Prediction of Compression Properties in Three Orthotropic Directions for Some Important Turkish Wood Species Using Ultrasound

Abstract

Compression properties in three orthotropic directions for some important Turkish wood species, including Calabrian pine (Pinus brutia Ten.), Taurus cedar (Cedrus libani), Oriental beech (Fagus orientalis), and sessile oak (Quercus petraea), were studied using non-destructive and destructive techniques. The materials used in the study consisted of 720 small clear specimens of nominal dimensions of 20 x 20 x 60 mm. The influence of equilibrium moisture content (EMC) was studied over four batches of 15 specimens each, conditioned for six to eight weeks before testing at a temperature of 20 ± 2 °C and at four different relative humidity conditions (50%, 65%, 85%, and 95%). Time of flight values were measured with a commercial ultrasonic tester. Using the time results from the ultrasound device, the wave velocities (length/time) and Edyn values were calculated. Samples were also tested in uniaxial compression to determine the Young's modulus and compression strength values in three orthotropic directions. The Edyn correlated well with the Young's modulus and compression strength of the specimens; coefficients of determination ranged between 0.75 and 0.96. Moisture content seems to have more influence than density on sound velocities. Results showed that there is a weak and mostly negative correlation between the density of the specimens and the sound velocity values.

Evaluation of heating temperature and time on bending properties of Taurus cedar wood

“…Such strong relationships between the ultrasonically determined Edyn and MOE in bending for heat-treated woods were reported by Yılmaz Aydın and Aydın (2018b) for oriental beech (R 2 : 0 75 to 0.82), Yılmaz Aydın (2020) for oak wood (R 2 : 0.75 to 0.89), and Holeček et al (2016) for Norway spruce (R 2 : 0.91 to 0.92). Furthermore, the R 2 between Edyn and MOE (Young's modulus) determined by US and compression test were reported by Güntekin et al (2015a; for Taurus cedar (R 2 : 0.95), and Yılmaz Aydın and Aydın (2017) for oriental beech (R 2 : 0.84 to 0.94). Heat treatment applications, particularly at high temperatures and long exposure duration, cause intense color changes.…”

“…However, the decrease in density with the increase in duration is more apparent when the temperature was 210°C, and around 6.25% decrease was observed. Density of the unmodified samples are in harmony with reported values (g/cm 3 ) of 0.497 (Efe 2021), 0.502 (Sofuoğlu and Kurtoğlu 2015), 0.510 (Söğütlü 2017), 0.520 (As et al 2001), 0.523 (Berkel 1951), 0.512 (Demetçi 1986), 0.574 and 0.588 for juvenile and mature wood, respectively (Bal et al 2012), 0.468 and 0.512 for heart and sapwood wood, respectively (2013), 0.498 (Güntekin and Yılmaz Aydın 2016), 0.570 (Güntekin et al 2015a; b; c), 0.53 ) and 0.480 to 0.490 (Yılmaz Aydın and Aydın 2018a).…”

“…predicted some elastic constants using 1 MHz shear wave propagation. Güntekin et al (2015a; predicted moisture induced dynamic and static MOE of Taurus cedar using US (22kHz) propagation and compression test, respectively. Güntekin et al (2015) evaluated the effect of moisture on VLL, static and Edyn, and Young's modulus for Taurus cedar wood.…”

Measurement of Linear Springs’ Stiffness Factor Using Ultrasonic Sensing

“…In general, both temperature and humidity have effects on ultrasonic waves [ 29 , 30 ]. To verify the sensitivity and stability of our ultrasonic testing instrument, we measured the stiffness factors of each spring at different times on the same day (under different temperatures and humidity levels).…”

“…In summary, the results in Table 1 and Figure 8 show clearly that our ultrasonic testing instrument can accurately measure the stiffness factor of springs, that it can fully realize the performance of the traditional Jolly's scale, that its measurement results are more accurate than those of Jolly's scale. In general, both temperature and humidity have effects on ultrasonic waves [29,30]. To verify the sensitivity and stability of our ultrasonic testing instrument, we measured the stiffness factors of each spring at different times on the same day (under different temperatures and humidity levels).…”