Gary F. Dargush

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A stationary principle is developed for dynamical systems by formulating the concept of mixed convolved action, which is written in terms of displacement and force variables, using temporal convolutions and fractional derivatives. The classical canonical single-degree-of-freedom dynamical system is considered as an initial application. With this new(More)
  • G F Dargush
  • Physical review. E, Statistical, nonlinear, and…
  • 2012
The principle of mixed convolved action provides a new rigorous weak variational formalism for a broad range of initial value problems in mathematical physics and mechanics. Here, the focus is initially on classical single-degree-of-freedom oscillators incorporating either Kelvin-Voigt or Maxwell dissipative elements and then, subsequently, on systems that(More)
The objective of this study is to develop a new constitutive model for cyclic response of metals with much broader applicability. Accordingly, a two-surface damage thermoplasticity model is proposed to understand inelastic behavior and to evaluate a potential damaged state of the metals. This model, which derived from small strain theory, is formulated(More)
Flow diverter (FD) is an emerging neurovascular device based on self-expandable braided stent for treating intracranial aneurysms. Variability in FD outcome has underscored a need for investigating the hemodynamic effect of fully deployed FD in patient-specific aneurysms. Image-based computational fluid dynamics, which can provide important hemodynamic(More)
The classical theory of piezoelectricity defines linear size-independent electromechanical response in non-centrosymmetric dielectrics that involves coupling between the electric field and the mechanical strains. However, with the continuing push to develop novel microand nanoscale materials, structures and devices, there is a need to refine and explore(More)
OBJECTIVE The aim of this study is to explain the influence of peripheral interface stress singularities on the testing of tensile bond strength. The relationships between these theoretically predicted singularities and the effect of specimen size on the measured bond strength are evaluated. METHODS Finite element method (FEM) and boundary element method(More)
Over the last two decades, significant research effort has been directed toward the application of advanced technologies to improve the seismic performance of civil infrastructure. MCEER has played a role in that development. In this paper, we present an overview of the integrated MCEER research program aimed at the development of a new generation of(More)
Most control techniques in the structural engineering literature are aimed at improving performance of the primary structural system, but may have limited or even adverse effect on nonstructural components during strong seismic events. In this paper, we emphasize nonstructural performance using an active controller with a cubic nonlinearity. The controller(More)
Based on thermodynamic principles, we derive expressions quantifying the non-harmonic vibrational behavior of materials, which are rigorous yet easily evaluated from experimentally available data for the thermal expansion coefficient and the phonon density of states. These experimentally-derived quantities are valuable to benchmark first-principles(More)
A true variational formulation is developed for dissipative processes based upon the concept of mixed convolved action. Here the focus is on continuum problems associated with heat diffusion, as well as related second sound phenomena. The convolved action can overcome the shortcomings of typical action principles, such as Hamilton’s principle, to address(More)