Vibration amplification by repetitive pulsing of rapidly heated cylinders

Abstract

The fuel elements of a repetitively pulsed fast reactor are subjected to rapid heating in a time short with respect to their mechanical response time. As a result, vibration of the fuel elements occurs and, under certain conditions, these vibrations may be amplified considerably.This work is an experimental investigation of the amplification which occurs when a thin wall, hollow, stainless steel cylinder is repetitively heated internally by Joule heating. The results, which compare well with a theoretical analysis of this problem performed by another author, show that significant amplification of the vibrations can occur.The experimental technique is a variation of the resonance method for measuring natural frequency and internal damping. The apparatus could be adapted for use as a materials testing facility for high cycle, low stress fatigue studies since relatively large stresses could be induced with a rather small energy deposition per pulse.