Determination of Fixed Base Natural Frequencies of Dual Foundation Shipboard Equipments by Shake Tests

摘要

The report investigates the application of resonance testing to determine the fixed base natural frequencies of an in-place shipboard equipment-foundation system which is supported at two base points. Translation of the base points can cause the structure to rotate as it translates. A method was previously proposed which required the simultaneous use of two shakers capable of phase control and a range of force ratios at each driving frequency; this method would be quite difficult and expensive to apply in the field. A new technique is proposed herein which requires only one shaker to be applied at a time, thereby reducing the difficulties and restrictions considerably. An application of the technique to a theoretical system, and an analog simulation of a shake test utilizing the new method are presented. (Author)