Laboratory for Dynamics of Machines and Structures 
Frequency-based structural modification for the case of base excitation
 M. Česnik, J. Slavič, P. Čermelj and M. Boltežar
Journal of Sound and Vibration, Volume 332, Issue 20, 30 September 2013, Pages 5029–5039

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Abstract
When estimating a structure's fatigue life during vibrational test the stress frequency-response function (SFRF) to the base excitation is required. The response to this base excitation can be numerically obtained by solving the equilibrium equations for each frequency of interest. In this research we propose a new method, that can be used to obtain the SFRF of a base-excited structure using the modal model of the unconstrained structure, only. By further developing the idea of a structural modification using the response function this research significantly reduces the computation time and the amount of data sent to the fatigue-analysis software. The new method is presented on two numerical examples: a simple beam structure and a Y-shaped structure. Using numerical examples, the effects of the modal truncation, the matrix singularity and the damping are discussed.
Authors

Researcher

Martin Česnik, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  martin.cesnik@fs.uni-lj.si
  +386 1 4771 227
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Associate Professor

Janko Slavič, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  janko.slavic@fs.uni-lj.si
  +386 1 4771 226
jankoslavic     jankoslavic    
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Director of R&D

Primož čermelj, PhD

  Iskra Mehanizmi, d.d., Lipnica
  pcermelj@iskra-mehanizmi.si
  +386 4 53 55 100
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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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