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Fractography combined with unsupervised pattern recognition of acoustic emission signals for a better understanding of crack propagation in adhesively bonded wood

  • Gaspard ClercEmail author
  • Markus G. R. Sause
  • Andreas J. Brunner
  • Peter Niemz
  • Jan-Willem G. van de Kuilen
Original
  • 7 Downloads

Abstract

In this paper, acoustic emission (AE) signals obtained during quasi-static crack propagation in adhesively bonded beech wood were classified using an unsupervised pattern recognition method. Two ductile one-component polyurethane (1C-PUR) adhesives with the same formulation except for one system being reinforced with short polyamide (~ 1 mm long) fibers were compared to a relative brittle phenol–resorcinol–formaldehyde (PRF) adhesive. Using only localized AE signals, it was shown that the signals originating from the crack propagation could be classified into two different clusters. Comparing the AE signals with a new fractography method, it was estimated that different clusters are due to distinct failure mechanisms, with signals of cluster 1 being associated with wood failure and signals of cluster 2 with adhesive failure. The obtained results suggest that for the PRF adhesive the wood fibers help to slow down the crack propagation. A similar but lesser effect was noted for the polyamide fibers added to the 1C-PUR adhesive matrix.

Notes

Acknowledgements

The authors thank Dr. Sébastien Josset (Henkel AG) for providing 1C-PUR adhesives as well as the Swiss Innovation Agency (Innosuisse) for the financial support (Project No. 18958.1).

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Architecture, Wood and Civil EngineeringBFH, Bern University of Applied SciencesBielSwitzerland
  2. 2.Institute of Materials Resource ManagementUniversity of AugsburgAugsburgGermany
  3. 3.Laboratory for Mechanical Systems EngineeringEmpa, Swiss Federal Laboratories for Materials Science and TechnologyDübendorfSwitzerland
  4. 4.Wood TechnologyTechnical University of MunichMunichGermany
  5. 5.TU Delft, Faculty of Civil Engineering and GeosciencesBiobased Structures and MaterialsDelftThe Netherlands

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