http://arthra.ugal.ro/handle/20.500.14043/25370 2026-04-06T07:37:10Z 2026-04-06T07:37:10Z Diaconescu, Emanuel Spînu, Sergiu http://arthra.ugal.ro/handle/20.500.14043/25380 2020-09-03T13:27:33Z 2010-01-01T00:00:00Z

Elastic-Plastic Contact Modeling. Part II: Numerical Simulations and Program Validation Diaconescu, Emanuel; Spînu, Sergiu Elastic plastic spherical contact is simulated using an algorithm proposed in a companion paper. Materials of contacting bodies are assumed to have different behaviours: rigid (R), elastic (E), elastic-plastic with isotropic hardening (EP) or elastic - perfectly plastic (EPP). Algorithm improvements allow for a high resolution in digitization problem. A modified interference equation is proposed for the EP-EP contact with symmetry about the common plane of contact. Program predictions are matched against numerical results already published and a good agreement is found. Experimental validation of residual print depth in the R-EPP contact gives further confidence in the newly proposed algorithm. THE ANNALS OF “DUNĂREA DE JOS“ UNIVERSITY OF GALAŢI FASCICLE VIII, 2010 (XVI), ISSN 1221-4590, Issue 1 TRIBOLOGY

2010-01-01T00:00:00Z Spînu, Sergiu Diaconescu, Emanuel http://arthra.ugal.ro/handle/20.500.14043/25379 2020-09-03T13:27:33Z 2010-01-01T00:00:00Z

Elastic-Plastic Contact Modeling. Part I: Algorithm Overview and Assessment of Plastic Strain Increment Spînu, Sergiu; Diaconescu, Emanuel A fast algorithm for elastic-plastic contact simulation is overviewed in this paper. Betti’s reciprocal theorem is employed to assess surface normal displacement and stress state in an elastic half-space in the presence of plastic strains. Resulting equations suggest problem decomposition in an elastic and a residual part, which cannot be solved independently. While solution of the former is available from Polonsky and Keer’s algorithm for elastic contact with arbitrarily shaped geometry, the latter requires assessment of plastic zone. Plastic strain increment is derived employing a universal algorithm for integration of elastoplasticity equations. Elastic-plastic contact problem is solved iteratively based on the reciprocal adjustment between pressure and plastic strain, until convergence is reached. THE ANNALS OF “DUNĂREA DE JOS“ UNIVERSITY OF GALAŢI FASCICLE VIII, 2010 (XVI), ISSN 1221-4590, Issue 1 TRIBOLOGY

2010-01-01T00:00:00Z Papadatu, Carmen-Penelopi http://arthra.ugal.ro/handle/20.500.14043/25378 2020-09-03T13:27:33Z 2010-01-01T00:00:00Z

Monitoring the Influence of Thermomagnetic Treatment on the Ion Nitrided Layer Using Microhardness Curves, for 42MOCR11 Steel Grade Case Papadatu, Carmen-Penelopi Each of the stages of heat treatment in magnetic field (AC or DC) influences the hardness and durability of different steels. This influence is extended in the case of the measured microhardness values obtained in the thermo-chemical treated layers. In this case, the thermo-chemical treatment was applied after the thermo-magnetic volume treatment. This paper highlights the influence of thermo-magnetic treatment on the superficial plasma nitrided layers studying the microhardness curves. These curves are determined by the microhardness values obtained in the surface layer – values, which correspond to each treatment regime. THE ANNALS OF “DUNĂREA DE JOS“ UNIVERSITY OF GALAŢI FASCICLE VIII, 2010 (XVI), ISSN 1221-4590, Issue 1 TRIBOLOGY

2010-01-01T00:00:00Z Mereuță, Valentin V. Palaghian, Liviu C. http://arthra.ugal.ro/handle/20.500.14043/25377 2020-09-03T13:27:33Z 2010-01-01T00:00:00Z

Surface Roughness Parameters Evolution Under Fatigue Loading Mereuță, Valentin V.; Palaghian, Liviu C. The main objective of this paper is to demonstrate that in order to have a complete characterisation of fatigue degradation it is necessary to analyze the evolution of surfaces roughness, which can become a stress concentration. An experimental investigation has been carried out to see the evolution of the roughness amplitude parameters under a constant amplitude fatigue loading. Several bending fatigue tests were carried out using a flat specimen. It has been also confirmed that stress level applied on the specimen has an influence on the evolution of the roughness parameters during a fatigue test. THE ANNALS OF “DUNĂREA DE JOS“ UNIVERSITY OF GALAŢI FASCICLE VIII, 2010 (XVI), ISSN 1221-4590, Issue 1 TRIBOLOGY

2010-01-01T00:00:00Z