Frequency Response Evaluation of Guitar Bodies with Different Bracing Systems

Abstract

Wood is a natural composite, having a porous structure, with a complex elastic symmetry specific to orthotropic solid, influenced by three mutually perpendicular planes of elastic symmetry. The classical guitar is obtained from different wooden species, each of them having their own elastic properties and, as a whole, forming a lignocellulosic composite structure. Generally, some constructive parts of the classical guitar body are based on symmetry, starting from the structural features of wooden plates, which are symmetrically cut, and some patterns of the stiffening bars. The other elements, such as the strings system, are not symmetric. This study aims to evaluate the frequency responses of the guitar body as a symmetrical mechanical system from constructive points of view. Because theoretical results (analytic and numeric) regarding the symmetrical systems cannot be applied to quasi-symmetric systems, the dynamic response was analyzed from experiments performed on four types of classical guitar body (without neck), different from each other by the pattern of stiffening bars placed inside of the top plate. The experiments were performed using a Brüel&Kjær mini-shaker to excite the structure, and the signal was captured with accelerometers. The symmetric behavior of coupled plates from the guitar body was noticed in the case of an applied dynamic force of 110 Hz and 440 Hz, but in the case of 146 Hz, 588 Hz, 720 Hz, quasi skew symmetrical modes were recorded.

Model-based evidence of the dominance of the guitar brace design over material and climatic variability for dynamic behaviors

“…The modal bases of each nominal configuration are given in this section. The [34], A guitar [4] and S guitar [35] respectively. Nevertheless, the high variability in term of soundboard shape and thickness, sound hole size and brace modifications prevent from consolidated test-model comparisons.…”

Influence of 3D Printing Direction in PLA Acoustic Guitars on Vibration Response

“…The experiment carried out featured experimental tests of the first five vibration modes, selected on the basis of the five natural frequencies, as it is these that cause the whole harmonic top to resonate, according to previous studies [ 37 , 38 ]. In this way, the generated vibration patterns can be visualised, showing the areas of the greatest and least vibration of the harmonic cap created in each case.…”

Methodology for the Acoustic Analysis of Acoustic Guitar Top Plates Designs by Additive Manufacturing

“…In order to analyse the repercussion of such a design of the soundboard structure, numerous studies have been developed to visualise the vibratory figures, and to understand the vibratory behaviour of the soundboard [3,8]. The study by Alejandro Torres et al [5] shows the creation of a framework for the vibration clamping and testing of wooden soundboards, using the technique and methodology developed by Chladni for the visualisation of the vibration patterns and also using laser visualisation techniques [3,7,9]. In this case, a virtual model of the designed top was generated and simulated virtually, and a great similarity was observed between both results.…”