Dynamic Plastic Response of an Immersed Pipe

The dynamic plastic deformation of a rigid-ideally plastic pipe subjected to an internal pressure is reduced when the pipe is surrounded by a fluid. A method to determine the added (virtual) mass which reflects the resistance of the fluid being displaced by the deforming pipe is described herein. The expression for the added mass is derived in form of an integral which in turn is solved by means of numerical techniques recognizing the asymptotic behavior of the argument. A single parameter family of curves is given for the added mass. An approximation in the form of a polynomial is also computed for the added mass in order to simplify the subsequent determination of the plastic deformation of the pipe.