Advertisement

Sports Engineering

, Volume 7, Issue 2, pp 89–96 | Cite as

Bungee jumping cord design using a simple model

  • J. W. KockelmanEmail author
  • M. Hubbard
Original Articles

Abstract

A simple energy model of a bungee jump is used to generate strain guidelines and practical design equations for the sizing of an all-rubber bungee cord. The cord is represented as a massless linear spring of elastic modulusE. A design strain between two and three (2<ε<3) is recommended to ensure a balance between lowg-forces in the cord (F/mg<3) and high factor of safety (f s >10). Cord design is essentially a two-step process. In the first step, the cord crossectional area is proportionally matched to the jumper's weight to ensure the specified design strain. In the second step, cord length is matched to the structure height so the jumper does not strike the ground. In a typical bungee jump using a body harness, the cord elongates 200% and exerts a maximum tensile force of three times the jumper's body weight. The ability of this model to predict strain accurately is enhanced by taking into account the viscoelastic nature of rubber.

Keywords

dynamics factor of safety g-force modelling natural rubber viscoelastic 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Braksiek, R.J. & Roberts, D.J. (2002) Amusement Park Injuries and Deaths.Annals of Emergency Medicine,39, 65–72.CrossRefGoogle Scholar
  2. Burton, R.R. & Whinnery, J.E. (2002) Biodynamics: Sustained Acceleration. In:Fundamentals of Aerospace Medicine (3rd ed.) (eds R.L. DeHart & J.R. Davis), pp. 151–152. Lippincott Williams & Wilkins, Philadelphia, PA, USA.Google Scholar
  3. Ciullo, P.A. & Hewitt, N. (1999)The Rubber Formulary, p. 96. Noyes Publications, Norwich, New York, USA.Google Scholar
  4. Elvin, D. (1999) On the Wild Side.Civil Engineering Magazine,69, 1–7.Google Scholar
  5. Haddad, H.M. (1995)Viscoelasticity of Engineering Materials, p. xviiii. Kluwer, Dordrecht, The Netherlands.Google Scholar
  6. Kagan, D. & Kott, A. (1996) The greater-than-g acceleration of a bungee jumper.The Physics Teacher,34, 368–373.CrossRefGoogle Scholar
  7. Menz, P.G. (1993) The physics of bungee jumping.The Physics Teacher,31, 483–487.CrossRefGoogle Scholar
  8. Palffy-Muhoray, P. (1993) Problem and solution: acceleration during bungee-cord jumping.American Journal of Physics,61, 379 and 381.Google Scholar
  9. Snyder, R.G. (1973) Impact: the ‘G’ system of units. In:Bioastronautics Data Book (2nd ed.) (eds J.F. Parker Jr & V.R. West), pp. 225–227. National Aeronautics and Space Administration SP-3006, Washington, D.C., USA.Google Scholar
  10. Strnad, J. (1997) A simple theoretical model of a bungee jump.European Journal of Physics,18, 388–391.CrossRefGoogle Scholar

Copyright information

© International Sports Engineering Association 2004

Authors and Affiliations

  1. 1.Department of Biomedical EnghineeringUniversity of CaliforniaDavisUSA
  2. 2.Department of Mechanical and Aeronautical EngineeringUniversity of California, DavisDavisUSA

Personalised recommendations