Preethi K.H.



Name            : Preethi. K. H.

Designation : Senior Lecturer

Qualification: Master of Technology (Machine Design)


ME Dissertation Project (2005):


                  “Contact stress analysis of compressor blade/disc assembly”




The stress analysis of single tooth attachments or ‘dovetails’ used to secure fan and compressor blades to disks in gas turbines has received the attention of several experimental and numerical investigations. A consideration of typical geometry and loading conditions for such joint indicates that a maximum principal tensile stress occurs on the free surface of the fillet radius at the root of the projection in both blade and disc. Not all failures of such components originate from cracks in this region, however, it is necessary to consider the stress distributions internal to the contact areas of the blade root and disc.


The aerodynamic loads on compressor blades are small in comparison to the radial loads due to rotation and many compressors have blades, which are located in axial dovetail slots in the periphery of the discs. It was therefore considered that a two-dimensional model of blade-disc joint would be more appropriate for carrying out the internal stress analysis. The photo elastic experimental techniques were extensively used to investigate the stress distributions in these joints using both live load analysis method and stress freezing techniques.


This report presents the details of parametric studies carried out to analyze the contact stress distributions around the dovetail type blade/disc interface of a fan of an aero engine. The effect of flank angle variation on the contact stress distribution was studied.


The investigations were carried out using the front-end commercial software ANSYS 5.4 with its contact stress analysis capabilities. Plane stress elements (PLANE42) were used in the FEM formulation of the problem. The interface between blade and disc was modeled using contact elements(CONTACT12).


Some typical results of the project work




Faculty of Mechanical Engineering Department

The Oxford College of Engineering

Bommanahalli, Hosur Road

Bangalore 560068



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