Study of Some Mechanical and Physical Properties of Wood of Some Selected Tree Species in Sulaimaniyah Governorate, North Iraq

Timber trading and pricing are primarily influenced by the mechanical and physical properties of wood. Different parameters of the wood including compressive strength, hardness, and wood density determine the quality of the timber. This study investigates the mechanical and physical characteristics of five selected tree species: Eucalyptus camaldulensis, Populus nigra, Melia azedarach, Paulownia tomentosa, and Gleditsia triacanthos. The samples were sourced from the Agricultural Engineering College and prior to the tests, confirmed to be free from defects and diseases. Mechanical testing revealed that the direction of applied force, whether parallel (P0) or perpendicular (P90) to the wood grain, significantly impacts compressive strength. The compressive strength values ranged from the highest for Eucalyptus camaldulensis (55.4 MPa) to the lowest for Paulownia tomentosa (25 MPa). Hardness values varied across species, with the highest observed in Gleditsia triacanthos (2758 N) and the weakest in Paulownia tomentosa (1016 N). The study classified the wood hardness into four categories: Very Soft Wood, Medium Hardwood, Softwood, and Medium Hardwood, based on compressive strength. Eucalyptus camaldulensis exhibited the highest density (0.9 g/cm³), while Paulownia tomentosa had the lowest (0.3 g/cm³). Moisture content also varied, with Eucalyptus camaldulensis showing the highest moisture content (77.21%) and Gleditsia triacanthos the lowest (48.1%). The findings suggest that Paulownia tomentosa is particularly suited for the wood carving industry, while Eucalyptus camaldulensis and Gleditsia triacanthos offer stronger timber, making them more suitable for diverse structural applications and due to their mechanical properties may be more suitable for use as street trees and in parks within Sulaimani governorate.