ABSTRACT
The effect of angle between growth-ring orientation and loading force on mechanical performance such as compressive strength, deformation and compression set-recovery of wood has not been fully understood. The specimens, with growth-ring orientations of 0° (G-0°, parallel to tangential direction), 15° (G-15°, angle between growth-ring and tangential direction) and 40° (G-40°), were compressed using a universal testing machine; meanwhile, strain distribution was recorded using digital image correlation (DIC). One specimen from each growth-ring orientation was scanned with X-ray computed tomography (X-ray CT) before and after compression test. Their micro-structure after compression test was imaged using a scanning electron microscope (SEM). The results show that compressive strength decreases and compression set-recovery increases as increasing the growth-ring orientation. In G-0° specimens, strain is easily accumulated in small regions in earlywood, resulting in structural compaction and collapse. The effect of latewood on compressive strength is small, resulting in a poor correlation between strain distribution and density profile. For G-40° specimens, strain is almost homogenously distributed in every layer of earlywood. Both earlywood and latewood restrain the specimen from deformation and failure. Hence, strain accumulates according to the ‘layers’ of earlywood. Strain distribution and structural changes in G-15° specimens were in between of G-0° and G-40° specimens.
Disclosure statement
No potential conflict of interest was reported by the author(s).