Vehicle Comfort
With every new vehicle generation, the customer expectations increase with respect to vehicle comfort quality. From a vehicle engineering standpoint, this requirement for improved comfort translates into the requirement to reduce the levels of tactile and acoustic vibration at comfort points by means of analysis and optimization.
The engine and gearbox excite the vehicle body over a wide frequency range. Road excitation is passed through the tire, chassis system and body to the vehicle occupants. Another important source of vehicle vibration excitation includes the turbulent flow of air around the vehicle. The combination of many excitation systems and the multiple response comfort points (vibration of seats, steering wheel and mirrors etc.) leads to a large number of responses at many frequencies. These responses must be reduced to acceptable target levels. The vibration team at CDH has many years of experience in the use of advanced CAE optimization tools to achieve customer defined vibration target levels.
Full Vehicle
- Full vehicle system modeling
- Low-frequency NVH analyses (motor excitation noise, road excitation noise)
- Influence and calibration of components in complete system to achieve optimal full vehicle vibration performance
- Time domain analyses
- Hybrid modelling
- Definition of target levels for full vehicle analyses
Body Development: Body in White and Trimmed Body
- Static analyses of body-in-white structure to determine bending and torsional stiffness, stiffness of chassis connection points and calculation of stress and strain distributions
- Optimization of body structure
- Equivalent radiated power calculations
- Panel participation factors
- Modal analyses of acoustic cavity
- Modeling of trim
- Correlation of test and analysis results
- Robustness analyses for evaluation of effects of production variability
Chassis
- Chassis system modeling
- Noise analysis with wheel inbalance loadcases
- Vibration analysis of steering system
- Assessment of body mounts
- Chassis system tuning
The purpose of acoustic analysis is to reduce the sound pressure level at comfort points in the passenger air cavity, such as driver ear position, to a minimum. This type of analysis is performed by creating an FE model of the acoustic cavity and coupling this to the structural model.
Sound Level Prediction
- Calculation of air-cavity eigenvalues and eigenvectors
- Analysis of sound pressure level (SPL) sensitivities
- Analysis of energy transfer paths for reduction of acoustic energy
Sound Pressure and Structural Vibration
Excitation:
- Excitation on longitudinals
- Frequency domain road excitation
- Time domain road excitation
- Digitalized road profile
- Engine idle / full load excitation
- Excitation through universal joint
- Wheel out-of-balance
- Radiator fan out-of-balance
Sensitivitätsanalysen
- Component sensitivity analyses in frequency and time domain
- Calculation and presentation of component sensitivity analyses as a color map to identify suitable design variables for optimization.
Energy Analyses
- Calculation of equivalent radiated power, normalized acoustic intensity, or velocity-squared distribution for radiating surfaces
- Identification of design variables for optimization
- Virtual transfer path analysis (TPA) to understand energy flow-paths
Participation-Factors (PPF/GPPF)
- Calculation and display of panel and grid participation-factors
Transient Analyses
- Analysis of transient phenomena with non-linear components
Probabilistic Analysis
- Studies to determine the effects on NVH performance of production variability
- Cost-of-quality analysis
- Kosten/Nutzenbewertung (Kostenfunktion)
- Stochastic analysis methods
- Probabilistic/Possibilistic Analysis
- Monte Carlo Analysis
- First Order Reliability Method (FORM)
- Extreme Value Analysis
- Stochastische Optimierung
