Design of a Composite Guitar Master Thesis Report Max Roest
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Technische Universiteit Delft Design of a composite guitar Master Thesis Report Max Roest Design of a composite guitar Master Thesis Report by Max Roest Student number: 4084217 Hand-in date: August 17, 2016 Supervisor: dr. ir. O.K. Bergsma, TU Delft Summary Today’s acoustic guitars are getting increasingly expensive due to the worsening availability of the highest quality woods. Composites show great promise in replacing wood in acoustic guitars as they are lightweight, are not as sensitive to environmental effects and are much stronger. Current composite guitars however do not sound as good as their wooden counterparts. Therefore this thesis research has been set-up to create a composite material that can match wood acoustically and therefore have all the benefits in terms of environ- mental sensitivity and strength while not compromising the sound quality of the instrument. A new com- posite is developed and extensively tested. This composite consists of a carbon fibre reinforced polyurethane foam and has a comparable acoustic response to high quality spruce used for guitar soundboards. With this new composite a complete composite guitar is designed, manufactured and tested. The psychoacoustic anal- ysis performed showed that the new composite guitar is considerably more wood like in its sound compared to current carbon fibre acoustic guitars. ii Preface Max Roest Delft, July 2016 It is over 20 years ago that I received my first guitar. A few months later, at the age of 4, I had my first guitar lessons. Now at the age of 24, it is hard to remember any period in my life where guitars and music have not played a major role in my life. However, it is not only making and listening to music that interests me about this wonderful instrument. Understanding why guitars are built in a certain way and how a good sounding guitar distinguishes itself from a bad sounding one is still a mystery and keeps me looking inside the guitar body after I played some first notes. Through my studies at the faculty of Aerospace Engineering at the Delft University of Technology, for me, the possibility to better understand guitars is now greater than ever. That is why, before even finishing my Bachelor degree, I approached professor O.K. Bergsma from the Structures & Materials department to discuss the possibility to conduct a Master’s Thesis on the design and production of a high quality composite guitar. Now almost three years later, I hand in this thesis report which contains a detailed description of the knowl- edge I have gathered on the topic of guitars and material acoustics relevant to musical instruments through- out the past year. My goal with this report is to provide a strong source of information for anyone with an interest in the topic of designing a musical instrument on a more scientific basis from either from modern composites. During this past year I have had the pleasure of working with many amazing people. Without these people my project would have never achieved anything close to the goals that I can now proudly claim to have achieved. Therefore I would like to thank the following people. Dr. Ir. O.K. Bergsma - For being the best supervisor I could have wished during this project. You have given me a great deal of trust and freedom to explore what I thought was most interesting and useful in my research. You were never too busy to listen to my latest updates, sometimes more than three times a day and acted amazingly quickly when I needed some urgent help. C. van Erck - Thank you for being my lovely girlfriend who has shown to be an awesome and unmissable help in the lab too. My parents Ada Brokers and Nico Roest - Thank you for buying me my first guitar at the age of 3 and every- thing that came after that. Hans Pluk - Thank you for all the work you have done in correcting this report and helping me to bring the quality of this report and the research conducted to a higher level with your critical questions and thinking. Fred Bosch - Thank you for all the hours you have helped me with my research and especially the complex production of the final guitar. Without your help the end result would by far not look this good. Victor Horbowiec - Thank you for all the great help and tips during the past few months. Your extensive knowledge about the production of composites has taken away a great number of problems. Gertjan Mulder - Thank you for helping me with your knowledge about testing and working with compos- ites. More importantly I would like to thank you for your positivity that you radiate to others every day. iii iv Preface Frans van Oostrum - Thank you for helping and teaching me the fine arts of analysing and processing small samples and the fun talks during my second lunch of the day. Other DASML technicians - A warm thank you to all other technicians, Cees, Johan, Bart, Berthil, Peter, Ed and Misja for helping me out with solving many of the tiny problems that occurred during the research. Prof. Dr. Ir. R. Benedictus - Thank you for giving me the opportunity to design and produce two composite guitars. I value the trust that I received from you to bring this somewhat risky investment in this project to a good end. Dr. Ir. F.Alijiani - Thank you for you support and dedication in bringing my project to a higher level. I con- sider it very special how fast you were able to help me out with one of the largest unknowns in my research, the damping analysis. Luca Marinangeli - Thank you for the fun times building the LSV set-up and helping me out with your knowl- edge about vibrations. Michael Greenfield - Thank you for answering my questions about the art of building guitars. Without your expert tips this guitar would not have sounded as good. Thank you to the following sponsors and companies: Sieko van Dam (Jules Dock) Thank you for all the fun hours making the moulds and milling the different parts. Felix Moonen (Jules Dock) Thank you for your great ideas and tight management of all the work that had to be performed for the moulds and guitar parts. Your brilliant idea of making a set of test moulds out of MDF made it possible to produce a high quality guitar. Haiko Dragstra (Komplot Mechanics) Thank you for helping me out with the CNC machines and the milling of the birdges. During our work together I have learned a great deal about the art of CNC milling. Ronald Heijnen (3M) - Thank you for sponsoring this research with the 3M K1 glass bubbles and for your enthusiasm about this project. Ramon van Rooij (Teijin Aramid) - Thank you for the support in the development of the Endumax compos- ite samples. Florinett AG - Thank you for the sponsoring of several wood samples and your enthusiasm about this project. Madinter - Thank you for the sponsoring of several wood samples and your enthusiasm about this project. Jelte Vonk (MC Technics) - Thank you for all the advice and helping me choose the correct products through- out the main research and the production of the composite guitar. Matthias Schubert (Toho Tenax) - Thank you for the sponsoring of the carbon filament and the lightning fast delivery. Rohacell - Thank you for providing me with foam samples for the production of the sandwich panel. Note to reader This thesis report is written with a broad audience in mind. This is done to not only provide the research community with a detailed report but also consider builders of musical instruments which often have con- siderably less experience with the engineering terminology used. The storyline of this thesis begins at the very broad question of how to change the sound of an instrument. The literature review presented in part one is therefore included in this thesis report as it provides the nec- essary scoping to understand the starting point for the main thesis content in part II and part III. Readers well-known with the engineering parameters relevant to structural mechanics and dynamics are therefore advised to read chapters 4 and 7 from part I as the other chapters provide a basic explanation of several engi- neering parameters and their respective measurement strategies. v Contents 1 Introduction 1 I Project SCOPING AND LITERATURE REVIEW4 2 Introduction TO MODERN STEEL STRING GUITARS5 2.1 Origin of the acoustic guitar....................................5 2.1.1 Early history of the guitar.................................5 2.1.2 First gut-stringed and nylon string guitars.........................7 2.1.3 North-American steel string guitar.............................7 2.2 Components of the acoustic guitar................................8 2.2.1 Overview of components, features and terminology....................8 2.2.2 Sound producing system.................................. 11 2.2.3 Relative importance of the guitar components in producing sound............ 13 2.2.4 Fingerstyle guitar and recent developments........................ 14 2.3 Currently produced composite guitars.............................. 14 2.3.1 Rainsong Guitars...................................... 15 2.3.2 Ovation Guitars...................................... 15 2.3.3 Composite Acoustics.................................... 15 2.3.4 Other composite guitar manufacturers.......................... 16 3 LEVELS OF SOUND DESCRIPTION AND MODIfiCATION 17 3.1 State of the art / Literature review................................. 17 3.1.1 Micro material level.................................... 17 3.1.2 Macro/bulk material level................................. 18 3.1.3 Structural level....................................... 18 3.1.4 External level........................................ 19 3.1.5 Relevance to research project............................... 20 4 Project RESEARCH PLAN 21 4.1 Research question, aims and objectives.............................. 21 4.2 Theoretical Content/Methodology................................ 23 4.3 Experimental Set-up....................................... 23 4.4 Project Planning and Gantt Chart................................