Fatigue behavior of high-strength and high-modulus polymeric libers was investigated based on nonlinear dynamic viscoelaslic analysis under tension-tension cyclic strain condition. Poly(vinyl alcohol) (PVA) and thermotropic polyester(Vectran) fibers were used as specimens. The zone nonlinear dynamic viscoelastic analysis was proposed as a new approach to investigate the nonlinear dynamic viscoelaslic behavior in ditferent deformation stages during one period of cyclic deformation for polymeric materials. It was found that the nonlinear dynamic viscoelaslicily strongly depended on the rigidity of backbone chains of polymers. The polymeric libers with rigid polymer chains showed remarkable nonlinear viscoelaslic characteristics comparing with that with flexible polymer chains. Also, it was found from the zone nonlinear dynamic viscoelastic analyses that the nonlinear viscoelastic behavior during cyclic deformation was predominantly induced during the recovery process rather than the tensile process for polymeric libers, and the more remarkable nonlinear viscoelastic behavior was exhibited in the zone with higher strain rate. The polymeric libers with rigid polymer chains exhibited more remarkable nonlinear viseoelasticity and poorer fatigue strength. At the onset of fatigue failure, a sudden increase in nonlinear dynamic viscoelasticily was observed for polymeric libers. The sudden increase was considered to relate with the remarkable irreversible structural changes before the fatigue failure for polymeric materials.
All Science Journal Classification (ASJC) codes
- Polymers and Plastics
- Materials Chemistry