Acoustics Analysis of a Speaker Using FEA Tools from ANSYS
There are many reasons for conducting acoustic simulations, such as:
- Noise reduction
- Sound quality improvement
- Sound propagation analysis
In some cases, Fluid Structure Interaction (FSI) plays an important role. This means that the structure experiences feedback from the surrounding fluid pressure.
Introduction to Coupled Acoustic Simulation in ANSYS Workbench
This short clip demonstrates the comfortable handling of a coupled acoustic simulation in ANSYS Workbench, specifically with respect to a loudspeaker case. A prerequisite for the acoustic simulation in ANSYS Workbench is the ACT Acoustics Extension.
Setup and Activation
The easy setup and activation in the extensions manager allows us to:
- Define acoustics elements, real constants, and material properties
- Apply acoustic boundary conditions and loads
- Analyze typical acoustics results such as the sound pressure level
Loudspeaker Geometry
The loudspeaker geometry consists of a simplified case and a membrane. The surrounding fluid is also part of the geometry. All parts together form a multi-body part.
Coupled Acoustics Simulation Process
The basis for the coupled acoustics simulation is a full harmonic response analysis. The process involves the following steps:
- Import the geometry.
- Apply the material data to all parts.
- Define the mesh size.
- Define the acoustic boundary conditions:
- Acoustic Body: All parts representing the fluid are applied to this object. Adjust material characteristics such as mass density and speed of sound depending on the fluid.
- Acoustic Radiation Boundary: This infinite radiation boundary assumes that the ratio of the pressure and outward normal velocity is equal to the characteristic specific acoustic impedance.
- Acoustic FSI Interface: All wall faces of the case must be selected. The intended strong coupled solution means that both displacement and pressure degrees are equal, and the two values of FSI are solved simultaneously.
- Define an excitation for the harmonic response analysis by setting the acoustic normal surface velocity at the loudspeaker membrane.
- Set the frequency range to 200 Hz.
- In the analysis settings, analyze the frequency range from 200 to 400 Hz with 66 solution intervals.
- Start the solving process.
Results and Analysis
Let's take a brief look at the results:
- Evaluate the frequency range of the two walls, revealing several frequencies where the membrane amplitude is significantly higher.
- Insert the acoustic sound pressure level (SPL). Generally, the absolute SPL has a specific unit. In some cases, it is recommended to weight the absolute SPL according to the threshold of human hearing, resulting in the unit called DBA.
- An animation of the pressure at one frequency can be achieved by inserting the pressure as a user-defined result.
- Analyze the far sound pressure field beyond the FEA computational domain by inserting the acoustic far field. This field enables evaluation of the SPL over the frequency at a certain location and analysis of the sound's directivity.
- Represent the SPL at different frequencies in a polar diagram to gain important information about the sound.
Conclusion
ANSYS Workbench enables various acoustic simulations, including pure acoustics and more complex simulations considering weak or strong coupled fluid structure interaction. Convenient pre- and post-processing combined with efficient solver technology allows for a faster understanding of sound generation and propagation.
For more information, please contact Ozen Engineering, Inc. or visit the link in the video description. Thank you for watching!
There are many reasons for acoustic simulation, such as noise reduction, sound quality, or sound propagation. In some cases, fluid-structure interaction (FSI) plays an important role, meaning the structure experiences feedback from the surrounding fluid pressure.
The following short clip demonstrates the comfortable handling of a coupled acoustic simulation in ANSYS Workbench, focusing on a loudspeaker case.
The prerequisite for acoustic simulation in ANSYS Workbench is the ACT Acoustics Extension, which allows easy setup and activation in the extensions manager.
This enables the definition of Acoustics elements, real constants, and material properties, the application of acoustic boundary conditions and loads, and the analysis of typical acoustic results, such as sound pressure level.
The loudspeaker geometry consists of a simplified case and a membrane, with the surrounding fluid as part of the geometry. All parts form a multi-body part. The basis for the coupled acoustics simulation is a full harmonic response analysis.
After importing the geometry, applying material data to all parts, and defining the mesh size, one can define acoustic boundary conditions. First, insert the acoustic body, applying all fluid-representing parts to this object.
Next, define the acoustic radiation boundary, an infinite radiation boundary assuming the ratio of pressure and outward normal velocity equals the characteristic specific acoustic impedance. Then, create the acoustic FSI interface by selecting all wall faces of the case.
The strong coupled solution means both displacement and pressure degrees are equal. The two FSI values are solved simultaneously. Typically, a harmonic response analysis requires excitation. Define acoustic normal surface velocity at the loudspeaker membrane, with a frequency range of 200 Hz.
In the analysis settings, analyze the frequency range from 200 to 400 Hz with 66 solution intervals. Now, start the solving process. Evaluate the frequency range of the two walls, revealing several frequencies where the membrane amplitude is significantly higher.
Insert the acoustic sound pressure level (SPL). Generally, the absolute SPL has the unit Pa. In some cases, weight the absolute SPL according to the threshold of human hearing, then the unit is called dBA.
An animation of the pressure at one frequency can be achieved by inserting the pressure as a user-defined result. Next, analyze the far sound pressure field beyond the FEA computational domain. Insert the acoustic far field, the pressure field of the sound.
The far field is the microphone, enabling evaluation of the SPL over the frequency at a certain location. Analyze the directivity of the sound, SPL on a perimeter of an imaginary sphere with respect to a specific frequency.
The representation of the SPL at different frequencies in a polar diagram gives important information about the sound. To summarize, ANSYS Workbench enables various acoustic simulations, from pure acoustics to complex simulations considering weak or strong coupled fluid-structure interaction.
Convenient pre- and post-processing combined with efficient solver technology allow faster understanding of generation, propagation, and sound. Control the noise, volume, and frequency of a sound. Thanks for watching! We hope you've gained insights about the performance of ANSYS.
Find out more through the video link in the description. Tune in next time for a discussion on Bernard spl accuracy through the hearing available on the belu master Network. For in-depth Sectico diversity patterns and Cord Portuguese design, please contact us now.
