Issue34

C. Baron Saiz et alii, Frattura ed Integrità Strutturale, 34 (2015) 608-621; DOI: 10.3221/IGF-ESIS.34.67 619 cylindrical constraints, which limit the thermal expansion. Stress distributions over the discs are uniform. Curved and pillar-shaped vanes rotors have similar behaviours, both in terms of stress distribution and maximum values reached on them, respectively equal to about 43MPa and 42MPa. Figure 14 : Von Mises stress maps on the internal vanes of the straight vanes disc. Better results have been obtained with the straight-vanes disc, whose maximum stress value is about 39 MPa, slightly lower than the other two configurations. In an exhaustive study of the performances of brake discs, it is also important to check the structural deformations. In this kind of applications, in fact, thermo-mechanical strains must be under control because excessive values could induce an irregular contact between pads and disc, so compromising the correct functionality of the braking system [8]. In the analysed rotors, strains develop mainly along the radial direction, due to the increase of temperature from the hub to the outer part of the disc. Highest deformations have been found at the pads-disc interface. This area is particularly stressed because of the applied braking forces and the thermal flux, which causes locally considerable thermal gradients. Fig. 15 represents amplified lateral views of the discs radial deformations; it is possible to perceive how discs start to curve themselves, turning into a cone shape. Figure 15 : Radial deformations on straight (left), pillar-shaped (centre) and curved-vanes (right) disc