MACHINE DESIGN I Science Olympiad Structure Competition Test Apparatus July 2006

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MACHINE DESIGN I Science Olympiad Structure
Competition Test Apparatus July 2006
Grand Valley State University Padnos College of
Engineering and Computing
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Grand Valley State University Padnos College of
Engineering and Computing

• Design Considerations
• From the structure requirements, the test
  apparatus must
• Be compatible with the competition structures
• Record the maximum load applied to the structure
  at failure
• Display the applied load as the test progresses
• Allow structure to deflect up to 20 mm maximum
• Have adequate measurement accuracy and
  resolution
• Be simple to build and utilize common materials
• Be easy to operate
• Have a reasonable total cost.

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Grand Valley State University Padnos College of
Engineering and Computing

• Evaluation of Conceptual Designs
• Four design concepts were evaluated based on
  weighted criteria.
• The selected design scored high for many criteria
  and overall.

Design Characteristic Importance Factor Design 1 Design 1 Design 2 Design 2 Design 3 Design 3 Design 4 Design 4
Design Characteristic Importance Factor Rank Score Rank Score Rank Score Rank Score
Height adaptability 5 2 0.10 3.5 0.18 3.5 0.18 1 0.05
Simple to operate 20 1 0.20 2.5 0.50 2.5 0.50 4 0.80
Simple to build 10 1 0.10 3 0.30 4 0.40 2 0.20
Adequate measurement resolution 20 1 0.20 2 0.40 3 0.60 4 0.80
Measurement accuracy 20 1 0.20 3 0.60 3 0.60 3 0.60
Availability of materials 5 4 0.20 3 0.15 1.5 0.08 1.5 0.08
Cost 20 3.5 0.70 3.5 0.70 2 0.40 1 0.20
Total Score By Design 100 1.70 1.70 2.83 2.83 2.75 2.75 2.73 2.73
Importance Factors Percentage of Total Rating Importance Factors Percentage of Total Rating                
Design Rank 1, 2, 3 or 4 (1 lowest, 4 highest) Design Rank 1, 2, 3 or 4 (1 lowest, 4 highest)                
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Grand Valley State University Padnos College of
Engineering and Computing

• Design Description
• Applied load is transferred through mounting
  brackets on moment arm
• Electric motor, or manual crank, turns lead screw
  that drives the sliding mass along the moment
  arm
• Linear scale provides variable measurements in 1
  mm (0.025 kg) increments
• Electric switches stop the test upon failure,
  when 20 mm deflection is observed, or at end of
  travel.

Applied Load Mounting Brackets
Moment Arm
Sliding Mass
Motor (optional)
Linear Scale
System Control Box (optional)
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Grand Valley State University Padnos College of
Engineering and Computing

• Design Components
• Components are standard and readily available
  items or were constructed using standard
  materials.
• Custom components were designed w/ CAD and
  verified using FEA software.

Lead Screw
End Cap w/ Roller Bearing
Motor Mount w/ Roller Bearing
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Grand Valley State University Padnos College of
Engineering and Computing

• Structure Test Operation
• Virtual Model
• Prototype Model

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Grand Valley State University Padnos College of
Engineering and Computing

• Mounting Location Change Procedure
• Bridge to Tower Changeover
• Load Application Location

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Grand Valley State University Padnos College of
Engineering and Computing

• Summary
• The design is rigid, well-rounded, adaptable, and
  addresses all structure test requirements
• Test apparatus accommodates all competition
  structures
• Maximum test load of 15 kg and deflection of 20
  mm cannot be exceeded or affected by operator
  error
• Real-time variable and peak load measurements
  with resolution of 0.025 kg and no delay
  associated w/ digital displays
• Design allows for minimal and consistent
  measurement error
• Low cost construction ( less than 150 for
  motorized prototype or 75 for non-motorized)
• Design reinforces engineering concepts used by
  students for competition
• Test apparatus could be built by competition
  students instructors.

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Questions