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Specific stiffness - Specific strength
General Information
Physical Insights
Example Uses
Simple Questions
Further Questions
This chart is useful for choosing light materials that are both strong and stiff.
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 material 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?
On the whole both strength and stiffness increase with density meaning that a number of materials have similar specific properties. Composites are better, but cost factors preclude widespread use. As a result the market is very competitive with steel being used where more strength is required (e.g. mountain biking), aluminium for general touring bikes and composites used for high performance racing bikes.
Select materials for a tennis racquet.
A premium price piece of equipment, tennis racquets can benefit from high price raw materials and production methods. The hoop alignment of fibres in CFRP composites offer excellent strength and stiffness allowing the use of high tension larger racquets compared to traditional wooden ones.
Select materials for a canoe.
Traditional open canoes are made from ABS thermoplastic, aluminium, wood or CFRP composite. Because the canoes are designed to be carried by one person on their head weight is crucial, but stiffness and strength are needed to traverse stretches of rapids.
Select materials for a police truncheon.
Now made of thermoplastic for good specific strength
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.
Rollover class name to view individual materals, click chart to return to class view. Hover mouse over property for brief definition.
