materials Flashcards
What is an elastic material ?
A material that does not have a limit of proportionality/can return to original shape
What is a plastic material ?
Material that can be permanently altered by applying force
What is the area under loading curve ?
Work done in stretching a spring
What is the area under unloading curve ?
energy released/stored
difference due to thermal
Where is the limit of proportionality ?
Where the graph is no longer a straight line
What is the limit of proportionality ?
Where a spring no longer obeys Hooke’s law
What is the elastic limit / Yield point ?
Where an object no longer returns to original length when force is removed
What does it mean if the loading and unloading curves end in the same place ?
the material behaves elastically
What does it mean if the loading and unloading curves don’t end in the same place ?
the material behaves plastically
How to calculate spring constant of 2 springs ‘in series’
spring constant of 1 spring / 2
How to calculate spring constant of 2 springs ‘in parallel’
spring constant of 1 spring x 2
What is tensile stress ? (and units)
F / A
Force per cross sectional area
Pa
What is tensile strain ? (and units)
(ΔL) / L
Extension per unit length
No Units
How to find the cross sectional area for tensile stress ?
Use a micrometer at several points and find a mean radius
- use A = πr²
How do you find the Youngs Modulus graphically ?
The gradient / Use values given with equation
