Abstract: The paper discusses the influence of the initial parameters on the strength parameters of S235JR steel at low stress triaxiality. The analysis was performed using the Gurson-Tvergaard-Needleman (GTN) material model, which takes into consideration the material structure. The initial material porosity was defined as the void volume fraction f0. The fully dense material without pores was assumed and the typical and maximum values of porosity were considered for S235JR steel in order to analyse the porosity effect. The strength analysis of S235JR steel was performed basing on the force-elongation curves obtained experimentally and during numerical simulations. Taking into consideration the results obtained, the average values of the initial void volume fraction fo = 0.001 for S235JR steel is recommended to use in a common engineering calculations for elements operating at low stress triaxiality. In order to obtain more conservative results, the maximum values of fo = 0.0024 may be used.
B I B L I O G R A F I A1. D. Teirlinck, F. Zok, J.D. Embury, M.F. Ashby, Fracture Mechanism Maps in Stress Space, Acta Metallurgica&apos
36, 5, 1213-1228. 1988.
2. A.L. Gurson, Continuum Theory of Ductile Rupture by Void Nucleation and Growth: Part I - Yield Criteria and Flow Rules for Porous Ductile Media, Journal of Engineering Materials and Technology. Transactions of the ASME, 99, l, 2-15. 1977.
3. V. Tvergaard, Influence of Voids on Shear Band Instabilities under Plane Strain Conditions, International Journal of Fracture, 17, 4, 389-407. 1981.
4. V. Tvergaard, A. Needleman, Analysis of the Cup-Cone Fracture in a Round Tensile Bar, Acta Metallurgica. 32, l, 157-169, 1984.
5. PN-EN 1993-1-10:2007 Eurocode 3: Design of Steel Structures - Part 1-10: Material Toughness and Through-thickness Properties.
6. G. Sedlacek, M. Feldmann, B. Kühn, D. Tschickardt, S. Höhler, C. Müller, W. Hensen, N. Stranghöner, W. Dahl, P. Langenberg. S. Münstermann, J. Brozetti, J. Raoul, R. Pope, F. Bijlaard, Commentary and Worked Examples to EN 1993-1-10 "Material toughness and through thickness properties" and other toughness oriented rules in EN 1993, JRC Scientific and Technical Reports. European Commission Joint Research Centre, 2008.
7. P.G. Kossakowski, An Analysis of the Load-Carrying Capacity of Elements Subjected to Complex Stress States with a Focus on the Microstructural Failure, Archives of Civil and Mechanical Engineering 10, 2, 15-39, 2010.
8. P.G. Kossakowski, W. Trąmpczyński, Numerical simulation of S235JR steel failure with consideration of the influence of microstructural damages [in Polish], Przegląd Mechaniczny 4, 15-22, 2011.
9. K. Nahshon, J.W. Hutchinson, Modification of the Gurson Model for shear failure, European Journal of Mechanics - A/Solids, 27. 1, 1-17, 2008.
10. A. Biegus, D. Czepiżak, Experimental and numerical studies upon load-bearing capacity of locally strengthened corrugated sheets, Archives of Civil Engineering, 55. 1. 11-28, 2009.
11. A. Biegus. D. Czepiżak, Evaluation of resistance of corrugated sheets under bending by a concentrated loads from the local suspensions, Archives of Civil Engineering. 56. 4. 283-297, 2010.
12. P. Iwicki, Sensitivity analysis of buckling loads of bisymmetric i-section columns with bracing elements. Archives of Civil Engineering, 56, l, 69-88, 2010.
13. U. Radoń, Analysis of reliability and stability of bar structures, Archives of Civil Engineering. 56. 2, 155-172. 2010.
14. M. Kamiński, P. Swita, Reliability modeling in some elastic stability problems via the generalized stochastic finite element method, Archives of Civil Engineering. 57. 3. 275-295, 2011.
15. J. Chróścielewski, M. Rucka, K. Wilde, W. Witkowski, Formulation of spectral truss element for guided waves damage detection in spatial steel Trusses, Archives of Civil Engineering, 55, l, 43-63, 2009.
16. W. Witkowski, M. Rucka, K. Wilde, J. Chróścielewski, Wave propagation analysis in spatial frames using spectral timoshenko beam elements in the context of damage detection, Archives of Civil Engineering, 55, 3, 367-402, 2009.
17. A.G. Franklin, Comparison between a quantitative microscope and chemical method for assessment on non-metallic inclusions, Journal of the Iran and Steel Institute, 207, 181-186, 1969.
18. PN-EN 10025-1:2005 Hot Rolled Products of Structural Steels - Part 1: General Technical Delivery Conditions.
19. P.G. Kossakowski, Simulation of ductile fracture of S235JR steel using computational cells with microstructurally-based length scales, Journal of Theoretical and Applied Mechanics, 50, 2, 589-607. 2012.
20. PN-EN 10002-1:2004 Metallic Materials - Tensile Testing - Part 1: Method of Test at Ambient Temperature.
21. J. Faleskog, X. Gao, C.F. Shih, Cell model for nonlinear fracture analysis - I. Micromechanics calibration, International Journal of Fracture, 89, 4, 355-373, 1998.
22. Abaqus 6.10 Analysis User&apos
s Manual, Dassault Systemes, 2010.
23. A.B. Richelsen, V. Tvergaard, Dilatant Plasticity or Upper Bound Estimates for Porous Ductile Solids, Acta Metallurgica et Materialia, 42, 8, 2561-2577, 1994.
24. J.W. Hancock, A.C. Mackenzie, On the mechanisms of ductile failure in high-strength steels subjected to multi-axial stress-states, Journal of Mechanics and Physics of Solids, 24, 2-3, 147-160, 1976. 
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