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Selected Works

Selected Works

Christopher Y. Tuan

Finite elements

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Viscoplastic Cap Model For Soils Under High Strain Rate Loading, Xiaoli Tong, Christopher Tuan Mar 2014

Viscoplastic Cap Model For Soils Under High Strain Rate Loading, Xiaoli Tong, Christopher Tuan

Christopher Y. Tuan

A viscoplastic cap model of the Perzyna type was developed for simulating high strain rate behaviors of soils. An associative viscous flow rule was used to represent time-dependent soil behaviors. The viscoplastic cap model was validated against experimental data from static and dynamic soil tests. The model was also compared with soil behaviors under creep and stress relaxation with good agreement. However, the model was unable to represent tertiary creep where strain softening became significant. The model was subsequently integrated into LS-DYNA for finite-element simulations of high strain rate behaviors of sandy and clayey soils in explosive tests. The significance …


Simulation Of Soil Behavior Under Blast Loading, J. An, Christopher Tuan Mar 2014

Simulation Of Soil Behavior Under Blast Loading, J. An, Christopher Tuan

Christopher Y. Tuan

A viscoplastic cap model was previously developed to address the high strain rate effect on soil behaviors. Although the model is an improvement over the inviscid cap model, it does not update soil density and bulk modulus as the shock wave propagates through the soil. Further, soil should be modeled as a three-phase porous media to accommodate various degrees of water saturation. This is especially true for the soil mass surrounding the source of energy release because each of the three phases responds differently to shock loading. A revised cap model comprising a Gruneisen equation of state for each of …