Flex Fatigue Resistance

Flexural fatigue is a critical concern in many applications where yarns or fabrics are subject to repeated bending or creasing. Examples include ropes, sailcloth, inflatable and/or temporary structures, etc. Improving the service life of products by increasing flex fatigue resistance is an important driver for the use of Vectran fibers.

Flex Fatigue Resistance

Fatigue testing of coated fabrics

Base Material Tenacity Loss at Failure Location 100 Cycles, % Failure Location
Vectran 0.8 Away from fatigued crease
Aramid 22.9 At crease

Flex fatigue results on 1500D yarn

Material Cycles-to-Failure
Vectran T97 115113
Aramid 1 5114
Aramid 2 40666
Aramid 3 1383
PBO 23821

Test Conditions: Tinius Olsen tester, ASTM D2176-97a, modified for yarn, 4.5 lb weight.

Flex fatigue results on 2 mm cords

Material Cycles-to-Failure
Vectran T117 41909
Aramid 1 2115
Aramid 2 14963
Aramid 3 8143
PBO 25158

Construction: Parallel core/extruded jacket.
Test conditions: 45 mm diameter pulley, 45 kg test load, 58 cycles/min., 5 tests/sample on cyclic test machine.

Bend Tolerance

Tolerance to bending around small radii is important in ropes and cables, as it allows the use of smaller running gears or termination hardware. Aerospace and rope manufacturers conducted pin diameter tests on Vectran braid and wire rope, respectively.

Breaking strength vs. pin/cord diameter ratio 8×1500/1 construction

Bend Tolerance

Breaking strength vs. D/d wire rope construction

Bend Tolerance