Research of an aircraft engine cylinder assembly integrity assessment – Thermomechanical FEM analysis

Failures of aircraft piston engine components are a common occurrence in practice. During operation, cylinder heads are components that are exposed to multiaxial thermomechanical loads leading to fatigue. Therefore, predicting the lifetime of the cylinder heads exposed to such loads is one of the most important tasks to ensure engine quality, durability and safety. This paper is the continuation of a comprehensive research of the Lycoming IO-360- B1F aircraft engine cylinder head failure. The failure of this type has already occurred during flight and about 50 failures like this have been registered from around the world, some of them with a fatal outcome and therefore require detailed research. This research includes the numerical stress and fatigue analysis of the cylinder assembly exposed to high cycle mechanical and thermal loads that failed due to a crack appearance on the cylinder head. A 3D cylinder assembly model was created. The locations with the highest stress values, both mechanical and thermal, were determined using numerical analysis. Also, the lifetime of the cylinder assembly has been determined, i.e. an integrity assessment has been carried out which will contribute to the consideration of the crack appearance problem. Defining the coupled thermomechanical load of the cylinder assembly in the numerical analysis gives special significance to this paper. The results obtained will serve to analyze the crack propagation in the cylinder head which is going to be the subject of further research.