On the assessment of train crankshafts fatigue life based on LCF tests and 2D-FE evaluation of J-integral

• Published in: Engineering failure analysis 2016-08, Vol.66, p.354-364
• Main Authors: Ktari, Ahmed, Haddar, Nader, Rezai-Aria, Farhad, Ayedi, Hassine Ferid
• Format: Article
• Language: English
• Subjects: Assessments; Behavior law; Chromium molybdenum steels; Crankshafts; Engineering Sciences; Fatigue behavior; Fatigue cracks; Fatigue life; Fracture mechanics; Fracture mechanisms; High strength steels; J integral; Lifetime prediction; Low cycle fatigue; Service life assessment
• ISSN: 1350-6307; 1873-1961; 1350-6307
• DOI: 10.1016/j.engfailanal.2016.05.011

Low cycle fatigue (LCF) tests were carried out on forged carbon steel (AISI 4130) used in V12 Diesel engine crankshafts, at room temperature and 300°C, under total strain control. These tests were performed in order to study the cyclic mechanical behavior, lifetime and damage mechanisms of the material. Then, a Chaboche nonlinear isotropic-kinematic hardening model available in the commercial FE code Abaqus was identified and a 2D-FE evaluation of J-integral, chosen as a crack driven force, has been carried out to estimate the crankshaft life under cyclic bending loads when a macroscopic crack propagates. It has been found that i) material lifetime was not affected by temperature at the studied domain, ii) the fractured surfaces examined with SEM exhibit typical features of ductile fracture behavior, and iii) the number of cycles spent until the total crankshaft fracture is relatively short compared to its total fatigue life. [Display omitted] •The LCF behavior, observed until specimen fracture, is studied at room temperature and at 300°C.•The fractured surfaces, examined using SEM, proves the ductile frature behavior.•A 2D-FE model was performed to study the crack propagation on crankshaft under LCF conditions.•It is found that the number of cycles until the crankshaft fracture is relatively short compared to its total fatigue life.