1. Graduate Student, Astronautics Research Group, School of Engineering Sciences, Univ. of Southampton, Highfield, Southampton SO17 1BJ, U.K. (corresponding author).
2. Senior Lecturer in Aerospace Structural Dynamics, School of Engineering Sciences, Univ. of Southampton, Highfield, Southampton SO17 1BJ, U.K.
3. Principal Stress Engineer, Composites, Smith Aerospace Mechanical Systems-Aerostructures, Kings Av., Hamble-le-Rice, Southampton SO31 4NF, U.K.