Shape memory alloys (SMA’s) are known to have many unique properties such as shape memory effect, superelasticity, etc, thus making the materials attractive for application in the medical, aerospace, and automotive industries. Many researchers and engineers are using shape memory alloys to solve existing problems and/or seek new opportunities. In this paper, SMA’s are used in conjunction with lip seals.  Lip seals are known to have the possibility of leakage due both to wear and to a drop in material stiffness as temperature increases.   Explored in this study is the use of SMA to improve seal effectiveness.

While keeping the same functionality of the original, an experimental version of the device was designed. A test rig was developed such that the device could be dynamically tested in an MTS damper test machine. Temperature and pressure in the chamber sealed by the lip seal were changed independently using a combination of heating tapes and hot fluid for temperature control and using a high pressure nitrogen source for controlling the chamber pressure. The volume and mass of leaked oil are used as metrics to quantify performance since oil leaks slowly making these metrics easy to measure. 

Custom made supplier seals were used to investigate ways to disassemble the seal, assemble SMA into the seal which included the development of  SMA joining methods, measure sealing force with and without SMA and determine SMA dimension. After seal assembly, i.e. integration of the SMA with the existing commercial seal, dynamic tests were performed to compare the performance of seals with and without SMA in terms of leak rate.  Results indicate that SMA has the potential to play an important role through its temperature activated stiffness increase and shape memory effects in maintaining clamping force and minimizing leakage over an extended temperature range.