PMID- 28327501
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20180223
LR  - 20181113
IS  - 1424-8220 (Electronic)
IS  - 1424-8220 (Linking)
VI  - 17
IP  - 3
DP  - 2017 Mar 22
TI  - Accurate Determination of the Frequency Response Function of Submerged and 
      Confined Structures by Using PZT-Patchesdagger.
LID - 10.3390/s17030660 [doi]
LID - 660
AB  - To accurately determine the dynamic response of a structure is of relevant 
      interest in many engineering applications. Particularly, it is of paramount 
      importance to determine the Frequency Response Function (FRF) for structures 
      subjected to dynamic loads in order to avoid resonance and fatigue problems that 
      can drastically reduce their useful life. One challenging case is the 
      experimental determination of the FRF of submerged and confined structures, such 
      as hydraulic turbines, which are greatly affected by dynamic problems as reported 
      in many cases in the past. The utilization of classical and calibrated exciters 
      such as instrumented hammers or shakers to determine the FRF in such structures 
      can be very complex due to the confinement of the structure and because their use 
      can disturb the boundary conditions affecting the experimental results. For such 
      cases, Piezoelectric Patches (PZTs), which are very light, thin and small, could 
      be a very good option. Nevertheless, the main drawback of these exciters is that 
      the calibration as dynamic force transducers (relationship voltage/force) has not 
      been successfully obtained in the past. Therefore, in this paper, a method to 
      accurately determine the FRF of submerged and confined structures by using PZTs 
      is developed and validated. The method consists of experimentally determining 
      some characteristic parameters that define the FRF, with an uncalibrated PZT 
      exciting the structure. These parameters, which have been experimentally 
      determined, are then introduced in a validated numerical model of the tested 
      structure. In this way, the FRF of the structure can be estimated with good 
      accuracy. With respect to previous studies, where only the natural frequencies 
      and mode shapes were considered, this paper discuss and experimentally proves the 
      best excitation characteristic to obtain also the damping ratios and proposes a 
      procedure to fully determine the FRF. The method proposed here has been validated 
      for the structure vibrating in air comparing the FRF experimentally obtained with 
      a calibrated exciter (impact Hammer) and the FRF obtained with the described 
      method. Finally, the same methodology has been applied for the structure 
      submerged and close to a rigid wall, where it is extremely important to not 
      modify the boundary conditions for an accurate determination of the FRF. As 
      experimentally shown in this paper, in such cases, the use of PZTs combined with 
      the proposed methodology gives much more accurate estimations of the FRF than 
      other calibrated exciters typically used for the same purpose. Therefore, the 
      validated methodology proposed in this paper can be used to obtain the FRF of a 
      generic submerged and confined structure, without a previous calibration of the 
      PZT.
FAU - Presas, Alexandre
AU  - Presas A
AD  - CDIF (Centre de Diagnostic Industrial I Fluidodinamica), UPC (Universitat 
      Politecnica de Catalunya), Av. Diagonal 647, 08028 Barcelona, Spain. 
      alex.presas@mf.upc.edu.
FAU - Valentin, David
AU  - Valentin D
AD  - CDIF (Centre de Diagnostic Industrial I Fluidodinamica), UPC (Universitat 
      Politecnica de Catalunya), Av. Diagonal 647, 08028 Barcelona, Spain. 
      david.valentin@upc.edu.
FAU - Egusquiza, Eduard
AU  - Egusquiza E
AD  - CDIF (Centre de Diagnostic Industrial I Fluidodinamica), UPC (Universitat 
      Politecnica de Catalunya), Av. Diagonal 647, 08028 Barcelona, Spain. 
      eduard.egusquiza@upc.edu.
FAU - Valero, Carme
AU  - Valero C
AD  - CDIF (Centre de Diagnostic Industrial I Fluidodinamica), UPC (Universitat 
      Politecnica de Catalunya), Av. Diagonal 647, 08028 Barcelona, Spain. 
      valero@mf.upc.edu.
FAU - Egusquiza, Monica
AU  - Egusquiza M
AD  - CDIF (Centre de Diagnostic Industrial I Fluidodinamica), UPC (Universitat 
      Politecnica de Catalunya), Av. Diagonal 647, 08028 Barcelona, Spain. 
      monica.egusquiza@upc.edu.
FAU - Bossio, Matias
AU  - Bossio M
AD  - CDIF (Centre de Diagnostic Industrial I Fluidodinamica), UPC (Universitat 
      Politecnica de Catalunya), Av. Diagonal 647, 08028 Barcelona, Spain. 
      matiasbossio1@gmail.com.
LA  - eng
PT  - Journal Article
DEP - 20170322
PL  - Switzerland
TA  - Sensors (Basel)
JT  - Sensors (Basel, Switzerland)
JID - 101204366
PMC - PMC5375946
OTO - NOTNLM
OT  - PZT actuators
OT  - exciters
OT  - modal analysis
OT  - submerged structures
COIS- The authors declare no conflict of interest.
EDAT- 2017/03/23 06:00
MHDA- 2017/03/23 06:01
PMCR- 2017/03/01
CRDT- 2017/03/23 06:00
PHST- 2017/03/03 00:00 [received]
PHST- 2017/03/17 00:00 [revised]
PHST- 2017/03/20 00:00 [accepted]
PHST- 2017/03/23 06:00 [entrez]
PHST- 2017/03/23 06:00 [pubmed]
PHST- 2017/03/23 06:01 [medline]
PHST- 2017/03/01 00:00 [pmc-release]
AID - s17030660 [pii]
AID - sensors-17-00660 [pii]
AID - 10.3390/s17030660 [doi]
PST - epublish
SO  - Sensors (Basel). 2017 Mar 22;17(3):660. doi: 10.3390/s17030660.