调制气流声源振动系统有限元分析与实验

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

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。

Numerical simulation based on dynamic finite element analysis and experimental research is performed forthe vibration system of an Air-Modulated Speaker. The rubber properties related to the requirement of generating low-frequencyand high-intensity sound for long distance broadcasting are discussed. The results of the simulation with M-R rubberconstitutive relation agree well with those of the experiments. The results show that the constitutive relation used here is validfor characterizing the vibration system in the condition of small rubber deformation. In an ideal instance, the vibration systemis a single DOF and centralized parametrical system. At low frequencies, the main displacement distortions are the tripleharmonicdistortions due to the nonlinear stiffness of the rubber. With the increase of frequency, the secondary harmonic distortionsinduced by the non-uniform distribution of magnetic field rise gradually and finally become the main distortion componentsnear the resonance frequencies. Voice coil offset is one of the main factors inducing the multi- order vibrationmodals.