Manufacturing Steps - McGill

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Manufacturing of composite violin top plates and design of composite tailpieces By : Maxime Beaulieu Supervised by : Prof. Larry Lessard and PhD student Steven Phillips Department of Mechanical Engineering, McGill University, Montreal Quebec Background Making a violin top plate out of composite material has the following advantages: Resistance to heat and humidity Fewer manufacturing steps Better material consistency Possible to make resonating plate lighter Excellent mechanical properties This project was first initiated last summer and the first prototypes had issues with delamination in areas where the wood core was present. Another violin part that could benefit from composite materials is the tailpiece. The tailpiece is a part used to hold the strings of the violin and it needs to be strong to withstand the high tension loading. Objectives Produce violin top plates using different combinations of carbon fiber/epoxy ply sequences to find the best sounding. Solve local delamination problem caused by the unique loading condition of a violin. Design a mold to manufacture violin tailpieces out of composites. Manufacturing Steps Conclusions Carbon fiber/epoxy can produce parts much lighter than spruce wood with sufficient stiffness. Composites allow freedom in the design of the top plates, such as the graduation of the thickness in different areas. The delamination problems were addressed by modifying the layup design. The flexibility of composite materials shows potential in designing violin tailpieces. Results Some composite defects from processing include: surface finish, core alignment, warping and unformed regions. Lack of pressure in certain regions or resin quality could be the cause. In general, the plates are lighter then a typical 2.5mm thick spruce plate which weighs 84g but some plates were made heavy on purpose for comparison. The delamination problems were addressed by changing the shape of the center core and removing the balsa from the edges. Some plates were made without using any core at all. By varying the shape of the pre-preg layers and balsa core, different graduations of thickness in the top plates were achieved. Acknowledgements : Peter Purich Luthier, Funding - NSERC Further research Test the violin top plates using the Chladni pattern method and Tap Tone method. A qualitative analysis of the acoustics when the plates are attached to the violin body. Design a way to add a composite bass bar to the top plates. 1 2 3 4 5 6 7 8 9 Mass(g) 48 65.2 127.6 65.1 65.5 62.3 67.6 70.7 68.4 Delamination Fig. Delamination problem from previous prototypes Fig. Violin Parts diagram 1. Balsa core cutting 2. Pre-preg cutting 3. Layup of the material 4. Vacuum bagging 5. Curing in the oven 6. Finished part 1. Traditional Tailpiece 3. 3D CAD Model of the tailpiece 4. 3D CAD mold of the tailpieces A total of 9 different top plates have been produced Fig. Core shape change Tailpiece Mold Design Innovative features of the mold: The tailpiece was redesigned to be thinner than traditional tailpieces Each cavity is a different variation of the tailpiece. One sided mold to make it cheaper to manufacture and easier to use. The tailpieces are made using the vacuum bag method. The lay out of the mold allows the possibility to produce each tailpiece individually to reduce the use of unnecessary material. The mold is made out of aluminum making it reusable, produces good surface finish and can be used in the oven. Surface finish Corner formation Core alignment 2. Modified tailpiece design

Transcript of Manufacturing Steps - McGill

Page 1: Manufacturing Steps - McGill

Manufacturing of composite violin top plates and design of composite tailpieces By : Maxime Beaulieu

Supervised by : Prof. Larry Lessard and PhD student Steven Phillips

Department of Mechanical Engineering, McGill University, Montreal Quebec

BackgroundMaking a violin top plate out of composite material has the following advantages:

•Resistance to heat and humidity

•Fewer manufacturing steps

•Better material consistency

•Possible to make resonating plate lighter

•Excellent mechanical properties

This project was first initiated last summer and the first prototypes had issues with

delamination in areas where the wood core was present.

Another violin part that could benefit from composite materials is the tailpiece. The tailpiece

is a part used to hold the strings of the violin and it needs to be strong to withstand the high

tension loading.

Objectives•Produce violin top plates using different combinations of carbon fiber/epoxy ply sequences to

find the best sounding.

•Solve local delamination problem caused by the unique loading condition of a violin.

•Design a mold to manufacture violin tailpieces out of composites.

Manufacturing Steps

Conclusions•Carbon fiber/epoxy can produce parts much lighter than spruce wood

with sufficient stiffness.

•Composites allow freedom in the design of the top plates, such as the

graduation of the thickness in different areas.

•The delamination problems were addressed by modifying the layup

design.

•The flexibility of composite materials shows potential in designing

violin tailpieces.

Results•Some composite defects from processing include: surface finish, core alignment, warping and

unformed regions. Lack of pressure in certain regions or resin quality could be the cause.

•In general, the plates are lighter then a typical 2.5mm thick spruce plate which weighs 84g but some

plates were made heavy on purpose for comparison.

•The delamination problems were addressed by changing the shape of the center core and removing

the balsa from the edges. Some plates were made without using any core at all.

•By varying the shape of the pre-preg layers and balsa core, different graduations of thickness in the

top plates were achieved.

Acknowledgements : Peter Purich – Luthier, Funding - NSERC

Further research•Test the violin top plates using the Chladni pattern method and Tap Tone method.

•A qualitative analysis of the acoustics when the plates are attached to the violin

body.

•Design a way to add a composite bass bar to the top plates.

1 2 3 4 5 6 7 8 9

Mass(g) 48 65.2 127.6 65.1 65.5 62.3 67.6 70.7 68.4

Delamination

Fig. Delamination problem from previous prototypes

Fig. Violin Parts diagram

1. Balsa core cutting 2. Pre-preg cutting 3. Layup of the material 4. Vacuum bagging 5. Curing in the oven 6. Finished part

1. Traditional Tailpiece

3. 3D CAD Model of the tailpiece 4. 3D CAD mold of the tailpieces

A total of 9 different top plates have been produced

Fig. Core shape change

Tailpiece Mold Design

Innovative features of the mold:

•The tailpiece was redesigned to be thinner than traditional tailpieces

•Each cavity is a different variation of the tailpiece.

•One sided mold to make it cheaper to manufacture and easier to use.

•The tailpieces are made using the vacuum bag method.

•The lay out of the mold allows the possibility to produce each tailpiece

individually to reduce the use of unnecessary material.

•The mold is made out of aluminum making it reusable, produces good

surface finish and can be used in the oven.

Surface finish Corner formation Core alignment

2. Modified tailpiece design