The presentation describes a simulation procedure for evaluating the performance of noise control systems. The studied systems are focused on reducing the noise at specific frequencies and can be either passive or active systems. A passive system is typically an installation with tuned vibration absorbers mounted to the structure. Active noise control systems can for example be a system with loudspeakers that with help of a control unit tries to minimize the noise with the help of a number of control microphones. In designing this types of systems the properties of the devices as well as the mounting locations very important. It is therefore necessary to investigate a large number of actuator locations and performing this on a large scale finite element model would be very time consuming.

The method includes a dynamic condensation procedure of the finite element model, which reduces the size of the system of equations to be solved in the numerical analysis. This condensation does not introduce any approximations and the accuracy is only limited to the quality of the numerical models.

The procedure involves a number of steps from the response analysis for the primary excitation to running optimization of the locations of the system devices. There is an ongoing work to make use of the Hyperstudy environment for these simulations and using Radioss to solve the large scale finite element problems.

The simulation procedure investigated is focused on noise in a propeller aircraft and a generic aircraft model of is used to illustrate the procedure.

## The Author

**Peter Davidsson**

Creo Dynamics AB

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