Mechanism by Which Heat Treatment Influences the Acoustic Vibration Characteristics of Bamboo

The multi-layered and multi-scale refined structure of bamboo gives bamboo musical instruments a unique tonal quality. This study employed heat treatment to enhance the acoustic vibration stability of bamboo materials. The hammering method was subsequently employed for conducting multi-point impact excitation tests on instrument-grade bamboo, and the resulting vibration response was subjected to modal analysis. Next, we investigated the acoustic vibration characteristics of bamboo, including its sound vibration efficiency, timbre, and acoustic stability, in terms of its macroscopic gradient structure, ultra-microstructure, molecular scale, key components, and pore structure. Modal analysis revealed that the first three damping ratios of Xipi were 94.55%, 7.89%, and 26.60% higher than those of Erhuang, respectively. The relative stiffness of Xipi across the first three modes was 1.22, 1.22, and 1.18 times that of Erhuang, indicating a generally higher structural rigidity. The first three natural frequencies of Xipi were approximately 1.20, 1.20, and 1.19 times higher than those of Erhuang, and its fundamental transfer function value was 1.5 times greater, suggesting a lower susceptibility to low-frequency resonance. Modal shapes showed distinct vibration behaviors between the two types: Xipi exhibited a more effective energy transmission path in the second mode and less structural distortion in the third mode, potentially indicating higher structural integrity. This research provides support for developing new technologies to select and process bamboo materials for musical instruments.