Static Design and Dynamic Analysis of Light Weight Machinery Support Structures
Abstract Light weight truss-like structures to support shipboard machinery are currently under consideration for a variety of marine applications by the US Navy. The objective of this study was to develop the structural acoustic design principles for minimizing the transmission of vibration through the truss to the hull of a vessel and thereby reduce radiated sound. A design procedure was developed to select truss member sizes to satisfy specified design criteria, e.g., minimum weight, minimum radius of gyration, etc., while ensuring that the structure will support the design loads. The procedure interacts with the ANSYS finite element computer code to perform structural analysis. The resulting truss configurations were then analyzed to determine their dynamic performance using the SARA family of finite element programs that incorporate a continuum beam element to increase computational efficiency. A number of two dimensional and three dimensional truss configurations have been analyzed. Results will be presented illustrating the influence of a variety of design parameters on the force transmissibility between excitation point and truss support points. In addition the strong influence of local drive point admittance on the force transmissibility will be illustrated.