An integral constitutive equation for nonlinear plasto-viscoelastic behavior of high-density polyethylene

1995 ◽  
Vol 35 (17) ◽  
pp. 1339-1347 ◽  
Author(s):  
J. Lai ◽  
A. Bakker
Keyword(s):  
Constitutive Equation ◽  
High Density Polyethylene ◽  
Viscoelastic Behavior ◽  
High Density ◽  
Integral Constitutive Equation

Viscoplastic Constitutive Equation of High-Density Polyethylene

2007 ◽  
Vol 340-341 ◽  
pp. 1097-1102 ◽  
Author(s):  
Yukio Sanomura ◽  
Mamoru Mizuno
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
High Density Polyethylene ◽  
Kinematic Hardening ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
High Density ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Creep Theory

A viscoplastic constitutive equation based on the kinematic hardening creep theory of Malinin-Khadjinsky and the nonlinear kinematic hardening rule of Armstrong-Frederick is formulated to describe the inelastic behavior of high-density polyethylene under various loading. The gentle progress of back stress by the introduction of loading surface in the viscoplastic strain space and smaller material constant under unloading can be expressed. Material constants are identified by various stress-strain curves under compression at constant strain rate and creep curves under compression at constant stress. The viscoplastic model can describe stress-strain curve under compression with change in strain rate and shear stress-strain curve including unloading. The model can qualitatively describe stress-strain curves under compression with changed strain rate including unloading, but it is quantitatively insufficient.

Effect of bark flour on viscoelastic behavior of high density polyethylene

2010 ◽  
Vol 45 (9) ◽  
pp. 1007-1016 ◽  
Author(s):  
Kamini Sewda ◽  
S.N. Maiti
Keyword(s):  
Storage Modulus ◽  
High Density Polyethylene ◽  
Volume Fraction ◽  
Viscoelastic Behavior ◽  
Peak Shift ◽  
High Density ◽  
Mechanical Restraint ◽  
Higher Temperature ◽  
Tan Δ ◽  
Damping Peak

The dynamic mechanical behavior of high density polyethylene (HDPE) in HDPE/bark flour (BF) composites on varying the volume fraction (Φf) of BF (filler) from 0 to 0.26 has been studied. The storage modulus decreases with increase in BF content up to Φf = 0.07, which is attributed to a pseudolubricating effect by the filler. The storage modulus for the composites at Φ f = 0.20 is higher than HDPE in all other temperature zones due to enhanced mechanical restraint by the dispersed phase. At Φf = 0.07, the loss moduli were either marginally lower or similar to that of HDPE, which is due to the ball-bearing effect of the filler as well as decrease in the crystallinity of HDPE. Above Φf = 0.07, the loss moduli were higher than HDPE. The α-relaxation region of the damping peak shifted toward the higher temperature side with increase in BF content. In the presence of the coupling agent, maleic anhydride-grafted HDPE (HDPE-g-MAH), the storage modulus values were marginally lower than those of the HDPE/BF systems. In the HDPE/BF/HDPE—g—MAH composites, the variations of the loss moduli were similar but values lower than those of the HDPE/BF systems. Damping peak shift in the α-region toward higher temperature was more than those of the HDPE/BF systems, which may be due to the hindrance to the relaxation due to an enhanced phase interaction. The values of tan δ were higher than the rule of mixture for both the composites.

scholarly journals Reliability of Free Inflation and Dynamic Mechanics Tests on the Prediction of the Behavior of the Polymethylsilsesquioxane–High-Density Polyethylene Nanocomposite for Thermoforming Applications

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2753
Author(s):  
Fouad Erchiqui ◽  
Khaled Zaafrane ◽  
Abdessamad Baatti ◽  
Hamid Kaddami ◽  
Abdellatif Imad
Keyword(s):  
Finite Element Method ◽  
High Density Polyethylene ◽  
Numerical Study ◽  
Viscoelastic Behavior ◽  
High Density ◽  
The Finite Element Method ◽  
Precise Knowledge ◽  
Least Squares Optimization ◽  
Dynamic Mechanical Testing ◽  
Thermoforming Process

Numerical modeling of the thermoforming process of polymeric sheets requires precise knowledge of the viscoelastic behavior under conjugate effect pressure and temperature. Using two different experiments, bubble inflation and dynamic mechanical testing on a high-density polyethylene (HDPE) nanocomposite reinforced with polymethylsilsesquioxane HDPE (PMSQ–HDPE) nanoparticles, material constants for Christensen’s model were determined by the least squares optimization. The viscoelastic identification relative to the inflation test seemed to be the most appropriate for the numerical study of thermoforming of a thin PMSQ–HDPE part. For this purpose, the finite element method was considered.

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