Computational Simulation of Micro- to Macroscopic Deformation Behavior of Cavitated Rubber Blended Amorphous Polymer Using Second-Order Homogenization Method

2014 ◽  
Vol 626 ◽  
pp. 74-80 ◽  
Author(s):  
Makoto Uchida ◽  
Naoya Tada
Keyword(s):  
Deformation Behavior ◽  
Volume Fraction ◽  
Amorphous Polymer ◽  
Computational Simulation ◽  
Fem Simulation ◽  
Homogenization Method ◽  
Second Order ◽  
Localized Deformation ◽  
Macroscopic Deformation ◽  
Rate Form

To evaluate the effect of the size of the microstructure on the mechanical property of the cavitated rubber blended (voided) amorphous polymer, the FEM simulation based on the rate form second-order homogenization method, in which rates of the macroscopic strain and strain gradient are given to the microstructure, was performed. Computational simulations of micro-to macroscopic deformation behaviors of amorphous polymers including different sizes and volume fractions of the voids were performed. Non-affine molecular chain network theory was employed to represent the inelastic deformation behavior of the amorphous polymer matrix. With the increase in the volume fraction of the void, decrease and periodical fluctuation of stress and localized deformation in the macroscopic field were observed, and were more emphasized with the increase in the size of the void. These results were closely related to the non-uniform deformation and volume increase of the void in the microscopic field.

Computational Simulation of Scale-Dependent Non-Uniform Deformation Behavior of Polymer Foam

2016 ◽  
Vol 725 ◽  
pp. 456-461 ◽  
Author(s):  
Makoto Uchida ◽  
Keita Suzuki ◽  
Yoshihisa Kaneko
Keyword(s):  
Deformation Behavior ◽  
Volume Fraction ◽  
Computational Simulation ◽  
Homogenization Method ◽  
Heterogeneous Structure ◽  
Polymer Foam ◽  
Foam Model ◽  
Bending Resistance ◽  
Rate Form ◽  
Polymer Wall

Polymer foam is widely used in the engineering field because of various functions such as lightweight, shock absorbing, insulation and so on. However, the strength of the material dramatically decreases with the increase in the volume fraction of the foam. Furthermore, deformation behavior of the material strongly depends on the microscopic heterogeneous structure consisting of foam and polymer wall. In the present study, a micro-to macroscopic deformation behavior of polymer foam is modeled using the rate-form second-order homogenization method. To model the microscopic structure consisting of foam and polymer wall, a hexagonal shape periodic structure was used, and the molecular chain network theory was used to represent an elastic-viscoplastic deformation behavior of polymer wall. The effect of the sizes of macroscopic and microscopic structures on the mechanical behavior of LDPE foam was investigated by computational simulation of bending of cantilever. The bending resistance, in other words, resistance to the strain gradient clearly depended on the comparative size between microscopic and macroscopic structures. For smaller foam model, the strain distributions were point symmetry, and those for different sizes of specimens were same. On the other hand, in larger foam model, strain field was not symmetry, and the magnitude of the asymmetry was emphasized for small specimen. Large difference in the macroscopic strain increasing with the microscopic size induced these asymmetry, and it caused size-dependent bending resistance of the LDPE foam.

MULTISCALE COMPUTATIONAL EVALUATION OF ELASTO-VISCOPLASTIC DEFORMATION BEHAVIOR OF AMORPHOUS POLYMER CONTAINING MICROSCOPIC HETEROGENEITY DURING UNIAXIAL TENSILE TEST

2010 ◽  
Vol 02 (03n04) ◽  
pp. 235-255 ◽  
Author(s):  
MAKOTO UCHIDA ◽  
NAOYA TADA
Keyword(s):  
Finite Element ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Amorphous Polymer ◽  
Element Model ◽  
Strength Distribution ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Viscoplastic Deformation ◽  
Heterogeneous Microstructures

The two-scale elasto-viscoplastic deformation behavior of amorphous polymer was investigated using the large deformation finite element homogenization method. In order to enable a large time increment for the simulation step in the plastic deformation stage, the tangent modulus method is introduced into the nonaffine molecular chain network theory, which is used to represent the deformation behavior of pure amorphous polymer. Two kinds of heterogeneous microstructures were prepared in this investigation. One was the void model, which contains uniformly or randomly distributed voids, and the other was the heterogeneous strength (HS) model, which contains a distribution of initial shear strength. In the macroscopic scale, initiation and propagation processes of necking during uniaxial tension were considered. The macroscopic nominal stress–strain relation was strongly characterized by the volume fraction and distribution of voids for the void model and by the width of the strength distribution for the HS model. Non-uniform deformation behaviors in microscopic and macroscopic scales are closely related to each other for amorphous polymers because continuous stretching and hardening in the localized zone of the microstructure brings about an increase in macroscopic deformation resistance. Furthermore, computational results obtained from the homogenization model are compared to those obtained from the full-scale finite element model, and the effect of the scale difference between microscopic and macroscopic fields is discussed.

Mesoscopic Modeling of Deformation Behavior of Semi-Crystalline Polymer

2005 ◽  
Vol 297-300 ◽  
pp. 2915-2921
Author(s):  
M. Uchida ◽  
Yoshihiro Tomita
Keyword(s):  
Deformation Behavior ◽  
Tensile Deformation ◽  
Cell Model ◽  
Computational Simulation ◽  
Crystalline Polymer ◽  
Homogenization Method ◽  
Unit Cell ◽  
Semicrystalline Polymer ◽  
Amorphous Phases ◽  
Tension And Compression

In present study, we clarify the micro- to mesoscopic deformation behavior of semicrystalline polymer unit cell by using large deformation finite element homogenization method. Crystalline plasticity theory with penalty method for enforcing the inextensibility of chain direction and nonaffine molecular chain network theory were applied to the representation of the deformation behavior of crystalline and amorphous phases, respectively, in composite microstructure of semicrystalline polymer. The different directional tension and compression are applied to the 2- dimensional plane strain semi-crystalline unit cell model. A series of computational simulation clarified highly anisotropic deformation behavior of microstructure of semi-crystalline polymer, which is caused by rotation of chain direction and lamella interface, and manifests as a substantial hardening/softening. This anisotropy for tensile deformation is higher than that for compressive deformation.

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