Angle of incidence effects for underwater shock using generic computational models, rev. 1

The modeling techniques used to develop several generic models of the shock response of submarines are described. The result is three overlapping models: (1) CAPS, in which the directly arriving shock wave is applied to a rigid capped cylinder that contains a large spring supported mass; (2) REFLECT, in which a rigid cylinder capped by hemispheres is subjected to direct and reflected shock waves resulting from an explosive source at an arbitrary location; and (3) TDEF, in which the directly arriving shock wave drives a deformable capped cylinder that is modeled by a combination of rigid body modes, beam modes, and axisymmetric shell modes. How the computer programs for these models provide the ability to perform damage assessments, is described, particularly regarding the significance of angle of incidence. Each computer code evaluates the temporal response of the structure for an explosive source situated at a specified angle relative to the axis. Results are evaluated for the center of mass and points at each end of the cylindrical segment. When a sequence of heading angles covering a quarter circle is input, the magnitude of the instantaneous (vector) velocity and acceleration at each point is monitored for its maximum value.