Methodology

24 августа, 2015

Pokraskin

The experimentation was divided into two steps: the first part run on pin — collar specimens realized according to ISO 10123 [13], and the second one carried out on bigger sized shaft-hub couplings. The bigger sized specimens allow larger gaps for given temperature, so asto make possible the assembly process with practical temperature differentials between the parts; furthermore the bigger size allows to increase the time available for assembly operations. All the specimens were manufactured with C40 UNI EN 10083-2 steel [14], without any surface treatment. All the specimens were pushed out with the same press (Italsigma, 100 kN) and the complete force-displacement diagram was recorded. The push-out speed was set at 0.5 mm/s throughout the experimentation. Press fit specimens were assembled by means of the aforementioned press, while the clearance, shrink fit and cryogenic-fit ones were assembled manually. All the specimens assembled with adhesive cured more than 24 h at a R. T. of 20°C, in order to achieve a complete

polymerization [15]. In the case of adhesively bonded joints assembled with clearance, the shear strength of the adhesive tad_cl can be calculated according to:

where A is the coupling surface and Ftot is the push-out force. Eq. (1) holds true for clearance specimens assembled at any temperature. In the case of joints assembledwith interference and no adhesive, Eq. (2) is used, in which m is the mean coefficient of friction between the mating parts, evaluated at decoupling.

Fnt = PA (2)