ISO 20975-1:2023 繊維強化プラスチック複合材 — ラミネートの厚さ方向特性の測定 — Part 1: 直接引張および圧縮試験 | ページ 6

3.1

tensile stress

σ_33T

tensile force, carried by the test specimen at any particular moment, divided by the initial cross-sectional area of the specimen at the specimen mid-length

Note 1 to entry: It is expressed in megapascals, MPa.

3.2

tensile failure stress or strength

σ_33TM

tensile stress (3.1) at the moment of failure, or when the load reaches a maximum value

Note 1 to entry: It is expressed in megapascals, MPa.

3.3

tensile failure strain

ε_33TM

through-thickness strain at the tensile failure stress or strength, σ_33TM (3.2)

Note 1 to entry: It is expressed as a dimensionless ratio or in percent, %.

3.4

modulus of elasticity (chord) in tension

E_33T

chord modulus obtained from the ratio of the stress difference (σ” minus σ') and the corresponding strain difference (ε” = 0,002 5 minus ε' = 0,000 5)

Note 1 to entry: It is expressed in megapascals, MPa.

Note 2 to entry: A ratio of the stress difference (σ” minus σ') and the corresponding strain difference (ε” minus ε') may be used if failure strain, ε_33TM, is less than 0,002 5. Where this is the case, ε”, and the corresponding value of σ”, should be taken as the maximum values of strain and stress, respectively, in the linear region of the stress-strain response.

3.5

compressive stress

σ_33C

compressive force, carried by the test specimen at any particular moment, divided by the initial cross-sectional area of the specimen at the specimen mid-length

Note 1 to entry: It is expressed in megapascals, MPa.

3.6

compressive failure stress or strength

σ_33CM

compressive stress (3.5) at the moment of failure, or when the compressive load reaches a maximum value

Note 1 to entry: It is expressed in megapascals, MPa.

3.7

compressive failure strain

ε_33CM

through-thickness strain at the compressive failure stress or strength, σ_33CM (3.6)

Note 1 to entry: It is expressed as a dimensionless ratio or in percent, %.

3.8

modulus of elasticity (chord) in compression

E_33C

chord modulus obtained from the ratio of the stress difference (σ” minus σ') and the corresponding strain difference (ε” = 0,002 5 minus ε' = 0,000 5),

Note 1 to entry: It is expressed in megapascals, MPa.

Note 2 to entry: A ratio of the stress difference (σ” minus σ') and the corresponding strain difference (ε” minus ε') may be used if failure strain, ε_33CM, is less than 0,002 5. Where this is the case, ε”, and the corresponding value of σ”, should be taken as the maximum values of strain and stress, respectively, in the linear region of the stress-strain response.

3.9

Poisson’s ratio

ν

negative ratio of the strain, ε_n, in one of the two axes normal to the direction of loading, to the corresponding strain ε, in the direction of loading, within the initial linear portion of the longitudinal versus normal strain curve

Note 1 to entry: It is expressed as a dimensionless ratio.

3.10

specimen coordinate axes

1, 2, 3

coordinate axes for the material with the fibres preferentially aligned in one direction

Note 1 to entry: The direction parallel with the fibre axes is defined as the “1” direction, the direction perpendicular and in the same plane as the “2” direction, and the direction perpendicular to the 1-2 plane as the “3” direction. For other materials, the “1” direction is normally defined in terms of a feature associated with the production process, such as the long direction for continuous sheet processes. The “2” direction is perpendicular to the “1” direction in the same plane, and the “3” direction is perpendicular to the 1-2 plane. Results for specimens cut parallel with the “3” direction are identified by the subscript “33” (e.g. E_33T). See Figure 1.

Note 2 to entry: The “1” direction is also referred to as the 0 degree (0°) or longitudinal directional, the “2” direction as the 90 degree (90°) or transverse direction, and the “3” direction as the through-thickness or out-of-plane direction.

Note 3 to entry: The specimen height corresponds to the through-thickness or out-of-plane direction dimension.

Figure 1 — Aligned fibre-reinforced composite plate element showing specimen coordinate axes