Propagation of mechanical vibration in structures

Experimental development of the vibrational intensity method: Dissertation

Jukka Linjama

Research output: ThesisDissertationCollection of Articles

Abstract

This study deals with the measuring techniques for estimating and characterising vibration propagation in thin beams and plates. The measurement method applied was the vibrational intensity technique for bending waves, which uses two or four motion sensors. This thesis contributes to method development and to the experimental verification of the methods. The aim of the experiments was (a) to test the accuracy and limitations of the known methods in controlled conditions and (b) to verify the alternative forms and extensions to the known methods that were developed. For bending vibration of beams, estimates for the moment and shear force components of power and the impedance are derived, and new estimates for the reflection coefficient are given. The frequency response technique with one reference signal is introduced and applied in experiments. For bending waves in plates, the applicability of the approximative two-transducer intensity method in practice is investigated, paying particular attention to the effect of the nearfields. The applicability of commercial laser-doppler vibrometers as motion sensors for use in vibrational intensity measurements is assessed. New energetic quantities, apparent intensities and field descriptors, are proposed to be used in connection with intensity measurements. Approximations for these quantities, which may be regarded as extensions of the two-transducer method, are derived and implemented in the experiments.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Helsinki University of Technology
Supervisors/Advisors
  • Karjalainen, Matti, Supervisor, External person
Award date31 Mar 1994
Place of PublicationEspoo
Publisher
Print ISBNs951-38-4408-0
Publication statusPublished - 1994
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

vibration
propagation
transducers
vibration meters
bending vibration
theses
sensors
estimates
frequency response
estimating
impedance
shear
moments
reflectance
approximation
lasers

Keywords

  • vibration
  • measurement
  • measuring methods
  • intensity
  • wave propagation
  • estimating
  • test methods
  • experimentation
  • accuracy
  • reflection
  • coefficients
  • elastic waves
  • structural analysis
  • plates
  • vibration meters
  • lasers

Cite this

@phdthesis{4abfcb97eefa428fa3295e7286eb5979,
title = "Propagation of mechanical vibration in structures: Experimental development of the vibrational intensity method: Dissertation",
abstract = "This study deals with the measuring techniques for estimating and characterising vibration propagation in thin beams and plates. The measurement method applied was the vibrational intensity technique for bending waves, which uses two or four motion sensors. This thesis contributes to method development and to the experimental verification of the methods. The aim of the experiments was (a) to test the accuracy and limitations of the known methods in controlled conditions and (b) to verify the alternative forms and extensions to the known methods that were developed. For bending vibration of beams, estimates for the moment and shear force components of power and the impedance are derived, and new estimates for the reflection coefficient are given. The frequency response technique with one reference signal is introduced and applied in experiments. For bending waves in plates, the applicability of the approximative two-transducer intensity method in practice is investigated, paying particular attention to the effect of the nearfields. The applicability of commercial laser-doppler vibrometers as motion sensors for use in vibrational intensity measurements is assessed. New energetic quantities, apparent intensities and field descriptors, are proposed to be used in connection with intensity measurements. Approximations for these quantities, which may be regarded as extensions of the two-transducer method, are derived and implemented in the experiments.",
keywords = "vibration, measurement, measuring methods, intensity, wave propagation, estimating, test methods, experimentation, accuracy, reflection, coefficients, elastic waves, structural analysis, plates, vibration meters, lasers",
author = "Jukka Linjama",
year = "1994",
language = "English",
isbn = "951-38-4408-0",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "170",
address = "Finland",
school = "Helsinki University of Technology",

}

Propagation of mechanical vibration in structures : Experimental development of the vibrational intensity method: Dissertation. / Linjama, Jukka.

Espoo : VTT Technical Research Centre of Finland, 1994. 117 p.

Research output: ThesisDissertationCollection of Articles

TY - THES

T1 - Propagation of mechanical vibration in structures

T2 - Experimental development of the vibrational intensity method: Dissertation

AU - Linjama, Jukka

PY - 1994

Y1 - 1994

N2 - This study deals with the measuring techniques for estimating and characterising vibration propagation in thin beams and plates. The measurement method applied was the vibrational intensity technique for bending waves, which uses two or four motion sensors. This thesis contributes to method development and to the experimental verification of the methods. The aim of the experiments was (a) to test the accuracy and limitations of the known methods in controlled conditions and (b) to verify the alternative forms and extensions to the known methods that were developed. For bending vibration of beams, estimates for the moment and shear force components of power and the impedance are derived, and new estimates for the reflection coefficient are given. The frequency response technique with one reference signal is introduced and applied in experiments. For bending waves in plates, the applicability of the approximative two-transducer intensity method in practice is investigated, paying particular attention to the effect of the nearfields. The applicability of commercial laser-doppler vibrometers as motion sensors for use in vibrational intensity measurements is assessed. New energetic quantities, apparent intensities and field descriptors, are proposed to be used in connection with intensity measurements. Approximations for these quantities, which may be regarded as extensions of the two-transducer method, are derived and implemented in the experiments.

AB - This study deals with the measuring techniques for estimating and characterising vibration propagation in thin beams and plates. The measurement method applied was the vibrational intensity technique for bending waves, which uses two or four motion sensors. This thesis contributes to method development and to the experimental verification of the methods. The aim of the experiments was (a) to test the accuracy and limitations of the known methods in controlled conditions and (b) to verify the alternative forms and extensions to the known methods that were developed. For bending vibration of beams, estimates for the moment and shear force components of power and the impedance are derived, and new estimates for the reflection coefficient are given. The frequency response technique with one reference signal is introduced and applied in experiments. For bending waves in plates, the applicability of the approximative two-transducer intensity method in practice is investigated, paying particular attention to the effect of the nearfields. The applicability of commercial laser-doppler vibrometers as motion sensors for use in vibrational intensity measurements is assessed. New energetic quantities, apparent intensities and field descriptors, are proposed to be used in connection with intensity measurements. Approximations for these quantities, which may be regarded as extensions of the two-transducer method, are derived and implemented in the experiments.

KW - vibration

KW - measurement

KW - measuring methods

KW - intensity

KW - wave propagation

KW - estimating

KW - test methods

KW - experimentation

KW - accuracy

KW - reflection

KW - coefficients

KW - elastic waves

KW - structural analysis

KW - plates

KW - vibration meters

KW - lasers

M3 - Dissertation

SN - 951-38-4408-0

T3 - VTT Publications

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -