Modeling of multi‐cycle deformation of polymers with various deformation programs

Abstract

Purpose -The purpose of this paper is to compare mechanical response of polypropylene in multi-cycle tensile tests with strain-controlled and mixed deformation programs and to develop constitutive equations that describe quantitatively the experimental data. Design/methodology/approach -Multi-cycle tensile tests are performed on isotactic polypropylene with strain-controlled (oscillations between fixed maximum and minimum strains) and mixed (oscillations between a fixed maximum strain and the zero minimum stress) programs. A constitutive model is derived in cyclic viscoelasticity and viscoplasticity of semicrystalline polymers, and its parameters are found by fitting observations. The effect of damage accumulation of material parameters is analyzed numerically. Findings -The model predicts accurately mechanical behavior of polypropylene in tests with numbers of cycles strongly exceeding those used to determine its parameters. In the regime of developed damage, material constants in the stress-strain relations are independent of deformation program. Originality/value -A novel constitutive model is derived in cyclic viscoelastoplasticity of semicrystalline polymers and comparison of its adjustable parameters is performed for different deformation programs.

In Situ Study of Strain-Dependent Ion Conductivity of Stretchable Polyethylene Oxide Electrolyte

“…This is a feature of the viscoelasticity of the semicrystalline polymer and indicative of a type of mechanical damage 33 . Further cyclic loading shows a monotonic change in stress with cyclic loading which appears to approach an asymptotic value 34 .…”

Anisotropic mechanical behavior of semi‐crystalline polymers: Characterization and modeling of non‐monotonic loading including damage

“…The applications include (but are not limited to) polymer matrix for fiber‐reinforced composites, synthetic membranes for geotechnical engineering or ion batteries, or pipe applications (see recent reviews for more details). The semi‐crystalline polymers are the subject of many scientific researches aiming to understand and characterize their nonlinear elasto‐viscoplastic behavior and the associated deformation mechanisms under different and complex loading paths …”

“…Numerous experimental and theoretical studies have been reported last decades to characterize and model the plastic damage deformation under uniaxial tension, which induces important large strain deformation along with significant volume change that constitute the fundamental mechanical properties of ductile polymers . The most recent reported modeling approaches for semi‐crystalline polymers include the use of two‐phase or three‐phase microstructural models, homogenization procedures, rheological models integrating the physics of polymer chains, or multiscale computational approaches . They often led to moderately accurate results concerning the fully time‐dependent anisotropic response of such materials to complex loadings in large strains.…”