Evaluation of true stress in engineering materials using optical deformation measurement methods

• Autorzy: Bogusz P. , Popławski A. , Morka A. , Niezgoda T.
• Języki publikacji: EN

Abstrakty

EN

The aim of the paper is to evaluate a method of determining true stress in the steel sample subjected to static axial tensile on a universal testing machine. The tensile specimens were made of steel ST3, which was chosen because of its relatively high plastic deformations. Strain measurement was performed using traditional extensometers and additionally a non-contact optical deformation measuring system. Material properties were obtain by the extensometer measurements. The optical equipment registered the investigated sample through the optical system composed of two cameras and calculated a three-dimensional model of the material deformation in time. Displacement fields in axial and radial directions were determined with Digital Image Correlation method (DIC). Then the logarithmic axial strain map and radius shrinkage map in the area of the neck were obtained. Characteristic dimensions of the neck: curvature and width were also measured. It allowed determination of cross-section area changes in the real time, and in the result, calculation of actual true stress in the material during failure process. In this case Bridgman's and other scientists' formulas of stress distribution in the neck were applied. A numerical model, where material properties of finite elements were described by the Johnson-Cooke material model, was developed in LS-PrePost software. The FEM model was computed in LS-DYNA solver. The output tensile curve and neck curvature radius were compared with relevant data obtained from the optical measuring system.

Słowa kluczowe

EN

true stress; optical deformation measurement; experimental studies; FEM; steel

• Wydawca: Łukasiewicz Research Network - Institute of Aviation ; European Science Society of Powertrain and Transport KONES Poland ; Wydawnictwo Instytutu Technicznego Wojsk Lotniczych
• Czasopismo: Journal of KONES
• Rocznik: 2012
• Tom: Vol. 19, No. 4
• Strony: 53--64
• Opis fizyczny: Bibliogr. 21 poz., rys.

Twórcy

autor

Bogusz P.

autor

Popławski A.

autor

Morka A.

autor

Niezgoda T.

• Military University of Technology Department of Mechanics and Applied Computer Science Gen. Sylwestra Kaliskiego Street 2, 00-908 Warsaw, Poland tel.: [phone], fax: [phone],

Bibliografia

• [1] Gromada, M., Miszuris, G., Evaluation of the flow curve in the tensile test and stress distribution in the minimal cross-section, Oficyna Wydawnicza Politechniki Rzeszowskiej, Rzeszów 2010.
• [2] Bridgman, P. W., Studies in large plastic flow and fracture: with special emphasis on the effects of hydrostatic pressure, Harvard University Press, Cambridge 1964.
• [3] Siebel, E., Schwaigerer, S., Zur Mechanik des Zugversuchs, Archiv für das Eisenhüttenwesen, Vol. 19, pp. 145-52, 1948.
• [4] Davidenkov, N. N., Spiridonova, N. I., Mechanical methods of testing. Analysis of the state of stress in neck of a tension test specimen, American Society for Testing and Materials, Vol. 46, pp. 1147-1158, 1947.
• [5] Dietrich, L., Miastkowski, J., Szczepiński, W., Nośność graniczna elementów konstrukcji, PWN, Warsaw 1970.
• [6] Malinin, N. N., Rżysko, J., Mechanika materiałów, PWN, Warsaw 1981.
• [7] Chen, W. H., Necking of a bar, International Journal of Solids and Structures, Vol. 7, pp. 685-717, 1971.
• [8] Needleman, A., A numerical study of necking in circular cylindrical bars, Journal of the Mechanics and Physics of Solids, Vol. 20, pp. 111-127, 1972.
• [9] Norris, D. M., Morgan, Jr. B., Scudder, J. K., Quinones, D. F., A computer simulations of the tension test, Journal of the Mechanics and Physics of Solids, Vol. 26, pp. 1-19, 1978.
• [10] Saje, M., Necking of a cylindrical bar in tension, International Journal of Solids and Structures, Vol. 15, pp. 731-742, 1979.
• [11] Zhang, K. S., Zheng, C. Q., Analysis of large deformation and fracture of axisymmetric tensile specimens, Engineering fracture mechanics, Vol 39, pp. 851-857, 1991.
• [12] Vazhentzev, Yu. G., Isaev, V. V., Problem of the stress state in the neck of cylindrical and flat specimens in tensile loading, Strength of Materials, Vol. 20, No. 4, pp. 495-499, 1988.
• [13] Cabezas, E. E., Celentano, D. J., Experimental and numerical analysis of the tensile test using sheet specimens, Finite element in analysis and design, Vol. 40, pp. 555-575, 2004.
• [14] Gabryszewski, Z., Gronostajski, J., Mechanika procesów obróbki pastycznej, PWN, Warsaw 1970.
• [15] Jasieński, Z., Wpływ nierównomierności odkształcenia na zależność naprężenia właśiwego od stopnia deformacji w szycje rozciąganej próbki metalowej, Archiwum Hutnictwa, Vol. 10, pp. 189-239, 1965.
• [16] Ling, Y., Uniaxial true stress-strain after necking, AMP Journal of Technology, Vol. 5, pp. 37-48, 1996.
• [17] Szczepiński, W., Metody doświadczalne mechaniki ciała stałego, PWN, Warszawa 1984.
• [18] Thomson, P. F., An analysis of necking in axi-symmetric tension specimens, International Journal of Mechanical Sciences, Vol. 11, pp. 481-490, 1969.
• [19] Zhnag, K. S., Li, Z. H., Numerical analysis of the stress-strain curve and fracture initiation for ductile material, Engineering fracture mechanics, Vol. 49, pp. 235-241, 1994.
• [20] Livermore Software Technology Corporation, LS-Dyna Keyword User’s Manual Volume I, ver 971, rev.1433, Livermore 29 may 2012.
• [21] Livermore Software Technology Corporation, LS-Dyna Keyword User’s Manual Volume II, ver 971, rev.1437, Livermore 29 may 2012.