Bonded drive shafts made of Al-tube with steel load transfer elements

The joining of rotationally symmetric machine parts using adhesive bonding, in either a basic way or in conjunction with shrinking, is longestablished in industrial engineering. For example, adhesives are used to secure roller bearings in their seats, gearwheels to shafts, and screws and bolts against loosening, with the latter being the most widespread industrial application. With the exception of the securing of screws/bolts, the other applications can be considered to be typical shaft/hub joints. The adhesives which are used are anaerobic curing acrylates. These are one-component products and are therefore simple to apply. They only cure in the absence of oxygen and in direct contact with metals, meaning that excess adhesive can be easily removed. The current state-of-technology for shaft/hub joints involves using similar types of materials for both the shaft and hub. However, if the shaft is made of steel and the joint of aluminum, then the different CTE of the materials leads to a lowering of the oversize and hence to a reduction in the load-bearing strength of the joint at elevated temperatures. This behavior will be discussed in this paper using the example of a drive shaft. This work has investigated whether a bonded joint between a load transfer element and aluminum tube can withstand the prevailing torsional loads. Firstly, the dimensions of a bonded joint for the case of static loads were estimated using an analytical approximation. Precise sizing was not possible under the given boundary conditions. It did become clear, however, that narrow tolerances for the dimensions of the substrates are imperative for an effective bonded joint. The subsequent experiments which were carried out on test specimens identified two adhesives with promising strength under static load conditions. It was also shown that test specimens having the theoretically determined oversize cannot be joined in practice. The application of a 'pseudo press fit', however, also leads to extremely effective bonded joints.