Materials Flashcards
What is the equation for density?
ρ = M / V
What is the equation for elastic strain energy?
E = ½FΔL
E = ½Ke²
How is the total spring constant calculated for springs in parallel?
kₜ = k₁+ k₂…
How is the total spring constant calculated for springs in series?
1/kₜ = 1/k₁ + 1/k₂…
What is Hooke’s law (equation)?
F = kΔL
or
F = ke
What is Elasticity?
The ability of a solid to regain its shape after it has been deformed.
What is Tensile Deformation?
The deformation of a solid due to stretching.
Change in shape of solid due to stretching force.
What is Compression Deformation?
The deformation of a solid due to compression.
Change in shape of solid due to compressive force.
What is ductility?
The ability to be drawn into wire, ductile materials have a very large plastic region.
What is a brittle material?
Materials with little plastic deformation. Failure is sudden.
What is stress?
The force per unit of cross-sectional area applied to a material.
What is strain?
The change in length of a material over its original length.
How is loading and unloading on a metal wire related (graph)?
The curve obtained during unloading follows parallel to the original curve.
What is an alloy?
An alloy is a mixture of two or more metals.
How do you calculate the density of an alloy with two metals?
ρ = (ρ₁V₁ + ρ₂V₂) / Vₜ
What is Hooke’s Law?
A string’s extension is direct proportion to the force applied up until the elastic limit of the material.
How do you calculate Young’s Modulus?
Stress / Strain
What part of a stress-strain graph acts proportionally?
The elastic region of the material.
What part of a stress-strain is the elastic region?
Where the graph acts proportionally.
When a stress-strain graph begins to curve what does that point represent?
The elastic limit of the material.
How is the elastic limit of a material represented on a stress-strain graph?
Where the graph begins to curve
What is the name for the type of curve created by a force-extension graph of a wire?
Hysteresis curves
What happens when a plastic material is stretched and then unstretched?
Tangled when unstretched with weak intermolecular forces between molecules.
These break during stretching but new bonds reform when the tension is removed.
How is work done loading linked to work done unloading for a wire that follows Hooke’s Law?
The work done when loading = The work done when unloading
How is energy lost due to deforming a wire calculated?
Energy Lost = Work Done Loading - Work Done Unloading
What is the elastic limit of a material?
The point until which a material will return to its original shape when tension is withdrawn.
What is the yield point of a material?
The point where there is a large permanent change in length with no extra load force.
The material starts to behave like a plastic.
