1. MTS, Struct. Technol. Group, The Aerospace Corp., El Segundo, CA 90245. E-mail: michael.w.vanik@aero.org
2. Prof., Div. of Engrg. and Appl. Sci., California Inst. of Technol., MS 104-44, Pasadena, CA 91125.
3. Grad. Student, Div. of Engrg. and Appl. Sci., California Inst. of Technol., MS 104-44, Pasadena, CA.