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.

Fatigue testing of coated fabrics

Base materialTenacity loss at failure location 100 cycles, %Failure location
Vectran0.8Away from fatigued crease
Aramid22.9At crease

Flex fatigue results on 1500D yarn

MaterialCycles-to-Failure
Vectran T97115,113
Aramid 15,114
Aramid 240,666
Aramid 31,383
PBO23,821

Test conditions: Tinius Olsen tester, ASTM D2176-97a, modified for yarn, 2 kg weight

Flex fatigue results on 2 mm cords

MaterialCycles-to-Failure
Vectran T11741,909
Aramid 12,115
Aramid 214,963
Aramid 38,143
PBO25,158

Construction: parallel core/extruded jacket. Test conditions: 45 mm dia 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 dia. ratio

Breaking strength vs. D:d ratio

Wire rope construction

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