OUT-OF-PLANE SOLUTIONS AND BIFURCATIONS OF SUBMERSIBLES IN FREE POSITIVE BUOYANCY ASCENT

The problem of motion stability of submersible vehicles in free positi ve buoyancy ascent is analyzed. Motion is allowed to occur in combined vertical and horizontal planes. Continuation and catastrophe theory t echniques are employed to trace all possible steady-state solutions in six degrees of freedom, while local linearization reveals their stabi lity properties. Vehicle geometric properties and control surface defl ections are used as the primary bifurcation parameters. It is shown th at multiple solutions may exist in the form of pitchfork bifurcation, solution separation, hysteresis, and teardrop branches. Regions in par ameter spaces are identified where extreme sensitivity of solutions to geometric properties and hydrodynamic modeling is present.