Techniques for Missile Defense (Flexible-Body Dynamics for Off-Nominal Penaid Signature Simulation)

The majority of penetration aids (penaids) are packed to conserve volume until ready for deployment, then inflated or erected to a final shape. Such "stowable" objects are necessarily constructed from flexible materials; their post-deployment motion will include (at least) small structural vibrations and energy loss to damping, as well as the usual rotational component (tumbling, or spin and precession for an axisymmetric conic decoy, more complex rotation in the general case). Potential discrimination techniques exist employing the time-dependent signatures of rotation, vibration or both. Off-nominal deployment, in which the object fails to reach its intended size, shape and/or rotational state must also be considered. In any case (nominal or off-nominal deployment) the physical interaction among the rotational and vibrational degrees of freedom can introduce potentially exploitable signature changes. This Proposal deals with the physics and mathematics of techniques for simulating the rotation and vibration of flexible penaids, including in particular the interactions between these motions. We build on a simulation developed under Phase I and also invoke the expertise of a subcontractor with extensive experience in the modeling of flexible structures.