阻尼处理对铝型材结构隔声特性的影响分析

Analysis of the Influence of Damping Treatment on Sound Insulation Characteristics of Aluminum Extruded Structures

水性阻尼涂料作为一种性能良好的减振降噪材料,目前已广泛应用于高速列车车体铝型材结构。在高速列车低噪声设计的方案设计阶段,通常缺少试验条件对比多种阻尼处理方案的降噪效果。基于复特征值法计算铝型材结构敷设阻尼材料后的阻尼损耗因子,并基于混合有限元-统计能量分析方法建立铝型材隔声特性预测模型,预测分析阻尼处理对铝型材隔声特性的影响。结果表明,阻尼材料对铝型材隔声特性的影响可分为“质量-刚度效应”和“阻尼效应”两部分,“质量-刚度效应”会使铝型材结构的模态特征发生变化,导致模态频率降低以及隔声低谷向低频偏移;“阻尼效应”会增大铝型材的阻尼损耗因子,改善共振频率处的隔声量;在铝型材结构外层敷设3 mm阻尼涂料时,在1/3倍频程频段100~400 Hz,阻尼的作用主要以“质量-刚度效应”为主;在500 Hz以上的频段,“质量-刚度效应”和“阻尼效应”共同影响频率隔声量,且阻尼效应逐渐凸显,并随着频率的升高而不断增大;当阻尼层厚度较小时,500 Hz以上的隔声增大主要以“阻尼效应”为主,随着阻尼材料厚度的增大,“质量-刚度效应”的增大幅度会较“阻尼效应”增大幅度更为明显。阻尼材料敷设在铝型材裸板更薄的一层时隔声性能更优。

As a good noise and vibration reduction material,water-based damping coating is widely used in high-speed train car body structures.At the scheme design stage of low-noise design of high-speed trains,it is not easy to compare the effects of various damping treatments due to test limitations.The damping loss factor of aluminum extruded structures with damping treatment was calculated based on the complex eigenvalue method.Then,a sound insulation characteristics prediction model of the structure was established based on the hybrid finite element-statistical energy analysis method.The influence of the damping treatment on the sound insulation characteristics of the structure was analyzed.The results show that the influence of damping treatment on the sound insulation characteristics of aluminum extruded structures can be divided into“mass-stiffness effect”and“damping effect”.The“mass-stiffness effect”changes the modal properties of the structures,resulting in a reduction of natural frequency and an offset of sound transmission loss valley to lower frequency.The“damping effect”increases the damping loss factor of the structures,resulting in the increase of sound transmission loss valley.When a 3 mm damping material treating on the bottom layer of aluminum extruded structures,the frequency dependent sound transmission loss is mainly dominated by“mass-stiffness effect”in the 1/3 octave frequency band of 100-400 Hz.And the“damping effect”begins to increase significantly with the increase of frequency above 500 Hz,the sound transmission loss is affected by both the“mass-stiffness effect”and the“damping effect”.When the thickness of the damping layer is small,the increase of the sound transmission loss above 500 Hz is mainly caused by the“damping effect”,with the increase of the damping layer’s thickness,the increase of the“mass-stiffness effect”is more obvious than the“damping effect”.When the damping material is treated on the thinner layer of the aluminum extruded structures,the sound insulation performance is better.