Issue 23

G. Scirè Mammano et alii, Frattura ed Integrità Strutturale, 23 (2013) 25-33; DOI: 10.3221/IGF-ESIS.23.03 31 Second cycle after start Last cycle before termination Line Test  lim (%)  p ( MPa) N f  max ( MPa)  min   A (%)  max   M (%)    SME (%)  max ( MPa)  min   A (%)  max   M (%)    SME (%) 1 Linear stress-strain 4.0 300 4 728 425 0.96 4.03 2.27 370 2.62 3.97 1.35 2 Constant-stress 4.0 300 3 579 311 0.57 4.099 23.03 310 2.08 4.08 2.00 3 Linear stress-strain 4.0 300 4 597 416 0.97 3.91 2.54 359 2.53 3.93 1.40 4 Constant-stress 4.0 300 3 301 311 0.53 4.048 23.07 312 1.99 4.05 1.26 5 Linear stress-strain 4.0 235 8193 367 0.76 4.03 2.47 328 1.86 4.02 1.36 6 Constant-stress 4.0 235 8 899 241 0.35 4.00 3.25 243 1.15 4.00 2.45 7 Linear stress-strain 4.0 235 8 000 380 0.80 4.00 2.40 339 1.91 3.99 2.08 8 Constant-stress 4.0 235 6 972 242 0.39 4.03 3.24 243 1.24 4.05 2.41 9 Linear stress-strain 4.0 170 18 723 293 0.60 4.00 3.00 267 1.30 3.88 2.58 10 Constant-stress 4.0 170 17 693 188 0.35 4.00 3.25 174 0.81 4.00 2.39 11 Linear stress-strain 4.0 170 14 673 320 0.61 4.03 3.02 288 1.42 4.02 2.20 12 Constant-stress 4.0 170 15 665 178 0.28 4.036 23.32 177 0.80 4.04 2.44 13 Linear stress-strain 4.0 105 21 678 248 0.50 4.00 3.10 228 0.94 3.98 3.04 14 Constant-stress 4.0 105 500 000 110 0.22 4.00 3.38 109 0.70 4.00 2.50 15 Linear stress-strain 4.0 82.8 500 000 221 0.42 3.96 3.54 196 1.08 3.95 3.27 16 Constant-stress 4.0 82.8 500 000 85 0.08 3.95 4.27 85 0.39 3.97 3.58 Table 1 : Comparison of fatigue results between the tests under linear stress-strain variation (39 MPa for each percent of strain) with maximum strain limited to 4% and the constant-stress tests with limited maximum strain of 4%. Figure 6 : Woehler’s diagram with the fatigue results for the tests under linear stress-strain variation and maximum strain of 4%. Woehler’s curve for the constant stress tests with maximum strain limited to 4% is shown for comparison (dashed line).