Exam 1 Terms (MSE 2001)

Determines price of materials

Material-driven costs

• Terrestrial abundance

• Extraction cost

• People-driven costs

People-driven costs

• Supply/demand

• Technology

• Geopolitics

• Speculation

Material-driven costs

• Terrestrial abundance

• Extraction cost

People-driven costs

• Supply/demand

• Technology

• Geopolitics

• Speculation

Stiffness

Force (stress) it takes to flex material

Strength

Force (stress) it takes to permanently deform material

Toughness

Energy it takes to break material

Performance parameters

• Load (kg, lb, N)

• Total elongation (mm, cm, in)

Stress (σ)

N/m², Pa

Strain (ε)

No units

Produces a stress-strain curve

Tensile test

Elastic deformation

• Deformation is temporary

• Stress/strain linear relationship

• Material returns to original shape

Plastic deformation

• Deformation is permanent

• Stress not proportional to strain

Poisson’s ratio

lateral strain / longitudinal strain (0.3 for most materials)

Yield stress (σᵧ)

“Strength,” stress to permanently deform material

Elastic modulus (E)

stress / strain

Increasing E makes a material…

More stiff

Ultimate tensile strength (UTS)

“Ultimate strength,” stress beyond which material fails/fractures

Ductility

Maximum strain (% elongation) at failure

Modulus of resilience (Ur)

Describes elastic energy per volume returned to material after stress

Coefficient of restitution

Performance parameter for modulus of resilience

Toughness

Energy per volume to break material