[分享]Reliability词汇- 1 (24Jul'04)

There are two internationally agreed specifications on reliability definitions:
(1) IEC STD 271 and 271A "List of basic terms, definitions, and related mathematics for reliability".
(2) MIL STD-721C" Definitions of terms for reliability and mainainability'.

Some useful definitions for the reader are:

Accelerated test: A test in which the applied stress level is chosen to exceed that stated in the reference conditions, in order to shorten the time required to observe the stress response of the item or magnify the response in a given time. To be valid, an accelerated test must not alter the basic modes and/or mechanisms of failure or their relative prevalence.

Administrative time: That interval during which mainenance orders are being prepared. It includes all administrative delays prior to and subsequent to actual initiation of maintenance action.

Apportionment: Assigning reliability requirements to individual items within a system to attain the specified system reliability.

Assurance, quality: A technique or science which uses all the known methods of quality control and quality engineering to

assure the manufacture of a product of acceptable quality standards.

Availability: the probability that the item(system) is operating satisfactorily at any point in time when used under stated condtions, where the total time includes operating time, active repair time and administrative time.

Availability, inherent: The probability that a system or equipment, when used under stated conditions, without consideration for any scheduled or preventative action, in an ideal support environment (i.e., available tools, spares, personnek, data, etc.), shall operate satisfactorily at a given point in time. It excludes ready time, preventative-maintenance downtime, logistics time, and waiting or administrative downtime.

Availability, operational: The proability that a system or equipment, when used under stated conditions in an actual operational environment, shall operate satisfactorily at a given point in time. It includes ready time, logistics time, and waiting or administrative downtime.

Burn-in: the operation of items prior to their ultimate application intened to stablize their characterristics and to identify early failures.

Burn-in period: the beginning of the working life of a component during which the failure rate falls rapidly as items defective in manufacture are subject to early failure.

burn-out period: The end of the working life of an items during which its failure rate increases rapidly as it becomes worn out.

Characteristic, operating: The curve which describes the probability of acceptance of a lot for various of process average.

Component: An article which is normally a combination of parts, sub-assemblies, or assemblies and is a self-contained element of a complete operating equipment and performs a function necessary to the operation of that equipment.

Condition monitoring: Techniques used to determine the health a set of equipments befoer they began to develp faluts which may need attention.

Conformity: the ability of an item to meet its stated performance and/or characteristic requirements, the assessment of which does not depend essentially on the passage of time.

Control, quality: A sientific system involving the application of all known industrial and statistical techniques to control the quality of the manufactured article throughout its various prodction phases.

Corrective action: A documented design process, procedure, or materials change implemented and validated to correct the cause of the failure or design deficiency.

Cut set: set of elements whose filure will cause the system to fail.

cut set, minimal: a set of elements which has no proper subset whose failure alone will cause the system to fail.

Cycle time: The time interval from one system failure to the next system failure.The cycle time is the sum of an uptime and a downtime.