Gas turbine engine components for military applications need to be designed with high strength to weight ratio, in addition to higher durability. Dovetail joints are used to secure compressor blades to rotor disc in a gas turbine. One of the weakest parts of the entire rotating assembly in gas turbine engine is the joint between rotor disc and the compressor blade. Stress analysis of dovetail attachments presents great challenges due to high stress concentration and weight budgeting. The objective of this paper is to conduct integrated stress analysis to evaluate the distribution of stresses in dovetail disc and blade attachment of compressor. The integrated method like finite elements technique and photoelasticity can provide accurate assessment of stress situation. Optimization of disc parameters using design of experiments is also done for redistribution of stress and mitigation of stress concentration. Slight variation in the dovetail geometry shows significant reduction of stress at dovetail joint.

The gas turbine is an internal combustion rotary engine. The most widely known gas turbine is the jet aircraft engine. The engine burns a lean mixture of fuel with compressed air. The hot pressurized combustion gases expand through a series of rotating turbine wheel and blade assemblies resulting in shaft power output, propulsive thrust or a combination of the two (Cohen and Saravanamuttoo, 1972). In the design of aero gas turbine engines, very high reliability and safety are required. The rotary parts in particular are designed with scrupulous care because their failure can cause a serious accident (Cohen and Saravanamuttoo, 1972). The compressor blades are made of aerofoil section to reduce the loss caused by turbulence and boundary separation.

Typical blade has heavy base and a twisted form to allow for the variation in tangential velocity along the blade length as well as to reduce the possibility of widely varying pressures, changes at different radial positions along the blade length (Smith, 1956). Materials that have been found to be suitable for use in blades are steels, titanium alloys and nickel base alloys. Titanium alloys are preferred to steel because of their lower density (nearly 50%). Titanium has superior oxidation resistance and also it has a decreasing strength with temperature (Metallic Materials Data Book, 2002).

The joint between a compressor or turbine blade and the rotor is frequently the weakest part of the entire rotating assembly (Durelli et al., 1958). A great amount of consideration has been given by designers to different means of realizing these joints and much experimental works have been conducted to develop more efficient joint configurations.

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