Engineering applications of NiTi shape memory alloys

This paper considers the use of martensitic NiTi shape memory alloys (SMAs) for technical applications in drive technology with a focus on bearing and gear technology. Within bearing technology, SMAs can be applied for the clearance adjustment of taper roller bearings using the extrinsic two-way effect. First constructive solutions show the axial motion of the outer ring to compensate the decreasing axial clearance as a result of different temperatures between shaft and housing. To compensate different thermal expansions SMAs offer improvements using the extrinsic two-way effect. With the help of steel springs the external load the SMA is working against can be realized. With given information about the stress-strain behavior for NiTi SMA under axial compression the necessary forces and compressions to reach the demanded elongations can be calculated. (c) 2007 Elsevier B.V. All rights reserved.