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C. Baron Saiz et alii, Frattura ed Integrità Strutturale, 34 (2015) 608-621; DOI: 10.3221/IGF-ESIS.34.67 612 Figure 6 : Main dimensions of the discs The main discs dimensions are summarized in Tab. 3. Dimension External diameter of braking surface (mm) 295 Internal diameter of braking surface (mm) 196 Hub diameter (mm) 55 Front and rear disc thickness (mm) 10.5 Vanes thickness (mm) 12 Pad surface, S pad (mm 2 ) 5475.8 Table 3 : Common dimensions of the discs. H EAT FLUX AND BRAKING FORCE INPUTS o perform the numerical simulations of the brake-fading test, the working conditions of the thermal and structural analyses have been preliminarily defined. In particular, the specific heat flux at the pads/disc interface and the braking forces have been calculated. All calculations have been made considering the input data reported in Tab. 1. Since the Ansys FEM code does not allow to setup the disk rotation during a transient thermal analysis, a specific routine has been developed. In particular, the annular braking surface has been subdivided in eight sectors, each one equal to the pad surface (S pad ). After, for every single wheel turn, the specific heat flux in a braking sector has been calculated and imposed, following an appropriate timing, to suitably simulate the relative rotational motion between pads and disk. Heat Flux On the basis of the law of conservation of energy, it can be assumed that almost all the kinetic energy of the vehicle during motion is equal to the heat generated after vehicle stops [1,7]. During the braking phase, in fact, due to the friction between pads and disc surfaces, the kinematic energy of a vehicle is transformed into thermal energy. In this study, as T