 Specific strength

Specific strength is strength divided by density, with the strength convention stated explicitly. For a uniform tie carrying tensile force $F$, allowable stress ${\sigma }_f$ requires area $A\ge F/{\sigma }_f$. Its mass $m=\rho AL$ is therefore at least $FL/({\sigma }_f/\rho )$. Maximizing ${\sigma }_f/\rho$ minimizes mass under this simple strength-limited model. A material with higher strength can still be worse if its density increases more. Mechanical fatigue, buckling, joining and temperature limits can impose additional constraints not captured by this single ratio.

Specific strength, also known as strength-to-weight ratio, is a material property that describes how much strength a material has relative to its weight. It is typically expressed as the ratio of a material's yield strength (or ultimate tensile strength) to its density.