Attenuation of sound radiation in concrete structure through the reduction of mechanical vibration

Abstract The efficiency of sound irradiance in structure has direct relation with its vibratory movement. Dynamic vibration absorbers (DVAs) are a low cost viable option for reducing vibrations in passive structures. Secondary systems attached to the primary system (structure) in order to reduce vibration. In this work it was used an experimental modal analysis procedure (EMA) for vibratory responses through impulsive excitations to determine the natural frequencies and the location of points suitable for attachment of DVAs in a concrete beam. Later it was designed and built DVAs to reduce vibration in a frequency band where the response of the human auditory system is more sensitive. The best project configuration for DVAs was evaluated for sensitivity thereof with respect to the change of the loss factor of the viscoelastic material used. Obtained reduction of more than 36% over the considered frequency band and over 70% in the region of the resonance frequency in which the DVAs were tuned.摘要 结构内声辐照度的效能与其振动行为存在直接关联。动力吸振器（Dynamic Vibration Absorbers，DVAs）是无源结构减振的低成本且切实可行的方案，通过附着于主系统（即目标结构）以实现减振目的。本研究采用脉冲激励下的振动响应实验模态分析（Experimental Modal Analysis，EMA）方法，以确定混凝土梁的固有频率以及适配动力吸振器安装的点位。随后设计并搭建了动力吸振器，用于在人类听觉系统响应最为敏感的频段内实现减振。针对所采用粘弹性材料的损耗因子变化，对最优动力吸振器配置方案的敏感性进行了评估。研究结果显示，在目标考察频段内减振率超过36%，在动力吸振器调谐的共振频率区域内减振率更是超过70%。