Ruggedness Testing of ASTM Standard Test Methods for Shape Memory Alloy Materials

The transition of shape memory alloy (SMA) actuators from prototype demonstration to commercialization and production use has been limited by the absence of accepted industry and regulatory testing and certification standards. To address this need, a committee was formed with members from industry, government and academia to develop and publish standard test methods that are specifically intended to measure SMA actuation properties. The committee was organized within the Aviation Vehicle Systems Institute (AVSI). In 2017 two standard test methods were published by ASTM as E3097 – “Standard Test Method for Mechanical Uniaxial Constant Force Thermal Cycling (UCFTC)” and E3098 – “Standard Test Method for Mechanical Uniaxial Pre-strain and Free Recovery (UPFR)”. Since their release both standards have been subjected to ruggedness testing to identify parameters and test factors that could impact the results of the test method. Test variables identified for evaluation included heating and cooling rates, upper and lower cycle temperatures, strain rate, dwell time and minimum load. Four laboratories independently performed a ruggedness test of the seven identified factors, with eight runs in two replicates, in accordance with E1169. Efforts to perform an ASTM Inter-Laboratory Study (ILS) to assess the precision and bias of both test methods are underway. An overview of the new standardized test methods, results and analysis from the ruggedness testing and an update on the progress of the ILS will be presented.