Difference between revisions of "Team F"

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(Design Development)
(Team Fα)
 
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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;
+
*Volume: 0.88 in^3;
Displacement: .3653;
+
*Displacement: 0.35 mm;
Score: .3214.
+
*Score: 0.308 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: 0.35 mm
 +
*Score: 0.315 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]]
  
 
==Synthesis of Designs==
 
==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.
+
The team decided to base the final design primarily on Team Fα's preliminary design because it performed better. The main element that we tried to maintain into our new design was the use of triangles in the central region of the arm, between each of the notches. We also cut away the portions past the notches, like in Team FΩ's design, because they did not add much structurally due to the position of the notches. The next task, which was not as directly informed by the earlier designs, was to determine how to remove mass from what remained.
  
 
==Design Development==
 
==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.
+
Step 1 was to find the ideal arrangement and orientation of the two triangular cuts in the center of the arm, since they had been arbitrary in earlier stages. In particular, we had to determine the ideal direction of the "strut" that the two triangles created and whether the triangles performed better if they were asymmetrically sized. The purpose here was to remove as much material as possible while retaining a triangular support structure.
  
 
Middle Bar Test 1:  
 
Middle Bar Test 1:  
Displacement: .298;
+
Displacement: 0.30 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .280.
+
Score: 0.280 mm*in^3.
  
 
Middle Bar Test 2:  
 
Middle Bar Test 2:  
Displacement: .2922;
+
Displacement: 0.29 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .277.
+
Score: 0.277 mm*in^3.
  
 
Middle Bar Test 3:  
 
Middle Bar Test 3:  
Displacement: .2682;
+
Displacement: 0.27 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .255.
+
Score: 0.255 mm*in^3.
  
 
Middle Bar Test 4:  
 
Middle Bar Test 4:  
Displacement: .2824;
+
Displacement: 0.28 mm;
Volume: .95 in^3;
+
Volume: 0.95 in^3;
Score: .268.
+
Score: 0.268 mm*in^3.
  
 
[[File:Selected from the 1st set of trials.png]]
 
[[File: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  
+
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.
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:  
 
Cut Test 1:  
Displacement: .358
+
Displacement: 0.36 mm;
Volume: .7 in^3
+
Volume: 0.70 in^3;
Score: .250
+
Score: 0.250 mm*in^3.
  
 
Cut Test 2:  
 
Cut Test 2:  
Displacement: .29
+
Displacement: 0.29 mm;
Volume: .72
+
Volume: 0.72 in^3;
Score: .209
+
Score: 0.209 mm*in^3.
  
 
Cut Test 3:  
 
Cut Test 3:  
Displacement: .277
+
Displacement: 0.28 mm;
Volume: .72
+
Volume: 0.72 in^3;
Score: .199
+
Score: 0.199 mm*in^3.
  
 
[[File:Selected from the 2nd set of trials.png]]
 
[[File: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.
+
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 without compromising too much stability.
  
 
Shelling Test 1:  
 
Shelling Test 1:  
Displacement: .4195
+
Displacement: 0.42 mm;
Volume: .50
+
Volume: 0.50 in^3;
Score: .210
+
Score: 0.210 mm*in^3.
  
 
Shelling Test 2:  
 
Shelling Test 2:  
Displacement: .323
+
Displacement: 0.323 mm;
Volume: .61
+
Volume: 0.61 in^3;
Score: .197
+
Score: 0.197 mm*in^3.
  
 
[[File:Selected from the 3rd set of trials.png]]
 
[[File:Selected from the 3rd set of trials.png]]
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Lightening Holes and Filleting Test 1:  
 
Lightening Holes and Filleting Test 1:  
Displacement: .3339
+
Displacement: 0.33 mm;
Volume: .59
+
Volume: 0.59 in^3;
Score: .196
+
Score: 0.196 mm*in^3.
  
Lightening Holes and Filleting Test 2:
 
Displacement:
 
Volume:
 
Score:
 
  
 
==Final Design==
 
==Final Design==
After testing the different cuts, shelling, and filleting options that were possible, we realized that the ultimate design included rounded edges. We kept the triangle and trapezoidal cut-outs in the center of the arm, but we filleted every edge possible on the inside and outside edges. We also added lightening holes through the sides to reduce the mass as much as possible while maintaining the same low displacement value.
+
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.
 +
 
 +
[[File:Final Robot Arm.png]]

Latest revision as of 23:23, 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: 0.35 mm;
  • Score: 0.308 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: 0.35 mm
  • Score: 0.315 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. The main element that we tried to maintain into our new design was the use of triangles in the central region of the arm, between each of the notches. We also cut away the portions past the notches, like in Team FΩ's design, because they did not add much structurally due to the position of the notches. The next task, which was not as directly informed by the earlier designs, was to determine how to remove mass from what remained.

Design Development

Step 1 was to find the ideal arrangement and orientation of the two triangular cuts in the center of the arm, since they had been arbitrary in earlier stages. In particular, we had to determine the ideal direction of the "strut" that the two triangles created and whether the triangles performed better if they were asymmetrically sized. 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 without compromising too much stability.

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.

Final Robot Arm.png