Compression (physics)

[2] The compressive forces may also be applied in multiple directions; for example inwards along the edges of a plate or all over the side surface of a cylinder, so as to reduce its area (biaxial compression), or inwards over the entire surface of a body, so as to reduce its volume.

[3] It affects the volume of the material, as quantified by the bulk modulus and the volumetric strain.

The inverse process of compression is called decompression, dilation, or expansion, in which the object enlarges or increases in volume.

When put under compression (or any other type of stress), every material will suffer some deformation, even if imperceptible, that causes the average relative positions of its atoms and molecules to change.

In general, the relation between the stress applied to a material and the resulting deformation is a central topic of continuum mechanics.

[5] Compression machines range from very small table top systems to ones with over 53 MN capacity.

Gases are often stored and shipped in highly compressed form, to save space.

Slightly compressed air or other gases are also used to fill balloons, rubber boats, and other inflatable structures.

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.

[7] This compression, moreover, obviates the shock which would otherwise be caused by the admission of the fresh steam for the return stroke.