Maciej Ryś, M.Sc., Eng.

Department of Mechanics of Materials (ZMM)
Division of Micromechanics of Materials (PMM)
position: assistant
telephone: (+48) 22 826 12 81 ext.: 418
room: 142
e-mail: mrys

Recent publications
1.Ryś M., Skoczeń B., Coupled constitutive model of damage affected two-phase continuum, MECHANICS OF MATERIALS, ISSN: 0167-6636, DOI: 10.1016/j.mechmat.2017.08.015, Vol.115, pp.1-15, 2017
Abstract:

A broad class of metastable materials, including selected alloys (e.g. stainless steels) used for applications in radiation environment (particle accelerators), is characterized by simultaneous occurrence of the plastic strain driven phase transformation and evolution of nano/micro damage. Plastic flow in such materials is usually accompanied by dynamic evolution of microstructure, resulting from the strain induced fcc-bcc phase transformation. Two-phase continuum is composed of austenitic matrix (fcc) and martensitic inclusions (bcc), represented by type Eshelby ellipsoidal entities embedded in ductile matrix. The matrix remains entirely plastic, and contains micro-cracks and micro-voids representing ductile damage. On the other hand, the inclusions are characterized by much higher yield stress and their behavior is generally brittle. Thus, brittle damage develops in the inclusions. The origin of damage is mechanical (manufacturing and load induced defects), and related to the source of radiation (primary or secondary particles flux). Among the lattice defects induced by radiation, the clusters of nano/micro voids are accounted for. The constitutive model takes into account the evolution of mechanically and radiation induced nano/micro damage in the presence of microstructure evolution, reflected by the plastic strain driven dynamic change of proportions between the matrix and the inclusions. The model is multiscale since the processes that occur at different scales (micro, meso, macro) are addressed, and coupled, since both phenomena: phase transformation and damage are described by coupled equations. Application to irradiated corrugated shells, components of thermo-mechanical compensation systems, are presented.

Affiliations:
Ryś M.-IPPT PAN
Skoczeń B.-Cracow University of Technology (PL)
2.Egner H., Ryś M., Total energy equivalence in constitutive modeling of multidissipative materials, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, ISSN: 1056-7895, DOI: 10.1177/1056789516679496, Vol.26, No.3, pp.417-446, 2017
Abstract:

In the present work, the total energy equivalence hypothesis was applied in constitutive modeling of engineering materials. The approach originally developed for damaged materials, was extended to modeling not only damage but also other dissipative phenomena, like phase transformation, in a consistent manner. The proposed model was examined by means of parametric studies to show its ability to reflect different experimentally observed features of real materials.

Keywords:

Constitutive modeling, dissipative material, plasticity, damage, phase transformation

Affiliations:
Egner H.-other affiliation
Ryś M.-other affiliation
3.Ortwein R., Ryś M., Skoczeń B., Damage evolution in a stainless steel bar undergoing phase transformation under torsion at cryogenic temperatures, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, ISSN: 1056-7895, DOI: 10.1177/1056789516656746, Vol.25, No.7, pp.967-1016, 2016
Abstract:

Phase transformation driven by plastic strains is commonly observed in austenitic stainless steels. In the present paper, this phenomenon is addressed in connection with damage evolution. A three-dimensional constitutive model has been derived, and scalar variables for damage and the volume fraction of the transformed phase were used. The model was solved using Abaqus UMAT user defined procedure, as well as by means of simplified one-dimensional approach for a twisted circular bar. Large experimental campaign of tests was performed, including martensite content measurements within the cross-section and on the surface of the bar during monotonic and cyclic loading. Based on the residual angle of twist, damage variable was calculated. The global response of torque versus the angle of twist was measured as well. Comparison between the experimental results and the results obtained from the simplified one-dimensional approach and from the full three-dimensional approach are presented. It turns out that one-dimensional formulation agrees quite well with full three-dimensional model. Thus, much simpler approach can effectively be used. Moreover, experimental results agree well in terms of the martensite content evolution and relation: torque versus the angle of twist. Damage evolution is correctly predicted in terms of the maximum values. Lastly, the evolution of damage during cyclic torsion is discussed, as the experimental results indicate rather surprising effect of unloading modulus recovery after each reversion of twist direction

Keywords:

Cryogenic temperatures, plastic strain-induced phase transformation, torsion, damage evolution, constitutive model, martensite, austenitic stainless steels

Affiliations:
Ortwein R.-CERN (CH)
Ryś M.-other affiliation
Skoczeń B.-Cracow University of Technology (PL)
4.Ryś M., Constitutive Modelling of Damage Evolution and Martensitic Transformation in 316L Stainless Steel, ACTA MECHANICA ET AUTOMATICA, ISSN: 1898-4088, DOI: 10.1515/ama-2016-0020, Vol.10, No.2, pp.125-132, 2016
Abstract:

n 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

Keywords:

Constitutive Modelling, Dissipative Materials, Phase Transformation, Damage Evolution

Affiliations:
Ryś M.-other affiliation
5.Egner H., Skoczeń B., Ryś M., Constitutive and numerical modeling of coupled dissipative phenomena in 316L stainless steel at cryogenic temperatures, International Journal of Plasticity, ISSN: 0749-6419, DOI: 10.1016/j.ijplas.2014.08.005, Vol.64, pp.113-133, 2015
Abstract:

A macroscopic material model for simulation of coupled dissipative phenomena taking place in FCC metals and alloys at low temperatures is developed. Three phenomena: plastic flow, plastic strain induced transformation from the parent phase ( to the secondary phase ( and evolution of micro-damage are studied using a thermodynamically consistent framework. The experimental results indicate a correlation between decreasing damage rate and increasing martensite content. For the micro-damage evolution in the parent austenitic phase a generalization of the classical isotropic ductile damage concept to anisotropic model has been adopted. The kinetics of damage evolution is based on the accumulated plastic strain as a driving force of ductile damage. On the other hand, the deterioration of the brittle secondary phase is described by the damage evolution equation expressed in the form of tensorial function, where the damage tensor depends directly on the stresses applied. This formulation accounts both for the isotropic damage, and for the oriented damage due to different effects of the stress tensor. Total amount of damage in the representative volume element is obtained via the linear rule of mixture. The results obtained in the course of numerical simulations fit well the experimental data

Keywords:

B. Constitutive behavior, A. Microcracking, A. Phase transformation, Cryogenic temperature

Affiliations:
Egner H.-other affiliation
Skoczeń B.-Cracow University of Technology (PL)
Ryś M.-other affiliation