Timber Screw Connection: Study of the Strain along the Interface Using Optical Measurement Techniques and Simulations

Cedou Kumpenza*, Andreas Ringhofer, Thomas Krenke, Adeayo Sotayo, Maximilian Pramreiter, Ulrich Müller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In various engineering applications, self-tapping screws are used to connect timber members. To describe their load-deformation relationship, a better understanding of the strain along the mechanical interface (i.e., timber-screw interface) is required. With a focus on the axial loading of self-tapping screws, only a few studies have dealt with the determination of the strain based on optical measurement techniques. Therefore, in the present study, the strain distribution at the timber-screw interface was monitored during pull-out tests using an optical measurement technique, called electronic speckle pattern interferometry (ESPI). Strains obtained from the ESPI measurements were compared with the results obtained from structural simulations conducted with finite element modelling (FEM). Three different types of solid spruce wood (Picea abies (L.) Karst.) specimens with different grain orientations connected with self-tapping screws (thread length lg = 130 mm, outer thread diameter d = 12 mm) were tested in withdrawal. There was a good agreement between the ESPI and FEM results, confirming that ESPI was a suitable measurement technique. The study also provided insights and results regarding the region of strain concentrations across the length of self-tapping screws.

Original languageEnglish
Pages (from-to)3859-3873
Number of pages15
Issue number2
Publication statusPublished - 1 May 2020


  • Electronic speckle pattern interferometry
  • Finite-element modelling
  • Norway spruce
  • Optical measurement technique
  • pull-out test
  • Self-tapping screw
  • Solid Timber
  • Strain measurement
  • Pull-out test
  • Solid timber

ASJC Scopus subject areas

  • Building and Construction
  • Bioengineering
  • Waste Management and Disposal
  • Environmental Engineering

Fields of Expertise

  • Sustainable Systems

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)
  • Experimental

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