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.
根據(jù)金屬骨架多孔材料的特點(diǎn),在Biot-Allard剛性骨架多孔材料內(nèi)流吸聲模型的基礎(chǔ)上,考慮金屬的熱導(dǎo)特性,推導(dǎo)出一種新的、形式較簡單的有效體積模量表達(dá)式,從而得到了一種擴(kuò)展的吸聲模型。
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.
在分析輪胎/道路噪聲發(fā)聲機(jī)理的基礎(chǔ)上,建立了輪胎/道路噪聲各主要噪聲源的發(fā)聲模型,并將輪胎和道路的噪聲波合成得到總的時(shí)域波形,通過離散傅立葉變換得到輪胎/道路噪聲的頻譜,得出了時(shí)域耦合因子行陣和頻域耦合因子行陣,為低噪聲輪胎花紋和低噪聲路面的研究和設(shè)計(jì)提供了理論依據(jù)和技術(shù)路線。
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.
根據(jù)光面輪胎、條狀花紋和大塊狀花紋的發(fā)聲特點(diǎn),對原來的發(fā)聲模型進(jìn)行修正,提出了適用于非小塊狀花紋的發(fā)聲試驗(yàn)物理模型,并編制相關(guān)程序BPTNS和BPODS,仿真試驗(yàn)驗(yàn)證了模型的準(zhǔn)確性。
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軟件數(shù)值計(jì)算了隔板長度變化以及隔板數(shù)目變化時(shí),對應(yīng)的燃燒室聲模態(tài),并比較了它們的變化對燃燒室聲模態(tài)造成的影響。
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軟件建立了某車型的室內(nèi)聲場有限元模型,用SYSNOISE軟件對該有限元模型進(jìn)行自由模態(tài)分析,得到聲場的各階模態(tài)頻率和振型,將聲模態(tài)分析結(jié)果與汽車內(nèi)外部的激勵(lì)源頻率特性進(jìn)行對比,為改善車內(nèi)聲學(xué)特性,對車內(nèi)噪聲預(yù)測提供了參考。
In this paper,ultrasonic simulation method has been applied to study seismic waves affected by Karst zone in limestone of North China coalfield.
應(yīng)用地震波超聲模擬方法，研究了華北型煤田的煤系底部奧灰?guī)r巖溶發(fā)育帶對地震波的響應(yīng)特征，為地震勘探技術(shù)應(yīng)用于礦井臺水提供了依據(jù)。