Description of Fatigue Crack Growth Rate Notched Members under Tension and Bending Using the ΔJ ― Integral Range

摘要

The paper contains the results of experimental tests of the fatigue crack behaviour examined for 10HNAP steel under tension and bending in the conditions of different stress ratios R. For the tests under tension the plane specimens with central, symmetric stress concentrator in the from of the slots with side notches were used, while for bending plane specimens with external unilateral V-notch as stress concentrator were tested. While testing a constant stress ratio R was kept, and accounted for -0.5, -0.3, 0, 0.5. The results of the experimental tests have been described by a nonlinear formula based on ΔJ-integral range. The change of the stress ratio R from the value of - 0.5 and - 0.3, 0 to 0.5 caused the fatigue crack growth rate in ΔJ-integral range for tension: 4.5·10~(-3) MPa·m ≤ ΔJ ≤ 1.78·10~(-1) MPa-m, and for bending: 9·10~(-3) MPa·m ≤ ΔJ ≤ 1.78·10~(-1) MPa-m. The proposed formula for the description of fatigue crack growth rate, including ΔJ-integral range, satisfactorily describes the results obtained experimentally for 10HNAP steel.