Unraveling viscoelastic properties of Philippine Mahogany and manufactured acoustic guitar for improving acoustic performance of materials

Abstract

The acoustic conversion efficiency is one of the parameters used to assess the acoustic performance of a material, which is dependent on the values of tan delta and complex modulus. Studies so far have been conducted looking at tan delta and complex modulus [1], but the specific components of these, which are the storage and loss modulus, and how it affects the tan delta and complex modulus, and therefore acoustic conversion efficiency has yet been studied. Moreover, the effect of heat treatment on the storage and loss modulus, which is more affected by the process have yet been explored. This study aims to characterize the dynamic mechanical properties of Philippine Mahogany, to gain some insights on tuning the acoustic performance of materials for musical instruments, as well as to gain insights on the effect of heat treatment on these properties, composition and to compare it to that of a manufactured guitar. Dynamic Mechanical Analysis (DMA) and Thermogravimetric analysis (TGA) were used to accomplish these objectives. The DMA results showed that storage modulus, loss modulus, complex modulus, and tan delta decreased upon heat treatment, while the sample from guitar showed highest storage modulus, loss modulus, and complex modulus, and lowest tan delta. The TGA results showed minute differences in composition between treated and untreated samples. However, this provided explanation on the difference in the mechanical properties of the samples. Noteworthy, even with tan delta <0.1 for both samples, storage modulus wasn’t dominating the tan delta for both. This study showed the importance of looking at the storage and loss modulus components in improving the acoustic performance of materials as well as the effect of heat treatment on Philippine Mahogany.