Low Cycle Fatigue under Varying Strain Conditions : Effects of Mean Plastic Strain and Stress

Loading sequence effect on fatigue life of Type 316 stainless steel

“…These can be summarized into four basic reasons: (1) stress intensification effect, (2) damage interaction effect, (3) damage sequence effect, and (4) crack mouth opening effect. In a strain-controlled H-L sequence two-step test, the stress amplitude of the second step became larger than the results reported for the constant amplitude test [8,[11][12][13][14][15][16]. The strain hardening induced in the first step raised the stress amplitude of the second step.…”

“…The loading sequence effect was also investigated by fatigue tests conducted for strain-controlled conditions. A strain amplitude sequence of H-L in the two-step test reduced the fatigue life of Type 304 [11], 304L [8,12], 305 [13], 316 [14] and 316L [15,16] stainless steels. On the contrary, the opposite sequence, the L-H sequence caused a longer fatigue life than that predicted by the LDR.…”

“…The damage interaction effect is brought about by interaction of different strain amplitudes. According to the damage models, the interaction of multiple strain amplitudes accelerates damage accumulation [13,23,24]. The damage interaction is explained by fatigue damage model, while the stress intensification effect is explained by the crack growth model.…”

Metodologia enxuta para desenvolvimento de componentes estruturais, suportada por ferramentas de projeto, processo de manufatura e ensaios de materiais

“…Segundo Kim, Son & Park (2008), a regra de Palmgren -Miner (1945, apud DRAPER, 2008 (KIKUKAWA et al, 1977) De acordo com a teoria linear de Palmgren -Miner, uma fração do dano em qualquer nível de tensão é linearmente proporcional à razão entre o número de ciclos da operação e o número de ciclos total que produz a falha neste nível de tensão. O dano total é dado como a somatória de todas as frações e a falha ocorre quando esta é igual ou maior que 1, conforme mostrado pela equação 5.3.…”