顶端带吸声柱体道路声屏障插入损失的研究

应用间接边界元法，分析在道路交通噪声等效频率400Hz时，对于顶端带吸声柱体声屏障，吸声柱体在不同直径时插入损失的变化规律。指出通过在声屏障顶端增加吸声圆柱体来提高声屏障的插入损失时，顶端吸声柱体的直径宜大于0．3m，其附加衰减可达2-5dB，最后进行了案例分析，为声屏障优化设计提供定量依据及参考。     

ABS生产线噪声分析及治理

根据ABS生产线的噪声污染状况的现场调查,结合生产性噪声的特点,采用沈阳工业大学振动噪声研究所方案,利用隔声罩、吸声体、声屏障和隔声间等措施对其噪声进行综合治理。     

铝硅闭孔泡沫铝吸声性能研究

利用熔体转移发泡法制备了不同孔隙率(厚度为20mm;孔隙率为67.3%、77.7%、80.4%、88.1%)和不同厚度(孔隙率为79.6%;厚度为10、20、30mm)的铝硅闭孔泡沫铝,运用驻波管法对其吸声性能进行了测试,对其吸声机理进行了探讨,并研究了孔隙率和厚度对其吸声性能的影响.结果发现铝硅闭孔泡沫铝吸声主要是通过亥姆霍兹共振器结构和孔壁微孔以及裂缝等来实现的,实验进一步证实其吸声特性曲线符合理论分析.铝硅闭孔泡沫铝的孔隙率和厚度对其吸声性能影响显著:吸声系数随孔隙率增加而增加;低频阶段,吸声系数随厚度的增加而提高,高频阶段,吸声系数随厚度的增加而下降,但整体吸声性能受厚度影响较小,只出现了最高吸声系数向低频处迁移的现象.     

轨道交通的声屏障技术研究

在现场测量、实验的基础上，研究了轻轨交通噪声的频率特性，分析总结了目前常见声屏障的优缺点。开发研制了两种阻抗复合型声屏障，由于其独特的结构设计，声屏障有能够防止雨尘侵害的显著优点。混响室测试表明，在轻轨交通噪声的主要频率范围100-4000Hz内，该声屏障吸声性能十分出色。性能优良的新声屏障是治理城市轻轨交通噪声的一种很好手段。     

KTV包间低频噪声控制

KTV包间内的噪声污染主要在低频63 Hz～125 Hz,噪声级一般可以超过105 dB,其噪声源边界排放噪声也超出了相应的限值,针对KTV包间的噪声污染,介绍了目前比较成熟的噪声处理方案。首先KTV包间内的墙壁、顶棚、门和地板隔声处理;其次是介绍包间采取的吸声材料和广泛应用的吸声结构;包间音箱设备的隔振处理;包间内减少声波的泄露;以及新型局域共振声子晶体的理论及应用。     

复合建筑材料吸声降噪性能分析及试验研究

以胶合板、海绵和泡沫为试验材料,并制备胶合板组合海绵或泡沫的复合材料,采用驻波管法测试了这3种单一材料及复合材料的吸声系数,比较了它们的吸声降噪性能。结果表明,复合材料的吸声降噪性能明显优于单一材料,在中频1 000 Hz处出现了最佳吸收峰,其中46 mm厚的复合泡沫材料的吸声性能最优,吸声系数高达95.5%;复合材料的降噪系数NRC值也同样明显高于单一材料的NRC值,其中36 mm厚的三层复合海绵材料和及46 mm厚的四层复合泡沫材料的NRC值分别达到了0.39和0.36,表明这两种复合材料都具有良好的吸声降噪效果,能够满足现代居住环境的吸声降噪需要。     

一种具有球形孔隙的高孔率泡沫钛合金

通过对粉体熔化发泡法的改进,制备了孔率高达90%的毫米级球孔泡沫钛合金。这种泡沫钛合金的压缩曲线包括弹性区、压缩平台区和"密实化"区等3个阶段。由于是脆性破坏,其中的压缩平台呈锯齿状。这种泡沫钛合金的压缩破坏是通过垂直于载荷方向的孔隙逐层坍塌破碎而不断推进的,"密实化"是碎块的不断堆积过程。孔壁上的微孔对该泡沫钛的吸声性能有利,未作任何处理的试样在1500-3000 Hz的声频范围内吸声系数最低为0.4左右,在3000-6300 Hz则吸声系数超过0.6,共振频率超过0.9。在较高声频段,这种泡沫钛试样的主要吸声机制为黏滞耗散。     

泡沫铝复合板低频吸声性能实验分析与研究

摘 要：泡沫铝是一种新型的吸声材料,在中高频具有良好的吸声效果,本文研究采用泡沫铝复合板来提高其低频吸声性能。研究表明,泡沫铝复合结构具有较好的低频吸声性能,在500Hz～1KHz吸声系数提高较大。通过在材料一侧添加可以背衬进一步提高其吸声系数,在空腔厚度为30mm时复合板的吸声系数最好,在频率400Hz附近出现吸声峰值0.82。     

泡沫铝材料对发电机噪声的隔音性能研究

采用泡沫铝材料对柴油发电机的混合频率噪音进行隔音处理,分析了发电机噪声的频谱特点,将不同孔结构、不同厚度、不同复合方式的泡沫铝材料应用于发电机外壳,并比较了隔音效果。研究结果表明,泡沫铝材料对于发动机的混合型噪音,在高频段有明显的隔音效果,而在低频段隔音效果不明显。闭孔泡沫铝在大于500Hz的高频段的隔音效果比开孔的好,而在63~125 Hz的低频段,开孔泡沫铝的隔音效果好。泡沫铝与钢板复合后,对于低频噪声隔音效果有明显的作用。保持泡沫铝与钢板间一定的空腔距离,隔音频率段明显降低。20 mm厚度的闭孔泡沫铝与钢板复合并保持20 mm的空腔距离,可降低10~20dB的噪音。     

磁性聚氨酯泡沫的微观形貌及低频吸声性能

针对传统聚氨酯泡沫吸收低频噪声效果较差的问题,采用一步全水发泡法制备添加磁性颗粒（羰基铁粉（CIP））的聚氨酯泡沫。搭建磁性聚氨酯泡沫（MPF）的吸声实验平台,从宏观和微观的角度研究聚醚多元醇与异氰酸酯的配比及CIP对MPF吸声性能的影响。通过SEM观测MPF的微观形貌,采用统计学方法对泡孔尺寸进行分析,并利用阻抗管和传递函数法对64~1 600 Hz范围内MPF的吸声性能进行测试。实验结果表明,CIP的加入,使MPF平均孔径减小,孔径对数分布标准差增加,开孔率和低频吸声性能得到提高,特别是低于500 Hz部分;当聚醚多元醇与异氰酸酯比例为100：60、CIP含量为5wt%时,MPF的低频吸声性能最优,其64~500 Hz范围内的平均吸声系数达到0.22。     

Acoustic properties of closed-cell aluminum foams with different macrostructures

As structural materials, closed-cell aluminum foams possess obvious advantages in product dimension, strength and process economics compared with open cell aluminum foams. However, as a kind of structure-function integration materials, the application of closed-cell aluminum foams has been restricted greatly in acoustic fields due to the difficulty of sound wave penetration. It was reported that closed-cell foams with macrostructures have important effect on the propagation of sound waves. To date, the relationship between macrostructures and acoustic properties of commercially pure closedcell aluminum foams is ambiguous. In this work, different perforation and air gap types were designed for changing the macrostructures of the foam. Meanwhile, the effect of macrostructures on the sound absorption coefficient and sound reduction index were investigated. The results showed that the foams with half-hole exhibited excellent sound absorption and sound insulation behaviors in high frequency range(2500 Hz). In addition, specimens with air gaps showed good sound absorption properties in low frequency compared with the foams without air gaps. Based on the experiment results, propagation structural models of sound waves in commercially pure closed-cell aluminum foams with different macrostructures were built and the influence of macrostructures on acoustic properties was discussed.     

Sound Absorption Performance and Mechanism of Aluminum Foams with Double Main Pore-Porous Cell Wall Structure

To enhance the sound absorption performance of open-cell aluminum foam, the double main pores-porous cell walls (DMP-PCW) aluminum foams via infiltration casting of preforms mixed with two sizes of NaCl particles are prepared. The pore structure, sound absorption performance, and mechanism of DMP-PCW aluminum foam are investigated. The pore structure consists of double-sized main pores similar to the NaCl particles and the cell wall pores formed by the connections between NaCl particles. It is found that the static flow resistivity of DMP-PCW aluminum foam reaches an optimum value of 28105 Pa.s m⁻² when the volume proportion of small main pores increases, the size of cell wall pores decreases, and the number of cell wall pores per unit main pore surface area (NPPA) increases. At 800–6300 Hz, the average absorption coefficient is 0.89. In addition, the Wilson model predicts the sound absorption properties of DMP-PCW aluminum foam. The predicted values agree well with the measured values. The finite-element acoustic simulations and dynamic viscous-thermal permeability calculations reveal that the improved sound absorption performance of DMP-PCW aluminum foam is correlated to the enhanced sound transmission caused by increased NPPA and increased viscous-thermal loss due to the double main pore structure.     

高速列车阻尼喷涂式铝型材减振降噪特性试验

为探究某种阻尼材料对高速列车铝型材地板的减振降噪效果,以波纹状铝型材为基板,先后对其喷涂厚度为2 mm和4 mm的阻尼层,并在隔声室中进行空气声隔声及结构振动声辐射的测试及比对分析。结果显示,随阻尼层厚度的增加,铝型材的空气声隔声效果增加,尤其在500 Hz之后的中高频段;其中,2 mm阻尼层能在铝型材裸板的基础上使计权隔声量提高4.5 dB,阻尼层厚度增至4 mm,计权隔声量再提高2.4 dB。在100 Hz ～250 Hz,2 mm阻尼层对降低铝型材的振动声辐射水平起反作用,而4 mm阻尼层能够起到一定作用;在315 Hz ～400 Hz,阻尼层厚度对其振动声辐射几乎没有影响;500 Hz以上,随阻尼层厚度的增加,铝型材振动声辐射水平大大降低,其中,500 Hz、1 250 Hz和3 150 Hz 三个频段的降低量最为显著。     

Primary investigation on sound absorption performance of highly porous titanium foams

A novel sort of cellular titanium foam, whose total porosity was achieved as high as 86%–90% and main pores were spherically millimeter-scaled, was recently prepared successfully by an improved foaming method of melting the metallic powder. This titanium foam showed a good performance of sound absorption, and its sound absorption coefficient could be more than 0.6 in the sound-wave frequency range of 3150–6300 Hz and even exceed 0.9 at the resonance frequency. The main mechanism of sound absorption for this foam should be of interference silencing due to the surface reflection when the sound wave frequency is lower than about 4250 Hz, and the viscous dissipation when the frequency is higher than about 4250 Hz. A reticular product with millimeter-scaled pore size and about 90% porosity was also made by means of slurry-immersed sintering, and the resultant titanium foam might display an effect for sound absorption, but on the whole, its absorption was evidently inferior to that of the cellular product. The corresponding sound absorption coefficient could not be above 0.2 until sound-wave frequency is higher than 3150 Hz, keeping a relatively low value except for resonance occasion only, on which it could reach up to around 0.9 at about 4000 Hz.     

复合板件内损耗因子的声激励测量方法

以泡沫铝夹芯板为研究对象,分别应用稳态半功率点带宽法与混响室声激励法测得其内损耗因子。根据统计能量分析预测模型,将实验室实测泡沫铝夹芯板隔声量代入其中,逆推出预测模型中内损耗因子真值,并与以上两种方法测得的内损耗因子进行了对比分析,结果表明:半功率点带宽法仅能测得泡沫铝夹芯板的结构损耗因子,而混响室声激励法则能够综合考虑其结构阻尼和吸声损耗,从而获得更适用于隔声预测的综合内损耗因子。研究内容可为存在吸声损耗的复杂板件内损耗因子的获取提供方法借鉴。     

闭孔泡沫铝压缩性能研究

闭孔泡沫铝作为一种新型多孔金属材料,被应用于各个领域,但其压缩力学性能受到孔隙率、孔洞结构参数、相对密度及材料基本力学性能等的影响,因此针对某闭孔泡沫铝企业研究出的一款新型产品,在确定其相关参数后进行10组试样的压缩力学试验,确定其应力-应变曲线,分析各段曲线意义和产生机理,并针对其特有的压缩力学性能,研究在外力作用下的吸能表现,为该型号的闭孔泡沫铝材料在各个行业中的应用提供技术支持和参考依据。