On the application of FEM to deformation of high-density polyethylene

Abstract

This paper presents a study that uses finite element method (FEM) to simulate deformation behaviour of high-density polyethylene (HDPE) when subjected to tensile loading, either without or with the presence of pre-cracks. For the former, dog-bone-shaped model of HDPE was deformed under uni-axial tensile (UT) loading beyond the initial yielding, to generate stable necking in the gauge section. The paper proposes a simple correction factor to determine the equivalent von Mises stress that is needed for the input to the FEM model, in order to generate the same loading level as that observed experimentally for neck propagation. The paper points out that such consistency in the loading level could not be generated in the past mainly because of a misconception that axial stress in the neck was regarded as the equivalent of the von Mises stress. The study also explored the consideration of crack growth in double-edge-notched tensile (DENT) specimen, and showed that the conventional von Mises yield function, with the assumption of isotropic work hardening, cannot be directly applied to simulate the deformation behaviour of DENT specimen. Instead, empirical parameters were employed to reflect the polymer orientation during the necking process. The paper shows that FEM models for both UT and DENT tests can reproduce the experimental load-displacement curves quite accurately, and concludes that with a proper yield function to reflect the deformation involved in the mechanical tests, the deformation behaviour observed experimentally can be accurately mimicked using the FEM simulation.

Application of digital image correlation method to biogel

“…6a. Further information on the stress state within a uniaxial tensile specimen can be found in reference [30].…”

“…7b, it can be seen that at a concentration of 4% the curve is almost linear. Concentrations above 4% followed the linear trend which is typical in network polymers [30] rather than nonlinear quadratic polynomial.…”

A Finite Element Analysis of a Tapered Flat Sheet Tensile Specimen

“…7 and equation (15) as well as the correction factors given in equations (16), (17), (21) and (22)] should be limited to the maximum strain range of 100% or less (beyond the onset of diffuse necking but before any significant damage due to growth of micro-voids at localized necking). Determination of the plastic behavior of materials such as solid polymers and their finite element analysis up to a strain level of 250% under uniaxial tension can be found in the works such as by G'Sell and Jonas [27] and Kwon and Jar [28].…”

23. Study on the Behaviour of High-Density Polyethylene (Hdpe) Pipes Buried, on the Explosion’s Effect

“…The behavioural-modelling of HDPE activity is treated by different authors in [7][8][9][10][11][12][13][14][15], resulting in various constitutive equations. Starting from those presented in [2] and [16] and through laboratory experiments, the characteristic curve of the HDPE material was obtained ( Figure 1) by using HDPE's properties presented in Table 1.…”