Modal Identification Tests on a Liquid Propellant Tank and Support Structure.

Abstract

Modal identification tests were performed on a liquid propellant tank and its support structure in several configurations and by using different identification techniques. The tank was tested in an empty state and when filled with liquid. It was suspended in two configurations: in an equatorial and polar mounting condition. For the purpose of modal identification, a classical modal survey test on a seismic block as well as a base-excited qualification test on a multi-axis vibration test facility were utilised. The dynamic forces, transmitted from the tank to the support structure and from the support structure to the table of the vibration simulator, were also measured during the qualification tests. The results of the modal identification tests are described and discussed. The identified modal data of the different types of tests are compared with each other.