Relationship To Elasticity
In general, elastic modulus is not the same as stiffness. Elastic modulus is a property of the constituent material; stiffness is a property of a structure. That is, the modulus is an intensive property of the material; stiffness, on the other hand, is an extensive property of the solid body dependent on the material and the shape and boundary conditions. For example, for an element in tension or compression, the axial stiffness is
where
- A is the cross-sectional area,
- E is the (tensile) elastic modulus (or Young's modulus),
- L is the length of the element.
Similarly, the rotational stiffness is
where
- "I" is the moment of inertia,
- "n" is an integer depending on the boundary condition (=4 for fixed ends)
For the special case of unconstrained uniaxial tension or compression, Young's modulus can be thought of as a measure of the stiffness of a material.
Read more about this topic: Stiffness
Famous quotes containing the words relationship and/or elasticity:
“Some [adolescent] girls are depressed because they have lost their warm, open relationship with their parents. They have loved and been loved by people whom they now must betray to fit into peer culture. Furthermore, they are discouraged by peers from expressing sadness at the loss of family relationships—even to say they are sad is to admit weakness and dependency.”
—Mary Pipher (20th century)
“One of the reforms to be carried out during the incoming administration is a change in our monetary and banking laws, so as to secure greater elasticity in the forms of currency available for trade and to prevent the limitations of law from operating to increase the embarrassment of a financial panic.”
—William Howard Taft (1857–1930)