Physical and mechanical characterization of structural wood used in pakistan

Six species of wood (Vachellia nilotica, Eucalyptus camaldulensis, Ziziphus mauritiana, Albizia lebbeck, Melia azedarach, Dalbergia sissoo) were tested in compression and tension parallel to the grain. The specimens were collected from different areas of Pakistan. The compressive strengths, tension parallel to grain and hardness of the wood were determined by testing rectangular shape wooden specimens (ASTM D143 2014, Janka 1906). It was observed that compressive and tensile strength of Vachllia nilotica parallel to the grain is higher than other species whereas, Eucalyptus camaldulensis hardness behaviour along radial and tangential surface is higher among the wooden samples tested.

Hygrothermal effect on axial compressive properties of bionic bamboo element

Bionic bamboo element is innovative form inspired by honeycomb, and its axial compressive strength and node’s contribution to strength under different environment were studied to explore the mechanical properties. Crack morphology and stress distribution were analyzed. The results indicated that, the strength of bionic bamboo element was 50.72 MPa, while the strength declined by 39.74%, 43.85% and 36.05% after being immersed in water for 30 days and hygrothermal pretreatment for 30 days and 15 days. Node had negative influence on strength due to fiber hydroscopic swelling and loose compared with the control samples, and lower humidity condition was beneficial to enhance the compressive strength, e.g. the strength of samples in humidity 20% condition for 30 days improved by 56.70% compared with the control group. Crack showed hierarchical damage with fibers’ tear in length and fracture in lateral, stress distribution exhibited symmetry, and the maximum stress focused on the end of bionic bamboo element, and its thin wall was susceptible damaged. Bionic bamboo element retained the mechanical superiority of bamboo culm and promoted its recombination utilization.