Spring 2017 SpiderBot Material Trade Off Study

Material Trade of Study

By Daniel Matias – Manufacturing Engineer

 

Requirements:

A level 1 requirement states that SpiderBot shall lift itself off the ground. To achieve this, and still maintain a stable, mobile robotic platform, SpiderBot will be made of an inexpensive, lightweight material with a high tensile strength.

 

Introduction

Traditionally walking robots have proven to be a challenge. Proper walking mechanism selection can either means success or failure. Walking robots experience large amounts of shock and vibration that can cause stress fractures and material deformations. The study aims to present all materials considered for SpiderBot’s use.

Materials:

The materials considered in this trade-off are aluminum, acrylic, and plywood. A fixed volume of 1/8’’ thickness, 6’’ wide, and 12’’ long sheets are being used when comparing the materials. Also considered is the strength of the material to ensure our robot will not break under the weight of the components.

Calculations:

 

The following table shows the cost and mass of the set volume

Material

Cost

Mass

Aluminum

$17.14

398 g

Acrylic

$5.07

174.5 g

Plywood

$2.50

98.8 g

The following is a table of the tensile and compressive strength of the three materials.

Material Tensile Strength Compression Strength
Aluminum 310 MPa 20 GPa
Acrylic 69 MPa 124 MPa
Plywood 31 Mpa 36 MPa

Conclusion:

Although plywood is the cheapest and the lightest, acrylic is more suited for our robot due to the inexpensive, toy requirement. Aluminum could be reduced in size since it is stronger, but the material and machine shop costs would exceed our budget when all the qualities of acrylic can satisfy requirements.

Resources:

 

https://www.mcmaster.com/#acrylic-sheets/=16uqxrr

https://www.mcmaster.com/#standard-aluminum-sheets/=16uqxy0

http://www.woodworkerssource.com/shop/product/18balpack3.html

http://www2.glemco.com/pdf/NEW_MARTERIAL_LIST/Alumina%206061-T6.pdf

http://www.engineeringtoolbox.com/wood-density-d_40.html

https://www.metalsdepot.com/catalog_search.php?search=s318T6

http://edge.rit.edu/edge/P14418/public/4-Subsystems%20Design/Plywood%20Materials.pdf

http://www.builditsolar.com/References/Glazing/physicalpropertiesAcrylic.pdf

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