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3 Febbraio, 2014 17:00 oclock
Seminario Matematico e Fisico di Milano

Covariance of the second law

Paolo Mariano, Università di Firenze
Dipartimento di Matematica, Politecnico di Milano, Via Bonardi 9 - Aula Consiglio VII piano
Abstract

In my talk I shall discuss consequences of the requirement of covariance (structure invariance under diffeomorphism-based changes in observers) of the mechanical dissipation inequality, written for classes of bodies admitting processes along which their material texture changes irreversibly – mutant bodies, in short.
Mine is a tentative to answer the following question: Do the ideas leading to Nöther’s theorem admit counterparts in fully dissipative setting?
I shall discuss the question in the special case of standard elastic-plastic materials in large-strain regime, showing not only that the second law is a source of a priori constitutive restriction and the expression of the dissipation (the standard use of the second law in continuum mechanics), but also that the requirement of its covariance allows us to determine in addition the existence of the stress tensor, and the pointwise balances of standard and configurational actions, all arising from a unique source.
The choice of considering elastic-plastic materials is dictated just by the will of having at disposal a classical setting that can be easily detected by a not particularly specialized audience.
However, the technique that I shall indicate can be used also for viscous and general complex bodies (and I shall sketch briefly the way). In the last case, it would furnish a safe tool for determining appropriately balance equations for wide classes of complex materials in dissipative setting in case we are interested in constructing new models.

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Mathematical Seminars
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