The strength of any timber is highest in direction of
an angle of 60 degree to grains
an angle of 0 degree to grains
an angle of 90 degree to grains
an angle of 120 degree to grains
An angle of 0 degree to grains; Wood has three principal axes namely longitudinal, tangential and radial axes. Since it is orthogonal material m it has three values of modulus of elasticity varying by as much as 150 to 1, three shear moduli varying from 20 to 1, and six Poisson’s ratios varying by 40 to 1.
For different strength:
a) Compressive strength: The compressive strength is found to be highest when acting parallel to the axis of the growth. However compressive strength perpendicular to fibres of wood is much lower than that parallel to fibres of wood. Compressive strength parallel to fibre varies from 30.0 to 77.5 N/cm2.
b) Tensile strength: Tensile strength along direction parallel to the grain is found to have greatest strength that can be developed under any other kind of stress. Tensile strength parallel to fibres is of the order 80.0 to 190.0 N/cm2.
c) Shearing strength: Resistance to shear in across direction is found 3 to 4 times greater than that along fibres. The shear strength along fibre is found of the order 6.5 to 14.5 N/mm2.
∴ The strength of timber is highest in the direction of an angle of 0° to the grains.
