[分享]Reliability词汇- 2 (25Jul'04)

Debugging: the operation of an equipment or complex item prior to being put into service to detect and replace parts that are defective or expected to fail and to correct errors in fabrication or assembly.

defect: a characteristic which does not conform to applicable specification requirements and which adversely affects or potentially effects the quality of a device.

Degradation: A gradual impairment in ability to perform the required function.

Derating: the intentional reductin of stress/stength ratio in the application of an item, usually for the purpose of reducing the occurrence of stress-related failures.

Design adequacy: The probability that the system will successfully accomplish its mission, given that the system is operating within design specifications.

Downtime: The total time during which the system is not in an acceptable operating conditions.

Early failure period: that period during which the failure rate of some items is decreasing rapidly (sometimes also known as burn-in period).

Effectiveness, system: the probability that the system can successfully meet an operational demand within a given time under specified conditions.

Element: A term used generally to refer to a part, assembly, component, equipment, complete operating equipment, and/or system.

environment: The aggregate of all external conditions either natural, manmake, or self-induced (such as temperature, humidity, radiation, magnetic and electric fields, shock, vibration and so on ) that influences the form, perfomance, reliability or survival of an item.

Environmental stress screening(ESS): A series of tests conducted under environmental stresses to disclose latent part and workmanship defects in order to execute conrrective action.

Estimation: The evaluation of a statistical parameter for a population from a set of sample data in such a way so as to give the best indication to the true value of such a parameter.

Failure: The termination of the ability of an item to perform its required function within previously specified limits.

Failure analysis: Subsequent to a failure, the logical systematic examination of an item, its construction, appliation and documentation to identify the failure mode, and to determine the failure mechanism and its basic cause.

Failure, catastrophic: failures that are both sudden and complete.

Failure, complete: Failures resuiting from deviations in characteristic(s) beyond specified limits such as to cause complete lack of the required function. Note thatlimits referred to in this category are special limits specified for this purpose.

Failure, degradation: Failures that are both gradual and partial.

Failure density: At any point in the life of an item, the incremental change in the number of failures per associated incremental change in time.

Failure, early: The failures of components, equipments and systems which occur duing the initial life phase of such devices and which are generallly caused by initial prodcution, assembly, test, installation or commissioning errors.

Failure effect: the consequence(s) a failure mode has on the operation, fucntion or status of an item. Failure effects may be classified as local effects, next-higher effects and end-item effects.

Failure, gradual: failure that could be anticipated by prior examination.

Failure, indenpendent: A failure which occurs in a random manner and which has no relationship or association with any other failure.

Failure mechanism: A physical, chemical, thermal or any other process which results in failure.

Failure, misuse: Failure attributable to the application of stresses beyond the stated capabilities of the item.

Failure mode: the mechanism through which the failure occurs,that is, short, open, fracture, excessive wear, etc. Also, the effect by which a failure is observed,e.g. and open or short-circultcondition, or a gain change.

Failure mode and effects analysis(FMEA): A procedure by which each potentical failure mode in a system is analysed to determind the results or effects thereof on the system and to classify each potential failure mode according to its severity.

Failure, partial: Failures resulting from deviations in characteristic(s) beyond specified limits but not such as to cause complete lack of the required function.

Failure, random: any failure whose cause and/or mechanism makes its time of occurence unpredictable.

Failure rate: the total number of failures within a population, divided by the total number of life units represented by that population, during a particular measurement interval under stated conditions.

Failure rate, assessed: The failure rate of an item determined within stated confidence limits from the observed failure rate of nominally identical items. Note that, alternatively, point estimated may be used, the basis of which must be defined.

Failure rate, constant: that period duing which failures of some items occur at an approximately uniform rate.

Failure rate, instantaneous: At a particular time, the rate of change of the number of items that have failed divided by the number of items surviving.

Failure, secondary(dependent): Failure of an item caused either directly or indirectly by the failure of another item.

Failure, sudden: Failures that could not be anticipated by prior examanation.

Failure, wear-out: A failure that occurs as a result of deterioration processes or mechanical wear and whose probability of occurance increased with time.