Вы можете отметить интересные вам фрагменты текста, которые будут доступны по уникальной ссылке в адресной строке браузера.

Physical compression

Physical compression

Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume. The opposite of compression is tension.

Explanation

Compression has many implications in material science, physics and structural engineering, for compression yields noticeable amounts of stress and tension.

By inducing compression, mechanical properties such as compressive strength or modulus of elasticity, can be measured. Scientists may utilize press machines to induce compression.

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.

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.

ee also

* Buckling
* Strength of materials
* Compression member
* Rarefaction


Wikimedia Foundation. 2010.

  
Share  

Look at other dictionaries:

  • Compression (physical) — Compression test on a universal testing machine Physical compression is the result of the subjection of a material to compressive stress, which results in reduction of volume as compared to an uncompressed but otherwise identical state. The… …   Wikipedia

  • Compression — may refer to: In physical science Compression (physical), the result of the subjection of a material to compressive stress Compression member, a class of structural elements, of which a column is the most common specific example Compressibility,… …   Wikipedia

  • Physical therapy — Infobox Disease Name = Physical therapy Caption = This physical therapist is assisting two children with polio holding on to a rail whilst they exercise their lower limbs. Physical therapy, also known as Physiotherapy in many English speaking… …   Wikipedia

  • Compression fossil — Fossil seed fern leaves from the Late Carboniferous of northeastern Ohio. A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression… …   Wikipedia

  • Physical training uniform — The physical training uniform is a military uniform used during calisthenics drills and, in some cases, very casual periods of time (off duty time during Initial Entry Training in the Army, for example). The United States Army, Marines, Navy, and …   Wikipedia

  • Homogeneous charge compression ignition — Thermodynamics …   Wikipedia

  • Homogeneous Charge Compression Ignition — Homogeneous Charge Compression Ignition, or HCCI, is a form of internal combustion in which well mixed fuel and oxidizer (typically air) are compressed to the point of auto ignition. As in other forms of combustion, this exothermic reaction… …   Wikipedia

  • Disk compression — A disk compression software utility increases the amount of information that can be stored on a hard disk drive of given size. Unlike a file compression utility which compresses only specified files and which requires the user designate the files …   Wikipedia

  • Container compression test — The container compression test measures the compressive strength of packages such as boxes, drums, and cans. It usually provides a plot of deformation vs compressive force. It is commonly used to evaluate shipping containers made of corrugated… …   Wikipedia

  • Data compression ratio — Data compression ratio, also known as compression power, is a computer science term used to quantify the reduction in data representation size produced by a data compression algorithm. The data compression ratio is analogous to the physical… …   Wikipedia