Crack Paths 2009

C O N C L U S I O N

Fatigue loading on metallic alloys systematically leads to plastic strain at micro or

micro-macro scales [12, 13, 14]. Furthermore, crack initiation and propagations is

closely related to plasticity development on one site (or different sites) inside the

material; then, the plasticity initiation and propagation should be coupled to crack

initiation and propagation [15, 16, 17]. In this work is presented a simple model

associating the plastic strain at fracture with: the number of cycles of fatigue life, the

isotropic properties of material and two constant related to hardness and loading regime.

Current plastic strain is higher in the first fatigue steps and decreases with the number of

cycles until fracture. Plastic strain at fracture is higher for ductile alloys undergoing

high loading, even if fatigue life decreases. No intermediate effects such as hardening

rule (change in yield condition with the progression of plastic deformation) were taken

into account in this model.

A C K N O W L E D G E M E N T S

W ewant to express our gratitude to the University of Michoacan ( U M S N H )and the

Technologic Institute of Morelia (ITM) in Mexico for the facilities received to carry out

this work; a special mention of gratitude to C O N A C Y(The National Counsel for

Science and Technology in Mexico) for the financial support destined to this project.

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