Floweday G., Petrov S., Tait R.B., Press J.
Sasol Advanced Fuels Laboratory, Department of Mechanical Engineering, University of Cape Town, South Africa; Department of Mechanical Engineering, University of Cape Town, South Africa; Origen Engineering Solutions, Cape Town, South Africa
Floweday, G., Sasol Advanced Fuels Laboratory, Department of Mechanical Engineering, University of Cape Town, South Africa; Petrov, S., Department of Mechanical Engineering, University of Cape Town, South Africa; Tait, R.B., Department of Mechanical Engineering, University of Cape Town, South Africa; Press, J., Origen Engineering Solutions, Cape Town, South Africa
This study resulted from an engineering failure investigation related to diesel engine piston failures which occurred during a bench dynamometer engine durability test programme. The test programme aimed at evaluating the effects of various fuel types on the durability of fuel system components in passenger car diesel engines. A number of unexpected cylinder head, turbocharger and piston failures were experienced during the course of the test programme. This study focused on the cause of the piston failures experienced during these tests.Analyses of the fractured pistons revealed that thermo-mechanical fatigue initiation occurred as a result of primary silicon phase cracking and subsequent micro-crack formation due to excessive thermo-mechanical loading. Progressive formations of such micro-cracks lead to flaws that were of sufficient magnitude to initiate propagation by high cycle fatigue mechanisms.The investigation also revealed that the excessive thermo-mechanical piston loading was caused by over-fuelling and a combination of elevated and poorly controlled post intercooler air temperature. There was no evidence to suggest that the failures were related to the test fuel formulations. © 2011 Elsevier Ltd.
Air temperature; Cylinder head; Damage and failure; Engine durability; Engineering failures; Fuel formulation; Fuel types; High cycle fatigue; Intercoolers; Microcrack formation; Modern high performance; Piston failure; Primary silicon; System components; Test programme; Thermo-mechanical; Thermo-mechanical loading; Thermomechanical fatigue; Automobiles; Cracks; Diesel engines; Durability; Engines; Fatigue damage; Fracture; Fuels; Pistons; Engine pistons