Flutter of Flexible Hydrofoil Struts 



EI bending stiffness 



F hydrod.ynam.ic force 



GJ torsional stiffness 



g structural damping coefficient ; also, gravitational ac- 



celeration 



H amplitude of bending displacement h 



h linear displacement of strut at elastic axis 



I a total mass moment of inertia of strut and tip attachments 



about elastic axis 



I* added moment of inertia of pod about elastic axis, ap- 



' proximated by the added moment of inertia of a prolate 



spheroid. 



j ^ 



[Kj stiffness matrix of strut 



[K'J effective stiffness matrix of the strut-fluid system 



L strut length along elastic axis 



/ distance from free surface to tip of strut along elastic 



axis 



M oscillatory moment about elastic axis per unit span of 



strut, positive in direction of positive 



M pod pod mass 



M* j added mass of pod 



ImJ mass matrix of strut 



Im*J added mass matrix of strut 



I M 1 I effective mass matrix of the strut-fluid system 



m mass per unit span along elastic axis 



367 



