On optimal stress for shaft–hub connections (polygon connections)

In machine elements many different methods for connecting shaft and hub are specified in different standards. A not so common shaft–hub connection is the polygon profile as specified in DIN 32711 (P3G) and DIN 32712 (P4C). This type of connection is an alternative to key or spline connections. The practical point of the connection is the easy assembly and disassembly, but as for all shaft–hub connections the drawback is the high stress leading to a limited strength of these connections. The polygon connection design is to some extent due to an old production method, i.e. it is not design/ optimized for reducing the maximum stress. In the present paper it is shown how the connection strength can be improved significantly by the use of shape optimization. The focus here is both on the highest contact stress (compression) but also on the largest tensile stress. Overall reduction in the stress in the order of 20% to 40% is found relative to standard design.