Evaluation of FEM based Fracture Mechanics Technique to Estimate Life of an Automotive Forged Steel Crankshaft of a Single Cylinder Diesel Engine

Tensile properties and fracture toughness at service temperatures of an optimized pearlitic ductile iron alloy for automotive crankshafts

“…This advantage is further improved if the cold start temperature of the engine is below zero, for example at 10ºC. The linear regression obtained in Figure 14 gives a K IC value of 37 MPa•m 1/2 for this condition, which leads to a critical crack size of 1.3 mm considering the same crankshaft geometry as above [17]. If the same crack growth rate as before is assumed (10 -3 mm/min), the time to fracture would increase to 19 h of driving.…”

“…This means that the toughness increases by 9.1 MPa•m 1/2 from cold start, at 25ºC, to stable engine regime, at 90ºC. Taking the stress intensity factors for a forged steel crankshaft modeled in [17] as an example, 1.5 mm and 2.5 mm cracks cause stress intensity factors of 40 MPa•m 1/2 and 50 MPa•m 1/2 respectively. Thus, if a crankshaft after the design from [17] and manufactured in the material studied in this work stands a cold engine start while having a 1.5 mm crack, it should not break until the crack grows up to 2.5 mm.…”

“…Taking the stress intensity factors for a forged steel crankshaft modeled in [17] as an example, 1.5 mm and 2.5 mm cracks cause stress intensity factors of 40 MPa•m 1/2 and 50 MPa•m 1/2 respectively. Thus, if a crankshaft after the design from [17] and manufactured in the material studied in this work stands a cold engine start while having a 1.5 mm crack, it should not break until the crack grows up to 2.5 mm. Hypothesizing an engine speed of 2000 rpm, a peak fatigue cycle each 4 turns (significant only during the expansion cycle) and a torque ratio of 0.1 from start to average running condition [18], an estimated crack growth rate of 10 -3 mm/min [19,20] would lead to 16 h of driving until fracture, what turns out far longer than the time between refueling stops.…”

Study on the Relationship between Combustion Parameters and Cylinder Head Vibration Signal in Time Domain

“…Considering the complex structure of ICEs, three-dimensional modelling is a better choice to reflect the structural feature and transfer characteristics of the ICEs. Finite Element Analysis has been used to optimize the vibration-acoustic performance [24] and component failure analysis of ICEs, such as connecting rods [25], crankshafts [26], and so on. The above studies were mainly conducted with static finite element analysis method.…”

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

“…With consideration of rotating external bearing loads, torsional vibrations and internal centrifugal loads, a three-dimensional finite element analysis followed by a local boundary element analysis was used for stress calculations. Metkar et al [11] has conducted a comparative study of two methods of fatigue life assessment of a single cylinder diesel engine crankshaft by using fracture mechanics approach based on linear elastic fracture mechanics (LEFM) and a developed critical distance approach (CDA).…”