Issue 30

A. Fernàndez-Canteli et alii, Frattura ed Integrità Strutturale, 30 (2014) 327-339; DOI: 10.3221/IGF-ESIS.30.40

by arranging the stress range sequence intervening in the basic stress block in a random manner. After direct conversion of the load to stress for the cylindrical specimens used in the test, the stress ranges corresponding to the 18 levels considered in the load collective, the number of cycles in the original block and those in the basic stress block are exposed in Tab. 2. The number of total cycles to failure for the tests performed under variable loading according to Holmen and the corresponding number of replications of the basic stress blocks necessary to achieve failure are displayed in Tab. 3.

Number of cycles

Number of cycles

Accumulated number of cycles applied in the original histogram

Accumulated number of cycles applied in the basic loading block

Stress range level

Normalized stress range

corresponding to the original histogram

corresponding to the basic loading block

18 17 16 15 14 13 12 11 10

0.7750 0.7324 0.6897 0.6471 0.6044 0.5618 0.5191 0.4765 0.4338 0.3912 0.3485 0.3059 0.2632 0.2206 0.1779 0.1353 0.0926 0.0500

18869 10915 16967 22927 33314 41992 56802 66522 83321 90008 103360 103360 101594 104832 90695 79438 54029

25 14 22 30 44 55 75 88

18869 29784 46751 69678 102992 144984 201786 268308 351629 441637 544997 648357 749951 854783 945478 1024916 1078945 1109733

25 39 61 91

135 190 265 353 464 584 721 858 993

111 120 137 137 135 139 120 105

9 8 7 6 5 4 3 2 1

1132 1252 1357 1429 1470

72 41

30788

Table 2: Stress ranges corresponding to the 18 levels considered in the load collective and number of cycles in the original block and basic stress block

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