Effect of contact geometry on the contact stresses in a flat with rounded edge contact

Abstract

The blade-disc dovetail interface in an aero-engine compressor is characterized by a non-uniform pressure distribution which can be obtained by an equivalent flat with rounded edge-on-plate configuration. The contact tractions for a mating pair are affected by many parameters which include, contact geometry, loading conditions, and material properties; with contact geometry being one of the prominent factors. In the present work, a 2-D elastic and elasto-plastic finite element analysis has been carried out for a rounded contact geometry to study the influence of the radius of the corners R鑒 and length of the flat region �2a�. It is observed that the peak tensile stress in the fretting direction decreases with increasing �a� (for constant �R�) which is likely to delay the crack initiation. Also, as compared to elasto-plastic analysis, elastic analysis overestimates peak tensile stress and possibly gives a conservative estimate for the fretting fatigue life. Further, the effect of modelling elastic-plastic behaviour is significant for low a/R ratio (for constant �R�). However, opposite trend was observed when �R� was varied keeping �a� constant. Also, it is found that the effect of contact geometry cannot be characterized using a single parameter like a/R ratio or contact area.

Keywords

• Dovetail
• Flat with rounded edge
• Fretting
• Contact geometry