Tensile strength of softwood in LR orthotropy plane

A description of pine wood failure in uniaxial stress states is presented in this work. From among the available experimental formulas, Hankinson and Kollman's and Ashkenazi criterion were considered. To obtain a description of failure, a number of tests were conducted. These tests made it possible to determine the tensile strength, taking into consideration the strength values for four grain angles. For the grain angle equal 0° the tensile strength depends linearly on density. Furthermore, two failure mechanisms were found. In the first mechanism the wood underwent rupture transverse to grain. The second mechanism appeared when the wood was ruptured along the grains. For a interval (0°, Θ0) of the grain angle, mainly the first mechanism influenced the failure of pine wood as a result of the rupture of latewood grains. In this case the tensile strength depends on density. The angle Θ0 < 25° was determined. Apart from the above interval, the density had no influence on the tensile strength which is characteristic when first and second mechanism fail only the earlywood. In this work the description of pine failure with a marked separation of the two mechanisms was carried out by Ashkenazi criterion.