Chapter 6 - Materials Flashcards
What is tensile deformation?
When a material stretches as a result of a force
Compressive Deformation
When a material squashes as a result of a force
Hooke’s Law
The extension of a wire is directly proportional to the force acting upon it (F=kx)
Elastic Deformation
Spring returns to original length when force is removed
Plastic Deformation
Spring does not return to original length after force is removed
Stress
Force applied per unit cross sectional area of a wire
Strain
The fractional change in the original length of the wire
Young Modulus
The ratio of stress & strain for a particular material
Ultimate Tensile Stress
The maximum stress a material can withstand before breaking
The limit of proportionality on a stress-strain graph
The point where the material stops obeying Hooke’s law and the gradient decreases
The elastic limit on a stress-strain graph
The point from where the material will no longer return to its original shape once the force is removed
The yield point on a stress-strain graph
The point where the material starts to stretch without any extra load
What does the stress-strain graph for a brittle material look like?
A straight line through the origin
What does the stress-strain graph for a ductile material look like?
A straight line which then curves downwards twice before breaking
What does the stress-strain graph for rubber look like?
A curved line when loading, with a similar line below it when unloading
