Issue 48

P. Dhaka et alii, Frattura ed Integrità Strutturale, 48 (2019) 630-638; DOI: 10.3221/IGF-ESIS.48.60 630 Focused on “Showcasing Structural Integrity Research in India” Effect of contact geometry on the contact stresses in a flat with rounded edge contact Pankaj Dhaka, Raghu V. Prakash Indian Institute of Technology Madras, India pdhakanith@gmail.com , https://orcid.org/0000-0001-7250-7845 raghuprakash@iitm.ac.in, https://orcid.org/0000-0002-8888-022X A BSTRACT . 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’ 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. K EYWORDS . Dovetail; Flat with rounded edge; Fretting; Contact geometry. Citation: Dhaka, P., Prakash, R.V., Effect of contact geometry on the contact stresses in a flat with rounded edge contact, Frattura ed Integrità Strutturale, 48 (2019) 630-638. Received: 04.01.2019 Accepted: 25.01.2019 Published: 01.04.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION nvestigation of the contact behaviour is an indispensable exercise for many applications ranging from aero-engine and automotive components to orthopedic implants, hoists, power plant and electronic components [1-6]. The detrimental effect of a poor contact could be either loss of clearance in assemblies due to wear at the interface [2, 3, 6] or complete failure due to crack initiation and propagation at the mating interface [1, 4]. The damage gets even more aggravated in the fretting regime where the sliding between the contact pair is of small amplitude (ranging between few microns to about 200 microns) because of smaller contact zone size which leads to highly localized stresses. The contact I