According to the characters of porous metals,a new effective bulk modulus formula with simpler expression was obtained by considering the heat exchange between the metallic skeleton and air in pore on the basis of phenomenological Biot-Allard model,therefore an extended sound absorption model was put forward.
根据金属骨架多孔材料的特点,在Biot-Allard刚性骨架多孔材料内流吸声模型的基础上,考虑金属的热导特性,推导出一种新的、形式较简单的有效体积模量表达式,从而得到了一种扩展的吸声模型。
The sound-generating models for the main sources of tire/road noise were established based on analysis of the sound generating mechanisms of tire/road noise, and the total time-domain wave was obtained by combining the noise waves of the tire and road.
在分析轮胎/道路噪声发声机理的基础上,建立了轮胎/道路噪声各主要噪声源的发声模型,并将轮胎和道路的噪声波合成得到总的时域波形,通过离散傅立叶变换得到轮胎/道路噪声的频谱,得出了时域耦合因子行阵和频域耦合因子行阵,为低噪声轮胎花纹和低噪声路面的研究和设计提供了理论依据和技术路线。
Based on the sound-generating charateristics of smooth tread,ribbed patterns and block patterns of tires,the original sound-generating model was revised,a physical model suitable for sound-generating test of tire with non-small block patterns was proposed,the relative programmes BPTNS and BPODS were worked out,and the accuracy of the model was confirmed by the simulation test.
根据光面轮胎、条状花纹和大块状花纹的发声特点,对原来的发声模型进行修正,提出了适用于非小块状花纹的发声试验物理模型,并编制相关程序BPTNS和BPODS,仿真试验验证了模型的准确性。
Acoustic modes of the combustion chamber were calculated with FEM software ANSYS when the length and number of baffles change,and the influences of the changes on the acoustic modes are compared.
利用ANSYS软件数值计算了隔板长度变化以及隔板数目变化时,对应的燃烧室声模态,并比较了它们的变化对燃烧室声模态造成的影响。
Analysis is done to compare the results of acoustic model analysis with the excitation frequency characteristics of both inside and outside of the car,which provides the evidence for the cab noise prediction and the acoustic characteristic i.
采用Hypermesh软件建立了某车型的室内声场有限元模型,用SYSNOISE软件对该有限元模型进行自由模态分析,得到声场的各阶模态频率和振型,将声模态分析结果与汽车内外部的激励源频率特性进行对比,为改善车内声学特性,对车内噪声预测提供了参考。
In this paper,ultrasonic simulation method has been applied to study seismic waves affected by Karst zone in limestone of North China coalfield.
应用地震波超声模拟方法，研究了华北型煤田的煤系底部奥灰岩岩溶发育带对地震波的响应特征，为地震勘探技术应用于矿井台水提供了依据。