Materials, Properties and Design

· Material failure under operating conditions is also important. For a light-strong structure the log-log plot of a failure strength against material density is of value in material selection. The colored zones represent the same material classes as before, and the red line represents a selected value of (σ_f /ρ), where σ_f is an appropriate failure mode.
· For a ductile metal that should remain in its elastic range, σ_f would be the yield stress of the material, σ_y. For a brittle ceramic, the fracture stress would be used. In a compression situation, either a yield stress or a buckling stress could be employed.

From: Ashby, Materials Selection, Pergamon (1993)