CAE Knowledge

Technical Acoustics - Introduction, calculation methods and applications

The participants learn the basic concepts of acoustics and get familiarized with the analytical analysis methods and the estimation methods. The seminar also covers modern numerical analysis tools like FEM, BEM and FMBEM. These issues will be discussed based on practical applications.

• Introduction: Terms, concepts and tools of acoustics
  • terms and basic phenomena
  • frequency, wavelength
  • speed of sound in solids, liquids and gases
  • sound pressure, sound velocity, sound intensity, sound power
  • wave number
  • Helmholtz number as a non-dimensional number for the classification of low-frequency and high-frequency

• Quantitative meausres of sound
  • time domain, frequency domain, FFT
  • sine tone, wide band noise
  • frequency partitioning in bands: third-octave, octave
  • levels, decibel and filter

• Basics of air-borne sound
  • basic equation of linear acoustics
  • analytical solutions: plane wave, spherical wave, dipole, circular piston radiatior
  • application: Kundts tube (impedance tube) for the determination of absorption properties
  • basics of room acoustics: modal description, statistical model, reverberation time, diffuse field distance
  • sound radiation
  • reflection, refraction, diffraction and scattering of acoustic waves
  • absorption in acoustics: wall impedance, transfer impedance, absorption in the fluid
  • acoustic wave guide, Helmholtz resonator

• Basics of structure-borne sound
  • bending waves, sound radiation of plates
  • what is coincidence frequency and radiation efficiency?
  • basic equation of machine acoustics
  • classical estimation process for machine acoustics
  • application: efficient computation of the sound radiation of a train wheel
  • Comparison of results from structure-borne sound and and air-borne sound analyses

• Overview on modern computational methods in acoustics
  • Finite Element Method (FEM)
  • Boundary Element Method (BEM)
  • Fast Multipole Boundary Element Method (FMBEM)
  • Statistical Energy Analysis (SEA)
  • geometrical acoustics, ray tracing

• Coupled systems
  • coupled systems by means of matrix coupling
  • when do we have to take into account coupling?
  • dynamics of fluid filled containers
  • acoustic excitation of structures

• Outlook on psycho-acoustics
  • auditory sensation area
  • the human sense of hearing
  • Spectral masking, temporal masking
  • frequency and time resolution of human ear
  • curves of equal loudness
  • auditory sensation related determination of loudness by Zwicker DIN 45631

  

Is acoustics computable at all? Which of the various simulation and computational methods do I need for the solution of my own acoustic problems? What is about result quality, that I can achieve? I am familiar with structural analysis by means of FEM, but I want to tackle acoustic questions where many terms are unknown to me. Why is the sum of 0dB and 0dB equal to 3dB? When you find yourself in any of these statements, then this seminar is an offer for you to get an entry into acoustics or to substantiated refresh the knowledge of fundamentals.