Material Properties Flashcards

Flashcards on material properties, including mechanical and thermal properties.

Stress

Force per unit area

\sigma = \frac{F}{A}

Strain

Extent of deformation i.e. how much deformation per unit length

\epsilon = \frac{\Delta L}{L_0}

Modulus (Young Modulus)

Slope of stress-strain curve (elastic region); Indicator of stiffness

E = \frac{\sigma}{\epsilon}

Elastic behavior

If stress is removed, there is no strain (deformation is non-permanent); Linear relationship between stress-strain; Hooke’s law is followed

Plastic behavior

If stress is removed, the strain still exists (deformation is non-permanent) due to breakage and reorientation of atomic bonds; Non-linear relationship between stress-strain; Hooke’s law is not followed

Poisson ratio

Ratio of lateral to axial deformation

Yield strength

Transition of elastic to plastic region; The stress corresponding to the intersection of this line and the stress–strain curve as it bends over in the plastic region; Set strain offset of 0.002 (by convention), draw a parallel line to linear stress-strain curve, determine the stress that intersects stress-strain curve

Ultimate tensile strength

Maximum stress

Ductility

The extent of plastic deformation until fracture occurs; The opposite of brittleness

Toughness

The ability of a material to absorb energy and plastically deform before fracturing; Combination of strength and ductility; Measured by area under curve of stress-strain curve

Viscosity

Resistance force by fluid to movement

Density

Mass per unit volume

\rho = \frac{m}{V}

Specific heat

The amount of heat required to change the temperature (without phase change) per unit mass

Thermal conductivity

The amount of heat conducted per unit length (thickness) if there is a temperature gradient

\frac{Q}{\Delta t} = \frac{kA\Delta T}{d}