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National Standard of the People's Republic of China
Reliability and maintainability terms
Reliability and maintainability terms1 Subject content and scope of application
This standard specifies the basic terms and definitions in the field of reliability and maintainability. This standard applies to reliability and maintainability activities carried out on various products. 2 Basic concepts
2.1 Product item
GB/T 3187----94
Replaces GB318782
Any component, part, assembly, equipment or system that can be considered separately. It can be composed of hardware, software or both. In some cases, it can also include people.
Product can refer to the product as a whole or a sub-sample of the product.
Repaired productrepaired item
Repairable product that is actually repaired after failure. 2.3 Non-repaired itemNan-repaired itemA product that is not repaired after failure.
Non-repaired product may be repairable or non-repairable. 2.4 Serviceservice
Provide a set of functions to the user through some arrangement 2.5 Required functionFunction that a product must have in order to provide a given service 2.6 Instant of time
A single point on a time scale.
The time scale may be continuous, such as calendar time, or discrete, such as a number of periods. 2.7 Time intervaltime interval
The part between two given moments on a time scale. 2.8 Durationtime duration
The difference between the end points of a time interval.
2.9 Accumulated timeaccumulated time
The sum of the durations with given conditions within a given time interval. 2.10 Measure
Measure
Function or quantity used to describe a random variable or a random process. Note: Distribution function and mean are measures of random variables. 2.11 Operation
All technical and management activities that enable a product to perform its specified functions (considering the need to adapt to changes in external conditions) Approved by the State Administration of Technical Supervision on December 6, 1994, and implemented on July 1, 1995
GB/T 3187-94
2.12 Modification (for products) Modification (of an item) All technical and management activities that change a product 3 Characteristics
3. 1 Effectiveness
The ability of a product to meet specified quantitative service requirements. It is a comprehensive reflection of the inherent capabilities and availability of the product. 3.2
Inherent capability capability
The ability of a product to meet specified quantitative service requirements under given internal conditions. 3.3 Durability
The ability of a product to perform its specified functions under specified conditions of use and maintenance until the limit state. The limit state of a product can be characterized by the end of its service life, economic and technical unsuitability, etc. 3.4 Reliability reliability
The ability of a product to perform specified functions under specified conditions and within a specified time interval. 3.5 Maintainability
The ability of a product to maintain or restore the state of being able to perform specified functions under specified conditions and in accordance with specified procedures and means.
3.6 Maintenance support performance The ability of a maintenance organization to provide the resources required for maintaining a product under specified conditions and in accordance with specified maintenance policies. 3.7 Availability availability
The ability of a product to perform specified functions under specified conditions and at specified times or time intervals, provided that the required external resources are guaranteed. It is a comprehensive reflection of the reliability, maintainability and maintenance support of a product. The external resources here are different from maintenance resources and have no effect on the availability of the product. 3.8 Dependability
A collective term that describes availability and its influencing factors: reliability, maintainability and maintenance support. It is generally used in non-quantitative descriptions. 4 Events and States
4.1 Failure
4.1.1 Failure
An event in which the product ceases to be able to complete the specified functions. 4.1.2 Critical failure Failure that may lead to personal injury, damage to important objects, or other intolerable consequences. 4.1.3 Non-critical failure Failure that is unlikely to lead to personal injury, damage to important objects, or other intolerable consequences. 4.1.4 Misuse failure
Failure caused by the stress applied during use exceeding the allowable range of the product. 4.1.5 Nishandling failure Failure caused by improper or careless operation of the product. Weakness failure
Failure caused by the weakness of the product itself, with the applied stress not exceeding the allowable range of the product. Design failure
Failure caused by improper product design.
4.1.8 Manufacturing failure
manufacturing failure
GB/T 3187-94
Failure caused by the manufacturing of the product not following the design or specified manufacturing process. 4.1.9 Aging failure; wearout failure Failure in which the probability of failure increases with the passage of time. It is the result of the inherent process of the product. 4.1.10 Sudden failure Failure that cannot be predicted by prior detection or monitoring. Gradual failure; drift failure 4.1. 11
Failure caused by the gradual change of the specified performance of the product over time. This failure can be predicted through prior detection or monitoring, and sometimes it can be avoided through preventive maintenance. Catastrophic failure
Sudden failure that makes the product completely unable to complete all the specified functions. 4.1.13
Relevant failure
Failure that must be taken into account when interpreting test or work results or calculating reliability values. The criteria for taking it into account shall be specified.
4.1.14 Non-relevant failureFailure that should be excluded when interpreting test or work results or calculating reliability values. The criteria for exclusion shall be specified.
5Primary failure
Failure of a product that is not directly or indirectly caused by the failure or malfunction of another product. sSecondary failure
Failure of a product that is directly or indirectly caused by the failure or malfunction of another product. 4.1.17
Failure cause
Matters related to the design, manufacturing or use stages that cause the failure. Failure mechanism
Physical, chemical or other process that causes the failure. 9Systematic failure, reproducible failure4. 1. 19
Failure that is related to a certain cause and can only be eliminated by modifying the design or manufacturing process, operating procedures, documents or other related factors. Corrective maintenance without modification measures usually cannot eliminate this cause of failure. This failure can be induced by simulating the cause of failure. 4.1.20
Complete failure
Failure that is completely unable to complete all specified functions. Degradation failure
Failure that combines gradual failure and partial failure. 4.1.22 Partial failure Failure that is not a complete failure.
4.2 Failure
4.2.1 Fault
The state in which the product cannot perform the specified function. This does not apply to preventive maintenance or other planned activities or to the lack of external resources. Faults are usually the state after the product itself fails, but may also exist before failure. 4.2.2 Critical fault
Faults that may cause personal injury, damage to important objects, or other intolerable consequences 4.2.3 Non-critical faults Faults that are unlikely to cause personal injury, damage to important objects, or other intolerable consequences. 3
4.2.4 Major fault
Faults that affect the main function.
5 Minor faults
Faults that do not affect the main function.
Misuse fault
GB/T 3187--94
Faults caused by stress applied during use that exceeds the allowable range of the product. 4.2.7 Mishandling faults Faults caused by improper or careless operation of the product. 4.2.8 Weakness fault Fault caused by the inherent weakness of the product when the applied stress does not exceed the allowable range of the product. 4.2.9
Design faultdesign fault
Fault caused by improper product design.
Manufacturing faultmanufacturing fault
Fault caused by the product not being manufactured according to the design or specified manufacturing process. 4.2.11Aging faultageing fault; wearout faultFault caused by a failure whose probability of occurrence increases with time. It is the result of the inherent process of the product.Program-sensitive faultprogram-sensitive fault4.2.12
Fault that occurs when executing certain special instruction sequences. 4.2.13
Data-sensitive faultdata-sensitive faultFault that occurs when processing special forms of data. 4.2.14
Complete faultfunction-preventing faultcomplete fault; function-preventingfaultFault in which the product cannot perform all specified functions at all. 4.2.15
Partial fault partial fault
A fault of a product that is not a complete failure.
4.2.16 Persistent fault A fault of a product that persists until corrective repair is completed. Intermittent fault
A fault of a product that recovers to perform its specified function for a limited duration without any corrective repair. This fault often recurs.
4.2.18 Determinate fault A fault of a product that produces a certain response as a result of a certain action, and the fault manifests itself in that the response produced for all actions is constant.
Indeterminate fault
4.2.19 Indeterminate fault
A fault of a product that produces a certain response as a result of a certain action, and the fault manifests itself in that the error in the response depends on the action taken.
For example, a data-sensitive fault may be a type of indeterminate fault. 4.2.20 Latent fault A fault that does exist but has not yet been discovered.
Systematic faultsystematic fault
Fault following systematic failure.
4.2.22 Fault modefault mode
A state of a malfunctioning product relative to a given specified function. 4.2.23 Faulty itemfaultyitem
A faulty product.
4.3 Errors and mistakes
4.3.1 Errorcrror
GB/T 3187-94
The difference between a calculated, observed, measured value or condition and a true, specified, theoretically accurate value or condition. A faulty product can cause an error. For example: a faulty computing device can produce a calculation error. 4.3.2 Mistakemistake
A person's behavior that produces an undesirable result. 4.4 Product state
4.4.1 Operating state
operating state
The state of a product when it is performing its specified function. 4.4.2 Non-operating state The state of a product when it is not performing its specified functions. 4.4.3
Standby state
The product is in an available state during the demand time, but is not performing its specified functions. 4.4.4 Idle state; free state The product is in an available state during the non-demand time, but is not performing its specified functions. 4.4.5 Disable state; outage The state of a product when it cannot perform its specified functions for any reason. 4.4.6 External disabled state The product is in an available state, but is in an inoperable state due to lack of required external resources or due to activities arranged outside of maintenance. 4.4.7 Down state; internal disabled state The state in which a product cannot perform its specified functions due to a failure or during preventive maintenance. 3 Up state
The state in which a product can perform its specified functions provided that the required external resources are guaranteed. 4.4.9 Busy state The product is executing a function requested by a user and is therefore unable to accept other users. 4.4.10 Critical state The product may cause casualties, damage to important objects or other intolerable consequences. A critical state may be the result of a fatal failure, but not necessarily. Usable state
5 Maintenance
5.1 Maintenance
External non-operating state
Non-operating state
Unusable state
Internal non-operating state
Accepting preventive maintenance
Figure 1 Classification of product states
All technical and management activities, including supervision, carried out to keep or restore the product in a state where it can perform the specified functions. Maintenance may include modification of the product.
5.2 Maintenance philosophy A set of rules for organizing and implementing maintenance.
Maintenance policy
GB/T 3187- 94
Description of the relationship between the maintenance work line, maintenance agreement level and maintenance level in product maintenance maintenance5.4
Maintenance line
The place where maintenance is performed on the product according to the specified maintenance level. For example: the maintenance line is the use site, the repair workshop, and the manufacturing plant. The differences between maintenance lines are the technical level of the personnel, the equipment of tools, the site, etc. 5.5Indenture level (for maintenance) The level into which the product is divided according to the needs of the maintenance work. It may be a component, circuit board, or component. The division of maintenance agreement levels depends on the complexity of the product structure, the accessibility of each component unit, the technical level of the maintenance personnel, the test equipment, safety considerations, etc.
5.6Level of maintenanceThe arrangement of maintenance activities at a specific maintenance agreement level. For example: maintenance activities are the replacement of components, printed circuit boards, assemblies, etc. 5.7Preventive maintenancePreventive maintenanceMaintenance performed at predetermined time intervals or according to specified criteria to reduce the probability of product failure or prevent functional degradation. 5.8Corrective maintenanceMaintenance performed to restore the product to a state where it can perform the specified functions after fault identification. 5.9 Controlled maintenance controlled maintenance A method of maintaining the desired service quality by systematically using central monitoring equipment and/or sampling to conduct technical analysis to minimize preventive maintenance and reduce corrective maintenance. 5.10 Scheduled maintenance scheduled maintenance Preventive maintenance performed according to a predetermined schedule. 5.11 Unscheduled maintenance unscheduled maintenance Maintenance that is not performed according to a predetermined schedule but is performed after abnormal signs of product status are found. On-site maintenance; in sits maintenance; field maintenance 5.12
Maintenance performed at the place where the product is used. 5.13 Off-site maintenance off-site maintenance Maintenance performed at a place other than the place where the product is used. For example, repairing a component unit of a product at a maintenance center. 5.14 Remote maintenance remote maintenance Maintenance performed without direct human contact with the product. 5.15 Automatic maintenance automatic maintenance Maintenance performed without human intervention. bZxz.net
Deferred maintenance
After fault identification, the corrective maintenance is delayed according to the prescribed maintenance rules if it is not immediately carried out. 5.17 Basic maintenance activity At a given maintenance agreement level, the maintenance work may be decomposed into work units. 5.18 Maintenance action; maintenance task A series of basic maintenance work performed according to a given intention. For example, fault diagnosis, fault location and functional inspection or their combination.
Erepair
5.19 Repair
Corrective maintenance performed by a repair person on a product. 5.20 Fault recognition fault recognition activity.
5.21 Fault localization fault localization GB/T 3187-—94
Work performed to identify the fault unit of the product according to the maintenance agreement level. 5.22 Fault diagnosis fault diagnosis
Work performed to identify, locate and determine the cause of the fault. Fault correction fault correction
Fault location is the work performed to restore the ability of a faulty product to perform specified functions. 5.24 Function check-out The work performed to verify that the product has restored its ability to perform specified functions after the fault has been eliminated. 5.25 Restoration; recovery The work of restoring the ability of a faulty product to perform specified functions. Supervision; monitoring
The work of manually or automatically observing the status of a product. 5.27
Maintenance entity maintenance entity Any component of a product that may fail and can be clearly identified for replacement and repair by alarm or any other means.
Function-affecting maintenance function-affecting maintenance Maintenance that interrupts or weakens one or more specified functions of the product being repaired. Function-affecting maintenance is divided into maintenance that prevents function and maintenance that weakens function. Function-preventing maintenance 5.29
Maintenance that causes the repaired product to completely lose all functions and be unable to perform specified functions. 5.30 Function-degrading maintenance Function-degrading maintenance Maintenance that degrades one or more specified functions of the product being repaired, but does not cause a complete loss of all functions. 5.31 Function-permitting maintenance Maintenance that does not interrupt or degrade any required function of the product being repaired. 6 Time concepts
6.1 Time related to maintenance
6.1.1 Maintenance time Maintenance time The time interval for performing maintenance (manual or automatic) on a product. Including technical delays and logistical delays. Maintenance man-hours MMH Maintenance man-hours 6. 1.2
The cumulative maintenance time expressed in hours spent by all maintenance personnel in a specified maintenance work or a specified time interval Actual maintenance time Active maintenance time C6.1.3
Maintenance time excluding logistical delays.
6.1.4 Preventive maintenance time Preventive maintenance time Maintenance time for performing preventive maintenance on a product. Including technical delays and logistical delays inherent in preventive maintenance. 6.1.5 Corrective maintenance time The time to perform corrective maintenance on a product. This includes the technical delays and logistical delays inherent in corrective maintenance. 6.1.6 Active preventive maintenance time The actual time to perform preventive maintenance on a product. 6.1.7 Active corrective maintenance time The actual time to perform corrective maintenance on a product. 6.1.8 Undetected fault time The time between failure and identification of a fault. No-demand time
Available time
Maintenance time
GB/T 3187-
Operation time
Unavailable time
Undetected fault time
"Administrative delay
Actual maintenance time
Preventive maintenance time
Actual preventive maintenance time
Corrective maintenance time
Available time
Time when operation is unavailable due to external factors
Actual corrective maintenance time
Fault location
Figure 2 Time diagram
Administrative delay
6.1.9 Administrative delay (for corrective maintenance) Fault repair
Repair time
The accumulated time during which corrective maintenance is not carried out on the faulty product due to administrative reasons. 6.1.10 Logistic delay logistic delay check
The cumulative time during which maintenance cannot be carried out in order to obtain the required maintenance resources. Administrative delay is not included. Logistic
Logistic delay may be caused by the following reasons: time to arrive at the unattended location, or failure to obtain spare parts, experts, test equipment, data and suitable environmental conditions. Fault correction time6.1.11
The actual corrective maintenance time during which fault repair is carried out. 6.1.12 Technical delay technical delay The cumulative time used for auxiliary technical activities related to the maintenance activity itself. Check-out time
The actual corrective maintenance time during which functional check-out is carried out. 6. 1. 14
Fault diagnosis time fault diagnosis time The time during which fault diagnosis is carried out.
Fault localization time fault localization time6. 1. 15
The actual corrective maintenance time during which fault localization is carried out. 6.1.16
Repair time
The actual corrective maintenance time for the product. 6.2 Time related to product status
6.2.1 Operating time
operating time
The time interval during which the product is in operating status. 6.2.2 Non-operating time The time interval during which the product is in non-operating status. 6.2.3 Required time
GB/T 3187 --- 94
The time interval during which the user requires the product to be in a state where it can perform the specified functions. 6.2.4 Non-required time Non-required time The time interval during which the user does not require the product to be in a state where it can perform the specified functions. 6.2.5 Stand-by time
The time interval during which the product is in a standby state. 6.2.6 Idle time idle time; free time The time interval during which the product is in an idle state. 6.2.7 Disabled time Disabled time The time interval during which the product is in a disabled state. 6.2.8 Down time
The time interval during which the product is in an unavailable state. 6.2.9 Accumulated down time The accumulated time during which the product is in an unavailable state within the specified time interval. 6.2.10 External disabled time external disabled time, external loss tine The time interval during which the product is in an external disabled state. 6.2.11 Up time
The time interval during which the product is in an available state. 6.3 Time related to reliability characteristic quantity
6.3.1 Time to first failure timeto first failure The total continuous working time from the first entry of the product into a usable state to failure. Time to failure time to failure
The total continuous working time from the first entry of the product into a usable state to failure or from recovery to the next failure. Time between failures time between failures6.3.3
The duration between two adjacent failures of a repaired product. 6.3.4
Operating timebetween failures The total continuous working time between two adjacent failures of a repaired product. 6.3.5 Time to restoration;time to recovery The time interval during which the product is in an unusable state due to failure. Useful life
The time interval during which the product, under specified conditions, starts from a specified moment and ends when the failure density becomes unacceptable or the product's failure is considered unrepairable.
6.3.7 Early failure period Early failure period A period of time that may exist in the early life of a product, during which the instantaneous failure density (for repaired products) or instantaneous failure rate (for unrepaired products) is significantly higher than the subsequent period. 6.3.8 Constant failure intensity period Constant failure intensity period A period of time during which the failure density of repaired products is approximately constant. 6.3.9 Constant failure rate period Constant failure rate period A period of time during which the failure rate of unrepaired products is approximately constant. 6.3.10 Wear-out failure period A period of time that may exist in the late life of a product, during which the instantaneous failure density (for repaired products) or instantaneous failure rate (for unrepaired products) is significantly higher than the previous period. 7 Characteristic quantity
7.1 Availability characteristic quantity
GB/T 3187--94
A(t) instantaneous availability7.1.1 Instantaneous availability
The probability that the product is in a state where it can perform the specified function under the specified conditions and at the specified time, provided that the required external resources are guaranteed.
U(t) instantancous unavailabilityInstantaneous unavailability
The probability that the product is in a state where it cannot perform the specified function under the specified conditions and at the specified time, provided that the required external resources are guaranteed.
7.1.3 Average availabilityA(ti, t2)meanavailabilityThe mean value of the instantaneous availability within the specified time interval (ti, t2). That is, A(t+tz)
tz — tiJt
7.1.4 Mean unavailability U(ti, t2）mean unavailability The mean value of instantaneous unavailability in the specified time interval (ti, t2). That is, U(tr+t2)
7.1.5 Asymptotic availability Aasymptotic availabilityt.
U(t)da
The limit of instantaneous availability when time tends to infinity (if it exists) Under certain conditions, such as when the failure rate and the repair rate are constant, the asymptotic availability can be expressed as: MUT
A MUT+MDT
Where: MDT-mean unavailability time; MUT-mean available time.
7.1.6 Steady-state availability steady-state availability The mean value of instantaneous availability in the specified time interval under steady-state conditions. Under certain conditions, such as when the failure rate and the repair rate are constant, the steady-state availability can be expressed as: MUT
MUT+MDT
Where: MDT - mean unavailable time; MUT - mean available time.
7.1.7 Asymptotic unavailability The limit of instantaneous unavailability (if it exists) when time tends to infinity. Under certain conditions, such as when the failure rate and the repair rate are constant, the asymptotic unavailability can be expressed as: It
Where: MDT -
- mean unavailable time;
MUT - mean available time.
GB/T 3187.-
MDT+MUT
7.1.8 Steady-state unavailability The mean value of instantaneous unavailability within a specified time interval under steady-state conditions. Under certain conditions, such as when the failure rate and the repair rate are constant, the steady-state unavailability can be expressed as: U
where; MDT—mean unavailability time;
MUT—mean available time.
MDT + MUT
7.1.9 Asymptotic mean availability A
The limit (if any) of the average availability in the asymptotic mean availability time interval (ti, t2) when t2 tends to infinity. That is,
A - limA(t,t2)
This value does not depend on t.
）Asymptotic mean unavailability
The limit (if any) of the average unavailability in the asymptotic mean unavailability time interval (ti, t2) when t2 tends to infinity. That is,
U = limU(t,tz)
This value does not depend on t.
7.1.11 Mean available time
Expected available time.
mean up time
7.1.12 Mean accumulated down time
Expected accumulated down time in a specified time interval. 7.2 Reliability characteristic quantity
7.2.1 Reliability R(t1,t2) reliability The probability that a product can complete a specified function under specified conditions and within a specified time interval (t, t2). 7.2.2
Instantaneous failure rate (t) The ratio of the conditional probability of failure in the time interval (t, t + △) to the length of the interval △, assuming that the product is in an available state at time t, when t approaches 0 (if it exists). That is, a(t)
P(t ≤T<+ AtIT >I)
Here T represents the time before failure or the time before the first failure. GB/T 3187-94
7.2.3 Average failure rate a(tt)mean failurerate is the mean value of the instantaneous failure rate within the specified time interval (t,2). That is, X(ti,t2)
?a(t)dt
7.2.4 Instantaneous failure intensity Z(t) instantaneous failure intensity The ratio of the average number of peak failures of the repaired product in the time interval (t, t + △) to the interval length △t, when △ approaches (the limit (if it exists). That is,
E(N(t+ At) - N(t))
Z(t) lim
Where; N(t)--
The number of failures in the time interval (0, t);
E——represents expectation.
mean failure intensity
7.2.5 Average failure density Z(t1, t2)
The mean value of the instantaneous failure density in the specified time interval (t1, t2). That is, Z(tr, t2) =
t2 — tJ
Z(t)de
7.2.6 Mean time to first failure
mean time to first failure
Expected time before first failure.
7.2.7 Mean time to failure MTTF
mean time to failure
Expected time before failure.
7.2.8 Mean time between failures MTBFmean timebetween failuresExpected time between failures.
Mean operating time between failures MTBFmcan operating time between failuresExpected time between failures.
7.2.10 Failure rate acceleration factorfailure rate acceleration factorThe ratio of the failure rate of the product under the accelerated test condition to the failure rate under the reference test condition within the same time. 7.2.11 Failure intensity acceleration factorfailure intensity acceleration factor factor The ratio of the number of failures of the repaired product under two different stress conditions within the same period of time. 7.3 Maintainability characteristic quantity
7.3.1 Maintainability
The probability that the product can maintain or recover to perform the specified function under the specified conditions of use and within the specified time interval when maintenance is carried out under specified conditions and according to the specified procedures and means. 7.3.2 Instantaneous repair rate μ(t) instantaneous repair rate Assuming that the product is in an unrepaired state at time t, the ratio of the conditional probability that it can be repaired within the time interval (t, t + △) to the length of the interval △, the limit when △ tends to 0 (if it exists). That is, P(t
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