Experimental Determination of the Yield Stress Curve of the Scotch Pine Wood Materials

Gunay E., Aygun C., Kaya S. T.

3rd International Congress on Advances in Applied Physics and Materials Science, Antalya, Turkey, 24 - 28 April 2013, vol.1569, pp.65-72 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 1569
  • Doi Number: 10.1063/1.4849230
  • City: Antalya
  • Country: Turkey
  • Page Numbers: pp.65-72
  • Gazi University Affiliated: Yes


Yield stress curve is determined for the pine wood specimens by conducting a series of tests. In this work, pinewood is modeled as a composite material with transversely isotropic fibers. Annual rings (wood grain) of the wood specimens are taken as the major fiber directions with which the strain gauge directions are aligned. For this purpose, three types of tests are arranged. These are tensile, compression and torsion loading tests. All of the tests are categorized with respect to fiber orientations and their corresponding loading conditions. Each test within these categories is conducted separately. Tensile and compression tests are conducted in accordance with standards of Turkish Standards Institution (TSE) whereas torsion tests are conducted in accordance with Standards Australia Specimens are machined from woods of Scotch pine which is widely used in boat building industries and in other structural engineering applications. It is determined that this species behaves more flexibly than the others. Strain gauges arc installed on the specimen surfaces in such a way that loading measurements arc performed along directions either parallel or perpendicular to the fiber directions. During the test and analysis phase of yield stress curve, orientation of strain gauge directions with respect to fiber directions arc taken into account. The diagrams of the normal stress vs. normal strain or the shear stress vs. shear strain are plotted for each test. In each plot, the yield stress is determined by selecting the point on the diagram, the tangent of which is having a slope of 5% less than the slope of the elastic portion of the diagram. The geometric locus of these selected points constitutes a single yield stress curve on sigma(1)-sigma(2) principal plane. The resulting yield stress curve is plotted as an approximate ellipse which resembles Tsai-Hill failure criterion. The results attained in this work, compare well with the results which are readily available in the literature.