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RELIABILITY IN TECHNOLOGY - BASIC CONCEPTS - TERMS AND DEFINITIONS - GOST 27-002-89 (approved by the Decree of the State Standard of the USSR dated ... Relevant in 2018
To the terms "Assigned service life", "Assigned resource", "Assigned storage period" (clauses 4.10; 4.9; 4.11)
The purpose of establishing the assigned service life and assigned resource is to ensure the forced early termination of the use of the object, for its intended purpose, based on safety requirements or technical and economic considerations. For objects subject to long-term storage, a designated storage period can be set, after which further storage is unacceptable, for example, from security requirements.
When the object reaches the assigned resource (the assigned service life, the assigned storage period), depending on the purpose of the object, the features of operation, technical condition and other factors, the object may be decommissioned, sent for medium or major repairs, transferred for use for other purposes, re-preserved (in storage), or a decision may be made to continue operation.
The assigned service life and the assigned resource are technical and operational characteristics and do not relate to reliability indicators (durability indicators). However, when establishing the assigned service life and the assigned resource, the predicted (or achieved) values of the reliability indicators are taken into account. If a safety requirement is established, then the assigned service life (resource) must correspond to the values of the probability of no-failure operation in relation to critical failures close to one. For safety reasons, a time safety factor can also be entered.
The time of normal functioning of any TS is limited by the inevitable changes in the properties of materials and parts from which they are made. That is why durability is determined by the service life and resource.
The service life is determined by the calendar duration of the operation of the technical equipment from its beginning or renewal after repair to the limit state.
They differ: - average service life or mathematical expectation of service life:
Where t sl i - life time i-th TU; f(tsl) is the lifetime distribution density;
Average service life before decommissioning TWed.sl.cn- this is the average service life from the start of operation of the technical equipment to its decommissioning;
Gamma Percent Life Tsl.γ is the service life during which the object does not reach the limit state with a given probability γ percent:
In addition to the service life, the durability of TS is characterized by its resource.
A resource is the operating time of specifications from the start of operation or its resumption after repair until the limit state occurs.. Unlike the definition of the concept life time, concept resource operates not with a calendar duration, but with the total operating time of technical specifications. This operating time in the general case is a random value. Therefore, along with with the concepts of the assigned resource, the durability is estimated by the average resource, gamma-percentage resource and other types of resources.
Calendar service life and operating time TU. PR - prevention; tps– limit state time Assigned resourceRn– is the total operating time of TU, upon reaching which operation must be terminated, regardless his condition. Average resourceRWed– resource expectation.
Where r is the resource of some TS; f(r) is the probability density of the quantity r.
Gamma- percentage resourceRγ – operating time, during which the TS does not reach the limit state with a given probabilityγ percent.
Warranty resource RG is a legal concept. This resource determines when a manufacturer accepts claims for the quality of manufactured products. The warranty resource coincides with the running-in period.
12. Reliability of software (by). Reliability and failure of the software, stability of the operation of the software.
The solution of any task, the performance of any function assigned to a computer operating in a network or locally, is possible with the interaction of hardware and software. Therefore, when analyzing the reliability of the computer performing the given functions, one should consider a single complex of hardware and software. By analogy with the terms adopted to denote the reliability indicators of technical specifications, under reliability software (BY) the property of this software to perform the specified functions is understood, maintaining its characteristics within the established limits under certain operating conditions.
Software reliability is determined by its reliability and recoverability. Software reliability– this property remains operational when used to process information in an IS. The reliability of software is estimated by the probability of its operation without failures under certain environmental conditions during a given observation period. In the above definition, software failure is understood as an unacceptable deviation of the characteristics of the functioning of this software from the requirements. Certain environmental conditions- this is a set of input data and the state of the IS itself. The specified observation period corresponds to the time, necessary to perform on Computer of the problem being solved.
Software reliability can be characterized by the average time of occurrence of failures during the operation of the program. It is assumed that the hardware of the computer is in good condition. From the point of view of reliability, the fundamental difference between software and hardware is that programs do not wear out and their failure due to a breakdown is impossible. Consequently, the characteristics of the software functioning depend only on its quality, which is predetermined by the development process. This means that software reliability is determined by its correctness and depends on the presence of errors introduced in it at the stage of its creation. In addition, the manifestation of software errors is also related to the fact that at some points in time, previously unseen sets of data that the program is not able to process correctly may arrive for processing. Therefore, the input data to a certain extent affect the functioning of the software.
In some cases, they talk about sustainability of the software. This term refers to the ability of software to limit the consequences of its own errors and adverse effects of the external environment or to resist them. The stability of software is usually ensured by introducing various forms of redundancy, which make it possible to have duplicate program modules, alternative programs for the same applications.
dachas, to exercise control over the process of program execution.
Lecture . RELIABILITY INDICATORS
The most important technical characteristic of quality is reliability. Reliability is estimated by probabilistic characteristics based on statistical processing of experimental data.
The basic concepts, terms and their definitions that characterize the reliability of technology and, in particular, engineering products, are given in GOST 27.002-89.
Reliability- the property of the product to maintain, within the established time limits, the values of all parameters that characterize the ability to perform the required functions in the specified modes and conditions of use, maintenance, repairs, storage, transportation and other actions.
Product reliability is a complex property that may include: failure-free operation, durability, maintainability, storability, etc.
Reliability- the property of the product to continuously maintain operability for a given time or operating time under certain operating conditions.
Working condition- the state of the product, in which it is able to perform the specified functions, while maintaining the acceptable values of all the main parameters established by the regulatory and technical documentation (NTD) and (or) design documentation.
Durability- the property of the product to maintain operability over time, with the necessary interruptions for maintenance and repair, up to its limiting state, specified in the technical documentation.
Durability is determined by the occurrence of events such as damage or failure.
Damage- an event consisting in a violation of the serviceability of the product.
Refusal- an event resulting in a complete or partial loss of product performance.
Working condition- the state in which the product meets all the requirements of regulatory and technical and (or) design documentation.
Faulty state- a condition in which the product does not meet at least one of the requirements of the regulatory and technical and (or) design documentation.
A defective product may be functional. For example, a decrease in the density of the electrolyte in batteries, damage to the lining of a car means a faulty condition, but such a car is operational. An inoperable product is also defective.
Operating time- duration (measured, for example, in hours or cycles) or the amount of work of the product (measured, for example, in tons, kilometers, cubic meters, etc. units).
Resource- the total operating time of the product from the beginning of its operation or its renewal after repair until the transition to the limit state.
limit state- the state of the product, in which its further operation (application) is unacceptable due to safety requirements or is impractical for economic reasons. The limit state occurs as a result of exhaustion of the resource or in an emergency.
Life time- calendar duration of operation of products or its renewal after repair from the beginning of its use to the onset of the limit state
Unhealthy state- the state of the product, in which it is not able to normally perform at least one of the specified functions.
The transfer of a product from a faulty or inoperable state to a serviceable or operable one occurs as a result of restoration.
Recovery- the process of detecting and eliminating the failure (damage) of the product in order to restore its performance (troubleshooting).
The main way to restore performance is repair.
maintainability- property of the product, which consists in its adaptability to maintaining and restoring a working state by detecting and eliminating a defect and malfunction by technical diagnostics, maintenance and repair.
Persistence- the property of products to continuously maintain the values of the established indicators of its quality within the specified limits for long-term storage and transportation
Shelf life- calendar duration of storage and (or) transportation of the product under specified conditions, during and after which serviceability is maintained, as well as the values of reliability, durability and maintainability indicators within the limits established by the regulatory and technical documentation for this object.
H
Rice. 1. Product state diagram
To quantitatively characterize each of the properties of product reliability, such single indicators as time to failure and failure, time between failures, resource, service life, shelf life, recovery time are used. The values of these quantities are obtained from test or operation data.
Comprehensive reliability indicators, as well as the availability factor, the technical utilization factor and the operational availability factor, are calculated from the input of single indicators. The nomenclature of reliability indicators is given in Table. 1.
Table 1. Approximate nomenclature of reliability indicators
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Reliability property |
Name of indicator |
Designation |
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Single indicators |
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Reliability |
Probability of failure-free operation Mean time to failure MTBF Mean time between failures Failure rate Remanufactured Product Failure Flow Average failure rate Failure Probability |
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Durability |
Average resource Gamma percentage resource Assigned resource Installed resource Average service life Gamma Percent Life Assigned Life Assigned Life |
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maintainability |
Mean recovery time Probability of recovery Factor of repair complexity |
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Persistence |
Average shelf life Gamma Percent Shelf Life Assigned shelf life Assigned shelf life |
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Generalized indicators |
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|
Set of properties |
Availability factor Technical utilization factor Operational Readiness Ratio |
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Indicators characterizing the reliability
Probability of uptime individual product is evaluated as:
Where T - time from start to failure;
t - time for which the probability of failure-free operation is determined.
Value T can be greater than, less than or equal to t. Therefore,
The probability of failure-free operation is a statistical and relative indicator of the preservation of the operability of the same type of mass-produced products, expressing the probability that, within a given operating time, failure of products does not occur. To establish the value of the probability of failure-free operation of serial products, the formula for the average value is used:
Where N- number of observed products (or elements);
N o- the number of failed products over time t;
N R- the number of workable products at the end of time t testing or operation.
The probability of failure-free operation is one of the most significant characteristics of product reliability, as it covers all factors that affect reliability. To calculate the probability of failure-free operation, data are used that are accumulated through observations of operation during operation or during special tests. The more products are observed or tested for reliability, the more accurately the probability of failure-free operation of other similar products is determined.
Since uptime and failure are mutually opposite events, the estimate failure probabilities(Q(t)) determined by the formula:
Calculation average time to failure (or mean uptime) based on the results of observations is determined by the formula:
T i - uptime i-th element (product).
Statistical evaluation of the mean time between failures is calculated as the ratio of the total operating time for the considered period of testing or operation of products to the total number of failures of these products for the same period of time:
Statistical evaluation of the mean time between failures is calculated as the ratio of the total operating time of the product between failures for the considered period of testing or operation to the number of failures of this (their) object (s) for the same period:
Where T - number of failures per time t.
Durability indicators
The statistical estimate of the average resource is as follows:
Where T R i - resource i-th object;
N- the number of products delivered for testing or commissioning.
Gamma percent resource expresses the operating time during which the product with a given probability γ percent does not reach the limit state. Gamma percentage life is the main design indicator, for example, for bearings and other products. The essential advantage of this indicator is the possibility of its determination before the completion of testing of all samples. In most cases, a 90% resource criterion is used for various products.
Assigned resource - the total operating time, upon reaching which the use of the product for its intended purpose must be terminated, regardless of its technical condition.
P oneestablished resource is understood as a technically justified or predetermined value of the resource provided by the design, technology and operating conditions, within which the product should not reach the limit state.
Statistical evaluation average service life determined by the formula:
I 
Where T sl i - life time i-th product.
Gamma Percent Life represents the calendar duration of operation, during which the product does not reach the limit state with a probability , expressed as a percentage. To calculate it, use the ratio
Appointed term services- the total calendar duration of operation, upon reaching which the use of the product for its intended purpose must be terminated, regardless of its technical condition.
Underestablished service life understand the feasibility study provided by the design, technology and operation, within which the product should not reach the limit state.
The main reason for the decrease in the durability of the product is the wear of its parts.
Product quality - a set of product properties that determine its suitability to meet certain needs in accordance with the purpose (GOST 15467-79). According to international standard ISO 8402.1994, quality is defined as a set of characteristics of an object (activity or process, product, service, etc.) related to its ability.
The quality of products (works, services) is determined by such concepts as "characteristic", "property" and "quality". A characteristic is the relationship of dependent and independent variables, expressed in the form of text, a table, a mathematical formula, a graph. It is described, as a rule, functionally. A product property is an objective feature of a product that can be manifested during its creation, operation or consumption. Product quality is formed at all stages of its life cycle. The product property is expressed by quality indicators, i.e. quantitative characteristics of one or more product properties included in quality and considered in relation to certain conditions its creation and operation or consumption.
Depending on the role performed in the evaluation, classification and evaluation indicators are distinguished. Classification indicators characterize the belonging of products to certain group in the classification system and determine the purpose, size, scope and conditions of use of products. All industrial and agricultural products are systematized, have a code designation and are included in the All-Russian Classification of Products (OKP) in the form of various classification groups. Classification indicators are used on initial stages assessment of product quality to form groups of analogues of the evaluated products. As a rule, these indicators do not participate in the assessment of product quality.
Estimated indicators quantitatively characterize those properties that form the quality of products as an object of production and consumption or operation. They are used to standardize quality requirements, assess the technical level in the development of standards, quality assurance in control, testing and certification. Estimated indicators are divided into functional, resource-saving and environmental.
1. Functional indicators characterize the properties that determine the functional suitability of products to meet specified needs. They combine indicators of functional suitability, reliability, ergonomics and aesthetics:
1.1. indicators of functional suitability characterize the technical essence of the product, properties that determine the ability of the product to perform its functions under specified conditions of use for its intended purpose (for example, single indicators - load capacity, capacity and water resistance, complex indicators - calorie content, productivity);
1.2. product reliability indicators characterize its ability to maintain over time (within the established limits) the values of all specified quality indicators, subject to specified modes and conditions of use, maintenance, repair, storage and transportation. Single indicators of reliability are indicators of reliability, maintainability, durability and persistence, complex (providing several properties) - reliability and recoverability:
Durability - the property of the product to maintain performance to the limit state with the necessary breaks for maintenance and repairs. The limiting state of the product is determined depending on its circuit design features, operating mode and scope of use. For many non-repairable products (for example, lighting lamps, gears, household electrical and radio appliance assemblies), the limit state coincides with a failure. In some cases, the limit state is determined by the achievement of a period of increased failure rate. This method determines the limit state for the components of automatic devices that perform critical functions. The use of this method is due to a decrease in the efficiency of operation of products, the components of which have an increased failure rate, as well as a violation of safety requirements. The period of operation of non-repairable products to the limit state is established based on the results of special tests and is included in the technical documentation for the products. If it is impossible to obtain in advance information about the change in the failure rate, the limit state of the product is determined by a direct examination of its condition during operation.
The limiting state of repaired products is determined by the inefficiency of their further operation due to aging and frequent failures or increased repair costs. In some cases, the criterion for the limit state of repaired products may be a violation of safety requirements, for example, in transport. The limit state can also be determined by obsolescence.
Durability is reduced with improper operation of buildings and structures, overloading of structures, as well as with pronounced destructive influences environment(action of moisture, wind, frost, etc.). Of great importance to ensure durability is right choice constructive solutions, taking into account the peculiarities of the climate and operating conditions. Increased durability is achieved by using building and insulating materials that are highly resistant to freezing and thawing, moisture resistance, biostability, and protection of structures from the penetration of destructive agents into them, and above all liquid moisture. In the building codes and regulations in force in the USSR, the following degrees of durability of enclosing structures are established: I degree with a service life of at least 100 years, II - 50 years and III - 20 years.
Durability indicators characterize the property of the product to maintain performance to the limit state with the necessary breaks for maintenance and repairs. These include resource, gamma percentage resource, assigned resource, average resource, resource up to the first overhaul, overhaul life, total life, average service life, median service life, service life before the first overhaul, service life between repairs, service life before decommissioning.
Durability is determined by two conditions: physical or obsolescence
- Physical deterioration occurs when further repair and operation of an element or system becomes unprofitable, since the costs exceed the income in operation;
— Obsolescence means that the parameters of an element or system do not correspond to the modern conditions of their operation.
There are indicators of durability that characterize the durability in terms of operating time and calendar service time. An indicator that characterizes the durability of a product by operating time is called a resource; an indicator characterizing the durability in calendar time - the service life. There are resource and service life before the first overhaul, between overhauls, before the rejection of the product.
– Operating time is the duration (or volume) of the product, measured in hours (moto-hours), kilometers, cycles, cubic meters or other units specific to this machine. The operating time cannot be mixed with the calendar duration (service life), since two products for the same service life may have unequal (different operating time);
Т = 1/m * Σti
where ti is the operating time of the i-th object between failures; m is the number of failures.
There are: daily operating time, monthly operating time, operating time to the first failure, operating time between failures, operating time between two overhauls. Operating time is one of the indicators of reliability. It is measured in hours (minutes), cubic meters, hectares, kilometers, tons, cycles, etc. Earning depends on specifications product and its operating conditions. Thus, the daily operating time of an excavator, expressed in cubic meters of excavated soil, depends on the duration of its work, on physical properties soil, from the volume of the bucket, etc. Since the operating time is influenced by such factors as the temperature and humidity of the environment, the difference in the structure and strength of the parts and mechanisms that make up the device, etc., the operating time can be considered a random variable. Its characteristics are mean time to failure for non-repairable devices and mean time between failures (MTBF) for repairable devices.
Time between failures is a technical parameter that characterizes the reliability of a repaired device, device or technical system.
The average duration of operation of the device between repairs, that is, it shows how much time is on average accounted for by one failure. It is usually expressed in hours.
For software products, this usually means a period until the program is completely restarted or the operating system is completely rebooted.
Time between failures - from the end of the restoration of the healthy state of the object after a failure until the next failure occurs.
MTBF is the equivalent parameter for a non-repairable device. Since the device is non-repairable, this is simply the average time that the device will work before it breaks.
At the design stage of a product, its average time to first failure or time to failure is calculated according to the reliability characteristics of components; during the operation of the product, these indicators are determined by the methods of mathematical statistics according to the data on the operating time of the same type of devices.
- Resource - the total operating time of the product to a certain state, specified in the technical documentation, There are a resource before the first repair, overhaul, assigned, full, residual, total, etc.
Technical resource - the operating time of a technical device (machine, system) until it reaches the limit state, in which its further operation is impossible or undesirable due to a decrease in efficiency or an increased danger to humans. The technical resource is a random variable, since the duration of the device’s operation until it reaches the limit state depends on a large number of factors that cannot be taken into account, such as environmental conditions, the structure of the device itself, etc. Distinguish between average, gamma-percentage and assigned resource.
The assigned resource is the operating time of the product, upon reaching which its operation must be terminated, regardless of the technical condition of the product. This resource is assigned in the technical documentation, taking into account safety and economy.
Technical Average Resource is the mathematical expectation of a technical resource;
Technical gamma-percentage resource - operating time during which the device does not reach the limit state with a given probability (g percent);
The duration of the assigned technical resource is determined by the conditions safe operation devices.
Full technical resource - operating time from the beginning to the end of operation for a non-restorable product or to repair for a restored one.
The remaining technical resource is the estimated operating time from the considered moment to the end of operation or to repair.
The total technical resource is the operating time of the restored product throughout its service life before decommissioning.
Motor resource - the operating time of any machine with an internal combustion engine (car, tractor, etc.) or the internal combustion engine itself to the limit state at which their further operation is generally impossible or is associated with an unacceptable decrease in efficiency and violations of safety requirements. The motor resource for transport vehicles is determined by the mileage in kilometers traveled from the start of operation until the limit state is reached. For tractors and other non-transport vehicles, as well as for internal combustion engines, the motor resource is determined by the number of hours of operation, for agricultural combines - by the number of hectares of harvested area.
Also used are indicators such as limit and allowable wear.
Limit wear is the wear corresponding to the limit state of the wearing product. The main signs of approaching wear limit are an increase in fuel consumption, a decrease in power, a decrease in the strength of parts, i.e., further operation of the product becomes technically unreliable and economically inexpedient. When the wear limits of parts and connections are reached, their full resource (Tp) is exhausted, and it is necessary to take measures to restore it.
Permissible wear - wear at which the product remains operational, i.e. when this wear is reached, parts or connections can work without their restoration for another whole overhaul period. Permissible wear is less than the limit, and the residual life of the parts has not been exhausted.
Service life is the period of time from the start of operation of a technical device until it reaches its limit state. The service life includes the running time of the device and downtime of all kinds, due to both maintenance and repair, as well as organizational or other reasons. The service life of devices of the same type may be different, because. it is influenced by many random factors that cannot be taken into account, for example, the manifestation of the features of the structure of the device, the conditions of its operation. Therefore, to quantify the service life, probabilistic indicators are used, for example, the average service life (the mathematical expectation of the service life) and the gamma-percentage service life (the calendar period of operation during which the device does not reach the limit state with a given gamma% probability).
Assigned service life - the period of operation, after which the product is decommissioned completely (and subject to write-off) or sent for examination of its technical condition in order to determine its suitability for further work. If the device is operated continuously, then its service life coincides with the technical resource. In all other cases, the ratio between the service life and resource of the device is determined by the intensity of operation.
Intensity of operation, an indicator characterizing the mode of use of the product; is expressed as the ratio of the duration of operation of the product to the calendar period (in hours) during which the operating time is carried out.
That is, the resource and service life indicators have much in common, since they are determined by the same limit state, but differ significantly from one another. With the same resource, there may be a different service life depending on the intensity of use of the product. For example, two engines each with a resource of 12 thousand motor-hours per year with an intensity of operation of 3 thousand and 6 thousand motor-hours will have a service life of the first 4 years, the second 2 years, respectively.
Thus, in order to increase the durability of repaired machines, individual assemblies, connections, and parts by restoring them, choosing a rational method of restoration and coating material, and determining the consumption of spare parts, it is very important to know and be able to evaluate the values of ultimate wear and other indicators of durability.
The main technical evaluation indicators of durability are resource and service life. When characterizing the indicators, the type of action after the onset of the limit state of the object should be indicated (for example, the average resource before overhaul; gamma-percentage resource before the average repair, etc.).
List of used literature
1. Basovsky L. E., Protasiev V. B. Quality management: Textbook. - M .: INFRA - M, 2001. -212 p.
2. Beleicheva A.S., Gafforova E.B. Expert evaluation of products - a tool for determining customer satisfaction//Methods of quality management.-2002-№6
3. Gissin V.I. Product quality management: Textbook. allowance. - Rostov n / a: Phoenix, 2000.
According to GOST 13377-75, a resource is the operating time of an object from the beginning or resumption of operation until the onset of the limit state.
Depending on how the initial moment of time is chosen, in what units the duration of operation is measured, and what is meant by the limit state, the concept of resource receives a different interpretation.
As a measure of duration, any non-decreasing parameter characterizing the duration of the object's operation can be chosen. Units for measuring the resource are chosen for each industry and for each class of machines, units and structures separately. From the point of view of the general methodology, the unit of time remains the best and most universal unit.
Firstly, the operating time of a technical object in the general case includes not only the time of its useful operation, but also breaks during which the total operating time does not increase, BUT! during these breaks, the object is exposed to the environment, loads, etc. The aging process of materials causes a decrease in the total resource.
Secondly, the assigned resource is closely related to the assigned service life, which is defined as the calendar duration of the object's operation before it is decommissioned and measured in units of calendar time. The assigned service life is largely related to the pace scientific and technological progress in this industry. The use of economic and mathematical models to justify the assigned resource requires measuring the resource not only in units of operating time, but also in units of calendar time.
Thirdly, in the problems of forecasting the residual resource, the functioning of the object in the segment of forecasting is a random process whose argument is time.
Calculating the resource in units of time makes it possible to set forecasting tasks in the most general form. Here it is possible to use units of time, both continuous independent variables and discrete ones, for example, the number of cycles.
The initial moment of time in calculating the resource and service life at the design stage and at the operation stage is determined differently.
At the design stage, the initial moment of time is usually taken as the moment the object is put into operation, or, more precisely, the beginning of its useful functioning.
For objects in operation, as the initial one, you can choose the moment of the last inspection or preventive measure, or the moment of resumption of operation after a major overhaul. It can also be an arbitrary moment at which the question of its further exploitation is raised.
The concept of the limiting state corresponding to the depletion of the resource also allows for different interpretations. In some cases, the reason for the termination of operation is obsolescence, in others - an excessive decrease in efficiency, which makes further operation economically unfeasible, and thirdly - a decrease in safety indicators below the maximum permissible level.
It is not always possible to establish the exact signs and values of the parameters at which the state of the object should be qualified as limiting. With regard to boiler equipment, the basis for its write-off is a sharp increase in the failure rate, downtime and repair costs, which makes further operation of the equipment economically unfeasible.
The choice of an assigned resource and an assigned (planned) service life is a technical and economic task that is solved at the stage of developing a project assignment. This takes into account the current technical state and the pace of scientific and technological progress in this industry, the currently accepted normative values of the coefficients of efficiency of capital investments, etc.
At the design stage, the assigned resource and service life are given values. The task of the designer and developers is to select materials, constructive forms, dimensions and technological processes so as to provide the planned values of indicators for the designed object. At the design stage, when the object has not yet been created, its calculation, including resource assessment, is carried out on the basis of regulatory documents, which in turn are based (explicitly or implicitly) on statistical data on materials, impacts and operating conditions of similar objects. Thus, resource prediction at the design stage should be based on probabilistic models.
In relation to operated objects, the concept of resource can also be interpreted in different ways. The main concept here is the individual residual resource - the duration of operation from this moment time to reach the limit state. Under operating conditions, according to the technical condition, the overhaul periods are also assigned individually. Therefore, the concept of an individual resource is introduced until the next medium or major overhaul. Similarly, individual terms are introduced for other preventive measures.
At the same time, individual forecasting requires additional costs for technical diagnostics tools, for built-in and external devices that record the level of loads and the state of the object, for the creation of microprocessors for the primary processing of information, for the development of mathematical methods and software that allow obtaining reasonable conclusions based on the collected data. information.
Currently, this problem is a top priority for two groups of objects.
The first includes civil aviation aircraft. It was here that sensors were first used to register the loads acting on the aircraft during operation, as well as resource sensors that make it possible to judge the damage accumulated in the structure, and, consequently, the residual resource.
The second group of objects for which the problem of predicting an individual residual resource has become relevant are large power plants. These are thermal, hydraulic and nuclear power plants, large systems for the transmission and distribution of energy and fuel. Being complex and responsible technical objects, they contain stressed components and assemblies, which, in case of an accident, can become a source of increased danger to people and the environment.
A number of thermal power plants, designed for a service life of 25-30 years, have now exhausted their resource. Since the equipment of these power plants is in a satisfactory technical condition, and they continue to contribute significant contribution into the country's energy sector, the question arises of the possibility of further operation without interruptions for the reconstruction of the main units and assemblies. For pronouncement informed decisions it is necessary to have sufficient information on the loading of the main and most stressed elements during the entire previous period of operation, as well as on the evolution of the technical condition of these elements.
When creating new power plants, among which nuclear power plants are of particular importance, it is necessary to provide for their equipping not only with early warning systems for failures, but also with more thorough tools for diagnosing and identifying the state of their main components, recording loads, processing information and establishing a forecast regarding changes in technical states.
Resource Forecasting - component reliability theory. The concept of reliability is complex, it includes a number of properties of the object.
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