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Durability indicators assess the loss of performance of an object over the entire period of its operation. All indicators of this property of reliability are divided into two groups: indicators of technical resource and service life.
Durability indicators explicitly introduced part of in the scope of the content of the criteria for restoring parts, make it difficult for factory specialists to use them. The development of TP for the restoration of a part, taking into account the values of the post-repair operating time, requires long-term studies of changes in dimensions, clearances and tightness in mates, the shape and relative position of surfaces and other parameters during the operation of the repaired units. Only the duration of such studies exceeds the acceptable time for the technological preparation of the recovery production.
Durability metrics are related to the concepts of resource and service life. A resource is called the operating time of a product in hours from the start of operation to the onset limit state when further operation is dangerous or economically impractical. Here it comes about the total time of actual work, usually taken into account in the operational log.
Durability indicators characterize the property of an object to maintain its working ability until the onset of the limiting state at installed system maintenance and repair.
Durability indicators characterize the product's ability to maintain performance up to the limiting state (due, for example, to the inexpediency of its further operation) with the necessary breaks for Maintenance and repairs. Resource and service life can serve as indicators of durability.
Durability indicators determine the mathematical expectation of a resource.
Durability indicators can be expressed in units of time or in cycles of work. The main indicators of durability include: technical, average and assigned resources, service life, assigned service life.
Durability indicators are divided into: gamma percent, average before current (or major) repairs, full, average before write-off. Gamma percentages are indicators that have or exceed, on average, a specified number (y) percent of products of a given type. They characterize the durability of products with a given probability of maintaining their performance.
Durability indicators characterize the property of an object to remain operational until the onset of a limiting state with an installed maintenance and repair system.
Durability indicators characterize the property of an object to remain operational until the onset of the limiting state in accordance with GOST 13377 - 75 with an established system of maintenance and repairs.
The service life indices for the recoverable equipment numerically, as a rule, significantly exceed the service life indices for the non-recoverable electronic equipment or its elements: after the repair, the equipment becomes operational again. It should be emphasized that, in contrast to the reliability indicators, the durability indicators are usually not calculated, but are assigned taking into account the operating experience of similar types of equipment and economic factors.
Introduction
The individual parts of the machine are not subject to the same wear. In the event that the machine is operated in accordance with its intended purpose, subject to the prescribed maintenance and repairs, wear appears as a normal, relatively slow natural process. However, violation of the rules for the technical operation of the machine leads to the fact that its parts begin to undergo increased wear.
The process of gradual change in the size of a body during friction, associated with the separation of the material from the friction surface and (or) its permanent deformation, is called wear.
Wear is the result of wear, which manifests itself in the form of separation or permanent deformation of the part material.
Durability concept
Durability is the property of an object to maintain an operable state until a limit value is reached with an installed maintenance and repair system.
The main indicators of durability include:
1) average resource (for example, average operating time up to overhaul, average operating time from overhaul to write-off);
2) gamma-percentage resource (operating time during which the object does not reach the limit). A parameter is understood as a certain output characteristic of a part, interface, assembly unit or a car as a whole, which is taken as one or several technological quality indicators. A parameter value exceeding the limits of the limit value is classified as a failure, if at the same time a violation of the operational state of the object occurs, i.e. such a state in which the values of all parameters characterizing its ability to perform preset functions, meet the requirements of the normative and technical and (or) design documentation.
Failures are usually divided into sudden and gradual. Sudden failures are characterized by an abrupt change in the values of one or more parameters of an object. They occur at random moments in time, which cannot be accurately predicted, but one can only characterize the occurrence or non-occurrence of a given event with a certain probability. A gradual failure is characterized by a gradual change in one or more parameters of an object. For example, a monotonous increase in the wear of parts of the cylinder-piston group of the engine, a decrease in fuel efficiency and power. The division of failures into gradual and sudden ones is conditional. For example, the gradual wear of the working surfaces of the gearbox parts increases the clearances and leads to a sudden self-switching off of the gear.
Component parts of cars are subdivided into repaired and not repaired. For the former, the regulatory and technical and (or) design documentation provides for repairs, and for the latter it is not provided. The reliability of products is determined by their reliability, durability, maintainability and preservation.
Reliability - the property of an object to continuously maintain a functional state for some time or operating time.
The main indicators of reliability are:
1) the probability of failure-free operation (the probability that within the specified operating time the object does not fail);
2) mean time between failures (the ratio of the operating time of the restored object to the average value of the number of its failures during this operating time);
3) the parameter of the flow of failures (the ratio of the average number of failures of the restored object for its arbitrarily small operating time to the value of this operating time).
Routine repair ensures the trouble-free operation of the repaired units, assemblies and parts at a run no less than to the next TO-2. Reducing the downtime of the car is achieved by using the aggregate method of repair, in which faulty or requiring major repairs of units and assemblies are replaced with serviceable ones taken from the working capital. Revolving fund component parts a car can be created both directly at the ATP and at exchange offices, at regional central workshops and repair plants.
Medium repair (CP) of vehicles is provided for cases of their operation in difficult road conditions; held at intervals of more than one year. With it, the following repair work can be performed: replacing an engine that has reached a limiting state and requires major repairs, troubleshooting other units with the replacement or repair of parts, body painting and other work that would ensure the restoration of the car in good condition.
Overhaul (CR) of cars, units and assemblies is designed to ensure the assigned resource of the vehicle and its components by restoring their serviceability and close to full (at least 80% pre-repair) restoration of the resource and ensuring other normalized properties. When KR replace or restore any units and parts, including the base. As a rule, cars and assemblies are subjected to no more than one major overhaul. Basic part passenger car and the bus is the body, the truck is the frame. The basic parts of the units include: in the engine - the block of cylinders; in the gearbox, rear axle, steering gear - crankcase; in the front axle - a front axle beam or an independent suspension cross member; in the body or in the cabin - the body; in the frame - longitudinal beams.
Centralized RC of complete trucks insufficiently effective due to the fact that due to small production programs and the universal nature of production, transport costs for the delivery of repair stock and repaired products increase, cars are diverted from the field of operation for a long time. In this regard, the CR of complete vehicles should be carried out mainly for those of them that operate in especially difficult road conditions with intensive use. In this case, the KR and CP of cars should be as close as possible to the ATP and be produced using ready-made units, assemblies and parts that come into specialized cars and their components for repair. Saving time is achieved due to the fact that the objects of repair do not wait until the units and assemblies removed from them are repaired.
Aggregate method is an impersonal method of current repair, in which faulty units are replaced with new or pre-repaired ones. Replacement of units can be performed after a product failure or as planned.
Lecture . RELIABILITY INDICATORS
The most important technical quality characteristic is reliability. Reliability is assessed by probabilistic characteristics based on statistical processing of experimental data.
Basic concepts, terms and their definitions characterizing the reliability of equipment and, in particular, mechanical 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 characterizing 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: reliability, durability, maintainability, preservation, etc.
Reliability- the property of a 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 capable of performing the specified functions, while maintaining the permissible values of all basic parameters established by the normative 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.
Longevity is due to 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 as a result of which there is a complete or partial loss of the product's performance.
Working condition- the state in which the product meets all the requirements of the normative and technical and (or) design documentation.
Faulty condition- a condition in which the product does not meet at least one of the requirements of the normative and technical and (or) design documentation.
A defective product may be functional. For example, a decrease in the density of electrolyte in batteries, damage to the lining of a car means a malfunctioning condition, but such a car is operational. A defective product is also defective.
Running time- duration (measured, for example, in hours or cycles) or the amount of work of a product (measured, for example, in tons, kilometers, cubic meters, etc.).
Resource- the total operating time of the product from the beginning of its operation or its renewal after repair to the transition to the limiting state.
Limit state- the state of the product, in which its further operation (use) is unacceptable for safety requirements or inexpedient for economic reasons. The limiting state occurs as a result of resource exhaustion or in an emergency.
Life time- the calendar duration of the operation of products or its renewal after repair from the beginning of its use until the onset of the limiting state
Inoperative 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 the product from a faulty or inoperative state to a working or functional state occurs as a result of restoration.
Recovery- the process of detecting and eliminating the failure (damage) of the product in order to restore its operability (elimination of the malfunction).
The main way to restore performance is repair.
Maintainability- the property of a product, which consists in its adaptability to maintaining and restoring a working condition by detecting and eliminating a defect and malfunction through 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- the 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 indicators of reliability, durability and maintainability within the limits established by the regulatory and technical documentation for this object.
N
Rice. 1. Product state diagram
To quantitatively characterize each of the properties of a product's reliability, there are single indicators such as MTBF and MTBF, MTBF, resource, service life, shelf life, recovery time. These values are derived from test or operational data.
Complex indicators of reliability, as well as the availability factor, the technical utilization factor and the operational availability factor, are calculated by the submitted unit indicators. The nomenclature of reliability indicators is given in table. 1.
Table 1. Approximate nomenclature of reliability indicators
|
Reliability property |
Indicator name |
Designation |
||
|
Unit indicators |
||||
|
Reliability |
Probability of no-failure operation Mean time to failure Mean time between failures Mean time between failures Failure rate Failure flow of the recoverable product Average failure rate Probability of failure | |||
|
Durability |
Average resource Gamma Percentage Resource Assigned Resource Installed resource Average service life Gamma Percentage Service Life Assigned Service Life Specified Service Life | |||
|
Maintainability |
Average recovery time Probability of recovery Repair complexity factor | |||
|
Persistence |
Average shelf life Gamma Percentage Shelf Life Assigned shelf life Assigned shelf life | |||
|
Generalized indicators |
||||
|
A set of properties |
Availability ratio Technical utilization ratio Operational readiness ratio | |||
Indicators characterizing reliability
Probability of uptime an individual product is assessed as:
where T - time from start of work to failure;
t - the time for which the probability of failure-free operation is determined.
The magnitude T can be greater, less or equal t.
Consequently, 
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 a failure of products does not occur within a given operating time. To establish the value of the probability of no-failure operation of serial products, use the formula for the average value:
where N- the number of items (or items) monitored;
N o- the number of failed products over time t;
N R- the number of workable products by the end of time t testing or operation.
The probability of failure-free operation is one of the most significant characteristics of a product's reliability, as it encompasses all factors that affect reliability. To calculate the likelihood of no-failure operation, data collected from observation of operation during operation or during special tests are used. The more products are monitored or tested for reliability, the more accurately the likelihood of failure-free operation of other similar products is determined.
Since uptime and failure are mutually opposite events, the assessment probability of failure(Q(t)) determined by the formula:
Payment mean time to failure (or mean time of failure-free operation) according to the results of observations is determined by the formula:
T i - uptime i th element (product).
Statistical estimation of mean mean time between failures 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 estimation of mean mean time between failures 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 refusals over 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 Percentage Resource expresses the operating time during which the product with a given probability γ percent does not reach the limit state. The gamma percent life is a basic calculation indicator, for example, for bearings and other products. A significant advantage of this indicator is the ability to determine it before the completion of tests of all samples. In most cases, a 90% resource criterion is used for various products.
Assigned resource - total operating time, upon reaching which the use of the product for its intended purpose must be terminated, regardless of its technical condition.
NS odestablished resource is understood as a technically justified or specified value of the resource provided by the design, technology and operating conditions, within which the product should not reach the limiting state.
Statistical assessment average service life determined by the formula:
I 
where T sl i - life time i th product.
Gamma Percentage Life is the calendar duration of operation during which the product does not reach the limit state with the probability expressed as a percentage. To calculate it, use the ratio
The appointed time service- 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 techno-economically justified service life provided by the design, technology and operation, within which the product must not reach the limit state.
The main reason for the decrease in the durability of the product is the wear of its parts.
Repairability indicators
Recovery chance - R v (t v) represents the probability that an accidental product recovery time t v will be no more than the given one, i.e.
Average recovery time determined by the formula
where T v k
- recovery time kth refusal of the object, equal to the sum of the time spent on finding the refusal t O and time t at
to eliminate it;
T - the number of facility failures for a given period of testing or operation.
Downtime ratio TO a is an indicator characterizing the likelihood of product restoration at any time,
where t i- downtime before repair i- ro products
t v i- recovery time i th product;
NS - number of refusals.
Repair complexity factor estimates the volume of repair work per year in physical units repair complexity. The repair complexity coefficient is the sum of the repair complexity coefficients of the mechanical part of the machine r m and its electrical part R NS :
Unit of repair complexity of the mechanical part r m - this is the repair complexity of a certain conventional machine, the labor intensity of the overhaul of the mechanical part of which, in terms of volume and quality, meets the requirements of the technical specifications for repairs, is equal to 50 hours in the same organizational and technical conditions of an average repair shop of a machine-building enterprise
Unit of repair complexity of the electrical part r NS - this is the repair complexity of a certain conventional machine, the labor intensity of the overhaul of the electrical part of which, in terms of volume and quality, meets the requirements of the technical specifications for repair, is equal to 12.5 hours under the same conditions as r m. .
The initial data for determining the repair complexity of various models of equipment are the technical characteristics contained in the passports, as well as empirical formulas and coefficients reflecting the specifics of the machines and equipment being evaluated.
Maintainability factor parts, assembly, products TO rem.pr. used to characterize the product when troubleshooting individual units and parts.
The maintainability factor of a unit (part) of a product is characterized by the ratio of the time of direct repair (replacement) of an individual unit (part) to the total time spent on repairing a product, including identifying a product defect, disassembling, assembling and setting up.
Persistence indicators
Shelf life is called the calendar duration of storage and (or) transportation of the product under specified conditions, during and after which the values of quality indicators remain within the established limits.
The persistence index is assessed by statistical methods based on test results.
Average shelf life determined by the formula:
G 
de T with
-
shelf life i th product.
Gamma Percentage Shelf Life - the calendar duration of storage and (or) transportation of the product, during and after which the indicators of reliability, durability and maintainability of the product will not go beyond the established limits with the probability expressed as a percentage.
Assigned storage period there is a calendar duration of storage under specified conditions, after which the use of the product for its intended purpose is not allowed, regardless of its technical condition.
The established shelf life is called the technically-economically feasible (or specified) shelf life provided by the design and operation, within which the indicators of reliability, durability and maintainability remain the same as they were for the product before its storage and (or) transportation.
Transportability indicators
Transportability indicators characterize the ability of products to maintain their suitability (reliability) during transportation, as well as the suitability for movement, not accompanied by operation or use.
The group of indicators of transportability includes the characteristics of the preparatory and final operations associated with the transportation of the product to its destination. Preparatory operations are, for example, packing, loading the product onto a vehicle, securing, etc. The final operations are as follows - removing fasteners, unloading, unpacking, assembling, installing on workplace etc.
Indicators of transportability of the product are selected and evaluated in relation to a specific mode of transport (road, rail, water or air), or even to a specific type of transport.
The main indicators of transportability are the coefficients:
TO d - coefficient characterizing the proportion of transported products that retain their original properties within the specified (permissible) limits;
K v - the coefficient of the maximum possible use of the capacity, volume or carrying capacity of a vehicle or container.
Coefficient K d , characterizing the proportion of transported products that retain their initial properties within specified limits during transportation, is calculated by the formula:
G 
de Q v
-
mass (weight) or quantity in pieces or other units of measurement of products (products) unloaded from the vehicle and retaining the values of other quality indicators within acceptable limits;
Q n - mass of products, quantity in pieces or other units of measurement loaded into a vehicle for transportation.
Coefficient TO d is a complex indicator that characterizes both transportability and preservation during transportation.
TO 
coefficient
K
v
the maximum possible use of the volume of a vehicle or container for transporting products is determined by the formula:
where N v - the maximum possible use of the capacity of a vehicle or container, expressed in units of production;
V- unit volume;
and - the capacity of the vehicle or container;
Y- coefficient of standard losses of vehicle capacity (for example, for the device of passages).
In addition to the above coefficients, NSeconomic indicators of transportability , that is, indicators characterizing the costs associated with the implementation of the operations of preparation for transportation, the transportation itself, as well as the final work after transportation.
A wide variety of products, as well as methods and means of their transportation, do not allow us to give a complete list of indicators of transportability. However, the indicators of transportability include such as:
Average labor intensity of preparation of one product for transportation (including packing, loading and fastening),
Average cost of preparatory operations for transportation,
The average cost of transporting one product over a distance of 1 km by a certain mode of transport or a certain vehicle,
Average labor intensity or cost of unloading and other final transportation operations,
The average duration of loading and unloading a batch of a specific quantity from, for example, a certain type of railroad car.
Generalized reliability indicators
Availability factor K G characterizes the probability that the product will be operational at an arbitrary point in time, except for the planned periods during which the product is not intended to be used for its intended purpose. Average statistical value TO G determined by the formula
where t i
-
total operating time i-th product in a given operating interval,
i- total recovery time i-th product for the same period of operation,
N- the number of monitored products in a given operating interval.
If the mean MTBF and the mean recovery time of the product after failure are determined at a given operating interval, then
where T O
-
average operating time 
products to failure, that is, an indicator of failure-free operation,
T v - average recovery time or time of forced downtime of a product due to failures - an indicator of maintainability
Technical utilization rate TO ti calculated by the formula:
where T 0
-
mean time between failures;
then- duration of maintenance;
R- duration of scheduled repairs;
v- duration of unplanned recoveries.
Reliability as a complex property. Reliability components.
Reliability
Durability- the property of an object to remain operational until the onset of the limiting state with the necessary maintenance. A limiting state is a state of an object in which its further operation is impossible (or impractical).
Maintainability
Persistence- the property of an object to preserve the values of indicators of reliability, durability and maintainability during and after storage and (or) transportation.
Sustainability- the property of the system to continuously maintain stability for a certain time interval. Stability is the ability of a system to move from one stable regime to another under various disturbances.
Vitality- the property of the system to withstand large disturbances of the mode, preventing the cascade (chain) development of accidents and mass shutdown of consumers, which is not provided for by the algorithm of the emergency automation.
Security- the property of the object does not create situations dangerous for people and environment in all possible modes of operation and emergency situations.
3. The main indicators of reliability. - quantitative characteristic of one or more properties that determine the reliability of an object .
They are divided into single characterizing one property, and complex characterizing several properties. Single indicators are mainly used to characterize individual structural elements, complex- for load nodes and systems as a whole.
Single indicators of reliability.
They can be divided into indicators of reliability and recoverability.
The main quantitative characteristic of failure-free operation is the probability of failure-free operation P (t), i.e. the probability that no failure will occur in a given time interval (or within a given operating time) under given operating conditions. The function that characterizes the opposite event is the probability of failure, or unreliability. It's obvious that
Distribution density random variable... This is the derivative of the distribution function:
4. Reliability- property of an object to continuously maintain operability for a given time. The performance of an element is the state of an element in which it is capable of performing the specified functions with the parameters established by the relevant requirements of the technical documentation.
5. Maintainability- property of an object, which consists in its adaptability to the prevention, detection and elimination of failures and malfunctions, to maintain and restore operability through maintenance and repairs.
Durability concept. Indicators of durability.
Durability- the property of an object to remain operational until the onset of the limiting state with the necessary maintenance. Limit state- such a state of the object in which its further operation is impossible (or impractical).
Durability indicators:
resource, technical resource- the total operating time of the object from the beginning of its operation or its renewal after repair to the transition to the limit state;
assigned resource- total operating time, upon reaching which the operation of the facility should be terminated regardless of its technical condition;
life time- the calendar duration from the start of operation of the facility until the transition to the limit state at which the facility is subject to write-off.
Many indicators of product quality are functions of its parameters. Thus, the indicator of drill durability depends on the width of the guide strip (geometric parameter) and on the mechanical characteristics of the drill material (structural parameters).
Durability - the property of a product to remain operational until the onset of a limiting state with an established system of maintenance and repairs. The unit indicators of durability are the average resource, the average service life. The term “resource” is used when characterizing the service life of a product, and service life is used when characterizing the service life by calendar time.
The establishment of a list of technical requirements implies the need for predictive research, taking into account the development trends of the corresponding types of electrical products and their changes technical characteristics, as well as the study of the main directions of development of technology and organization of the production of these products. Forecasts should be developed for specific technical indicators. technical parameters, indicators of durability and reliability, design characteristics, materials used, changes in technological methods, etc.
Usually buyers pay willingly great price for products with a reputation for durability. However, a few caveats must be made here. The price increase should be within reasonable limits. In addition, if a given type of product quickly becomes obsolete, consumers are unlikely to want to overpay for the increased durability of the trash. Therefore, the use in advertising of statements that a given brand of personal computers will last much longer than others may not have the desired effect, since these capabilities and characteristics of products are constantly improving. Manufacturers wrist watch(eternal, not subject to significant changes in the technology of production of goods), on the contrary, often use indicators of durability in advertising.
If the durability indicator is a technical and economic parameter, then the reliability indicator is determined by the complex technical parameters and characterizes mainly the quality of the main pipeline. The increase in the level of reliability is based on the development and implementation of technical and organizational measures. The limit for increasing reliability is determined by an economic indicator, the excess of which makes a number of measures to improve the reliability of a structure ineffective.
Durability is the property of a product to remain operational (with possible interruptions for maintenance and repair) until destruction or other limiting state. The indicators of durability are the service life before the first overhaul and the overhaul life, resource, etc.
Let us consider the influence of another qualitative indicator - durability on the level of efficiency of the parametric series. For machines, the durability can be estimated by the service life, which represents the calendar duration of the product's operation until destruction or another limiting state (the limiting state can be established by changes in the parameters of the product, in terms of economic indicators, etc.).
Let's consider the economic essence of the longevity indicator. Machines, equipment, devices, like any means of production ... always take part entirely in the labor process and always only partly in the process of value creation. They never add more value than they lose on average due to their wear and tear. Thus, there is a big difference between the cost of a machine and that portion of the cost that is periodically transferred from it to the product. There is a big difference between a machine as an element of value creation and a machine as an element of product formation. The longer the period during which the same machines serve over and over again in the same labor process, the greater this difference.
The role of indicators of durability and reliability of machines at this stage of technical development
For planning, and therefore, for the subsequent accounting and control of the implementation of plans, it is necessary to develop a system of indicators of the durability and reliability of products in relation to its industry characteristics and to specific operating conditions.
In our press, the following data were published, allowing us to judge the influence of the indicators of the durability of products on the required size of production capacity.
However, such quantitative characteristics of quality as durability and reliability have a close relationship with the cost (price) of the product, which makes it possible to develop methods for establishing the value of the product depending on the durability or reliability. Using the durability indicator as an example, we will develop a method to determine the dependence of the total cost (price) of a product as a function of durability Td.
The durability indicator Td has a very great importance when considering the functioning of technical systems over long time periods.
The indicators of the object's durability include the standard service life (storage period), service life until the first major overhaul, gamma-percentage resource (this is the operating time during which the object will not reach the limit state with a given probability) and other indicators (see GOST 27.002-83 ).
Statistical research methods occupy an important place in qualimetry. Many indicators of product quality are determined using statistical methods from empirical data or from operational statistics. Examples of statistical quality indicators are, for example, precision indicators of machine tools and devices (variance, standard deviation, range), reliability indicators (probability of no-failure operation, MTBF, failure rate), durability indicators (average resource, gamma-percentage resource). In any set of mass production, there is a dispersion of quality indicators. This dispersion can be
Durability indicators characterize the ability of a product to maintain performance up to the limiting state (due, for example, to the inexpediency of its further operation) with the necessary breaks for maintenance and repairs. Resource and service life can serve as indicators of durability.
Durability is the property of equipment to maintain performance up to the limit state with the necessary breaks for maintenance and repair. The service life of a machine is an indicator of its durability.
Durability indicators characterize the ability of a product to remain operational until a certain limiting state occurs (due, for example, to the economic inexpediency of subsequent repairs) with the necessary breaks for maintenance and current repairs. Durability indicators include average, gamma percent or median life, etc.
The indicators of durability are the gamma percentage resource / v average resource / g assigned resource average resource between current (overhaul) repairs Kt.r (Kkr), average resource before write-off / ohm average resource before current (overhaul) repairs gamma percentage period service life average service life average service life between current (overhaul) repairs average service life before current (major) repairs average service life before write-off.
Durability is the property of a product to maintain its performance up to the limit state with the necessary breaks for maintenance and repairs. Lifetime and service life are quantitative indicators of durability.
The durability of an object is its ability to remain operational under specified operating conditions. The operating time to failure is taken as the main indicators of the durability of an underground facility, i.e. the time of failure-free operation from the moment of the start of operation to the onset of the limit
Reliability is understood as the property of a product to perform specified functions, maintaining its performance indicators within the established limits for the required period of time or the required operating time. The reliability of the product is determined by the reliability of its operation, maintainability, preservation, as well as the durability of its parts. The low reliability of a number of products leads to large economic losses. For example, significant losses of time and money cause downtime for replacement of parts and repair of various mechanisms, completed with products of chemical enterprises. Therefore, to assess the quality of some types of chemical products, one cannot restrict oneself to traditional instantaneous or calculated indicators, but it is necessary to use probabilistic ones.
Reliability laboratory collects and analyzes information on the actual level of reliability and durability of products in operation, calculates reliability indicators, examines technical documentation in order to ensure the required level of reliability. The reliability service organizes product tests at the stands, monitors the progress of operational tests, laboratory workers visit consumers to resolve disputes and collect data.
The norms and standards for the quality of raw materials, semi-finished products, finished products combine the requirements of the current standards and specifications for the quality of raw materials and products, indicators of reliability and durability, product grade, and economic operation.
In machine design
