Numerical modelling in acoustics and dynamics
ISVR Consulting provides a comprehensive acoustics and vibration modelling service. We use a wide range of industry standard software for numerical modelling and simulation. This enables designs to be tested with a computer model and acoustical or vibration problems can be found and solved before committing expenditure on building prototype machines or actual buildings.
ISVR Consulting uses the ANSYS Finite Element code to assist with the design of structures to prevent excessively high levels of forced vibration. The finite element method is used to predict natural frequencies of vibration, the response of a structure to force inputs, and the resulting stress levels. Our experience in finite element modelling includes:
- Vibration isolation of engines and pumps, and design of machinery rafts
- Design of production machinery to avoid vibration-induced misalignments
- Low noise design to avoid resonances in constant speed machinery
- Control of vibration transmission in buildings
- Dynamic and static stress analysis
Statistical Energy Analysis is a method of predicting the transmission of high-frequency noise and vibration through built-up structures. It is ideal for exploring complex noise and vibration issues and identifying problems early in the design of a product or a structure. The SEA method can then be used to optimise a final design before a physical prototype is built, saving both time and money.
SEA modelling is used to study noise and vibration in a wide range of applications ranging from cars and trucks to aircraft, spacecraft, ships, electronic equipment, buildings, consumer products and more.
In the SEA method, the structure being modelled is split into smaller, interacting subsystems. The response of the structure to different forms of excitation, either mechanical or acoustical, is calculated from the strength of the coupling between subsystems and the distribution of damping. The degree of complexity and the frequency range over which the results are valid are constrained to some extent by the statistical nature of the model.
ISVR Consulting was recently asked to predict the noise levels in critical areas of a ship, including crew or passenger accommodation, work and machinery rooms. The ship was a large tanker. Statistical Energy Analysis was used to predict the noise levels from engines and machinery reaching critical areas via airborne and structure-borne paths, and to deduce whether the noise levels would meet the International Maritime Organization (IMO) Guidelines for noise levels on board ships.
ISVR Consulting currently uses VA One software for SEA modelling.
Boundary Element methods are used to model the patterns of sound radiated from vibrating surfaces and the diffraction of sound fields around structures. We use VA One software model for this.
Our experience includes the modelling of the sound field radiated by high-lift slats on aircraft and the design of an engine test bed to reduce installation effects. Research in ISVR has modelled the diffraction of sound around the human head (for acoustic imaging and virtual stereo). Other applications include the design of silencers, optimisation of sounders and alarms for maximum efficiency, and the modelling of loudspeaker systems.
(Acknowledgement: ANSYS and VA One are trademarks of ANSYS INC and the ESI Group respectively.)