抄録
Testing for bending fatigue crack propagation under mixed-mode condition was carried out using the fatigue and the annealed slant precracks with the different slant angles, β, in a rectangular plate. As a result, bent fatigue crack from the fatigue precrack with β=45deg. propagated under mixed-mode condition with the mode II stress intensity factor (K_<II>)_<est>, while that from the fatigue precrack with β=60deg. propagated under mode I crack behavior. This is because the compressive residual stress near the fatigue precrack was apt to contact between the upper and the lower crack surfaces in the precrack with smaller slant angle. The fatigue crack propagation rates during bending had almost the same relation for all the data, using the mixed-mode stress intensity factor (K_M)_<est>, which derived from the (K_I)_<est> and (K_<II>)_<est> evaluated from the discontinuous displacement measured along the crack.
