Dumond Patrick, Baddour Natalie
Department of Mechanical Engineering, University of Ottawa, 161 Louis Pasteur, CBY A205, K1N 6N5 Ottawa, Canada.
Springerplus. 2013 Oct 24;2:558. doi: 10.1186/2193-1801-2-558. eCollection 2013.
Although many improvements in the manufacturing of guitars have been made recently, one aspect that has often been overlooked is that of the acoustical consistency of the final manufactured product. The aim of this paper is to create a better understanding of the effect of a brace on the frequencies of vibration of the brace-soundboard system. This paper seeks to shed light on why a luthier 'tunes' braces when a guitar soundboard is hand-manufactured. A simple analytical model of a rectangular brace and soundboard is derived from first principles using Kirchhoff plate theory in order to develop insight into the effect of the soundboard's stiffness and brace thickness on the frequencies of the combined system. Natural frequencies and modeshapes of the combined system are calculated via the assumed shape method. Results show that by adjusting the thickness of the brace in order to compensate for the stiffness of the plate, one of the natural frequencies of the combined system can be adjusted to meet a desired value. However, simultaneously adjusting several natural frequencies cannot be done with a rectangular brace. Therefore modifications to the shape of the brace are explored.
尽管近期吉他制造工艺有了诸多改进，但最终制成产品的声学一致性这一方面却常常被忽视。本文旨在更深入地理解音梁对音梁 - 共鸣板系统振动频率的影响。本文力图阐明在手工制作吉他共鸣板时，制琴师为何要“调整”音梁。运用基尔霍夫板理论从基本原理推导出一个矩形音梁和共鸣板的简单分析模型，以便深入了解共鸣板刚度和音梁厚度对组合系统频率的影响。通过假定形状法计算组合系统的固有频率和振型。结果表明，通过调整音梁厚度以补偿板材刚度，可将组合系统的一个固有频率调整到期望值。然而，使用矩形音梁无法同时调整多个固有频率。因此，对音梁形状的修改进行了探讨。
