Structural Analysis and Computer Applications FINITE ELEMENT ANALYSIS

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Structural Analysis and Computer
ApplicationsFINITE ELEMENT ANALYSIS
Bobsleigh

• Liz Hobart
• Joel Stevenson

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Feel the Rhythm, Feel The Ride, Get On Up, Its
Bobsled Time
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History

• First bobsleigh developed in late 19th century
  when the Swiss attached a steering mechanism to a
  toboggan
• First bobsleigh club founded in 1897 in St.
  Moritz, Switzerland
• In 1923 the Fédération Internationale de
  Bobsleigh et de Tobogganing (FIBT) established
• Appeared in the first Winter Olympics in 1924 as
  a four-man race

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Assumptions

• Bobsleigh shape
• No dynamic forces
• No push bars
• Fibreglass shell not modelled
• Restraints

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Specifications
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Load Case 1 - Start

• Force to push a 210kg bob to a speed of 40km/h
  over 50m at 30? angle( ?K 0.03)
• Friction force 65N per runner
• Push force 57.8N per crew member

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Push Start Animation
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Load Case 2 - Cruising

• Instant crew members enter bob
• Dynamic forces ignored
• Force 9.8kN x 4 point loads

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Load Case 3 Crash Load

• 8.5 kN/m2 UDL applied to front section of bob
• Based on momentum of bob travelling at 140km/h

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Convergence Study
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Results Start

• Maximum deflection
• 0.5 mm in Y-direction

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Results - Cruising

• Maximum 7.8mm deflection downwards

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Results Crash Load

• Maximum deflection 40.2mm at centre
• Stress concentrations at edges of section
  1380MPa

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Crash Animation
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Modelling Difficulties

• Many plates at different orientations to achieve
  curves
• Complex grading
• Contains some triangular elements and Q8 plates
  with sharp angles
• Used in uncritical areas

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Conclusion

• Deflections not large enough to warrant change in
  material or extra reinforcement
• Injury to members more likely due to bob tipping
  over than crushing

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Any Questions?