Untersuchungen zum Größeneinfluss auf die Gestaltfestigkeit/Kerbwirkungszahlen von Welle-Nabe-Verbin

FKM 2015
Issue number 325
Project no. 294 II
97 pages

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Abstract:

The design strength tests carried out to date on compression joints (PV) and parallel key joints (PFV) served to statistically validate existing characteristic values such as the notch coefficients and to quantify qualitative statements on individual geometry variants. However, there were still uncertainties in the transfer of existing results to shaft diameters with DF > 150 mm.
The completed project now closes this knowledge gap with regard to the notch-effect coefficients for PV and PFV with shaft diameters DF > 150 mm. The fatigue strengths of a PV made of C45E with a smooth shaft and undercut as well as a PFV with undercut for shaft diameter DF = 230 mm were determined in rotating bending tests. The undercut and the keyway for the connections were manufactured geometrically similar to the reference diameter connections with DF = 40 mm. As the experimentally determined design strengths on the large diameters show, the notch coefficients determined from the back calculation agree with the proven algorithm using the K3 diagram according to DIN 743 and with the help of the ratio of the support coefficients ns(rP)/(n(r)-ns(d)) according to the FKM guideline. For the user, this means that the tried and tested procedure can be retained. To estimate the tribological slip and the resulting friction fatigue stress, tests were carried out for the material combinations C45E/C45E, 42CrMo4+QT/C45E and EN-GJS-600/C45E using the so-called friction block model to determine the friction fatigue strength. With the help of the fatigue strength verification according to the FKM guideline, the roughness factor KR,s,RD was determined as a function of joint pressure and slip. The differences in the design strength determined as a function of slip and joint pressure are a measure of the differences between the materials in terms of friction fatigue strength.
The parameter field was extended using the numerical simulation of PV and PFV and geometrically similar undercuts and feather keys as well as undercuts according to DIN 509 and feather keys according to DIN 6885 were examined for diameters DF = 40, 100, 230 and 500 mm. It was found that the connections with DF > 100 mm and geometrically similar undercuts exhibited lower stresses in the undercut than the connections according to the standard. The use of geometrically similar undercuts is therefore recommended.
The objective of the research project has been achieved.
Scope of report: 97 p., 73 fig., 38 tab, 47 lit.
Start of work: 01.01.2013
End of work: 30.09.2014
Funding body: BMWi / IGF-Nr. 17582 BR/1
Research unit: TU Chemnitz, Institute of Design and Drive Technology (IKAT), Chair of Design Engineering
Head: Prof. Dr.-Ing. E. Leidich
Editor and author: Dipl.-Ing. M. Lätzer
Chairman of the working group: Dr.-Ing. G. Romanos, Henkel AG + Co. KGaA, Garching
Chairman of the FKM Board: Dipl.-Ing. H. Rauen, VDMA, Frankfurt