Effects of Temperature Levels and Straining Frequency on the Rate of Crack Propagation in a Low Carbon Steel during Low Cycle Fatigue

Abstract

In the experiment, length of crack, which had started from a notch hole, was measured by(1) During a strain controlled low cycle fatigue test at 5cpm, the rate of crack propagation to be opposite of that of tensile ductility. The period of crack initiation becomes shorter as a temperature increases.initiated in the vicinity of a main crack tip. The main crack propagates rather rapidly by coalescing these micro cracks.Temperature dependence of the rate of crack propagation is effectively influenced by the change of test frequency.(3) The increase in the rate of crack propagation due to coalescing process is estimated qualitatively with the assumption that the micro cracks prohibit the decrease of ductility of a material in the vicinity of a main crack tip.

Computational Viscoplasticity-Based Modeling of Stress/Strain Response in Thermomechanical Fatigue Loads

“…Although TMF loadings can incorporate many additional submechanisms and interactions not present in LCF, (Refs. [4][5][6] it is reasoned that simulations of the current level of sophistication can be optimized to meet an intermediary goal of providing accurate initial stress/strain responses and the associated stress histories through the first 100 cycles of a load history.…”

Life Prediction Feasibility in TMF via Stress/Strain Data From a Viscoplasticity-Based Numerical Model

“…While Miller's model does not explicitly support nonisothermal cases, ANSYS can supply the model updated temperature-dependent parameters when it passes the boundary conditions with each successive simulation step [3]. Although TMF loadings can incorporate many additional submechanisms and interactions not present in LCF, [4][5][6] it is reasoned that simulations of the current level of sophistication can already meet an intermediary goal of providing accurate initial stress/strain responses and stress histories through the first 100 cycles of a load history.…”

Effect of Temperature on the Rate of Fatigue Crack Propagation in Steels during Low Cycle Fatigue

“…It was emphasized in th e previous p ap er that microcracks accumu lated in the vicinity of a main crack tip caused temperature-, time-dependent crack propagation rate. 3 ) Now, th e effec ts of stra in ra nge a nd tempera ture on the isotherm al fatiguc crack propagation rate in a uslenilic stainless steels, SUS304 a nd SUS347 were exa mined . Th e equation for the crack propagatio n rate in th e m etals containing microcracks is se t up.…”