Vibroacoustic measurements and analyses

Technical measurements* focused

To optimize structural properties:

  • experimental modal analysis – identification of modal parameters, tuning of systems – structural modifications of constructions (design of tuned mass dampers, etc.), optimization of CAE models, detection of critical points of structures, etc.
  • operational modal analysis – measurement of the response to real operating excitation (used for dimensional structures – steel constructions, railway vehicles, etc.)
  • operational deflection shapes (study of the vibrational behavior of structures in real conditions, search for “weak points” of structures – identification of loose connections, problem welds, etc.)
  • transfer paths analysis (identification of points of construction associated with high energy transmission, measurement of transmission characteristics, degree of isolation of flexible members, determination of the share of airborne and structure-borne noise, etc.)

For hybrid simulations – measurements of various characteristics (PSD, FRF, dynamic stiffness, SRS, …), parameters (natural frequencies, damping, modal mass…), time courses (response, excitation …) for the purposes of simulations and so on.

To improve sound quality** – various analyses from the field of sound quality – psychoacoustics (loudness according to Zwicker, Stevens, harshness, sharpness of sound, tonality, articulation index, etc.)

For diagnostics of machines without dismantling*** (especially various electric drives, etc.):

  • mainly vibrodiagnostics of rolling bearings, gears, electric motors (using advanced methods such as envelope analysis, cepstrum, crest factor, Kurtosis, STFT or wavelet analysis, synchronous filtering, etc.)
  • the analysis of signals in the time and/or frequency domain, including order analysis in the field of rotating machines
  • measurements and calculations in connection with operational balancing of rigid rotors (balancing in 1 or 2 planes)

For solution of reduction of excessive noise and vibration of machinery:

  • informative measurement and evaluation of noise and vibrations (not official measurements) – measurement of levels related to human noise load, measurement of mechanical vibration parameters (using calibrated instruments – follow-up to etalon)
  • identification of dominant sources of noise and vibration (using methods of frequency analysis, localization of noise sources through a microphone array, etc.)
  • proposal of modifications to reduce noise and vibration, assessment of their benefit (e.g. using repeated measurements)

* Measurements and analyses are performed using the 16-channel DAQ system LMS Scadas Mobile, Simcenter Testlab software. The measuring chain is calibrated before the measurement using the vibration calibrator B&K type 4294 and/or the acoustic calibrator B&K type 4231. When using excitation by means of a modal hammer, the system is calibrated using a verified weight. A 5-channel DAQ system NI USB – 4432 is available for developing methods and verifying applications (based on LabVIEW) for automated measurements (using the so-called “EoL Tester”).

** Binaural sound recording is realized using “Simcenter SCADAS 3D binaural headset”.

*** Evaluation of mechanical vibration (technical condition of machines) is usually based on the following procedures:

  • comparison of the severity of vibration with the reference values that are established by the relevant standards (these reference values are defined for different types and power of machines)
  • assessment of trend characteristics (severity of vibration or amplitudes of certain frequency components) – identification of gradual deterioration of the technical condition of the machine. By extrapolating these characteristics, it is possible to predict the need for maintenance or the failure of the given device.
  • comparison of the spectrum of the evaluated machine with the so-called reference spectrum (corresponds to the spectrum of a new machine of the same type after its run in) and subsequent identification of problematic frequency components. To these frequency components are assigned (based on the calculation of the so-called characteristic frequencies of different potential excitation sources) the relevant faulty components.