古琴共鸣体的声固耦合模态分析

Acoustic-structure coupling modal analysis of a Guqin resonator

模态分析中考虑古琴共鸣体与声腔内空气的声固耦合,得出不同固有频率下古琴的各阶位移场模态及声场模态。对比结构系统、声腔系统与耦合系统的仿真结果,研究空腔内空气对共鸣体壁板振动以及共鸣体壁板振动对腔内声压分布情况的影响。结果显示对古琴音量贡献较大的振动模态为呼吸模态,并且面板与底板以不同相位振动时表现的呼吸模态形式所辐射出的音量有所不同;理论推导建立了激励力频率与古琴发声响度之间的关系,为斫琴师根据激励力频率来调整古琴响度提供参考。

By considering the acoustic-structure coupling between a Guqin resonator and the air in the cavity in the modal analysis,the corresponding displacement field modes and acoustic field modes at different frequencies were obtained.The influences of the air inside the cavity on the vibration of the resonator as well as the influence of the vibration of the resonator on sound pressure in the cavity were investigated by comparing the simulation results of the coupled system with the structural system and the acoustic system.Results reveal that breathing modes have larger contribution to the Guqin＇s volume,and the radiating volume from the breathing modes has different forms when the faceplate and baseplate vibrate in different phases.The relationship between the frequencies of exciting forces and the volume of Guqin was built through theoretical deduction.This provides a reference for adjusting Guqin＇s volume by changing the frequencies of exciting forces.