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Heating an elastic solid by stressing it verses it's hardness.

  1. Aug 26, 2012 #1
    I bought a cheaper set of roller blade wheels (you get what you pay for). With new wheels installed I had to work much harder to take longer on my usuall route. The new wheels had a hardness of 82a. The original wheels had a hardness of 80a and the last set had a hardness of 85a. The new wheels seemed "dead". I put back the old wheels on the right roller blade and tested the skates hoping to notice a difference between the sets of wheels. After about a mile of skating (could not difinitively say which set was worse) I came home and took them off and noticed right away that the dead set of wheels was significantly warmer then the older and faster set of wheels. I' m guessing the heat my be a reason the new wheels feel so dead.

    Can different elastic solids of the same hardness heat up differently when stressed repeatedly? Do cheap rollerblade wheels have greater losses? Will an expensive wheel bounce higher then a cheap wheel of similar hardness?

    I rolled the wheels off a 37 inch counter, the dead wheel rebounded 17 inches and the "better" wheel rebounded 25 inches. Could this explain why the cheap set of wheels slows me down?

    Thanks for any help!
  2. jcsd
  3. Aug 27, 2012 #2
    What did you do to compare the bearing friction?

    Do you know if any of the wheels were through hardened or case hardened?
  4. Aug 27, 2012 #3

    I did not control for the bearings. Both sets of wheels did spin freely though and the bearings in each set were relatively low mileage.

    The product description for the wheels did not say if they were hardened. Is that done to "plastic" wheels? Even the "good" set was not too expensive.
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