Derveaux Grégoire, Chaigne Antoine, Joly Patrick, Bécache Eliane
INRIA Roquencourt, Projet Ondes, 78153 Le Chesnay Cedex, France.
J Acoust Soc Am. 2003 Dec;114(6 Pt 1):3368-83. doi: 10.1121/1.1629302.
This paper presents a three-dimensional time-domain numerical model of the vibration and acoustic radiation from a guitar. The model involves the transverse displacement of the string excited by a force pulse, the flexural motion of the soundboard, and the sound radiation. A specific spectral method is used for solving the Kirchhoff-Love's dynamic top plate model for a damped, heterogeneous orthotropic material. The air-plate interaction is solved with a fictitious domain method, and a conservative scheme is used for the time discretization. Frequency analysis is performed on the simulated sound pressure and plate velocity waveforms in order to evaluate quantitatively the transfer of energy through the various components of the coupled system: from the string to the soundboard and from the soundboard to the air. The effects of some structural changes in soundboard thickness and cavity volume on the produced sounds are presented and discussed. Simulations of the same guitar in three different cases are also performed: "in vacuo," in air with a perfectly rigid top plate, and in air with an elastic top plate. This allows comparisons between structural, acoustic, and structural-acoustic modes of the instrument. Finally, attention is paid to the evolution with time of the spatial pressure field. This shows, in particular, the complex evolution of the directivity pattern in the near field of the instrument, especially during the attack.
本文提出了一种吉他振动和声辐射的三维时域数值模型。该模型涉及由力脉冲激发的弦的横向位移、音板的弯曲运动以及声辐射。采用一种特定的谱方法来求解阻尼、非均匀正交各向异性材料的基尔霍夫 - 洛夫动态顶板模型。气 - 板相互作用采用虚拟域方法求解，时间离散采用守恒格式。对模拟的声压和板速度波形进行频率分析，以便定量评估能量通过耦合系统各组件的传递：从弦到音板以及从音板到空气。给出并讨论了音板厚度和腔体体积的一些结构变化对所产生声音的影响。还对同一把吉他在三种不同情况下进行了模拟：“真空”、具有完美刚性顶板的空气中以及具有弹性顶板的空气中。这使得能够对乐器的结构、声学和结构 - 声学模式进行比较。最后，关注空间压力场随时间的演变。这尤其显示了乐器近场中指向性图案的复杂演变，特别是在起始阶段。
