Stiffness and Damping in Mechanical Design






1.1 BASIC NOTIONS

1.1.1 Stiffness

Stiffness is the capacity of a mechanical system to sustain loads without excessive

changes of its geometry (deformations). It is one of the most important design

criteria for mechanical components and systems. Although strength is considered

the most important design criterion, there are many cases in which stresses in

components and their connections are significantly below the allowable levels,

and dimensions as well as performance characteristics of mechanical systems

and their components are determined by stiffness requirements. Typical examples

of such mechanical systems are aircraft wings, and frames/beds of production

machinery (machine tools, presses, etc.), in which stresses frequently do not exceed

3–7 MPa (500–1,000 psi). Another stiffness-critical group of mechanical

components is power transmission components, especially shafts, whose deformations

may lead to failures of gears and belts while stresses in the shafts caused

by the payload are relatively low.


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