Specific stiffness - Specific strength

General Information

• Specific properties are properties that have been divided by the material density.
• This chart is useful for identifying materials for components which require high stiffness and/or strength combined with low weight
• Composites provide a means of achieving good specific properties.

Physical Insights

• The bubbles are elongated along the specific strength axis, but not specific stiffness. This is because alloying and heat treatments have a strong effect on strength but little on stiffness and density
• Note that high strength and high stiffness often go together - this is because they are both largely controlled by the atomic bonding

Example Uses

• Bicycle frames require high specific stiffness to prevent bending and high specific strength to prevent failure, at low weight
• Aircraft have many aluminium structures because they offer low weight at sufficient strength and stiffness

Simple Questions

• Explain why bike frames are made from steel, aluminium alloy or carbon-fibre reinforced plastic?
• Select materials for a tennis racquet.
• Select materials for a canoe.
• Select materials for a cast for a police truncheon.

Further Questions

• Why are cast-iron cooking pans among the best when they are the heaviest?
• Why are composites used more widely for sports goods than elsewhere?

There are 2 separate populations for this class to improve clarity. Move the mouse over different parts of the class name to reveal each one.