Investigator: prof. RNDr. Jaroslav Polák, DrSc., dr. h. c.
Number of Project: 106/02/0584
Agency: Czech Science Foundation
Duration: 01. 01. 2002 - 31. 12. 2004

The goal of the present project is to propose a new life assessment method. For this purpose the kinetics of short crack growth in selected materials and under well-defined loading conditions is studied in order to find quantitative description of the short crack growth. The fatigue crack kinetics is studied on specimens cycled with different stress and plastic strain amplitudes from its initiation until the stage of a macrocrack growth. The effect of surface defects (inclusions, pores, etc.) is also considered. The parameters characterising the short crack growth will be established. These parameters will be used in proposing a new method of fatigue and residual fatigue life assessment. Simultaneously, the life curves (Manson-Coffin and Wöhler curves) of the materials will be measured and the results of the prediction method will be compared with actual fatigue life allowing the verification of the proposed method.

POLÁK J, MAN J, OBRTLÍK K, KRUML T: The shape of extrusions and intrusions produced by cyclic straining. Z. Metallkde. 94 (2003) 1327–1330.

POLÁK J: Plastic strain controlled short crack growth and fatigue life. Int. J. Fatigue 27 (2005) 1192-2001.

POLÁK J: Cyclic plastic response and fatigue life of duplex and superduplex stainless steel, Metallic Mater. 43 (2005) 280-289.