Chapter D: D Dystectic Mixture

D-?

D

Abbreviation for diamond.

?, ?

See also delta (?, ?).

D

damping

Decreasing, hindering, or slowing-down the time of motion vibration or oscillations.

damping capacity

The ability of a material to dissipate the energy of mechanical strain.

D'Arcet metal

An alloy used in fire sprinklers and fusible links and plugs, nominally composed of 50% bismuth, 25% lead, and 25 tin.

dasymeter

:An instrument used to measure the heat loss of a furnace by analysis of waste products and gases.

datum

:A theoretically exact point, axis, or plane derived from the true geometric counterpart of a specified datum feature. A datum is the origin or point of reference from which the location or geometric characteristics of features of a part are established.

datum feature

A specified feature of a part that is used to establish a datum.

datum reference frame

Sufficient datum features, those most important to the design of the part, are chosen to position the part in relation to a set of three mutually perpendicular planes, jointly called a datum reference frame. This reference frame exists only in theory and not on the part. Therefore, it is necessary to establish a method for simulating the theoretical reference frame from the actual features of the part. This simulation is accomplished by positioning the part on appropriate datum features to adequately relate the part to the reference frame and to restrict motion of the part in relation to it. These reference frame planes are...