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In this paper a purely phenomenological formulation and finite element numerical implementation for quasi-incompressible transversely isotropic and orthotropic materials is presented. The stored energy is composed of distinct anisotropic equilibrated and non-equilibrated parts. The nonequilibrated strains are obtained from the multiplicative decomposition of the deformation gradient. The procedure can be considered as an extension of the Reese and Govindjee framework to anisotropic materials and reduces to such formulation for isotropic materials. The stress-point algorithmic implementation is based on an elastic-predictor viscous-corrector algorithm similar to that employed in plasticity. The consistent tangent moduli for the general anisotropic case are also derived. Numerical examples explain the procedure to obtain the material parameters, show the quadratic convergence of the algorithm and usefulness in multiaxial loading. One example also highlights the importance of prescribing a complete set of stress-strain curves in orthotropic materials. [ABSTRACT FROM AUTHOR]

This paper experimentally studies the tensile deformation behavior of polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), and PC/ABS blends (with the blending ratios of PC to ABS being 80:20, 60:40, 50:50, and 40:60) from low to high strain rates. Using the universal MTS-810 machine and the split Hopkinson tension bar (SHTB) testing system, the quasi-static and impact tension tests are carried out at the room temperature. The curves of the true stress and the true strain are obtained. The deformation behaviors of PC, ABS, and PC/ABS blends are characterized in detail. The linear relationship between the strain rate and the yielding stress is given. [ABSTRACT FROM AUTHOR]

In this paper, we provide a constitutive model for overall (macroscopic) plastic deformation behavior in a rubber-toughened polymer blend. A porous plasticity theory is employed as a basis for the constitutive modeling. In our investigation, the polycarbonate (PC) is chosen as a matrix material of polymer blend. First, the true uniaxial stress-strain relation for PC, which is an important part of the constitutive model, is carefully measured. Secondly, finite element analyses of neck propagation in a tensile specimen of PC are performed to test the efficiency of the introduction of the accurately measured true stress-strain relation into the model. Then, in order to investigate local and average deformation behavior of the matrix material (PC) around cavitated rubber particles in polymer blend, an axisymmetric unit cell analysis is carried out. Finally, finite element analyses of the neck propagation in a tensile specimen of a rubber-toughened PC are performed, and the numerical results are compared to experimental results. It is revealed that the present constitutive model has the ability to well reproduce the behavior of a rubber-toughened polymer blend with rather small volume fraction of rubber particles, which is up to about 10%. However, for blends with larger volume fraction of the rubber particles, the discrepancy between the computational and the experimental results increases. Several possibilities of enhancing the model are discussed. [ABSTRACT FROM AUTHOR]