Different mechanical measures of a material

[Appity]

Hi all, I'm attempting to get a feel for the different mechanical measures of a material, e.g., strength, toughness, stiffness, etc. I'm looking around, and I can't seem to figure out where a measure of stretchiness would fit in, that being how much a material will actually stretch or deform before breaking. Is that a measure in and of itself, or is that just a naive way of thinking of toughness?

 

[quanto]

how about the example of a balloon. the "stretchiness" of it , or how much it can expand before it bursts, could be expressed as the maximum capacity of air it can hold. but then you go back to the concept of its toughness, along the lines of endurance or something.

 

[Mech_Engineer]

What you're looking for is a summary of strength of materials. This Wikipedia article does an ok job of discussing some of the basics: http://en.wikipedia.org/wiki/Strength_of_materials

A material's "modulus of elasticity" is a measure of its stiffness under deformation, "Yield strength" is how far it will deflect before permanently deforming, and "ultimate strength" is how far it will deflect before breaking. These terms can have different variants for different materials (e.g. steels vs. plastics vs. composites) but they all basically have these concepts at their core.

 

[Mech_Engineer]

Another critical component of material strength studies is a stress-strain curve: http://en.wikipedia.org/wiki/Stress–strain_curve