Figure 11.

(a) Young's modulus–density chart for engineering materials, including woods. The performance index E^1/2/ρ gives the performance of a material for resisting bending deflections: every point on a single line E^1/2/ρ has the same value of E^1/2/ρ. As the line moves to the upper left, the value of E^1/2/ρ increases. Woods loaded along the grain have comparable values to the best engineering materials, fibre composites (adapted from figure from MF Ashby, with permission). (b) Strength–density chart for engineering materials, including woods. The performance index σ^2/3/ρ gives the performance of a material for resisting bending stresses: every point on a single line σ^2/3/ρ has the same value of σ^2/3/ρ . As the line moves to the upper left, the value of σ^2/3/ρ  increases. Woods loaded along the grain have comparable values to the best engineering materials, fibre composites. Adapted from figure from Ashby, with permission. (Online version in colour.)