"The use of shape memory alloys as self-actuating drivers has heretofore been limited to devices such as a coupling, (U.S. Pat. No. 4,149,911 to Clabburn), a steam generator tube plug (U.S. Pat. No. 3,900,939 to Greacan) and a prestressed structural joint member (U.S. Pat. No. 4,294,559 to Schutzler)." . . . .