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NHV Optimization of Power UnitsMarket DriversWhile strength limits are being pushed further and further, requirements for noise reduction are becoming more stringent. Major noise sources in the engine are clearances in cranktrain bearings, piston liner contacts and contacts of the valve train and timing drives. In addition, focus is being placed on powertrain and transmission noise as other sources are reduced.
Simulation allows individual mechanical noise sources to be represented very accurately. The large amount of data resulting from acoustic analyses requires automatically compressed result evaluation. This evaluation serves as a decision aid for further optimization.
AVL ApproachThe elastic multi-body dynamics solution of EXCITE Power Unit, connecting FE-based flexible bodies via non-linear contact joints, is used for prediction of power unit vibration and acoustics. Because of non-linearities, forced vibration calculation is performed in the time domain. AVL’s structural dynamics software solution enables customers to investigate the noise phenomena of engines and transmissions including gear rattle, gear whine, chain noise and specific phenomena in the driveline.
AVL EXCITE Strengths- Optimized joint models reduce calculation time and improve accuracy for predicting non-linear physical behavior in contacts (bearings, piston-liner contact, engine mounts)
- Joint models enable analysis of noise generation mechanisms in the cranktrain (which are difficult to access through experiments)
- Realistic engine operating condition through transient engine run-up simulation
- Measurement-based automatic identification of engine mount parameters
- Acoustic post-processing with AVL IMPRESS (integral surface velocity levels, integral mean value of selected areas/parts, etc.)
- Sensitivity analysis of noise influencing design parameters
Your Benefits- Complete system approach yields accurate structure-borne noise levels up to 3.5kHz
- Reduction of experimental effort through noise optimization during design phase
- Detection of all critical resonances and shorter overall process time through transient engine run-up
- Accurate boundary conditions for chassis excitation (cabin noise) and airborne noise calculation
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