Calculating the Specific strength for the rod

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SUMMARY

The discussion focuses on calculating the maximal length and minimal width of a rod made from specific materials, particularly steel and carbon nanotubes, when subjected to gravitational forces. The concept of specific strength is crucial for determining the feasibility of supporting long rods, such as a 5 km or 50 km rod. The participants emphasize the need for formulas that incorporate specific strength values to ascertain the rod's structural integrity under various conditions. The conversation highlights the importance of material selection in engineering applications involving extreme lengths.

PREREQUISITES
  • Understanding of specific strength and its significance in material science.
  • Familiarity with structural engineering principles and calculations.
  • Knowledge of materials such as steel and carbon nanotubes.
  • Basic grasp of physics related to forces and material stress.
NEXT STEPS
  • Research the specific strength values of various materials, including carbon nanotubes.
  • Learn about structural analysis techniques for long-span structures.
  • Explore formulas for calculating bending stress and tensile strength in rods.
  • Investigate engineering applications of carbon nanotubes in construction and design.
USEFUL FOR

Engineers, material scientists, and students interested in structural integrity and material selection for long-span constructions will benefit from this discussion.

Eagle9
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Imagine the skyscraper and the very long rod placed on its top that rotates from horizontal position to upwards.
http://img109.imageshack.us/img109/4817/fhfn.png
I would like to know how is it possible to calculate/ascertain the maximal length and minimal width of the rod made of some certain material, let’s say steel. For example, is it possible to hold the rod with the length of 5 km horizontally (not by hands of course :smile:)? The rod will be broken? What, if I need to hold much longer rod (let’s say 50 km)? Which material should I use? How can I calculate its maximal possible length? As far as I know I need to use the values of Specific strength, right? In Wikipedia I found the article: http://en.wikipedia.org/wiki/Specific_strength and the values for various materials, then what? Let’s assume I am using the carbon nanotubes and I created the rod (not the elastic ribbon like Space Elevator’s cable), how can I calculate its possible maximal length? Is there any formula for this purpose? :smile:
 
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Does not anybody know this? :smile:
 

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