Internal Friction
Main article: Plastic deformation of solids See also: Deformation (engineering)Internal friction is the force resisting motion between the elements making up a solid material while it undergoes plastic deformation.
Plastic deformation in solids is an irreversible change in the internal molecular structure of an object. This change may be due to either (or both) an applied force or a change in temperature. The change of an object's shape is called strain. The force causing it is called stress. Stress does not necessarily cause permanent change. As deformation occurs, internal forces oppose the applied force. If the applied stress is not too large these opposing forces may completely resist the applied force, allowing the object to assume a new equilibrium state and to return to its original shape when the force is removed. This is what is known in the literature as elastic deformation (or elasticity). Larger forces in excess of the elastic limit may cause a permanent (irreversible) deformation of the object. This is what is known as plastic deformation.
Read more about this topic: Friction
Famous quotes containing the words internal and/or friction:
“When a person doesn’t understand something, he feels internal discord: however he doesn’t search for that discord in himself, as he should, but searches outside of himself. Thence a war develops with that which he doesn’t understand.”
—Anton Pavlovich Chekhov (1860–1904)
“The admission of Oriental immigrants who cannot be amalgamated with our people has been made the subject either of prohibitory clauses in our treaties and statutes or of strict administrative regulations secured by diplomatic negotiations. I sincerely hope that we may continue to minimize the evils likely to arise from such immigration without unnecessary friction and by mutual concessions between self-respecting governments.”
—William Howard Taft (1857–1930)