Laboratory for Dynamics of Machines and Structures 
Estimation of the frequency response functions for operational assemblies using independent source characterization
 D. Ocepek, T. Vrtač, G. Čepon and M. Boltežar
Mechanical Systems and Signal Processing, 2023

download pdf   https://doi.org/10.1016/j.ymssp.2022.109542
Abstract
In noise and vibration engineering, a structure's passive dynamic properties are often evaluated in terms of its frequency response functions (FRFs). The typical FRF measurement campaign consists of controlled structure excitation and the capturing of its response. However, exploiting operational excitation for FRF acquisition is not feasible, with many sources simply too complex to model or measure directly. In the present paper, an alternative approach is proposed for an indirect FRF estimation of a system in operation, in which the source is characterized independently of the final assembly. To overcome the issue of the unmeasurable excitation force, transfer path analysis (TPA) methods are proposed. TPA replicates the source excitations using the set of equivalent or pseudo forces that are an inherent property of the source. The assembly's FRFs are then evaluated on the basis of receiver responses and pre-determined pseudo forces for independent operational load cases at the source. Thus, a single source description can be applied to estimate the FRFs of any assembly with an identical source and arbitrary passive side.
Authors

Assistant Professor

Domen Ocepek, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  domen.ocepek@fs.uni-lj.si
  +386 1 4771 229

Young Researcher

Tim Vrtač, PhD Student

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  tim.vrtac@fs.uni-lj.si
  +386 1 4771 614

Professor

Gregor Čepon, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  gregor.cepon@fs.uni-lj.si
  +386 1 4771 229
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Professor

Miha Boltežar, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  miha.boltezar@fs.uni-lj.si
  +386 1 4771 608
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