View Single Post
  #31  
Old 12-06-2018, 12:38 PM
Rodger Knox Rodger Knox is offline
Registered User
 
Join Date: Jul 2013
Location: Baltimore, Md.
Posts: 2,431
Default

Quote:
Originally Posted by murrmac123 View Post
Not sure about that , Rodger.

If you compress a flexible steel bar, for example, you put the convex side into tension, and the concave side into compression, but there is no dimensional change.

Same with a guitar neck IMO.
"If you compress a flexible steel bar" implies (to an engineer) axial loading which means all of the cross section of the bar is in compression, and it will be shortened equal to the force time the modulus of elasticity. The rest of the quote seems to imply that you meant "bend" instead of "compress", which would put the convex side into tension, and the concave side into compression. The bend is a dimensional change, the convex side is stretched a bit by the tension and the concave side is squeezed a bit by the compression.

The concept I'm trying to get across is that any force applied to a material results in a deformation of that material, and that deformation is proportional to the force applied, and the modulus of elasticity of the material is the proportionality constant. All materials behave this way up to the elastic limit, which is the amount of force required for permanent deformation or failure.

This is basic mechanics of materials for an engineer, and there's a language that engineers use to discuss these concepts. Stress is a force per unit area, strain is the deformation caused by the stress. It's difficult for me to discuss these concepts without resorting to engineerspeak.

Sorry for the derail...
__________________
Rodger Knox, PE
1917 Martin 0-28
1956 Gibson J-50
et al
Reply With Quote