3.4: Materials, F Flashcards
Define: Elasticity
A property of a body to resume its original shape/size once the deforming force/stress has been removed
Define: Deformation
Change in shape of size of an object.
- Elastic - returns to OG shape
- Plastic - doesn’t return to OG shape
Define: Hooke’s law
An extension of an object is proportional to the force, provided the elastic limit is not exceeded
-F = kx
How do you find the overall force constant of a system ‘k’ of multiple springs/wires in series
k1 - 1/k=1/k + 1/k …..
k2
Same as capacitors (Think more distance)
How do you find the overall force constant of a system ‘k’ of multiple springs/wires in parallel
k1,k2 -k = k + k +k
Same as capacitors(Think more area)
Define: Stress
Force per unit cross sectional area
σ = F/A
Define: Strain
Extension per unit length
ε = x/I
Define: Ultimate tensile strength
Maximum stress a material can withstand (while being stretched/pulled) before it fails or breaks
What factors must engineers consider when designing a structure
- Ultimate tensile strength
- Breaking stress
Define: Elastic potential energy
Energy stored in a stretched material
Define: Young modulus for a material
Measure of stiffness of a material
Tensile stress over tensile strain, both are proportional until the limit of proportionality
What is given by the area contained under a stress-strain graph
Elastic potential energy (per unit volume)
-Gradient = YM
Define: Ductile
Can be drawn into wires and will show plastic deformation under tensile stress before breaking
Define: Malleable
Can be hammered into flat sheets, will show extensive plastic deformation under compressive forces
Define: Brittle
Will break will little/no plastic deformation
