Structural evolution and predictive modeling for nonlinear tensile behavior of tri-component elastic-conductive composite yarn during stretch

Abstract

In our previous research, a tri-component elastic-conductive composite yarn (t-ECCY) with sophisticated structure was fabricated in one twisting process on a modified ring spinning frame, which employed the elastane filament as a core and the stainless steel filament combined with rayon fibers as a helical winding around the extensible core. Herein, structural assessment in initial and straighten states, a predictive model for the tensile behavior of t-ECCY during stretch, and the micro-morphologies of fractured yarn surfaces under varying strain rates were investigated. The deformation mechanism of coils in t-ECCY is the initial separation of adjacent coil surfaces and gradual unwinding until it is free of coils. The straight-limit level of t-ECCY is mainly dependent upon the geometric disposition of its constituents inside and the elastane draft ratio. No obvious changes were found under cyclic stretch, indicating its compact structure and super elasticity. The essentially nonlinear tensile behavior of t-ECCY was emphasized based on the typical characteristic S-curve and cord method. A modified Vangheluwe–Hook tensile constitutive model by introducing an exponent to the exponential function was proposed to fit experimental curves under varying strain rates, and the ideal analytical equations were obtained by using the genetic algorithm with 1stOpt simulation software for the nonlinear regression with iteration procedures. It was demonstrated that the proposed analytical model can fairly well replicate the stress characteristics of yarn under different strain rates qualitatively and quantitatively. In addition, a sharp break dominates at lower strain rates, whereas a local pull-out break is found at higher strain rates.