Lifetime Predictions for High-Density Polyethylene under Creep: Experiments and Modeling

Abstract

Observations are reported in uniaxial tensile tests with various strain rates, tensile relaxation tests with various strains, and tensile creep tests with various stresses on high-density polyethylene (HDPE) at room temperature. Constitutive equations are developed for the viscoelastoplastic response of semicrystalline polymers. The model involves seven material parameters. Four of them are found by fitting observations in relaxation tests, while the others are determined by matching experimental creep curves. The predictive ability of the model is confirmed by comparing observations in independent short- and medium-term creep tests (with the duration up to several days) with the results of numerical analysis. The governing relations are applied to evaluate the lifetime of HDPE under creep conditions. An advantage of the proposed approach is that it predicts the stress-time-to-failure diagrams with account for the creep endurance limit.

Creep behavior of 3D printed polymer composites

“…PLA pellets were purchased from Filabot (Barre VT, USA) having a melt flow index (MFI) of 3 g/10 min at 190 C, density of 1.24 g/cm 3 , and the glass transition temperature (T g ) of 55-60 C. TPU pellets were supplied by LNS technologies (Scotts Valley, CA, USA) with shore hardness of 90 A, density of 1.14 g/cm 3 , T g of À33 C, and MFI of 32 g/10 min a 224 C. PEG chips were purchased from Acros Organics (New Jersey, USA) having an average molecular weight (MW) of 6000 Dalton.…”

“…They can be used in several applications including automotives, aerospace, textiles, sports, and military. For this purpose, an extensive study of their mechanical deformation behavior is necessary 3 . Generally, the elastic–plastic mechanical deformation occurring due to tensile, compression, shear or bending loads are considered while designing the materials and structures.…”

A Numerical Model to Predict the Relaxation Phenomena in Thermoset Polymers and Their Effects on Residual Stress during Curing—Part I: A Theoretical Formulation and Numerical Evaluation of Relaxation Phenomena

“…Like almost all polymers, epoxy is a viscoelastic material. In addition, it demonstrates a behavior intermediately between an elastic solid and a viscous fluid, so its mechanical properties are time-dependent, and it is affected by creep and stress relaxation phenomena [11,12]. Many efforts were made to model the polymer's viscoelasticity mathematically [13][14][15]: the viscoelastic functions generally depend on temperature and applied stress for polymers and other isotropic and homogeneous materials; they are interconnected, and their relative placement in the time domain was described by Grassia et al [16] A linear behavior is assumed for the material under study: the relaxation functions do not depend on the mechanical input applied to the system.…”

Effect of Thermal Aging on Viscoelastic Behavior of Thermosetting Polymers under Mechanical and Cyclic Temperature Impact

“…However, the long-term behavior of polymer composites is not fully researched, and there are no standardized solutions that are needed for civil engineering. Although viscous behavior has been studied in several papers [12,13], the influence of temperature on viscous behavior has yet to be determined. In some papers, the influence of working temperature on stiffness is studied [9,10], but this is for immediate response, and does not consider the viscosity of the material.…”

“…In some papers, the influence of working temperature on stiffness is studied [9,10], but this is for immediate response, and does not consider the viscosity of the material. Although there are papers about the creep of polymers [12,14,15], they use different models and materials, and it is difficult to turn the results into practical solutions. Thermal behavior of polymers and FRPs has also been studied before [11,16] and is researched sufficiently.…”