Topic 6 - Mechanical Properties

Question 1

Stress and Strain: What are they and why are they used instead of load and deformation?

Answer 1

These are size-independent measures of load and displacement.

Question 2

Elastic behavior: When loads are small, how much deformation occurs? What materials deform least?

Answer 2

-Reversible behavior often shows a linear relation between stress and strain.
-To minimize deformation, select a material with a large elastic modulus.

Question 3

Plastic behavior: At what point does permanent deformation occur? What materials are most resistant to permanent deformation?

Answer 3

-This permanent deformation behavior occurs when the tensile (or compressive) uniaxial stress reaches pheta y.

Question 4

Toughness and ductility: What are they and how do we measure them?

Answer 4

Toughness: The energy needed to break a unit volume of material.
Ductility: The plastic strain at failure.