THE UNIVERSITY OF QUEENSLAND Bachelor of Engineering Thesis The Manufacture and Acoustic Analysis of Hemp/Agave Fibre Reinforced Vinyl Ester Bio-Composite Guitar Student Name: Mohammad Noor Farhan ABD RAHIM Course Code: MECH4500 Supervisor: Dr. Luigi Vandi Prof. Martin Veidt Submission date: 28th October 2016 A thesis submitted in partial fulfilment of the requirements of the Bachelor of Engineering degree in Mechanical Engineering UQ Engineering Faculty of Engineering, Architecture and Information Technology Acknowledgement In completing this thesis report, I would like to express my sincerest appreciation to the people that helped me in making this thesis a success. Without their help and guidance, this thesis project would not achieve the level that it has. Special gratitude goes to Dr Luigi Vandi, my supervisor whose guidance and expertise enabled the project to be carried with ease and controlled manner. Without his insight and supervision, this project would not have been possible. Many thanks to Professor Martin Veidt, who provide essential guidance and feedback on various aspects of the project throughout the year. I would also like to thank John Milne, UQ Composite laboratory manager, for always being ready to help and share his wide technical knowledge on manufacturing processes and composite materials as well as providing an overall positive atmosphere in the laboratory. This project would also not have been possible without the feedback and opinions from UQ Composite Group members Juan, Nico, Clement and Charles, especially during the manufacturing phase. The 2015 project group for their effort in designing the guitar mould as well as provides the results from their findings. I would also like to thank the School of Mechanical and Mining Engineering for providing me the opportunity to complete this thesis and with world-class facilities. Special thanks to my family, friends and Azila, whose unending support enables me to complete this thesis. ii | P a g e Abstract This project provides feasibility studies on using a bio-composite material as substitutes to rare wood, commonly used in acoustic guitar construction. The objective of this project is to manufacture an acoustic guitar from Hemp/Agave Fibre Reinforced Vinyl Ester. The superior mechanical properties and repeatability in the manufacturing process of bio-composite prove to be an advantage when comparing to conventional wooden guitar. The material characterisation section of this report firstly investigates the mechanical properties of Hemp/Agave Fibre Reinforced Vinyl Ester. A sample plate utilising a different number of Hemp/Agave fibre layer is manufactured through resin infusion process and undergoes tensile testing. The repeated manufacturing process allow for adaptation to the resin infusion process in order to obtain a high-quality final product. Results from the tensile testing were used to make a decision on the guitar soundboard thickness, which is 4.92 mm. The initial guitar design was made in Computer Aided Design (CAD) based on the design of the previously completed guitar mould. The robustness of the guitar under strings tension was analysed via ANSYS 17.0 software. From the analysis, additional design such as foam core in carbon fibre insert and carbon fibre layer was introduced in order to reinforce the neck and the head section. The manufacture of the guitar includes the fabrication of the soundboard and the guitar body. The continuous body design and the complex geometry of the guitar body lead to the introduction of spiral tube and pleats in the layup in order to obtain a high-quality end product as well as having good mechanical properties. The testing and acoustic analysis section compare the acoustic performance of the guitar to a carbon fibre guitar manufactured by the 2015 project group. The loudness and the projection power of the bio-composite guitar are slightly lower than the carbon fibre. This is due to the overdesign of the bio-composite guitar in effort to strengthen the weaker section. However, the tonal quality of the guitar was more preferred as it closely matches that of a wooden guitar counterpart. The guitar prototype demonstrates the feasibility of using bio-composites as wood replacement in guitar construction. Improvements on the guitar design are recommended in order to optimise the guitar performance. iii | P a g e Table of Contents Acknowledgement ...................................................................................................................... ii Abstract ...................................................................................................................................... iii List of Figures ............................................................................................................................. 3 List of Table ............................................................................................................................... 3 List of Equations ......................................................................................................................... 5 1.0 Introduction .......................................................................................................................... 5 2.0 Project Overview .................................................................................................................. 7 2.1 Motivation ........................................................................................................................ 7 2.2 Problem Statement ............................................................................................................ 7 2.3 Objectives and Project Scope ........................................................................................... 7 2.4 Triple Bottom Line ........................................................................................................... 8 2.4.1 Environmental Measures ........................................................................................... 8 2.4.2 Economic Measures ................................................................................................... 8 2.4.3 Social Measures ......................................................................................................... 8 2.5 Project Milestones ............................................................................................................ 9 3.0 Literature Review ............................................................................................................... 10 3.1 Bio-composite ................................................................................................................. 10 3.1.1 Hemp ....................................................................................................................... 10 3.1.2 Agave ....................................................................................................................... 11 3.1.3 Hemp/Agave ............................................................................................................ 12 3.2 Bio-composite Guitars .................................................................................................... 12 3.3 Bio-Composite Manufacturing Methodologies .............................................................. 13 3.3.1 Resin Infusion .......................................................................................................... 13 3.4 Soundboard Criteria ........................................................................................................ 14 3.5 Guitar Acoustics ............................................................................................................. 15 3.5.1 Air Cavity ................................................................................................................ 15 3.5.2 Strings & Frets ......................................................................................................... 15 4.0 Material Characterisation ................................................................................................... 16 4.1 Objectives ....................................................................................................................... 16 4.2 Plate Manufacture ........................................................................................................... 17 4.2.1 Layup Configuration & Vacuum Bagging .............................................................. 17 4.2.2 Resin Infusion .......................................................................................................... 19 1 | P a g e 4.3 Mechanical Testing......................................................................................................... 20 4.4 Results Analysis ............................................................................................................. 23 4.4.1 Plate Results ............................................................................................................ 23 4.4.2 Mechanical Testing Results ..................................................................................... 24 4.5 Discussions and Prospects .............................................................................................. 26 5.0 Design ................................................................................................................................. 27 5.1 Design Features .............................................................................................................