1. Virtual GuitarPasi MarttilaCOMSOL Oy+358 9 2510 4051 2. OutlineIntroductionTuning Fork: Validate and VerifyVirtual Guitar: Design and InnovateConclusionQ & A 3. IntroductionWhat do we understand with ”Virtual Guitar”?Synthesizer vs. Physical simulation modelModeling and simulationSome key terms: model, simulation model and analysisWhat information these models can tell us?What else we can do with such virtual models? 4. Let’s Tune Our Instruments First!http://www.ultimate-guitar-tuner.com/standard-tuning/ 5. Tuning Fork: Validate and VerifyClassical example: Tuning ForkEigenmode 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.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.Acoustic-structure interaction: Final step is to study the acoustic pressure field generated by the vibrations of the prongs. 6. Tuning Fork: Validate and VerifyTuning Fork: Eigenmode analysisAnalysis is used to verify the dimensions of the fork (length of the prongs) to meet the design parameters... to verify the material properties for this specific design (mechanical)... to verify the numerical accuracy... to validate the chosen simulation method so that we can rely on the results 7. Tuning Fork: Validate and VerifyIn frequency response analysis the structure will be excited with harmonical load at given frequencyAir domain over the fork has also been simulated while acoustical pressure field created by vibrating prongs can be identified 8. Tuning Fork: Validate and VerifyAnd it sounds like this ... 9. Virtual Guitarhttp://www.publicdomainpictures.net/ 10. Virtual Guitar: Design and InnovateThree different analysis has been madeEigenfrequency analysis to find the eigenmodes and shapes of the guitarForced responce analysis with acoustic coupling to study the structural and acoustic response of the guitar in a harmonically loaded caseTime-dependent analysis to produce the sound of the guitar while all the dynamics and damping effects has been taken into accountSimulation assumptions:We imitate the vibrating string by applying the surface load to the bridgeVibration has been modeled as a damped time-dependent load case 11. Virtual Guitar: Eigenfrequency AnalysisFirst guitar model: Eigenfrequency and mode analysisOnly structural effects are in the simulationWith such model we can find eigenfrequencies (resonance) of the structureAs an output we get both the actual frequencies and the shape how structure vibrates 12. Virtual Guitar: Eigenfrequency Analysis 13. Virtual Guitar: Frequency Response AnalysisSecond guitar model: Forced response analysis in frequency domainBoth acoustical and structural effects are in the simulationWith such model we can simulate single frequencies and frequency sweeps while certain components are harmonically loaded (bridge in this case)As an output we get both the structucal response of the guitar and the acoustic pressure field of the simulated air domain 14. Virtual Guitar: Frequency Response Analysis 15. Virtual Guitar: Frequency Response Analysis 16. Virtual Guitar: Transient analysisThird guitar model: Time-dependent simulation with sampling frequency in audio range (22050Hz in this case)Both acoustical and structural effects are in the simulationCritical design parameters for simulation are material settings including the damping effectsWith such model we can study how guitar structure behaves and what kind of sound it producesSimulations are ”time hungry” and requires lots of wall clock time to run 17. Virtual Guitar: Transient analysis 18. Virtual Guitar: Transient analysis 19. Virtual Guitar: Transient analysisAnd it sounds like this ... 20. ConclusionModern simulation and modeling techniques are useful while designing musical instrumentsMaterial knowledge acts key role when producing reliable simulation resultsEigenfrequency and frequency response analysis can be run in minutes while full transient simulations might take daysMachinery is already available, computing power is cheap and simulation knowledgeistaughtat universities = Virtual Guitar is reality today!THANK YOU! 21. Q & A