Acta Univ. Agric. Silvic. Mendelianae Brun. 2006, 54, 23-30
Published online 2014-12-12

FEM effective suggestion of guitar construction

Vladimír Dániel, Petr Koňas

Ústav nauky o dřevě, Mendelova zemědělská a lesnická univerzita v Brně, Zemědělská 3, 613 00 Brno, Česká republika

Modal analysis of the whole guitar construction was performed. The results of eigenfrequencies were obtained. Stress in strings affects not only static loading of material, but also shift of eigenfrequencies. From obtained natural frequencies for solved spectrum such frequencies were used which coincides with assumed ribs new positions of ribs were suggested. Other ribs which do not carry out the mechanical function were removed. Also static reaction was evaluated and new position of ribs was adjusted. For final model new eigenfrequencies were computed and compared with previous ones. Significant changes were revealed in low frequencies (bellow 400 Hz) where fewer amounts of natural shapes were obtained. Approximately 50% were lost by adding of ribs. For chosen frequencies of equal temperament the harmonic analysis was performed. The analysis proved ability of oscillation for frequencies far of natural frequencies. The final model satisfies the requirement of minimization of static stress in material due to strings and allows very effective oscillation of top the guitar resonance board. In comparison with literature good agreement in amplitude size of front board and amount of modes in appropriate frequencies were achieved. Suggested model even offers higher amount of natural shapes in comparison with literature, namely in high frequencies. From additional comparison of eigenfrequencies and natural shapes the influence of ribs position on natural shapes was approved.


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