Stiffening Cello Bridges with Design

Abstract

In instruments of the violin family, the bridge is the part in charge of transferring the vibrational energy of the strings into the body and therefore contributes greatly to the sound of the instrument. The bridge needs to be light enough to efficiently transmit the strings’ movement yet rigid enough to support the static load of the strings. Historically, there have been several attempts at solving this problem with different designs, arriving in the early 1800s at the two current models: the French and the Belgian. Recently, in Cremona, Italy, the Amorim family of luthiers has developed a new cello bridge design. Inspired by their work, we study the influence of the shape of the legs of the cello bridge on its static and vibrational behavior through parametric modeling and simulations using the Finite Element Method. In particular, we perform displacement and modal analysis for different boundary conditions, providing in addition a detailed description of the mode shapes. We also compute and compare Frequency Response Functions for the different geometries. Our results show that shape can indeed be used to control the vibrational and static responses of the cello and consequently tune its sound.