1.1 This terminology standard is a compilation of definitions of technical terms related to force and deformation properties when evaluating a stress-strain curve of a textile. (See Figs. X1.1 and X1.2.) A chart showing the relationship of the basic terms is shown in Table 1. Terms that are generally understood or adequately defined in other readily available sources are not included.
1.2 For other terms associated with textiles, refer to Terminology D123.
TABLE 1 Relationship of Force and Deformation Terms
| Term | Symbol | Mathematical
Expression | Unit |
|---|
| Length | L | | mm (in.) |
| Extension | ΔL | | mm (in.) |
| Strain | | ΔL/L | |
| Elongation | | ΔL/L × 100 | % |
| Linear density | D1A | | tex (den) |
Cross-sectional
area | A | | mm2 (in.2) |
| Force | F | | N (lbf) |
| Tension | T | | N (lbf) |
| Strength | S | | N (lbf) |
| Tenacity | | F/D1A | mN/tex (lbf/den)B |
| Stress | | F/A | N/m2 (lbf/yd2)B |
A In computers, this may be given as “LD” instead of “D1”.
B For fibers, these inch-pound units are usually gf/den and gf/in.2