Determination of the effect of moisture content on some mechanical properties of micro-size oak wood and comparison with standard size samples

The aim of this study was to determine the effect of moisture content on some mechanical properties of micro-size Sessile oak wood and investigate the correlation between micro- and standard-size specimens. Sample trees were harvested from the Duzce Forest Enterprises in the northwestern part of Turkey. Six trees having straight stems were selected as sample trees. Logs of 3 m in length were cut from each tree. Micro- and standard-size test samples were prepared from lumbers cut from these logs. Standart-size specimens were conditioned in a climate chamber at a temperature of 20 °C and a relative humidity of 65 % for three weeks to target moisture content of 12 % while micro-size specimens were conditioned in a climate chamber or soak water at different temperatures and relative humidities to target moisture content of 8 %, 12 %, 16 %, 20 %, and >Fiber saturation point before testing. Bending strength, modulus of elasticity in bending, compression strength parallel to grain and tensile strength parallel to grain were determined using micro- and standard-size mechanical test samples. In the micro- and standard size samples, bending strengths were evaluated as 71.2 MPa and 99.4 MPa, modulus of elasticity in bending as 2741.3 MPa and 11394.1 MPa tensile strengths as 98.7 MPa and 93.8 MPa and compression strengths as 45.4 MPa and 46.6 MPa respectively. The results showed that the bending strength, modulus of elasticity and compression strength of the micro-size samples were lower compared to the standard-size samples, while the tensile strength was higher in the micro-size samples. The effect of moisture content on the all measured mechanical properties of Oak wood was also statistically significant. Furthermore, the regression analyses indicated a positive linear regression between the mechanical properties of micro- and standard-size samples. Micro-size specimens can be used to estimate the mechanical properties of Oak wood when obtaining standard-size specimens is not possible.