Institute of Physics of Materials AS CR, v. v. i. > Projects > Novel principles for life prediction in variable loading of components

Novel principles for life prediction in variable loading of components

Investigatorprof. RNDr. Jaroslav Polák, DrSc., dr. h. c.
Number of Project101/07/1500
AgencyGrantová agentura České republiky
Duration2006-12-31 - 2009-12-30

Anotace
Existing methods for life prediction of components are often not reliable and high safety factors must be used.
Recent research into fatigue damage of structural materials revealed new possibilities to evaluate the fatigue
life based not only on the stress amplitude but on the plastic strain amplitude. It is important to use a
differential characteristic, the growth rate of short cracks Within a proposed project new findings concerning
the effect of plastic strain amplitude and mean stress will be obtained. The rates of short cracks will be
measured and the kinetics of short crack growth for various values of plastic strain amplitudes and mean
stresses will be established. Simultaneously the fatigue life of smooth specimens cycled with various plastic
strain amplitudes and mean stresses will be determined and correlated with the rates of short crack in order to
propose more simple evaluation of relevant parameters.


2012

Polák J., Man J., Petrenec M., Tobiáš J.: Fatigue behavior of ferritic-pearlitic-bainitic steel in loading with positive mean stress. Int. J. Fatigue 39 (2012) 103-108

Polák J., Petrenec M., Man J., Obrtlík K.: Initiation and short crack growth in austenitic-ferritic duplex steel-effect of positive mean stress. Fatigue Fract. Eng. Mater. Struct. 35 (2012) 257-268



2011

Polák J., Petrenec M., Man J., Kruml T.: Cyclic plasticity and cyclic creep in austenitic-ferritic duplex steel. Key Eng. Mater. 465 (2011) 431-434

Polák J., Petrenec M., Man J.: Cyclic plasticity, cyclic creep and fatigue life of duplex stainless steel in cyclic loading with positive mean stress. Kovové materiály 49 (2011) 347-354



2010

Man J., Weidner A., Kuběna I., Vystavěl T., Skrotzki W., Polák J.: Application of FIB technique to study early fatigue damage in polycrystals. J. Phys.: Conf. Series 240 (2010) 012058



2009

Polák J., Man J., Vystavěl T., Petrenec M.: The shape of extrusions and intrusions and initiation of stage I fatigue cracks. Mater. Sci. Eng. A 517 (2009) 204-211

Man J., Obrtlík K., Polák J.: Extrusions and intrusions in fatigued metals. Part 1. State of the art and history. Philos. Mag. 89 (2009) 1295-1336

Man J., Klapetek P., Man O., Weidner A., Obrtlík K., Polák J.: Extrusions and intrusions in fatigued metals. Part 2. AFM and EBSD study of the early growth of extrusions and intrusions in 316L steel fatigued at room temperature. Philos. Mag. 89 (2009) 1337-1372



2007

Polák J., Man J., Vystavěl T., Zouhar L.: Fatigue crack initiation in crystalline materials - experimental evidence and models. Key Eng. Mater. 345-346 (2007) 379-382