Comsol, Virtual Guitar - Pasi Marttila


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Tonal Innovation Center (TONIC) hosted the second annual International Musical Instruments Seminar in Joensuu, Finland on 14th September- 16th September 2011.

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Comsol, Virtual Guitar - Pasi Marttila

  1. 1. Virtual Guitar<br />Pasi Marttila<br />COMSOL Oy<br />+358 9 2510 4051<br />
  2. 2. Outline<br />Introduction<br />Tuning Fork: Validate and Verify<br />Virtual Guitar: Design and Innovate<br />Conclusion<br />Q & A<br />
  3. 3. Introduction<br />What do we understand with ”Virtual Guitar”?<br />Synthesizer vs. Physical simulation model<br />Modeling and simulation<br />Some key terms: model, simulation model and analysis<br />What information these models can tell us?<br />What else we can do with such virtual models?<br />
  4. 4. Let’s Tune Our Instruments First!<br /><br />
  5. 5. Tuning Fork: Validate and Verify<br />Classical example: Tuning Fork<br />Eigenmode analysis to verify the design: Here we compute the fundamental eigenfrequency and eigenmode of a tuning fork. When correctly designed, the tuning fork vibrates at 440 Hz, a frequency known as standard concert pitch.<br />Forced responce analysis to hear the tone and fine tune the model: Here we excite the structure with a known frequency and study the response of the structure both visually and tonally.<br />Acoustic-structure interaction: Final step is to study the acoustic pressure field generated by the vibrations of the prongs.<br />
  6. 6. Tuning Fork: Validate and Verify<br />Tuning Fork: Eigenmode analysis<br />Analysis is used to verify the dimensions of the fork (length of the prongs) to meet the design parameters<br />... to verify the material properties for this specific design (mechanical)<br />... to verify the numerical accuracy<br />... to validate the chosen simulation method so that we can rely on the results<br />
  7. 7. Tuning Fork: Validate and Verify<br />In frequency response analysis the structure will be excited with harmonical load at given frequency<br />Air domain over the fork has also been simulated while acoustical pressure field created by vibrating prongs can be identified<br />
  8. 8. Tuning Fork: Validate and Verify<br />And it sounds like this ...<br />
  9. 9. Virtual Guitar<br /><br />
  10. 10. Virtual Guitar: Design and Innovate<br />Three different analysis has been made<br />Eigenfrequency analysis to find the eigenmodes and shapes of the guitar<br />Forced responce analysis with acoustic coupling to study the structural and acoustic response of the guitar in a harmonically loaded case<br />Time-dependent analysis to produce the sound of the guitar while all the dynamics and damping effects has been taken into account<br />Simulation assumptions:<br />We imitate the vibrating string by applying the surface load to the bridge<br />Vibration has been modeled as a damped time-dependent load case<br />
  11. 11. Virtual Guitar: Eigenfrequency Analysis<br />First guitar model: Eigenfrequency and mode analysis<br />Only structural effects are in the simulation<br />With such model we can find eigenfrequencies (resonance) of the structure<br />As an output we get both the actual frequencies and the shape how structure vibrates<br />
  12. 12. Virtual Guitar: Eigenfrequency Analysis<br />
  13. 13. Virtual Guitar: Frequency Response Analysis<br />Second guitar model: Forced response analysis in frequency domain<br />Both acoustical and structural effects are in the simulation<br />With such model we can simulate single frequencies and frequency sweeps while certain components are harmonically loaded (bridge in this case)<br />As an output we get both the structucal response of the guitar and the acoustic pressure field of the simulated air domain<br />
  14. 14. Virtual Guitar: Frequency Response Analysis<br />
  15. 15. Virtual Guitar: Frequency Response Analysis<br />
  16. 16. Virtual Guitar: Transient analysis<br />Third guitar model: Time-dependent simulation with sampling frequency in audio range (22050Hz in this case)<br />Both acoustical and structural effects are in the simulation<br />Critical design parameters for simulation are material settings including the damping effects<br />With such model we can study how guitar structure behaves and what kind of sound it produces<br />Simulations are ”time hungry” and requires lots of wall clock time to run<br />
  17. 17. Virtual Guitar: Transient analysis<br />
  18. 18. Virtual Guitar: Transient analysis<br />
  19. 19. Virtual Guitar: Transient analysis<br />And it sounds like this ...<br />
  20. 20. Conclusion<br />Modern simulation and modeling techniques are useful while designing musical instruments<br />Material knowledge acts key role when producing reliable simulation results<br />Eigenfrequency and frequency response analysis can be run in minutes while full transient simulations might take days<br />Machinery is already available, computing power is cheap and simulation knowledgeistaughtat universities = Virtual Guitar is reality today!<br />THANK YOU!<br />
  21. 21. Q & A<br />