传输特性进行测试,试验结果同理论分析结果基本吻合.这为声子晶体复杂梁杆结构的带隙特性研究及减振降噪设计提供了新的、简化的思路. 相似文献
2.
蜂窝状的声子晶体具有优秀的减振降噪特性,选择丁腈橡胶作为基底,钢作为散射体,通过构建不同蜂窝状的声子晶体模型以及改变几何材料参数,可以得到更宽的低频带隙,从而得到更好的减振效果。通过COMSOL软件,利用周期性边界条件和布洛赫理论进行建模,计算出其能带结构并和传输特性进行比较,分析了不同结构参数下的位移模式,寻找出最优越的蜂窝状声子晶体,在对带隙范围调控上提出了新的方法和思路。 相似文献
3.
为解决某制氧厂增压机组隔声罩通风问题,需要在隔声罩壁上开孔并安装通风消声器.首先利用NOR848声阵列成像仪识别了主噪声源为二级压缩机,继而采用近场声压测量对增压机二级压缩机进行了详细的噪声测试与频谱分析,并结合噪声源特性与降噪要求设计了一款三层串联式微穿孔板消声器.依据三维有限元理论和管道声模态理论初步确定了消声器结构参数,创建其声学模型,并利用有限元法分别分析膨胀腔长度、隔板数量、隔板位置等参数对传递损失的影响,并综合以上几种因素确定消声器最终结构.最后经有限元仿真求出消声器传递损失曲线,分析发现其在高频消声量达到要求,符合最初的降噪要求. 相似文献
4.
5.
6.
螺旋局域共振单元声子晶体板结构的低频振动带隙特性研究 总被引:1,自引:0,他引:1
低频振动和噪声的控制问题是当今环境面临的重要挑战。基于声子晶体的局域共振机理,设计一种新型的螺旋局域共振单元声子晶体板结构,并结合数值计算和试验测试对结构的低频振动带隙特性进行分析和验证。分析发现,共振带隙的产生是由螺旋共振单元的局域共振模态与板中传播的弹性波相互耦合作用造成的,而且带隙宽度与耦合强度直接相关。通过改变结构的材料和尺寸参数可以将共振带隙调节到满足实际应用要求的低频范围。数值计算结果与试验测试结果基本一致,同时证实所设计的结构在250 Hz以下的低频范围具有较宽的振动带隙,最低带隙频率低至42 Hz。这种结构设计及其研究结果为声子晶体研究提供了获得低频振动带隙的理论依据和有效方法,在低频减振降噪方面具有潜在的应用前景。 相似文献
7.
对于船艇机舱而言,当其噪声过于强烈时会给船员的正常工作带来十分不利的影响。有鉴于此,本文围绕船艇机舱噪声测试及其控制进行分析,首先介绍了船艇机舱噪声测试和噪声源确定,然后分析了噪声控制,主要包括降噪设备安装、柔性隔声罩设计、吸声饰面设计,最后结合实船测试进行了探讨,以期为业内人士提供有益参考。 相似文献
8.
针对声子晶体设计中存在模糊变量导致带宽不可靠问题,建立新型二维多组元局域共振型声子晶体,通过数值计算得到带隙曲线并探究带隙产生机制,并基于分析包覆层几何参数和材料参数对带隙影响结果,考虑将环状包覆层材料参数作为模糊变量,几何参数作为设计变量,通过拉丁超立方体抽样进行实验设计建立基于Kriging模型的声子晶体带隙优化模型,利用麻雀搜索算法(Sparrow Search Algorithm, SSA)对Kriging模型进行全局寻优,得到声子晶体最优设计解。结果表明,优化后带隙宽度从101.17 Hz变为224.164 Hz,增大121.5%,且带宽边界均在设计目标范围内,所提出的Kriging带隙优化模型在避免大量数值计算的同时,考虑了模糊变量的影响,具有较高的预测精度和可靠性,为声子晶体设计提供新研究思路。 相似文献
9.
10.
11.
声学超材料在低频减振降噪中的应用评述 总被引:10,自引:0,他引:10
低频机械波在传播过程中穿透力强,难以衰减,特别是次声频段的机械波易与机体器官发生共振,对身体造成危害。为了实现对低频机械波的有效控制,解决现代工业生产和生活中普遍存在的噪声污染问题,结合最近十几年发展起来的声子晶体和声学超材料,系统地总结和论述通过声子晶体和声学超材料解决低频振动噪声问题的新方法。归纳和总结典型的低频振动噪声来源和对其进行控制方面存在的一些困难,介绍低频振动噪声的危害。重点概括基于声子晶体禁带特性实现低频振动噪声被动控制的相关研究工作,主要介绍通过亚波长尺寸特征的杆、薄板和薄膜类结构来实现低频振动和噪声衰减的具体方法和效果。在声学超材料的理论框架下,讨论薄膜类结构在低频振动噪声衰减中的应用及其优缺点。通过结合实际工程需要和最新研究动态,对这一领域存在的问题和后续发展趋势进行总结。研究对推动声子晶体和声学超材料在工程实践中的应用具有一定的引导意义。 相似文献
12.
基于广泛研究的声子晶体单板结构,通过在板面之间周期贴附"弹簧-质量块"共振单元,提出局域共振型声子晶体双层板简化模型。通过对传统平面波展开法加以改进,建立改进平面波展开法用于计算该模型能带结构。数值结果和分析表明,在低频段,能带结构可以打开一条完整的带隙。扭簧以及软材料的尺寸和黏性对带隙的影响比较明显,但转动惯量对带隙几乎无影响。该研究方法及结果可以为工程中减振降噪领域双层板甚至夹层板类声子晶体结构的研究提供理论参考。 相似文献
13.
将局域共振声子晶体引入减振结构设计中,提出在橡胶减振材料中植入声子晶体的新型减振结构设计。通过有限元法计算位移频响曲线,研究了该结构的减振特性,并在此基础上进一步研究了周期层数、元胞尺寸、基体边长、中间层厚度及散射体尺寸对减振频段的调控作用。研究结果表明,该新型减振结构可以在280~1 000 Hz频段产生优良的减振效果,而各结构参数对禁带范围和频带宽度都具有很好的调控作用,使得针对特定频段的减振设计成为可能。该研究为航空航天领域新型减振器的设计提供了新的思路。 相似文献
14.
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
15.
16.
Sung-Hee Kim Suk-Yoon Hong Jee-Hun Song Won-Ho Joo 《Journal of Mechanical Science and Technology》2012,26(4):1003-1009
Noise from construction equipment affects not only surrounding residents, but also the operators of the machines. Noise that
affects drivers must be evaluated during the preliminary design stage. This paper suggests an interior noise analysis procedure
for construction equipment cabins. The analysis procedure, which can be used in the preliminary design stage, was investigated
for airborne and structure-borne noise. The total interior noise of a cabin was predicted from the airborne noise analysis
and structure-borne noise analysis. The analysis procedure consists of four steps: modeling, vibration analysis, acoustic
analysis and total interior noise analysis. A mesh model of a cabin for numerical analysis was made at the modeling step.
At the vibration analysis step, the mesh model was verified and modal analysis and frequency response analysis are performed.
At the acoustic analysis step, the vibration results from the vibration analysis step were used as initial values for radiated
noise analysis and noise reduction analysis. Finally, the total cabin interior noise was predicted using the acoustic results
from the acoustic analysis step. Each step was applied to a cabin of a middle-sized excavator and verified by comparison with
measured data. The cabin interior noise of a middle-sized wheel loader and a large-sized forklift were predicted using the
analysis procedure of the four steps and were compared with measured data. The interior noise analysis procedure of construction
equipment cabins is expected to be used during the preliminary design stage. 相似文献
17.
Cunfu He Huanyu Zhao Ruiju Wei Bin Wu 《Frontiers of Mechanical Engineering in China》2010,5(4):450-454
This paper theoretically and experimentally studies the existence of complete band gaps in two-dimensional (2D) phononic crystal
consisting of parallel steel rods in water with square lattice. The band structure of phononic crystal is calculated by a
plane wave expansion (PWE) method. Based on the well-known ultrasonic immersion transmission technique, the overlapping transmission
spectra of acoustic waves, a complete band gap, is experimentally measured along the two high-symmetry directions of the first
irreducible Brillouin zone. There is a very good agreement between the experimental result and the range of frequencies of
the complete band gap. 相似文献
18.
19.
Nailong ZHANG Wentong YANG Renyuan FEI 《Frontiers of Mechanical Engineering in China》2008,3(4):377-384
Currently, noise pollution is an environmental problem all over the world. The health and life of human beings are affected
by loud noise from high power generator sets. To reduce such noise, a sound-attenuated enclosure is widely used for its high
performance and convenient usage. By installing equipment in an enclosure, noise is controlled and prevented from radiating.
In this paper, noise control techniques for enclosures are presented. Enclosure development trends are predicted. 相似文献