A measure of a material's stiffness, expressed as the stress required to produce a unit of elastic strain in the same direction (if the material were capable of so much elastic strain). Determined as the slope of the elastic segment of a stress-strain curve produced during standardized tensile or compressive testing.
Elastic modulus is measured for all materials, typically as part of the suite of properties measured by standard tensile testing. For very brittle materials, the measurement can be done using acoustic methods instead. For heat treated and work hardened metals, elastic modulus stays the same even as strength rises and ductility drops.
The same suite of testing standards covers a number of properties that are derived from tensile stress-strain curves. ASTM tests include C1273 and C1366 for ceramics (at ambient and elevated temperatures, respectively), D412 for elastomers, D638 for plastics, D1623 for rigid polymeric foams, D3039 for polymeric-matrix composites, D3552 for metal-matrix composites, and E8 for metals.
ISO tests include 37 for elastomers, 527 for plastics, 1926 for rigid polymeric foams, and 6892 for metals. ISO testing standards for the tensile properties of ceramics are heavily fragmented.