Nonlinear thermomechanical response and constitutive modeling of viscoelastic polyethylene membranes

Bosi, F.; Pellegrino, Sergio

doi:10.1016/j.mechmat.2017.10.004

Cited by 18 publications

(20 citation statements)

References 25 publications

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“…The break elongation was 30% higher in the TD and 43% lower in the MD when compared to the material data sheet in Table 1, which might be caused by the laboratory conditions and influenced by the specimen size. The experimental measurements also confirmed previous studies showing that LLDPE is stiffer in the MD compared to the TD [3,5,6,15].…”

Section: Discussionsupporting

confidence: 88%

“…The structure of LLDPE leads to its heterogeneous non-linear behavior. LLDPE is very flexible, elongates under stress, absorbs a high level of impact energy, and thus, is suitable for making thin and ultra-thin films [5][6][7][8]. The mechanical properties of polyethylene depend on its complex structure [9], which leads to non-linear heterogeneous behavior during mechanical and numerical tests.…”

Section: Introductionmentioning

confidence: 99%

“…The double yield point is also mentioned in the literature [16]. The relation between yield stress, temperature, and strain rate can be described by constitutive laws [5,6,9,17], and the temperature-dependent mechanical properties of thin-layered materials have been addressed [18]. Upon comparing LDPE, LLDPE, and HDPE, LLDPE showed greater rate sensitivity than the other two materials under both static and dynamic regions of a compression test [9].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

et al. 2021

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Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

et al. 2021

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“…Since the orthotropy of StratoFilm 420 is not very pronounced [35], with a difference of ca. 12% between the two directions, the isotropic assumption has been shown to correctly predict the average stress at the center of the thin circular membrane [38]. Through this assumption, the yield point obtained by means of diaphragm inflation experiments represents an equi-biaxial limit as reported in Fig.…”

Section: Biaxial Yield Stressesmentioning

confidence: 78%

“…A large strain orthotropic thermomechanical constitutive model has been developed to describe the viscoelastic behavior of the material over a wide range of temperatures, strain rates, and mechanical loading conditions [37,38].…”

Section: Methodsmentioning

confidence: 99%

Molecular based temperature and strain rate dependent yield criterion for anisotropic elastomeric thin films

Bosi

Pellegrino

2017

Polymer

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A molecular formulation of the onset of plasticity is proposed to assess temperature and strain rate effects in anisotropic semicrystalline rubbery films. The presented plane stress criterion is based on the strain rate-temperature superposition principle and the cooperative theory of yielding, where some parameters are assumed to be material constants, while others are considered to depend on specific modes of deformation. An orthotropic yield function is developed for a linear low density polyethylene thin film. Uniaxial and biaxial inflation experiments were carried out to determine the yield stress of the membrane via a strain recovery method. It is shown that the 3% offset method predicts the uniaxial elastoplastic transition with good accuracy. Both the tensile yield points along the two principal directions of the film and the biaxial yield stresses are found to obey the superposition principle. The proposed yield criterion is compared against experimental measurements, showing excellent agreement over a wide range of deformation rates and temperatures.

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Experimental investigation and numerical simulation for structural evolution and stress distribution during the stretching process

Zhang

Lei

Bai

et al. 2022

Polymer Engineering & Sci

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In the preparation of polyethylene (PE) microporous membrane, the stretching process of PE/liquid paraffin (LP) blend is of great significance for improving the mechanical properties and optimizing the pore size and its distribution. In this study, we have adopted a method that combines experimental investigation and numerical simulation to explore crystal structure transformation and residual stress distribution of PE matrix during the stretching process. First of all, the X‐ray diffraction, small‐angle X‐ray scattering test, and tensile strength test are used to analyze these PE/LP blend samples that are processed at different stretching temperatures (110°C, 115°C, 120°C, 125°C) and different stretching ratios (2 × 2, 3 × 3, 4 × 4, 5 × 5). It is found that a higher temperature or larger ratio is beneficial for crystallizing of PE long chains and affecting the tension strength. After the extraction process, the obtained PE microporous membranes have more uniform pore size distribution and an increased pore diameter according to the results of scanning electron microscopy and porosity test. It is attributed to the fact that residual stress is more easily stored in the amorphous region of PE microporous membrane. PE microporous membranes can have higher crystallinity and well‐dispersed crystal region by controlling a matched temperature and ratio. It is inspired for optimizing the technological parameters in industrial production.

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Nonlinear thermomechanical response and constitutive modeling of viscoelastic polyethylene membranes

Cited by 18 publications

References 25 publications

Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Molecular based temperature and strain rate dependent yield criterion for anisotropic elastomeric thin films

Experimental investigation and numerical simulation for structural evolution and stress distribution during the stretching process

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