Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume. The opposite of compression is rarefaction. Compressive stress is the stress applied to materials resulting in their compaction (decrease of volume). ... The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. ... Rarefaction is the reduction of a mediums density, or the opposite of compression. ...

Explanation

Compression has many implications in material science, physics and structural engineering, for compression yields noticeable amounts of stress and tension. Materials science includes those parts of chemistry and physics that deal with the properties of materials. ... Physics (Greek: (phúsis), nature and (phusiké), knowledge of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space, and time and explaining them using mathematics. ... Taipei 101, the worlds tallest building as of 2004. ... Stress is the internal distribution of force per unit area that balances and reacts to external loads applied to a body. ... Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ...

By inducing compression, mechanical properties such as compressive strength or modulus of elasticity, can be measured. Scientists may utilize press machines to induce compression. Compressive strength is the capacity of a material to withstand axially directed pushing forces. ... In solid mechanics, Youngs modulus (also known as the modulus of elasticity or elastic modulus) is a measure of the Stiffness of a given material. ... This article or section does not cite its references or sources. ...

In engines

Internal combustion engine

In internal combustion engines it is a necessary condition of economy to compress the explosive mixture before it is ignited: in the Otto cycle, for instance, the second stroke of the piston effects the compression of the charge which has been drawn into the cylinder by the first forward stroke. The internal combustion engine is an engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today ( cars and trucks, generators, etc). ...

Steam engines

The term is applied to the arrangement by which the exhaust valve of a steam engine is made to close, shutting a portion of the exhaust steam in the cylinder, before the stroke of the piston is quite complete. This steam being compressed as the stroke is completed, a cushion is formed against which the piston does work while its velocity is being rapidly reduced, and thus the stresses in the mechanism due to the inertia of the reciprocating parts are lessened. This compression, moreover, obviates the shock which would otherwise be caused by the admission of the fresh steam for the return stroke. // The term steam engine may also refer to an entire railroad steam locomotive. ... A piston and cylinder from a steam engine A cylinder in an internal combustion engine is the space within which a piston travels. ... piston + connecting rod Components of a typical, four stroke cycle, DOHC piston engine. ...

See also

• Buckling
• Strength of materials
• Compression member