Lecture
Reliability theory is a science that studies the patterns of distribution of technical device failures, the causes and models of their occurrence.
The theory of reliability studies the methods of ensuring the stability of the operation of objects (products, devices, systems, etc.) in the process of design, production, acceptance, operation and storage.
Establishes and studies quantitative indicators of reliability. Examines the relationship between performance and reliability.
The basic concepts and definitions of the theory of reliability of technical devices are formulated in GOST 27.002 89 “Reliability in engineering. Basic concepts. Terms and Definitions"
1. General concepts
2. The status of the facilities
3. Defects, damage, failures
4. Temporary concepts .
5. Maintenance and repair
6. Reservation
7. Provision, determination and control of reliability
8. Reliability tests
Basic concepts, terms and definitions of concepts are given in accordance with [4].
Reliability - the property of an object to maintain over time, within established limits, the values of all parameters characterizing the ability
perform the required functions in the specified modes and conditions of use, maintenance, storage and transportation. Basis
other properties of reliability: reliability, durability, maintainability and retention, or certain combinations of these properties.
Reliability - the property of an object to continuously maintain a healthy state for some time or operating time.
Reliability indicators include: MTBF of the same type of products in operation; probability of failure
work; failure rate. So, for gas turbine engines (GTE)
Three types of MTBF are used: TVP - MTBF in flight, T dsd - MTBF for long-term engine removal, T s -
cumulative MTBF.
Durability - the property of an object to maintain a healthy state until the limit state occurs when the system is installed
maintenance and repair.
For example, the durability of a gas turbine engine is characterized by a designated and overhaul resource.
Maintainability - a property of an object, which consists in adaptability to maintain and restore a working condition -
Niya through maintenance.
It is determined by labor and material costs for its repair and maintenance. Maintainability is characterized by two
indicators: repair manufacturability (RT) and manufacturability during maintenance (TO). The main properties of repair technology
Onologichnosti are blockiness, interchangeability and recoverability. The main properties of manufacturability during maintenance:
Availability, accessibility and ease of removal.
Maintainability indicators include: average recovery time and average repair time and
Maintenance.
Persistence - the property of an object to maintain, within specified limits, the values of parameters characterizing the ability of an object to perform
required functions during and after storage and (or) transportation. The main indicator of persistence is its average shelf life.
Good condition - the state of the facility in which it meets all the requirements of the regulatory and technical and (or) design
(design) documentation.
Faulty condition - the state of an object in which it does not meet at least one of the requirements of the regulatory and technical and (or)
design (design) documentation.
A workable state is the state of an object in which the value of all parameters characterizing the ability to fulfill specified
functions that meet all the requirements of regulatory and technical and (or) design (project) documentation.
Inoperative state - the state of an object in which the value of at least one parameter characterizing the ability to perform
to take the specified functions, does not meet the requirements of regulatory and (or) design (project) documentation.
Note. For complex objects, it is possible to divide their inoperative states. Moreover, from the set of inoperative states
Partially inoperative states are distinguished in which the object is able to partially perform the required functions.
The limiting state is the state of the facility in which its further operation is unacceptable and inappropriate, or restoration
its working condition is impossible or impractical.
The criterion of the limiting state is a sign or set of signs of the limiting state of an object established by the regulatory and technical and
(or) design (design) documentation.
Note. Depending on the operating conditions for the same
object can be set two or more criteria for the limiting state.
Defect - each individual product non-compliance with the established requirements [5].
Damage - an event consisting in the violation of the healthy state of an object while maintaining a healthy state.
Failure - an event consisting in the violation of the operational state of the object.
Failure criterion - a sign or set of signs of violation of an object’s operational state
The cause of failure is the phenomena, processes, events and conditions that caused the failure of the object.
Consequences of failure - phenomena, processes, events, and conditions caused by the occurrence of an object failure.
Failure criticality - a set of signs characterizing the consequences of failure.
Note. The classification of failures by criticality (for example, by the level of direct and indirect losses associated with the onset of failure, or by labor
the recovery capacity after failure) is established by the regulatory technical and (or) design (design) documentation as agreed
communication with the customer on the basis of technical and economic considerations and safety considerations.
Resource failure - failure, as a result of which the object reaches the limit state.
Independent failure - failure not caused by other failures.
Dependent Failure - Failure due to other failures.
A sudden failure is a failure characterized by a stepwise change in the values of one or more parameters of the object.
A gradual failure is a failure resulting from a gradual change in the values of one or more parameters of an object.
Failure - a self-resolving failure or a single failure, eliminated by minor operator intervention.
Alternating failure - repeatedly arising self-eliminating failure of the same nature.
Explicit failure - failure detected visually or by regular methods and means of control and diagnosis in the preparation of the object
to use or in the process of its use as directed.
Latent failure - a failure that is not detected visually or by regular methods and means of monitoring and diagnosis, but detected during maintenance or by special diagnostic methods.
Constructive refusal - a refusal arising due to a reason related to imperfection or violation of established rules and (or) norms
design or construction.
Production refusal - a refusal arising due to an imperfection or violation of the established manufacturing process
repair or repair at the repair facility.
Operational failure - a failure that occurs due to a violation of the established rules and (or) operating conditions.
Degradation failure - failure caused by the natural processes of aging, wear, corrosion and fatigue, subject to all
established rules and (or) norms of design, manufacture and operation.
Operating time - the duration or volume of work of the object.
Note. The operating time can be both a continuous value (duration of work in hours, mileage, etc.), and integer
value (the number of duty cycles, starts, etc.).
MTBF - MTBF from the start of operation to the occurrence of the first failure.
Between failures - the operating time of an object from the end of the restoration of its operability after a failure to the occurrence of the next failure.
Recovery time - the duration of the restoration of the operational state of the object.
Resource - the total operating time of the object from the beginning of its operation or
its renewal after repair before the transition to the limit state.
Service life - the calendar duration of operation from the start of operation of the facility or its resumption after repair to the transition
to the limit state.
Shelf life - the calendar duration of storage and (or) transportation of an object, during which the values of parameters characterizing the ability to be stored within specified limits
object to perform specified functions.
Note. After the expiration date, the facility must comply with the requirements of reliability, durability and maintainability established by the regulatory and technical documentation for the facility.
Residual resource - the total operating time of the object from the moment of monitoring its technical condition to the transition to the limit state.
Note. The concepts of residual MTBF, residual service life, and residual shelf life are introduced similarly.
Assigned resource - total operating time, upon reaching which
operation of the facility should be discontinued regardless of its technical condition.
Assigned service life - the calendar duration of operation, at which achievement the operation of the facility must be pre-
sprinkled regardless of its technical condition.
Assigned storage period - calendar storage duration, upon reaching which storage of the object should be terminated
regardless of its technical condition.
Note. Upon the expiration of the assigned resource (service life, shelf life), the object must be taken out of service, and a decision must be made, provided for by the relevant regulatory and technical documentation - referral to repair, decommissioning, destruction, inspection and
setting a new deadline, etc.
In GA, service life is measured in flight hours, a calendar period (for example, up to 30 years), or the number of take-offs and landings.
Maintenance - maintaining a healthy state using technical operation methods.
Recovery is the process of transferring an object from an inoperative state to an operational one.
Repair - a set of operations to restore the serviceability or operability of products and restore the resources of products or their
fixed parts [6].
Serviced object - an object for which maintenance is provided for by normative and technical documentation and (or) design (project) documentation.
Maintenance-free facility - an facility for which maintenance is not provided for by normative and technical documents
Tation and (or) design (project) documentation.
The restored object is the object for which in the considered
carrying out restoration of a working condition is provided for in the regulatory and technical and (or) design (design)
documentation.
Unrecoverable object - an object for which, in the situation under consideration, the restoration of an operational state does not
provided in the normative-technical and (or) design (project) documentation.
A repaired object is an object, the repair of which is possible and is provided for by the normative-technical, repair and (or) design
(design) documentation.
Presentable object - an object the repair of which is impossible or is not provided for by the normative-technical, repair and (or) construction
torus (design) documentation.
Reservation - a way to ensure the reliability of the facility through the use of additional funds and (or) capabilities that are excessive in
wearing to the minimum necessary to perform the required functions.
Reserve - a set of additional funds and (or) opportunities used for reservation.
The main element is the element of the object necessary to perform the required functions without the use of a reserve.
Reserved element - an element designed to perform the functions of the main element in case of failure of the latter.
The multiplicity of the reserve is the ratio of the number of reserve elements to the number of elements reserved by them, expressed by an unabridged fraction.
Duplication - reservation with a reserve ratio of one to one.
A loaded reserve is a reserve that contains one or more reserve elements that are in primary element mode.
Light reserve - a reserve that contains one or more backup elements that are in less loaded mode than the main element.
Unloaded reserve - a reserve that contains one or more backup elements that are in unloaded mode before the start
performing their functions as the main element.
General reservation - reservation, in which the entire object is reserved.
Separate reservation - reservation at which separate elements of an object or their group are reserved.
Permanent backup - a backup in which a loaded reserve is used, and in case of failure of any element in the redundant group, the object performs the required functions by the remaining elements without switching.
Replacement reservation - reservation in which the functions of the main element are transferred to the reserve only after the failure of the main element.
Moving reservation - replacement reservation, in which a group of basic elements is reserved by one or more
reserve elements, each of which can replace any of the failed elements of this group.
Mixed reservation - a combination of different types of reservation in the same object.
Redundancy backup - redundancy in which the restoration of failed main and (or) backup elements of technical
skiing is possible without disrupting the operability of the facility as a whole and is provided for by operational documentation.
Backup without restoration - backup in which the restoration of failed main and (or) backup elements is technically impossible without disrupting the operability of the facility as a whole and (or) is not provided for by the operational documentation.
The probability of a successful transition to the reserve is the probability that the transition to the reserve will occur without an object failure, i.e. happen in time
not exceeding the permissible value of the interruption in functioning and (or) without reducing the quality of functioning.
Reliability Program - a document establishing a set of interrelated organizational and technical requirements and
events to be carried out at certain stages of the life cycle of an object and aimed at ensuring specified requirements
to reliability and (or) to increase reliability.
Determination of reliability - determination of numerical values of reliability indicators of an object.
Reliability control - verification of the compliance of the facility with the specified reliability requirements.
The calculation method for determining reliability is a method based on the calculation of reliability indicators using reference data on the reliability of components
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Theory of Reliability
Terms: Theory of Reliability