Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Detecting the thickness mode frequency in a concrete plate using backward wave propagation
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.ORCID-id: 0000-0002-5665-8288
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
2016 (Engelska)Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 139, nr 2, s. 649-657Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Material stiffness and plate thickness are the two key parameters when performing quality assurance/quality control on pavement structures. In order to estimate the plate thickness non-destructively, theImpact Echo (IE) method can be utilized to extract the thickness resonance frequency. An alternativeto IE for estimating the thickness resonance frequency of a concrete plate, and to subsequently enablethickness determination, is presented in this paper. The thickness resonance is often revealed as asharp peak in the frequency spectrum when contact receivers are used in seismic testing. Due to a lowsignal-to-noise ratio, IE is not ideal when using non-contact microphone receivers. In studying thecomplex Lamb wave dispersion curves at a frequency infinitesimally higher than the thickness frequency,it is seen that two counter-directed waves occur at the same frequency but with phase velocitiesin opposite directions. Results show that it is possible to detect the wave traveling with anegative phase velocity using both accelerometers and air-coupled microphones as receivers. Thisalternative technique can possibly be used in non-contact scanning measurements based on aircoupled microphones.

Ort, förlag, år, upplaga, sidor
Acoustical Society of America (ASA), 2016. Vol. 139, nr 2, s. 649-657
Nyckelord [en]
Thickness frequency, zero group velocity, backward wave propagation
Nationell ämneskategori
Infrastrukturteknik Geoteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-155909DOI: 10.1121/1.4941250ISI: 000373705300014Scopus ID: 2-s2.0-84957576596OAI: oai:DiVA.org:kth-155909DiVA, id: diva2:763333
Forskningsfinansiär
Trafikverket
Anmärkning

QC 20160412

Tillgänglig från: 2014-11-14 Skapad: 2014-11-14 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
Ingår i avhandling
1. Air-coupled microphone measurements of guided waves in concrete plates
Öppna denna publikation i ny flik eller fönster >>Air-coupled microphone measurements of guided waves in concrete plates
2014 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Quality control and quality assurance of pavements is today primarily based on core samples. Air void content and pavement thickness are parameters that are evaluated. However, no parameter connected to the stiffness is evaluated. There is a need for fast and reliable test methods that are truly non-destructive in order to achieve an effective quality control and quality assurance of pavements. This licentiate thesis presents surface wave testing using air-coupled microphones as receivers. The measurements presented in this work are performed in order to move towards non-contact measurements of material stiffness. The non-contact measurements are compared to conventional accelerometer measurements in order to compare the noncontact measurements to a “reference test”. The two appended papers are focused on evaluating one parameter in each paper. In the first paper all equipment needed to perform non-contact measurements are mounted on a trolley in order to enable measurements while rolling the trolley forward. It is shown that rolling measurements can provide rapid and reliable measurements of the Rayleigh wave velocity over large areas. However, the measurements are shown to be sensitive to misalignments between the microphone array and the measured surface. An uneven surface can thus cause major errors in the calculated results. The second paper presents an alternative method to evaluate the thickness resonance frequency of a concrete plate. It is demonstrated how the established Impact Echo method can give erroneous results when aircoupled microphones are used as receivers. Instead a method based on backward wave propagation is introduced. It is demonstrated how waves with negative phase velocities can be identified in a narrow frequency span close to the thickness resonance.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2014. s. ix, 32
Serie
TRITA-TSC-LIC, ISSN 1653-445X ; 14-004
Nyckelord
Non-destructive testing, Lamb waves, surface waves, air-coupled microphones, non-contact measurements
Nationell ämneskategori
Infrastrukturteknik
Identifikatorer
urn:nbn:se:kth:diva-155912 (URN)978-91-87353-51-2 (ISBN)
Presentation
2014-12-08, B25, Brinellvägen 23, Stockholm, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20141128

Tillgänglig från: 2014-11-28 Skapad: 2014-11-14 Senast uppdaterad: 2014-11-28Bibliografiskt granskad
2. Non-contact surface wave measurements on pavements
Öppna denna publikation i ny flik eller fönster >>Non-contact surface wave measurements on pavements
2017 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

In this thesis, nondestructive surface wave measurements are presented for characterization of dynamic modulus and layer thickness on different pavements and cement concrete slabs. Air-coupled microphones enable rapid data acquisition without physical contact with the pavement surface.

Quality control of asphalt concrete pavements is crucial to verify the specified properties and to prevent premature failure. Testing today is primarily based on destructive testing and the evaluation of core samples to verify the degree of compaction through determination of density and air void content. However, mechanical properties are generally not evaluated since conventional testing is time-consuming, expensive, and complicated to perform. Recent developments demonstrate the ability to accurately determine the complex modulus as a function of loading time (frequency) and temperature using seismic laboratory testing. Therefore, there is an increasing interest for faster, continuous field data evaluation methods that can be linked to the results obtained in the laboratory, for future quality control of pavements based on mechanical properties.

Surface wave data acquisition using accelerometers has successfully been used to determine dynamic modulus and thickness of the top asphalt concrete layer in the field. However, accelerometers require a new setup for each individual measurement and are therefore slow when testing is performed in multiple positions. Non-contact sensors, such as air-coupled microphones, are in this thesis established to enable faster surface wave testing performed on-the-fly.

For this project, a new data acquisition system is designed and built to enable rapid surface wave measurements while rolling a data acquisition trolley. A series of 48 air-coupled micro-electro-mechanical sensor (MEMS) microphones are mounted on a straight array to realize instant collection of multichannel data records from a single impact. The data acquisition and evaluation is shown to provide robust, high resolution results comparable to conventional accelerometer measurements. The importance of a perfect alignment between the tested structure’s surface and the microphone array is investigated by numerical analyses.

Evaluated multichannel measurements collected in the field are compared to resonance testing on core specimens extracted from the same positions, indicating small differences. Rolling surface wave measurements obtained in the field at different temperatures also demonstrate the strong temperature dependency of asphalt concrete.

A new innovative method is also presented to determine the thickness of plate like structures. The Impact Echo (IE) method, commonly applied to determine thickness of cement concrete slabs using an accelerometer, is not ideal when air-coupled microphones are employed due to low signal-to-noise ratio. Instead, it is established how non-contact receivers are able to identify the frequency of propagating waves with counter-directed phase velocity and group velocity, directly linked to the IE thickness resonance frequency.

The presented non-contact surface wave testing indicates good potential for future rolling quality control of asphalt concrete pavements.

 

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2017. s. 70
Serie
TRITA-JOB PHD, ISSN 1650-9501 ; 1025
Nyckelord
seismic testing, asphalt concrete, dynamic modulus, non-contact measurements, rolling measurements, surface waves, Lamb waves, MEMS microphones
Nationell ämneskategori
Geoteknik
Forskningsämne
Byggvetenskap
Identifikatorer
urn:nbn:se:kth:diva-201147 (URN)978-91-7729-263-0 (ISBN)
Disputation
2017-03-08, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20170209

Tillgänglig från: 2017-02-09 Skapad: 2017-02-09 Senast uppdaterad: 2017-02-13Bibliografiskt granskad

Open Access i DiVA

Fulltext saknas i DiVA

Övriga länkar

Förlagets fulltextScopus

Personposter BETA

Bjurström, Henrik

Sök vidare i DiVA

Av författaren/redaktören
Bjurström, HenrikRydén, Nils
Av organisationen
Jord- och bergmekanik
I samma tidskrift
Journal of the Acoustical Society of America
InfrastrukturteknikGeoteknik

Sök vidare utanför DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 320 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf