Material Selection

After deciding on a final design, the group was faced with a decision on which materials to use for production of the tetrahedral array and the T-base.  The final material selection was based primarily on vibration damping characteristics and machinability.  Other factors, such as cost, weight, and availability were also considered.  Below is a matrix illustrating how all the considered materials compared with each other, and which ones had the lowest wave speeds.

 

Materials Considered

Price of Material ($/ft) for 1 inch diameter

Density of Material (lb/in^3)

Speed of Sound Through Material (ft/s)

Polycarbonate

4.32

0.044

4415.82

ABS

5.2

0.04

4254.163

Carbon

13.8

0.0813

4791.61

Graphite

37.83

0.0643

9364.501

UHMW-PE

4.56

0.0336

2679.871

PEEK

97.92

0.047

5066.634

 

 

 

 

 

 

 

After comparing the densities, price, and conduction of sound in all 5 materials, the group determined that clearly ABS (Acrylanitrile Butadiene Styrene) plastic and UHMW-PE (Ultra High Molecular Weight Polyetheline) were the best choices for the purposes of vibration damping.  These two materials are shown in the highlighted regions shown in the matrix above.