Fatigue Crack Growth in 7050T7451 Aluminium Alloy Thick Section ...

DSTO-TR-1477Table 7Etched specimen calculated growth rate and EPS parametersPeakstresslevel MPaSpecimenNo.Type III EPSa 0(Optimised)Type III slopeβ(Optimised)Average βUsing TypeIII EPS360 KSIF100 0.0271 0.224 0.203KSIF110 0.0253 0.182KSIF129 0.0069 0.242KSIF162 0.026 0.168KSIF198 0.0209 0.197390 KSIF165 0.0085 0.305 0.256KSIF170 0.0228 0.281KSIF181 0.0139 0.266KSIF182 0.0213 0.226KSIF207 0.0394 0.201420 KSIF105 0.0177 0.365 0.380KSIF121 0.0076 0.415KSIF136 0.0129 0.339KSIF171 0.0061 0.392KSIF173 0.0073 0.363KSIF180 0.0059 0.392450 KSID101 0.011 0.489 0.458KSIF103 0.0111 0.408KSIF108 0.0092 0.5KSIF109 0.0207 0.41KSIF126 0.0093 0.482Table 8PeakStressMPa360MPalowerslope)390MPa(lowerslope)420MPa(lowerslope)450MPa(lowerslope)360MPa(higherslope)Calculated growth and EPS parameters for the peened specimensSpecimenNo.Type IV EPSa 0 (mm)Type IVβ (slope)Measureof fit: R 2KSIF 194 0.0651 0.0072 0.944KSIF 107 0.0135 0.0089 0.987KSIF 149 0.1161 0.0110 0.972KSIF 152 0.0095 0.0207 0.999KSIF 167 0.0541 0.0125 0.994KSIF 140 0.0335 0.0419 0.995KSIF 205 0.0711 0.0392 0.994KSIF 118 0.0212 0.0418 0.992KSIF 116 0.0479 0.0377 0.980KSIF 151 0.0261 0.0460 0.986KSIF 142 0.0479 0.1030 0.993KSIF 204 0.0349 0.0838 0.993KSIF 147 0.0270 0.0856 0.985KSIF 193 0.0318 0.0835 0.991KSIF 191 0.0433 0.0891 0.987KSIF 183 0.0309 0.1582 0.998KSIF 178 0.0130 0.3395 0.997KSIF 186 0.0285 0.1651 0.994KSIF 164 0.0110 0.2006 0.996KSIF 146 0.0500 0.1354 0.986KSIF 194 0.0805 0.908KSIF 107 0.1666 0.978KSIF 149 0.1748 0.927KSIF 152 0.0948 0.975KSIF 167 0.1224 0.903log meanof a 0 (mm)averageof βSD oflog a 00.0350 0.0121 0.4670.0363 0.0413 0.2100.0362 0.089 0.1000.0227 0.1998 0.279Average Maxcrack depth(failure) mm.0.1278 5.3828