= Specific strength
{title2=$\sigma_f/\rho$}
<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 $A\geq F/\sigma_f$. 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.
Back to article page
