Dynamics & Vibration Research Group

In many engineering applications it is of great importance to be able to predict the high frequency vibration response of a structure subjected to various loading conditions. Such predictions enable us to confirm that noise and vibration levels in a compartment (e.g. a ship cabin) are within given limits or that a structural component (e.g. a rotor) is not subjected to excessive dynamic stress which may cause fatigue problems and eventually failure. The current project aims to investigate the high frequency vibration transmission paths in a built-up structure, an understanding of which may help us to make more accurate predictions regarding the response characteristics of automotive, aerospace and marine vehicles.

Project Details

One of the methods used in industry today is called Statistical Energy Analysis (SEA) and can provide good predictions of high frequency noise and vibration levels in a built-up structure. SEA is based on power balance equations, and if the excitation power input to the system is given, the resulting average vibration levels can be calculated. However, SEA cannot fully account for energy flow along the stiffening members of a typical stringer-skin construction (e.g. an aluminium panel stiffened by beams attached on one side) commonly used in the aerospace and marine industries. This is an issue of concern, especially if the excitation is applied to one of these stiffeners. The present work is currently addressing this issue by considering improvements on the calculation of the average SEA power input to a plate due to excitation applied at its boundary.

A new modelling technique has been explored (where the plate is modelled as a power absorbing system, in which the power is carried by waves propagating towards a black hole located somewhere in the interior of the plate), and some promising results have been obtained for simple systems. The method is now applied to more complex built-up systems, and if successful, the method will improve SEA as a high frequency noise and vibration response prediction method.



(a) left: circular geometry.     (b) right: rectangular geometry.
SEA power convergence plot for a finite membrane with prescribed boundary displacements. The plots show the calculated deviation (in percentage) from the true SEA power input versus a measure of level of model detail.

Relevant/Recent Publications

1. R.H. Lande, R.S. Langley, P.J. Shorter, J. Woodhouse, "Statistical Energy Analysis of a built-up structure excited through its stiffening members", Proc. 10th International Congress on Sound and Vibration, Vol.2., 1083-1090, July 2003, Stockholm, Sweden.
2. R.H. Lande, R.S. Langley, "The energetics of cylindrical bending waves in a thin plate", submitted as a Letter to the Editor of the Journal of Sound and Vibration

Principal Investigator & Researchers

• Professor R. S. Langley
• Rolf Lande

Funding Bodies

• Universities UK (ORS award) 2002-2004
• Vibro-Acoustic Sciences, Inc. 2002-2004