Transport systems require materials that are stiff and strong, but at the same time are light and have enough toughness to survive accidental overloads and stress concentrations. Use the Specific modulus \(E / ho_{-}\)Specific strength \(\sigma_{f} / ho\) chart (Fig. 3.6) to identify materials that meet these criteria. Eliminate all ceramics on the grounds that they are brittle. Which material has the best combination of both specific modulus and specific strength? Which metal has the highest specific modulus? Which has the highest specific strength?

Fig. 3.6

Specific modulus, Elp (GPa/(kg/m)) Specific modulus - specific strength Metals and polymers: yield strength, oy Ceramics, glasses modulus of rupture, MOR Elastomers: tensile tear strength, a Composites: tensile failure, o Sid BC SigNa AIN 10-1 Yield before buckling Silicon WC Nontechnical ceramics Sica glass, Soda glass. Stone Brick Concrete Yield strain 10-4 Of E Lead alloys 10-4 10-3-- Foams Rigid polymer, foams PP Technical ceramics Diamond Composites CFRP Al alloys Steels Mg alloys Ti alloys Cast irons Wood GFRP Zinc alloys Cu alloys PA PMMA Polymers PC Epoxies Metals Design guidelines PE lonomers PTFE Leather Cork EVA 10-5 10-4 Silicones 10-2 Polyurethale Buckling before yield Elastomers MFA 15 10-1 Specific strength, /p (MPa/(kg/m))