Difference between revisions of "Team F"

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Team members: Isaac, Christine, Lindsay
 
Team members: Isaac, Christine, Lindsay
  
Team Fα's initial design involved several triangle cut-outs across the robot arm template. The triangles would provide support to the arm while removing much of the extraneous mass. The results of this design were as follows:
+
Team Fα's initial design involved several triangular extruded cuts across the robot arm template to minimize loss of the arm's structural support while removing much of the extraneous mass. The results of this design were as follows:
Volume: .88 in^3;
+
*Volume: 0.88 in^3;
Displacement: .3653 mm;
+
*Displacement: 0.37 mm;
Score: .3214 mm*in^3.
+
*Score: 0.3214 mm*in^3.
  
 
Team Alpha's Initial Design
 
Team Alpha's Initial Design
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Team members: Greg, Andrew
 
Team members: Greg, Andrew
  
The premise of Team FΩ's design was to do away with extraneous portions of the given design. The result was a curved, ''s''-shape piece that cut off the portions past the pre-cut notches under the hypothesis that these areas did not help the piece resist deformation. The curved structure was intended to eliminate the corners created by the notches so that stress could not focus on any particular spot. The results for this initial design are as follows: Volume: .90; Displacement: .27; Score: .243.
+
The premise of Team FΩ's design was to do away with extraneous portions of the given design. The result was a curved, ''s''-shape piece that cut off the portions past the pre-cut notches under the hypothesis that these areas did not help the piece resist deformation. The curved structure was intended to eliminate the corners created by the notches so that stress could not focus on any particular spot. The results for this initial design are as follows:
 
+
*Volume: 0.90 in^3
 
+
*Displacement: 0.27 mm
 +
*Score: 0.24 mm*in^3
  
 
Omega Group's Initial Design [[File:Omega group Initial Design.png]]
 
Omega Group's Initial Design [[File:Omega group Initial Design.png]]
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Middle Bar Test 1:  
 
Middle Bar Test 1:  
Displacement: .298 mm;
+
Displacement: 0.30 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .280 mm*in^3.
+
Score: 0.280 mm*in^3.
  
 
Middle Bar Test 2:  
 
Middle Bar Test 2:  
Displacement: .2922 mm;
+
Displacement: 0.29 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .277 mm*in^3.
+
Score: 0.277 mm*in^3.
  
 
Middle Bar Test 3:  
 
Middle Bar Test 3:  
Displacement: .2682 mm;
+
Displacement: 0.27 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .255 mm*in^3.
+
Score: 0.255 mm*in^3.
  
 
Middle Bar Test 4:  
 
Middle Bar Test 4:  
Displacement: .2824 mm;
+
Displacement: 0.28 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .268 mm*in^3.
+
Score: 0.268 mm*in^3.
  
 
[[File:Selected from the 1st set of trials.png]]
 
[[File:Selected from the 1st set of trials.png]]
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Cut Test 1:  
 
Cut Test 1:  
Displacement: .358 mm;
+
Displacement: 0.36 mm;
Volume: .7 in^3;
+
Volume: 0.70 in^3;
Score: .250 mm*in^3.
+
Score: 0.250 mm*in^3.
  
 
Cut Test 2:  
 
Cut Test 2:  
Displacement: .29 mm;
+
Displacement: 0.29 mm;
Volume: .72 in^3;
+
Volume: 0.72 in^3;
Score: .209 mm*in^3.
+
Score: 0.209 mm*in^3.
  
 
Cut Test 3:  
 
Cut Test 3:  
Displacement: .277 mm;
+
Displacement: 0.28 mm;
Volume: .72 in^3;
+
Volume: 0.72 in^3;
Score: .199 mm*in^3.
+
Score: 0.199 mm*in^3.
  
 
[[File:Selected from the 2nd set of trials.png]]
 
[[File:Selected from the 2nd set of trials.png]]
Line 79: Line 80:
  
 
Shelling Test 1:  
 
Shelling Test 1:  
Displacement: .4195 mm;
+
Displacement: 0.42 mm;
Volume: .50 in^3;
+
Volume: 0.50 in^3;
Score: .210 mm*in^3.
+
Score: 0.210 mm*in^3.
  
 
Shelling Test 2:  
 
Shelling Test 2:  
Displacement: .323 mm;
+
Displacement: 0.323 mm;
Volume: .61 in^3;
+
Volume: 0.61 in^3;
Score: .197 mm*in^3.
+
Score: 0.197 mm*in^3.
  
 
[[File:Selected from the 3rd set of trials.png]]
 
[[File:Selected from the 3rd set of trials.png]]
Line 94: Line 95:
  
 
Lightening Holes and Filleting Test 1:  
 
Lightening Holes and Filleting Test 1:  
Displacement: .3339 mm;
+
Displacement: 0.33 mm;
Volume: .59 in^3;
+
Volume: 0.59 in^3;
Score: .196 mm*in^3.
+
Score: 0.196 mm*in^3.
  
  
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The final design (shown below) had almost every corner rounded. This reduced the stress substantially. No holes were used in the end because they seemed to decease weight insignificantly at the expense of much higher displacements. We are happy with the final design that has measurements as follows:
 
The final design (shown below) had almost every corner rounded. This reduced the stress substantially. No holes were used in the end because they seemed to decease weight insignificantly at the expense of much higher displacements. We are happy with the final design that has measurements as follows:
  
Displacement: .29 mm;
+
Displacement: 0.29 mm;
Volume: .61 in^3;
+
Volume: 0.61 in^3;
Score: .17 mm*in^3.
+
Score: 0.17 mm*in^3.
  
 
[[File:Selected from the 3rd set of trials.png]]
 
[[File:Selected from the 3rd set of trials.png]]

Revision as of 21:05, 26 September 2012

Members

Preliminary Designs

Team Fα

Team members: Isaac, Christine, Lindsay

Team Fα's initial design involved several triangular extruded cuts across the robot arm template to minimize loss of the arm's structural support while removing much of the extraneous mass. The results of this design were as follows:

  • Volume: 0.88 in^3;
  • Displacement: 0.37 mm;
  • Score: 0.3214 mm*in^3.

Team Alpha's Initial Design Alpha group initial design.png

Team FΩ

Team members: Greg, Andrew

The premise of Team FΩ's design was to do away with extraneous portions of the given design. The result was a curved, s-shape piece that cut off the portions past the pre-cut notches under the hypothesis that these areas did not help the piece resist deformation. The curved structure was intended to eliminate the corners created by the notches so that stress could not focus on any particular spot. The results for this initial design are as follows:

  • Volume: 0.90 in^3
  • Displacement: 0.27 mm
  • Score: 0.24 mm*in^3

Omega Group's Initial Design Omega group Initial Design.png

Synthesis of Designs

The team decided to base the final design primarily on Team Fα's preliminary design because it performed better with virtually the same volume. The main quality that we tried to incorporate into our new design was the use of triangles in the central region of the piece, between each of the notches. We also cut away the portions past the notches, like in Team FΩ's design.

Design Development

Step 1 was to find the ideal arrangement and orientation of two triangle cuts in the center of the arm. The purpose here was to remove as much material as possible while retaining a triangular support structure.

Middle Bar Test 1: Displacement: 0.30 mm; Volume: 0.95 in^3; Score: 0.280 mm*in^3.

Middle Bar Test 2: Displacement: 0.29 mm; Volume: 0.95 in^3; Score: 0.277 mm*in^3.

Middle Bar Test 3: Displacement: 0.27 mm; Volume: 0.95 in^3; Score: 0.255 mm*in^3.

Middle Bar Test 4: Displacement: 0.28 mm; Volume: 0.95 in^3; Score: 0.268 mm*in^3.

Selected from the 1st set of trials.png

Middle Bar Test 2 (above) provided the lowest score and became the base model for step 2, which was to cut out a substantial, trapezoidal section near the applied force. An additional trapezoidal section was added towards the top of the arm as well. Each of the Cut Tests we performed involved different arrangements and sizes of the trapezoidal cuts. The goal here was to remove material from the end that had very little stress on it. Most of the stress was near the base of the arm, so the extra material at the end was unneeded.


Cut Test 1: Displacement: 0.36 mm; Volume: 0.70 in^3; Score: 0.250 mm*in^3.

Cut Test 2: Displacement: 0.29 mm; Volume: 0.72 in^3; Score: 0.209 mm*in^3.

Cut Test 3: Displacement: 0.28 mm; Volume: 0.72 in^3; Score: 0.199 mm*in^3.

Selected from the 2nd set of trials.png

Cut Test 3 (above) provided the lowest score and was used as the base model for the step 3, where we tested different depths of shelling. Here, the goal was simply to reduce as much weight as possible.

Shelling Test 1: Displacement: 0.42 mm; Volume: 0.50 in^3; Score: 0.210 mm*in^3.

Shelling Test 2: Displacement: 0.323 mm; Volume: 0.61 in^3; Score: 0.197 mm*in^3.

Selected from the 3rd set of trials.png

Shelling Test 2 (above) provided the best score despite being only marginally better than the score without any shelling at all. The small difference was still desirable, so Shelling Test 2 provided the base for the fourth and final step: lightening holes and filleting. Here, the goal was to round edges to decease stress build up on corners as well as to decrease volume with holes.


Lightening Holes and Filleting Test 1: Displacement: 0.33 mm; Volume: 0.59 in^3; Score: 0.196 mm*in^3.


Final Design

The final design (shown below) had almost every corner rounded. This reduced the stress substantially. No holes were used in the end because they seemed to decease weight insignificantly at the expense of much higher displacements. We are happy with the final design that has measurements as follows:

Displacement: 0.29 mm; Volume: 0.61 in^3; Score: 0.17 mm*in^3.

Selected from the 3rd set of trials.png