Noise Absorbing and Insulating Panel Model development
Challenge: Create FE model of Noise Absorbing and Insulating Panel by MSC Nastran
The acoustic impedance is usable to create model of vehicle panel trim parts such as floor carpet and dashboard insulator which have both functionalities of noise absorption and insulation.
However, the following problems are often found.
- Only noise absorbing characteristics are described because impedance characteristics of trim parts are modeled, which is a view from acoustic field.
- That means impedance characteristics of trim parts from a view of structural side as well as transmission of forces between structure and acoustic field through trim parts are failed to be modeled.
- Therefore, the acoustic impedance is not proper to model carpet with heavy layers since cutoff characteristics by structural excitation are not described.
How to resolve pains:
The following modeling approach is proposed, which frequency response characteristics of panel trim parts are modeled by frequency depending spring or damper after calculating the frequency response characteristics by physical test and/or simulation model.
Combining the created panel trim model with vehicle body FE model makes it possible to calculate acoustic characteristics of the body with MSC Nastran including panel trim characteristics.
The modal is created by applying trim option of ESTECH.NAST+
Strength of the Software
- The modeling approach is very unique because it creates degree of freedom of mean displacement which is perpendicular to panel surface attaching to the air, besides panel attaching surface, whose calculation load is light because frequency depending portion is limited.
