The response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress

This article presents a computational constitutive model for glass subjected to large strains, high strain rates and high pressures. The model has similarities to a previously developed model for brittle materials by Johnson, Holmquist and Beissel (JHB model), but there are significant differences. This new glass model provides a material strength that is dependent on the location and/or condition of the material. Provisions are made for the strength to be dependent on whether it is in the interior, on the surface (different surface finishes can be accommodated), adjacent to failed material, or if it is failed. The intact and failed strengths are also dependent on the pressure and the strain rate. Thermal softening, damage softening, time-dependent softening, and the effect of the third invariant are also included. The shear modulus can be constant or variable. The pressure-volume relationship includes permanent densification and bulking. Damage is accumulated based on plastic strain, pressure and strain rate. Simple (single-element) examples are presented to illustrate the capabilities of the model. Computed results for more complex ballistic impact configurations are also presented and compared to experimental data.

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Response of aluminum nitride (including a phase change) to large strains, high strain rates, and high pressures

Journal of Applied Physics ◽

10.1063/1.1589177 ◽

2003 ◽

Vol 94 (3) ◽

pp. 1639-1646 ◽

Cited By ~ 82

Author(s):

Gordon R. Johnson ◽

Timothy J. Holmquist ◽

Stephen R. Beissel

Keyword(s):

Aluminum Nitride ◽

Phase Change ◽

High Pressures ◽

High Strain ◽

Large Strains ◽

Strain Rates ◽

High Strain Rates

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Response of boron carbide subjected to large strains, high strain rates, and high pressures

Journal of Applied Physics ◽

10.1063/1.370643 ◽

1999 ◽

Vol 85 (12) ◽

pp. 8060-8073 ◽

Cited By ~ 142

Author(s):

Gordon R. Johnson ◽

Tim J. Holmquist

Keyword(s):

Boron Carbide ◽

High Pressures ◽

High Strain ◽

Large Strains ◽

Strain Rates ◽

High Strain Rates

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An improved computational constitutive model for glass

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2016.0182 ◽

2017 ◽

Vol 375 (2085) ◽

pp. 20160182 ◽

Cited By ~ 7

Author(s):

Timothy J. Holmquist ◽

Gordon R. Johnson ◽

Charles A. Gerlach

Keyword(s):

High Pressures ◽

High Strain ◽

Experimental Testing ◽

Laboratory Data ◽

Experimental Results ◽

Large Strains ◽

Strain Rates ◽

High Strain Rates ◽

Surface Strength ◽

Improved Model

In 2011, Holmquist and Johnson presented a model for glass subjected to large strains, high strain rates and high pressures. It was later shown that this model produced solutions that were severely mesh dependent, converging to a solution that was much too strong. This article presents an improved model for glass that uses a new approach to represent the interior and surface strength that is significantly less mesh dependent. This new formulation allows for the laboratory data to be accurately represented (including the high tensile strength observed in plate-impact spall experiments) and produces converged solutions that are in good agreement with ballistic data. The model also includes two new features: one that decouples the damage model from the strength model, providing more flexibility in defining the onset of permanent deformation; the other provides for a variable shear modulus that is dependent on the pressure. This article presents a review of the original model, a description of the improved model and a comparison of computed and experimental results for several sets of ballistic data. Of special interest are computed and experimental results for two impacts onto a single target, and the ability to compute the damage velocity in agreement with experiment data. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

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