PSI - Issue 14

Nikolay A.Makhutov et al. / Procedia Structural Integrity 14 (2019) 199–206 N.Makhutov et al./Procedia Structural Integrity 00 (2018) 000 – 000

206

8

Fig. 4. Theoretical and experimental local strains for smooth ( K t =5,1) and notched ( K t =1,5 - 5,1) specimens

Fig. 4 presents plots of the maximum logarithmic strains at the notch root against net nominal stresses for smooth ( K t =1) and notched specimens ( K t >1) made of austenite heat-resistant steel 80 Х 18 Н 10 Т . The experimental data are depicted by the points. Results of calculation according to equations (22) and (23) are shown by solid lines. These calculations were carried out with accounting for the 8-18% increase of the resistance to plastic deformation due to triaxial stress state in the notch zone. This figure demonstrates a good agreement between results of calculations according to equations (22) -(23) and experimental results for a wide range of strains (regions II and III). Several different materials, notch geometries and types of loading have been considered and similar agreement between theory and experiment was achieved. 4. Conclusions The proposed phenomenological model fits well to available experiment data on stress-strain response of material at the notch root in the wide range of plastic strains. It allows describing the performance of the notched components not only under normal loading regimes but also to predict its behavior when it is subjected to extreme loads. The presented approach provides the opportunity to assess residual strength and remaining lifetime of highly damaged structures . Acknowledgments Adibi-Asl R., Seshadri R. 2009. Improved Prediction Method for Estimating Notch Elastic-Plastic Strain. Journal of Pressure Vessel Technology. 135(4):041203-041203-9. Bannantine J., Comer J, Handrock J. 1990. Fundamentals of metal fatigue analysis. Prentice Ney Jersey. Hall edition, pp. 271. Hoffmann M., Seeger T. 1985. Generalized Method for Estimating Multiaxial Elastic –Plastic Notch Stresses and Strains, Part 1: Theory,” Trans. ASME, Journal of Engineering Materials and Technology,. 107. 250 – 254. Klesnil M., Lukas P. 1992. Fatigue of Metallic Materials. Materials Science Monographs.Volume 71. Elsevier. pp.270 Manson S., Halford G. 2006. Fatigue and Durability of Structural Materials. USA. ASM International., pp. 455 Makhutov N. 1981. Strain-based Fracture Criteria and Structural Strength Design. Mashinostroeniye publ, Moscow, pp. 271 (in Russian). Makhutov N. 2008. Strength and Safety. Basic and Applied Research. Nauka publ. Novisibirsk. pp 528 (in Russian). Makhutov N., Reznikov D. 2018. Methods for Assessment of Stress-Strain States in Stress Concentration Zones in Regular and Accident Loading Conditions. Problems of Safety and Emergency Situations. 4, 3-28 (in Russian) Molski K., Glinka G. 1981. A method of elastic – plastic stress and strain calculation at a notch root. Material Science and Engineering;50:93 – 100. Neuber, H., 1961. Theory of stress concentration for shear-strained prismatical bodies with arbitrary nonlinear stress – strain law. Journal of Applied Mechanics. 28, 544 – 550 Seege r T, Heuler P. 1980, Generalized application of Neuber’s rule. Jour nal of Testing and Evaluation;8.199 – 204. Stephens R.I., Fatemi, A., Stephens, R.R., Fuchs, H. 2000. Metal Fatigue in Engineering,” John Wiley, New York. pp.472 This work is financially supported by the Russian Foundation for Basic Research (grant 16-58-48008 IND_omi). References