ZAFER GARDAL, PhD, is a professor in the Department of Aerospace and Ocean Engineering and the Department of Engineering Science and Mechanics at Virginia Polytechnic Institute and State University in Blacksburg, Virginia. RAPHAEL T. HAFTKA, PhD, is a professor in the Department of Aerospace Engineering, Mechanics, and Engineering Science at the University of Florida in Gainesville. PRABHAT HAJELA, PhD, is a professor in the Department of Mechanical Engineering, Aeronautical Engineering, and Mechanics at Rensselaer Polytechnic Institute in Troy, New York.