Multiaxial fatigue criteria applied to motor crankshaft in thermoelectric power plants

Abstract

Fatigue failures of motor crankshafts operating in thermoelectric power plants have recently been reported. Stress fields provided by finite element calculations at critical points of a crankshaft that failed in service are used to test the structural integrity of the component. Taking into account the fact that the stresses acting at a given point are most likely out of phase, multiaxial fatigue criteria based on the von Mises stress are considered to be most suitable for predicting the fatigue behavior of the crankshaft. Using the von Mises stress, it was also possible to apply octahedral shear stress-based criteria and the results obtained have indicated that the crankshaft made of DIN 34CrNiMo6 steel should not suffer fatigue failure under the action of the stress fields in question. However, such failures have been occurring and this apparent discrepancy is presented and briefly discussed in the present study.

Crankshaft High-Cycle Bending Fatigue Experiment Design Method Based on Unscented Kalman Filtering and the Theory of Crack Propagation

“…Fonte analyzed a failed crankshaft from a diesel motor engine and discovered that the main reason for the failure may not be attributed to the part itself but to the misalignment of the main journals and a weakness in design close to the gear in the region where the crack was initiated [12]. Venicius applied multi-axial fatigue criteria to motor crankshafts in thermoelectric power plants to provide guidance for the selection of the material in the production [13]. Bulut proposed a new fatigue safety factor model to analyze the fatigue life of the crankshaft from a single-cylinder diesel engine under variable forces and speeds; in this way, the comprehensive evaluation of the safety of the crankshaft during the whole working period can be achieved [14].…”

Research on the Bending Fatigue Property of Quenched Crankshaft Based on the Multi-Physics Coupling Numerical Simulation Approaches and the KBM Model

“…Among these works, M. Leitner investigated the fatigue strength of multi-axially loaded gas engine crankshafts and pointed out that the model proposed by Spagnoli provided the best accuracy in both fatigue strength and crack angle [12]. Venicius also applied multi-axial fatigue criteria to motor crankshafts in thermoelectric power plants to provide guidance for the selection of the material in the production [13]. Bulut proposed a new fatigue safety factor model to analyze the fatigue life of the crankshaft from a single cylinder diesel engine under variable forces and speeds; in this way, the comprehensive evaluation of the safety of the crankshaft during the whole working period can be achieved [14].…”