Issue 48

P. Dhaka et alii, Frattura ed Integrità Strutturale, 48 (2019) 630-638; DOI: 10.3221/IGF-ESIS.48.60 632 where, p  is plastic strain,  is true stress, 0  , 0  are yield point values for true stress and true strain respectively, and  , n are Ramberg Osgood coefficient and exponent respectively (a) (b) Figure 1: (a) Schematic of flat-with-rounded-edge on plate configuration, (b) Meshed model Young’s Modulus (GPa) Poisson’s ratio Yield strength (MPa) α n 121 0.29 677.6 0.43 10 Table 1 : Material properties of Ti-6Al-4V. For validation of FEM Effect of contact geometry S. No. ‘a’ ‘R’ S. No. Objective ‘a’ ‘R’ 1 1.5 1.35 11 Effect of ‘a’ 1 1.35 2 0.5 1.35 12 2.7 1.35 3 0.1 1.35 13 4.05 1.35 4 0.005 1.35 14 Effect of ‘R’ 1.5 1 5 0.0005 1.35 15 1.5 0.75 6 1.5 0.135 16 1.5 0.5 7 1.5 2 17 Effect of a/R ratio 1 2 8 1.5 4 18 0.5 1 9 1.5 6 19 2 1 10 1.5 8 20 1 0.5 Table 2 : Analysis cases for the validation of finite element model The frictional interaction between the fretting pad and the plate was defined using Coulomb’s law of friction with a constant friction coefficient of 0.8; a value typically observed in experimental studies [8]. Combined Penalty (for shear traction) and augmented Lagrange (for normal contact) algorithm was used for contact formulation. The combined algorithm has been found particularly suitable for the fretting contact problems and computationally more efficient as compared to pure penalty formulation or pure Lagrange method [19]. A constant normal load (P) of 750 N has been