Using FEM and CFD to locate cracks in compressor blades for non destructive inspections

Damage to compressor blades is of critical importance in military aircraft engines. Irregular movements of throttle settings are mandatory requirement for pilots to perform various air combat maneuvers in military aircraft. It leads to excessive stresses on engine compressor blades in various flight regimes. Aircraft are also required to fly in varying atmospheric conditions ranging from negative temperature to over 50 degree Celsius in operations from deserts and tropics. The compressor blades are inspected exhaustively using non destructive inspection techniques during engine overhaul process. It is normally difficult and time consuming for service technicians to localize the damaged areas. A variety of non destructive inspections inspection methods like dye penetrant, eddy currents, magnetic particle testing and radiographic inspections are used that consume a large number of man machine hours increasing the cost of inspections. The possibilities of missing out internally damaged area due to micro cracks may still exist. Present research was focused on using computer simulation techniques such as finite element methods (FEM) and computational fluid dynamics (CFD) to predict the location of possible damaged areas on compressor blades. The results could be used for showing maximum stress concentration areas in the blades as visual slides as reference for carrying out non destructive inspections. In this manner the number of blades inspected by per unit time may substantially be increased to save inspection cost, repair time and result in focused fault isolation of cracks and damage in blades.