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Constitutive modelling of damage evolution and martensitic transformation in 316L stainless steel

Ryś M.

Acta Mechanica et Automatica

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2016

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Vol. 10, no. 2

125--132

EN

In this work, the constitutive model, derived with the use of thermodynamic of irreversible processes framework is presented. The model is derived under the assumption of small strains. Plastic strain induced martensitic phase transformation is considered in the austenitic matrix where the volume fraction of the martensite is reflected by a scalar parameter. The austenitic matrix is assumed as the elastic-plastic material and martensitic phase is assumed as randomly distributed and randomly oriented inclusions. Both phases are affected by damage evolution but there is no distinction in the model between damage in austenite and martensite.

2

Constitutive modelling and identification of parameters of 316L stainless steel at cryogenic temperatures

Ryś M.

Acta Mechanica et Automatica

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2014

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Vol. 8, no. 3

136--140

EN

In this work, a macroscopic material model for simulation two distinct dissipative phenomena taking place in FCC metals and alloys at low temperatures: plasticity and phase transformation, is presented. Plastic yielding is the main phenomenon occurring when the yield stress is reached, resulting in nonlinear response of the material during loading. The phase transformation process leads to creation of two-phase continuum, where the parent phase coexists with the inclusions of secondary phase. An identification of the model parameters, based on uniaxial tension test at very low temperature, is also proposed.

3

On non-equilibrium entropy in continuum thermodynamics of materials with memory

Huet C.

Archives of Mechanics

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1999

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Vol. 51, nr 2

123-154

EN

Based on previous works of the author, the fundamentals of some basic concepts and methods currently used in the formulation of constitutive equations for linear or non-linear dissipative materials are revisited. The principles of the local state - or local equilibrium state - frequently used as the basis of Thermodynamics of Irreversible Processes in connection with the problem of the definition of a non-equilibrium entropy - are discussed, with emphasis laid on materials with memory exhibiting - as in linear or non-linear viscoelasticity - a delayed response to a constant loading. A adiabatic relaxation experiment is defined, from which it is shown that the usual formulation of the local state principle is too strong, since the set of relations which holds in equilibrium, and which makes use of macroscopic variables only, can never be applied without modification out of equilibrium. The same holds for the non-equilibrium Gibbs equation generally associated with the corresponding formalism when written with the real stress and temperature involved in the process. For dissipative behaviour of the differential type of order one, called also Markovian behaviour, a non-equilibrium entropy can be defined and some of the equilibrium relations can be applied to non-equilibrium situations. From this, a basic thermodynamic classification of rheological behaviour is obtained. In the non-Markovian case, the results are applied to the method of internal variables. A criterion for identifying suitable internal variables is obtained. They should correspond to Markovian behaviour when directly stimulated.