An Analytical Model for Computing the Sound Power of an Unbraced Irregular-Shaped Plate of Variable Thickness

Abstract An irregular-shaped plate with dimensions identical to a guitar soundboard is chosen for this study. It is well known that the classical guitar soundboard is a major contributor to acoustic radiation at high frequencies when compared to the bridge and sound hole. This paper focuses on using an analytical model to compute the sound power of an unbraced irregular-shaped plate of variable thickness up to frequencies of 5 kHz. The analytical model is an equivalent thin rectangular plate of variable thickness. Sound power of an irregular-shaped plate of variable thickness and with dimensions of an unbraced Torres’ soundboard is determined from computer analysis using ANSYS. The number of acoustic elements used in ANSYS for accurate simulation is six elements per wavelength. Here we show that the analytical model can be used to compute sound power of an unbraced irregular-shaped plate of variable thickness

Mathematical Modelling and Acoustical Analysis of Classical Guitars and Their Soundboards

Research has shown that the soundboard plays an increasingly important role compared to the sound hole, back plate, and the bridge at high frequencies. The frequency spectrum of investigation can be extended to 5 kHz. Design of bracings and their placements on the soundboard increase its structural stiffness as well as redistributing its deflection to nonbraced regions and affecting its loudness as well as its response at low and high frequencies. This paper attempts to present a review of the current state of the art in guitar research and to propose viable alternatives that will ultimately result in a louder and better sounding instrument. Current research is an attempt to increase the sound level with bracing designs and their placements, control of natural frequencies using scalloped braces, as well as improve the acoustic radiation of this instrument at higher frequencies by deliberately inducing asymmetric modes in the soundboard using the concept of “splitting board.” Various mathematical methods are available for analysing the soundboard based on the theory of thin plates. Discrete models of the instrument up to 4 degrees of freedom are also presented. Results from finite element analysis can be utilized for the evaluation of acoustic radiation

Linking Liberatory Pedagogy to Engineering and Sustainable Development

This paper is written to link liberatory pedagogy with engineering education and sustainable development Its application to specifically, design education for community is explored through deconstructing of engineering student narratives to place understanding of power and privilege in a specific learning setting. The use of liberatory pedagogy for design education and SD is attempted where there is need of changes in understanding of learning outcomes for SD aimed at producing of sustainable physical products to address SD problems in community-based projects. We argue against the simple-minded approach of producing physical products and undermine the intersections of other knowledge forms within the community context. Without pedagogic intervention, we undermine other knowledge forms and cultures in its importance amidst technical knowledge seen as which is valid for SD. Extending liberatory pedagogy to constructivists’ perspective we discuss the importance of intervention in the broader image of the engineer as the technical expert who share knowledge in partnership for SD