PSI - Issue 17

Sebastian Vetter et al. / Procedia Structural Integrity 17 (2019) 90–97 Sebastian Vetter/ Structural Integrity Procedia 00 (2019) 000 – 000

94

5

a

b

c

, = 4400

Fig. 3. (a) measurement of torsional moment and twisting angle of the quasistatic load-increasing procedure of P-SHC H7-concave with / = 1 ; = 0 ; (b) permanent deformation of the shaft of P-SHC H7-concave with / = 0.5 ; = 0.5‰ ; (c) plasticization within the contact of P SHC H7-concave with / = 0.25 ; = 0 . Table 3. Specification of investigated P-SHCs with experimentally determined limits of torsional moments until permanent deformation occurs (shaft material: 42CrMo4+QT, hub material: C45E+N). Profile shape Relative joining length / Interference [‰] Limit of torsional moment , [Nm] Failure location H3-convex 1 0 4400 free shaft H3-convex 1 0.5 4400 free shaft H3-convex 0.75 0.5 3600 contact H3-convex 0.5 0.5 2400 contact H7-concave 1 0 4400 free shaft H7-concave 0.75 0 4400 free shaft H7-concave 0.25 0 3200 contact H7-concave 1 0.5 4400 free shaft H7-concave 0.5 0.5 4400 free shaft H7-flat 1 0 4400 free shaft H7-flat 0.5 0 2800 contact The fatigue strength of the P-SHCs was investigated for the typical load of rotating bending with and without static torsion in the area of high cycle fatigue. For the test series under rotating bending with static torsion, the level of the superimposed static torsion had to be determined. This was defined by the nominal stress ratio of torsion to bending / = 1 . The profile shape of a P-SHC caused local bending and torsion stresses at a free shaft, which were not constant over the circumference, in contrast to a circular cross-section. Therefore, a suitable equivalent diameter had to be selected to determine the nominal bending and torsion stresses. The mean diameter was used below as the equivalent diameter. Thus the equivalent resistance moments for bending and for torsion could be calculated. With the determined ratio / = 1 , it resulted in, according to equations (3) and (4), the torsional moment being twice as high as the bending moment at the failure critical location of the P-SHC. According to the investigations in Reinholz (1994), the failure critical location is thereby close to the hub edge. = = 32∙ ∙ 3 (3) = = 16∙ ∙ 3 (4) 2.4.2. Dynamic tests