**Eccentricity of loading.** Distance between the actual line of action of compressive or tensile loads and the line of action that would produce a uniform stress over the cross section of the specimen.

**Edge distance ratio.** Distance from the edge of a bearing strength test specimen to the center of the bearing hole, divided by the diameter of the hole. Edge distance ratio is generally reported with results of a bearing strength test

**Edge tearing strength.** Measure of the resistance of paper to tearing when folded over a V-notch beam and loaded in a tensile testing machine (ASTM D-827). Results are reported in lb or kg. See also tear resistance.

**Elastic hysteresis.** Difference between strain energy required to generate a given stress in a material and elastic energy at that stress. It is the energy dissipated as heat in a material in one cycle of dynamic testing. Elastic hysteresis divided by elastic deformation energy is equal to damping capacity.

**Elastic limit.** Greatest stress that can be applied to a material without causing permanent deformation. For metals and other materials that have a significant straight line portion in their stress-strain diagram, elastic limit is approximately equal to proportional limit. For materials that do not exhibit a significant proportional limit, elastic limit is an arbitrary approximation (apparent elastic limit).

**Elastic limit, apparent.** Arbitrary approximation of the elastic limit of materials that do not have a significant straight line portion on a stress-strain diagram. It is equal to the stress at which the rate of strain is 50% greater than at zero stress. It is the stress at the point of tangency between the stress-strain curve and a line having a slope with respect to the stress axis 50% greater than the slope of the curve at the origin.

**Elasticity.** Ability of a material to return to its original shape when load causing deformation is removed.

**Elongation.** Measure of the ductility of a material determined in a tension test. It is the increase in gage length (measured after rupture) divided by original gage length. Higher elongation indicates higher ductility. Elongation cannot be used to predict behavior of materials subjected to sudden or repeated loading.

**Embrittlement.** Reduction in ductility due to physical or chemical changes.

**Endurance limit.** Alternate term for fatigue limit.

**Energy absorption.** Energy required to fracture a specimen in an impact test. It is a measure of toughness or impact strength. Nil ductility transition temperature is derived from a series of energy absorption measurements at various temperatures.

**Engineering stress.** Load applied to a specimen in a tension or compression test divided by a cross section area of the specimen. The change in cross section area that occurs with increases and decreases in applied load is disregarded in computing engineering stress. It is also called conventional stress.

**Erichsen test.** Cupping test in which a sheet metal blank restrained at its edges is deformed at its center by a cone-shaped, spherical-end plunger until fracture occurs. Height of the cup (in mm) at fracture is an indication of ductility. (ASTM A-344).

**Expansion test.** Control and acceptance test for determining ductility of nonferrous metal tubing. A tapered pin is forced into the end of tubing to produce a specified increase in tube diameter. The tube is then examined for failure. (ASTM B-153). An alternate term is pin test.

**Extensometer.** Instrument for measuring changes in linear dimensions. Also called a strain gage.

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