Let RDx = RD at N=20 million. (8) RDx = 0.0013 inch for a = -11.20 (9) a = 7.3 + 6.4 log10 (0.0013) = -11.20 for a 3-sigma limit of 0.00204 inch (10) The RDx value is not the same as the . But RDx should be directly proportional to . So postulate that a = 7.3 + 6.4 log10 (0.0026) = -9.24 for a 3-sigma limit of 0.00408 inch (11) This was verified by experiment where the preceding time histories were doubled and CDI =1.0 was achieved after the rainflow counting. Thus, the following relation is obtained. (12) (13) log10 (N) = -6.4 log10 (RD) + (14) (15) (16) (17)
Let RDx = RD at N=20 million. (8) RDx = 0.0013 inch for a = -11.20 (9) a = 7.3 + 6.4 log10 (0.0013) = -11.20 for a 3-sigma limit of 0.00204 inch (10) The RDx value is not the same as the . But RDx should be directly proportional to . So postulate that a = 7.3 + 6.4 log10 (0.0026) = -9.24 for a 3-sigma limit of 0.00408 inch (11) This was verified by experiment where the preceding time histories were doubled and CDI =1.0 was achieved after the rainflow counting. Thus, the following relation is obtained. (12) (13) log10 (N) = -6.4 log10 (RD) + (14) (15) (16) (17)
electronic_rd_n_revB.docx