Issue 33

M. Sakane et alii, Frattura ed Integrità Strutturale, 33 (2015) 319-334; DOI: 10.3221/IGF-ESIS.33.36 321 ( )   n p A  (1) In the equation, A is the strain hardening coefficient and n the strain hardening exponent. (a) (b) Figure 2 : Strain path (a) and strain sequence (b) . Figure 3 : Cyclic stress-strain curves of five materials under proportional and nonproportional loadings. Materials Proportional Nonproportional n P A P (MPa) n NP A NP (MPa) SUS304 0.13 830 0.22 1860 Pure Ca 0.18 520 0.30 1330 Pure Ni 0.12 740 0.12 940 Pure Al 0.12 110 0.12 110 6061 Al 0.11 270 0.11 270 Table 2 : Cyclic hardening coefficient and exponent.