Accession Number : ADA254891


Title :   Systems of Evolution Equations in Thermochemical Equations


Descriptive Note : Final rept. 1 Sep 1988-29 Feb 1992,


Corporate Author : WISCONSIN UNIV-MADISON


Personal Author(s) : Tzavaras, Athanassios


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a254891.pdf


Report Date : 29 Apr 1992


Pagination or Media Count : 9


Abstract : In the framework of continuum mechanics the motion of deforming bodies is described by systems of nonlinear evolution equations, that arise by combining balance laws with constitutive relations characterizing the material response. The nonlinear character of the material response often induces a destabilizing mechanism that competes with dissipative mechanisms, such as viscosity or thermal diffusion. As a result of the competition coherent structures may appear, which at some level of modeling manifest themselves as singularities in the solutions of the corresponding model, These structures are diverse in nature, ranging from shock waves to shear bands to propagating phase boundaries, and no common theory can encompass all of them at present. Various instances of such phenomena were studied as part of the project. Specifically; (a) A class of test problems intended to test a thermoplastic instability mechanism for shear band formation at high strain rates. (b) Dynamics of spurt phenomena in viscoelastic flows. (c) Self-similar viscous and hydrodynamic limits for the equations of isentropic gas dynamics and the Broadwell system.


Descriptors :   *VISCOELASTICITY , *CONTINUUM MECHANICS , *THERMAL DIFFUSION , *VISCOUS FLOW , *SHEAR STRESSES , TEST AND EVALUATION , PLASTIC DEFORMATION , THERMOMECHANICS , COMPETITION , THEORY , MOTION , PHASE , DIFFUSION , THERMOPLASTIC RESINS , BALANCE , THERMOCHEMISTRY , SHOCK , RESPONSE , BOUNDARIES , MECHANICS , STRAIN RATE , INSTABILITY , HYDRODYNAMICS , BODIES , VISCOSITY , EQUATIONS , GAS DYNAMICS , RATES , STRUCTURES , MODELS , DYNAMICS , MATERIALS , SHOCK WAVES


Subject Categories : Fluid Mechanics
      Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE