Midterm 2 Flashcards
Shear Stress
Stress due to the application of transverse forces on a member (object)
Normal strain in a rod under axial loading
Deformation per unit length of the rod
Stress-strain Diagram
Diagram showing the characteristic of the properties of a material which does not depend on the length of the material
What are the two broad categories for materials
Ductile and brittle materials
Which properties affect the result of a stress strain diagram
Temperature of specimen and speed of loading
What are ductile materials
Ductile materials are materials that are able to yield at normal temperatures
What is strain hardening, work hardening, cold working
The strengthening of a metal by plastic deformation
What causes the strengthening during strain hardening
It occurs due to Dislocation movements and dislocation generation within the crystal structure of the material
What is necking
When the diameter of a portion of the specimen begins to decrease due to local instability
How to determine unknown yield location
Offset Young’s modulus (rise/run) by 0.2%
How do you know if a material behaves elastically
If the strains in a test specimen from a given load disappear when the load is removed
What is the elastic limit
The largest value of stress causing elastic behaviour within a material
When does plastic deformation take place
If the stress value does not return to zero after a load has been removed
What are brittle materials
A Material that reaches its breaking strength the same time it reaches its ultimate strength
Characteristics of ductile failure
- One piece
- Large deformation
Characteristics of brittle failure
-Many piece
-Small deformation
What is toughness
The ability of a material to absorb energy and plastically deform without fracturing (I.e. area under stress-strain curve)
What is Resilience, Ur
The ability of a material to store energy
Temperature effects on strength and strain
Strain is unaffected while strength in tensile decreases
What is hardness
Measure of resistance to surface plastic deformation (dent or scratches)
