Further Enhancement of Frequency Response and Damping Analysis Capabilities of the VAST Finite Element code (Phase III). Part III: Some New Features for Improved Modelling of Damped Structures


  1. Jiang, L.
  2. Chernuka, M.W.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN);MARTEC Ltd, Halifax NS (CAN)
This report presents several new analysis features which have recently been incorporated in the VAST program to further enhance its direct frequency response and damping analyses capabilities. First of all, a numerical algorithm for treating linear elastic incompressible materials has been implemented using selective reduced integration. This algorithm is activated automatically when the ratio of the bulk and shear moduli exceeds a prescribed value. This technique increases the accuracy of linear finite element analyses of damping materials which are normally nearly incompressible. Secondly, in addition to the frequency-dependent elastic moduli and material loss factor, a capability has been developed to also accept frequency-dependent complex Poisson's ratio in direct frequency response analyses. Because the elasticity matrix is not proportional to the Poisson's ratio, the element stiffness matrices must be regenerated at each loading frequency. Thirdly, the 8-noded shellelement is modified to allow the nodes to be placed arbitrarily in the thickness direction. With this modificaiton, the 8-noded shell elements can be combined with the solid elements to model damped structures where the face plates and the core material are represented by shell and solid elements, respectively. Finally, an additional option is provided for defining the frequency-dependent material properties of damping materials. TRUNCATED
Finite elements;Constrained layer damping;Damping loss factors;Structural acoustics;Complex Eigenproblem Solver;Incompressible material;Poisson's Ratio
Report Number
DREA-CR-98-448-PT-3;MARTEC-TR-97-24-PT-3 — Contractor Report
Date of publication
01 Oct 1997
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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