An efficient static correction algorithm with application to the hydrodynamic loading of thin shell structures

Abstract This paper treats the problem of correctly accounting for the quasi-static component of the response of a thin-shell structure to a dynamic loading which originates from a pressure disturbance within the body of a contained fluid. The importance of quasi-static structure response has been observed in BWR safety/relief valve (SRV) actuation tests which produce a pressure oscillation in the suppression pool as a consequence of the expansion and contraction of bubbles formed from air expelled from the SRV pipeline. The problem is treated within the context of a finite-element methodology which has been previously developed for the coupled analysis of a linear elastic structure in contact with a linear acoustic fluid. For problems involving a large number of degrees of freedom, the efficient application of this method requires reduction to a set of normal modes approximating the response of the coupled fluid-structure system. The coupled modes are synthesized from the fluid properties and a set of normal modes describing the behavior of the structure in the absence of the fluid. The proposed solution to the problem is to append a shape function, representing the quasi-static component of the structural response, to the set of modes computed by standard eigenvalue extraction. The success of the method is demonstrated by comparison of calculated results with measured structural response from a typical SRV test.