调制气流声源振动系统有限元分析与实验

用动力有限元方法对调制气流声源振动系统进行了数值模拟，基于电涡流传感器构建了实验系统进行了相关验证，并对产生低频强声和远距离语音广播条件下橡胶弹性元件特性进行了探讨。结果表明，M－R橡胶本构模型描述的振动系统与实验保持了较好的一致性，证明该本构模型描述初始小变形条件下的橡胶振动特性是有效的；理想情况下，动圈－橡胶结构的振动系统为单自由度振动系统，低频振动时，振动位移失真以橡胶等效刚度非线性引起的三次谐波失真为主，随着频率升高至共振频率附近，磁场不均匀等因素引起的二次谐波失真逐渐增大并成为主要失真分量；音圈偏置是导致系统出现多阶振动模态的主要诱因之一。

Finite Element Analysis and Experiment of the Vibration System of an Air-modulated Speaker

Numerical simulation based on dynamic finite element analysis and experimental research were performed for the vibration system of Air-Modulated Speaker. The rubber characteristic properties related to the requirement of generating low frequency high intensity sound for long range broadcast were discussed. The results of the simulation with M-R rubber constitutive equation were agreed well with that of the experiments. These results might be used as a evidence of that the constitutive equation we used is valid to characterize the vibration system in the range of small rubber distortion. In ideal instance, the vibration system is a single degree of freedom and centralized parametrical system. At low frequencies, the main displacement distortions are triple-harmonics induced by the rubber nonlinear stiffness. With the increase of frequency, the secondary harmonics induced by magnetic field non-uniform distribution rise and become the main distortion components near the resonance frequency round. Voice coil offset is the major factor inducing the multi-order vibration modal. When the rubber thickness increased, the resonance frequency decreased, and the displacement increased. It is suggested that an appropriate thickness might be chosen for the purpose of Air-Modulated Speaker.