JB/T 51099-2000 Reliability assessment index system and fault classification general rules for engineering agricultural machinery products
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T51099-2000
Reliability Assessment of Engineering and Agricultural Machinery
Evaluation Index System and General Rules for Fault Classification
(Internal Use)
2000-08-31 Issued
State Machinery Industry Bureau
2000-12-01 Implementation
JB/T51099—2000
This standard is a revision of JB/T51099--94 "Reliability Assessment and Evaluation Index System and General Rules for Fault Classification of Engineering and Agricultural Machinery Products". Editorial modifications were made to the original standard during the revision, and the main technical content remained unchanged. This standard replaces JB/T51099--94 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Tractor Standardization. The responsible drafting unit of this standard: Luoyang Tractor Research Institute. The main drafter of this standard: Gu Luping.
1 Scope
Machinery Industry Standard of the People's Republic of China
Reliability Assessment of Engineering Agricultural Machinery Products
Evaluation Index System and General Rules for Fault Classification
(Internal Use)
JB/T51099-2000
Replaces JB/T51099-94
This standard specifies the reliability assessment and evaluation index system of engineering agricultural machinery products (including complete machines and parts), fault definition, classification and judgment rules.
This standard is applicable to the analysis and evaluation of the results of user surveys and indoor and outdoor reliability tests of engineering agricultural machinery products. It guides the formulation of reliability assessment methods for engineering agricultural machinery products.
2 Definition of Failure
Any phenomenon in which the whole machine or parts cannot complete their specified functions or their performance indicators deteriorate beyond the range is called a failure.
2.1 Essential Failure··
Under the specified conditions of use, the failure caused by the inherent defects of the product itself is called an essential failure. For example, excessive deformation, fracture, early wear and fatigue, abnormal corrosion and aging, loosening or failure of fasteners, excessive performance degradation and "three leaks".
2.2 Dependent Failure
The derived failure caused by the essential failure is called a dependent failure. For example, when the connecting rod bolt breaks in the engine, resulting in a series of parts such as the connecting rod bearing, piston and cylinder block being damaged, the connecting rod Bolt breakage is an essential failure; damage to other parts caused by it is a subsidiary failure. 2.3 Misuse failure
Failures caused by users' illegal operation and use are called misuse failures. For example, the user fails to add oil or water as required by the manual, which causes the engine to overheat and the cylinder to stick; the user arbitrarily changes the structure or adjustment status of parts and components, overloads and causes damage to parts, etc. 3 Failure classification
3.1 Products are mainly classified by failure mode: a) Product performance is reduced;
b) Functional failure caused by excessive deformation, breakage, early wear and fatigue of parts; c) Water, oil, gas leakage or channel blockage; d) Fasteners are loose or the adjustment status is changed; e) Parts are loose, fall off, age, corrode and material deteriorate, etc. Approved by the State Bureau of Machinery Industry on August 31, 2000, implemented on December 1, 2000
JE:T51099-2000
3.2 Products are classified according to the degree of harm caused by the consequences of failures: they are divided into four categories: fatal failures, serious failures, general failures and minor failures. The codes, definitions and examples of failures are shown in Table 1.
Table 1 Failure Harm Classification Table
Fatal Failure
Serious Failure
General Failure
Minor Failure
Failure Definition
Failures that endanger or cause personal injury, cause the scrapping of major assemblies or cause major economic losses
Failures that seriously affect product functions or deteriorate the specified important performance indicators beyond the specified range, require shutdown for repair, have high repair costs, and cannot be eliminated within a short effective time. That is, the failure requires replacement of important external parts of the product or disassembly of the body to replace internal parts. It obviously affects the product function and the repair cost is medium. Failures that can be eliminated within a short effective time, that is, failures that require replacement or repair of external parts. It slightly affects the product function and will not cause temporary work interruption. Examples of failures are connecting rod or crankshaft breakage, flywheel fragmentation, frame or body breakage, wheel fall-off, etc. Engine burnout, severe cam wear, gear or bearing damage, severe "secondary leakage" cylinder liner inner surface strain requiring cylinder boring, high-pressure oil pump adjustment rod stuck, power drop exceeding 5%, fuel consumption increase exceeding 10%, etc. Fuel tank cracking, oil and water leakage, parts
Open welding or cracking, missing fuel tank cap, damaged switch, large pieces of paint peeling, etc.
Minor leakage, loose bolts, external
Failures with low repair costs, or failures that can be easily eliminated by adjusting and changing minor external fasteners, tools, and tools during daily maintenance
Firmware, wire desoldering, etc.
1 Effective time refers to the time from the shutdown of the product after the failure to the elimination of the failure and restoration to normal, including fault diagnosis, inspection, repair, debugging and necessary management time, but excluding the time wasted due to human or natural factors during the shutdown period. 2 Failure examples focus on the whole machine products under normal circumstances. 3 Minor leakage refers to leakage that can be eliminated after tightening. 4 Failure judgment rules
4.1 Reliability assessment should count the essential failures of the product. Subordinate failures and misuse failures are not counted as failures, but should be recorded truthfully in the failure registration form.
4.2 For the reliability assessment of mass-produced products, the focus is on assessing the fault conditions of the products within the warranty period specified by the factory. If the user uses and maintains the product according to the instructions provided by the manufacturer, and the parts are damaged or cannot be used normally within the warranty period specified by the factory, they are all considered faults or failures within the assessment scope. 4.3 The failure judgment standard for the deterioration ratio of the important performance indicators of the product relative to the lower limit of the specified factory indicators within the warranty period specified by the factory or the specified reliability assessment cut-off time shall be formulated by the standard committee responsible for the product standard. 4.4 An essential failure shall be determined as one failure number and can only be classified into one of the four types of failures. When an essential failure produces a subordinate failure, its failure category shall be determined according to the most serious consequence of the product. 4.5 According to the factory instructions, the replacement of random spare parts on schedule shall not be counted as essential failures, but records shall be made and explained in the test report.
4.6 Corresponding product failure instance statistical classification tables can be formulated for each type of product for reference by reliability assessment personnel. However, due to the differences in the structure, complexity, number of parts, etc. of the whole product, parts or components, even if the faults have similar names, due to the different nature of the fault, the difficulty of fault identification and elimination, the degree of harm of the fault, etc., the specific faults should be analyzed in detail in order to correctly determine the type of fault.
When determining the fault, the use conditions of the product failure should be understood in detail, including load status, cumulative working time, failure mode, consequences of the failure and other fault information, and detailed records should be made in the corresponding statistical tables. If necessary, the site (including damaged parts) should be retained or photos should be taken for analysis by reliability test personnel and design and manufacturing personnel. 5 Reliability Assessment Index System
5.1 Assessment Index and Calculation Method
Reliability assessment indicators should be able to quantitatively measure the reliability of products used under specified conditions. For complete agricultural machinery products, it is recommended to use MTTFF, MTBF and O value as the reliability indicators that must be evaluated; for component products, it is recommended to use LR, F(t), ^, or MTBF (MTTFF) as the reliability indicators that must be evaluated. Several other reliability evaluation indicators can also be added according to the characteristics of the product. Commonly used reliability indicators are: 5.1.1 Average working time before first failure MTTFF refers to the average working time when the product has its first fatal failure, serious failure or general failure, and its point estimate is: MTTFF
Where: n is the effective number of first failures in the surveyed or tested samples; - the number of products that have first failures (excluding minor failures) in the surveyed or tested samples: t—the cumulative working time when the i-th sample has the first failure, h; t—the cumulative working time of the ith sample that has not had the first failure at the time of the user survey or the end of the reliability test, h. (1)
For MTTFF, the lower limit of the one-sided confidence interval of the mean time to first failure with a confidence level of (1-α) is: (MTTFF)
where: α—risk coefficient (or significance level); (+
xia,2r+2)
xa,zr42)——the degree of freedom is (2 r+2), in the case of a one-sided confidence interval, it is the quantile of the x distribution with a confidence level of 1-α. 5. 1.2 Mean Time Between Failures MTBF
refers to the average working time between two consecutive failures of a repairable product. MTBF
where: n is the number of investigation samples or test samples specified in the reliability test specification; te is the cumulative working time of the ith investigation sample, and for the test test, it is the specified timed truncation test time, h; (2)
(3)
r is the sum of the number of failures (except minor failures) that occur during the use or test time of the investigated or tested sample. For MTBF, the lower limit of the one-sided confidence interval of the mean time between failures with a confidence level of (1-α) is estimated as follows: Where: xia.2n +2)
JB/T51099—2000
(MTBF）L
xia,2r +2)
One degree of freedom is (2r,+2), which is the quantile of the x? distribution with a confidence level of 1-α in the one-sided confidence interval. 5.1.3 Comprehensive score for fault-free performance
If a fatal fault occurs in a sample during the reliability assessment test of the whole machine or component, the comprehensive score for fault-free performance of the product is unqualified and its Q value is no longer calculated.
For reliability assessment tests without fatal failures, the comprehensive score Q of fault-free performance is calculated according to formula (5): T_S(K,E)
Q=100-
Where: T is the MTBF index value of similar advanced engineering agricultural machinery products at home and abroad; - the number of samples specified in the reliability assessment test specification; T. - the timed truncation test time specified in the reliability assessment test specification, h; r. - the total number of various types of failures that occur in the sample under assessment within the specified timed truncation test time; K, - the failure hazard degree of the i-th failure, determined by the fault category to which it belongs; E - the failure occurrence time coefficient of the i-th failure, determined according to the cumulative working time of the sample when the failure occurs. 5.1.4 The mean downtime failure time DTMTBF refers to the average working time between two adjacent downtime failures (including serious and fatal failures) of a repairable product: DTMTBF=
Where: r. - the sum of the number of downtime failures that occur in the investigated or assessed test sample during the use or test time. (5)
For DTMTBF, the lower limit of the one-sided confidence interval of the mean downtime failure interval with a confidence level of (1-α) is: (DTMTBF) L.
xα.2ra+2)
Where: x(a.zra+2)——the degree of freedom is (2rg+2), which is the quantile of the x distribution with a confidence level of 1-α in the one-sided confidence interval. 5.1.5 Failure (failure) rate.
The probability of a product failing in a unit time after 1 moment under specified operating conditions and in products that have not failed is called the failure rate or failure rate t. The observed value of the failure rate is usually calculated using the average failure rate, i.e., the ratio of the total number of product failures r to the total cumulative operating time in the investigated or tested samples:
Common units for failure rate are 1/h, 1/10 times, %/kh and 10-sm, etc. 5.1.6 Mean time to repair MTTR
refers to the average failure repair time required for a repairable product to be used to a certain moment, corresponding to its mean failure interval MTBF, i.e., the average effective time required to eliminate the required failure (except for minor failures). 4
JB/T51099-2000
In the formula: t is the repair time for the i-th failure (except for minor failures) in the investigated or tested samples, h. 5.1.7 Effectiveness A
The proportion of time that a product can maintain its specified function under specified conditions of use within a certain observation period is called effectiveness A. The observed value of the effectiveness is calculated according to formula (10): A
MTBF+MTTR
5.1.8 Reliable life LR (or Bio, Bso overhaul life) The working time of the product under the specified conditions of use when the reliability R reaches a certain required value is called the reliable life Lr. For example: Characteristic life: B63.2 Reliability life Lp368 with reliability R=36.8%; Rated life (specified): Bl. Reliability life Lo.9 with reliability R=90%; Median life: Bs. Reliability life Lo.50 with reliability R=50% Average life: The average service life of the product with an acceptable failure rate under the specified conditions of use. (10)
The service life of the repairable product under the specified conditions of use when 10% and 50% of the products reach the time when overhaul is required (that is, the service time when 90% and 50% of the products reach or exceed the time when overhaul is required) is called B1 and Bs overhaul life respectively. 5.1.9 Cumulative failure probability F() or reliability R(t) The cumulative probability of a product failing when it is used under specified conditions until a certain time is called cumulative failure probability F(1), also known as unreliability.
The observed value of cumulative failure probability F(t) is: F(t) =1-R(t) =(0)
Where: r()-
--The sum of the number of failures (except minor failures) that occurred in the investigated or assessed test sample during the use or test time t.
R(t)--Reliability of the product when it is used until time t. 5.1.10T Factory Annual Average Warranty Cost Rate PWCCw×100%
Where: Crs--Factory sales price of the product, RMB; Cw--Average warranty cost paid by the factory for each product during the first year of warranty, RMB. 5.2 Sources of reliability data
5.2.1 On-site reliability test
Generally, it can be combined with the actual use of the product, and the on-site reliability assessment test or fixed-point tracking on-site reliability test can be carried out under the supervision of a dedicated person. 5.2.2 Laboratory or test field reliability test is the responsibility of the reliability test personnel. According to the reliability test specifications, the reliability test is carried out in a laboratory with controlled conditions or in a test field with specified conditions. When using a rapid simulation test, it is necessary to determine the equivalent relationship between the simulation test and the actual use of the user. 5.2.3 User survey
Survey the reliability data of the actual use of the product by conducting a survey among the users of the product. 52ra+2)
Where: x(a.zra+2)——the degree of freedom is (2rg+2), in the case of a one-sided confidence interval, it is the quantile of the x distribution with a confidence level of 1-α. 5.1.5 Failure (failure) rate.
The probability of a product failing in a unit time after 1 moment in the specified working conditions and not failing yet is called the failure rate or failure rate t. The observed value of the failure rate is usually calculated using the average failure rate t, that is, the ratio of the total number of product failures r in the investigated or tested samples to the total cumulative operating time: wwW.bzxz.Net
The commonly used units of failure rate are 1/h, 1/10 times, %/kh and 10-sm, etc. 5.1.6 Mean time to repair MTTR
refers to the average failure repair time required for the mean failure interval MTBF of a repairable product when it is used to a certain moment, that is, the average effective time required to eliminate the required failures (except for minor failures). 4
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Where: t is the repair time of the ith fault (except for minor faults) in the investigated or tested sample, h. 5.1.7 Effectiveness A
The proportion of time that the product can maintain its specified function under the specified conditions of use within a certain observation period is called effectiveness A. The observed value of effectiveness is calculated according to formula (10): A
MTBF+MTTR
5.1.8 Reliable life LR (or Bio, Bso overhaul life) The working time when the reliability R reaches a certain required value under the specified conditions of use is called reliable life Lr. For example: Characteristic life: B63.2 Reliability R=36.8% of the reliable life Lp368; Rated life (specified): Bl. Reliability R=90% of the reliable life Lo.9; Median life: Bs. Reliability R = 50% reliable life Lo.50 Average life: The average service life of the product with an acceptable failure rate under specified conditions of use. (10)
The service life of a repairable product under specified conditions of use at which 10% and 50% of the products reach the time when they need a major overhaul (i.e., the time at which 90% and 50% of the products reach or exceed the time when they need a major overhaul) is called B1 and Bs overhaul life, respectively. 5.1.9 Cumulative failure probability F() or reliability R(t) The cumulative probability of a product failing when it is used under specified conditions of use until a certain moment is called the cumulative failure probability F(1), also known as unreliability.
The observed value of the cumulative failure probability F(t) is: F(t) =1-R(t) =(0)
Where: r()-
一-The sum of the number of failures (excluding minor failures) that occurred in the investigated or tested sample within the use or test time t.
R(t)-reliability of the product when it is used to time t. 5.1.10T Factory Annual Average Warranty Cost Rate PWCCw×100%
Where: Crs—factory sales price of the product, yuan; Cw-average warranty cost paid by the factory for each product during the first year of warranty, yuan. 5.2 Source of reliability data
5.2.1 On-site reliability test
Generally, it can be combined with the actual use of the product, and an on-site reliability assessment test or a fixed-point tracking on-site reliability test can be carried out under the supervision of a dedicated person. 5.2.2 Laboratory or test field reliability test is the responsibility of reliability test personnel, and reliability tests are carried out in a laboratory with controllable conditions or in a test field with specified conditions according to the reliability test specifications. When using rapid simulation tests, it is necessary to determine the equivalent relationship between the simulation test and the actual use of the user. 5.2.3 User survey
Conduct a survey among the users of the product to obtain reliability data of the actual use of the product. 52ra+2)
Where: x(a.zra+2)——the degree of freedom is (2rg+2), in the case of a one-sided confidence interval, it is the quantile of the x distribution with a confidence level of 1-α. 5.1.5 Failure (failure) rate.
The probability of a product failing in a unit time after 1 moment in the specified working conditions and not failing yet is called the failure rate or failure rate t. The observed value of the failure rate is usually calculated using the average failure rate t, that is, the ratio of the total number of product failures r in the investigated or tested samples to the total cumulative operating time:
The commonly used units of failure rate are 1/h, 1/10 times, %/kh and 10-sm, etc. 5.1.6 Mean time to repair MTTR
refers to the average failure repair time required for the mean failure interval MTBF of a repairable product when it is used to a certain moment, that is, the average effective time required to eliminate the required failures (except for minor failures). 4
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Where: t is the repair time of the ith fault (except for minor faults) in the investigated or tested sample, h. 5.1.7 Effectiveness A
The proportion of time that the product can maintain its specified function under the specified conditions of use within a certain observation period is called effectiveness A. The observed value of effectiveness is calculated according to formula (10): A
MTBF+MTTR
5.1.8 Reliable life LR (or Bio, Bso overhaul life) The working time when the reliability R reaches a certain required value under the specified conditions of use is called reliable life Lr. For example: Characteristic life: B63.2 Reliability R=36.8% of the reliable life Lp368; Rated life (specified): Bl. Reliability R=90% of the reliable life Lo.9; Median life: Bs. Reliability R = 50% reliable life Lo.50 Average life: The average service life of the product with an acceptable failure rate under specified conditions of use. (10)
The service life of a repairable product under specified conditions of use at which 10% and 50% of the products reach the time when they need a major overhaul (i.e., the time at which 90% and 50% of the products reach or exceed the time when they need a major overhaul) is called B1 and Bs overhaul life, respectively. 5.1.9 Cumulative failure probability F() or reliability R(t) The cumulative probability of a product failing when it is used under specified conditions of use until a certain moment is called the cumulative failure probability F(1), also known as unreliability.
The observed value of the cumulative failure probability F(t) is: F(t) =1-R(t) =(0)
Where: r()-
一-The sum of the number of failures (excluding minor failures) that occurred in the investigated or tested sample within the use or test time t.
R(t)-reliability of the product when it is used to time t. 5.1.10T Factory Annual Average Warranty Cost Rate PWCCw×100%
Where: Crs—factory sales price of the product, yuan; Cw-average warranty cost paid by the factory for each product during the first year of warranty, yuan. 5.2 Source of reliability data
5.2.1 On-site reliability test
Generally, it can be combined with the actual use of the product, and an on-site reliability assessment test or a fixed-point tracking on-site reliability test can be carried out under the supervision of a dedicated person. 5.2.2 Laboratory or test field reliability test is the responsibility of reliability test personnel, and reliability tests are carried out in a laboratory with controllable conditions or in a test field with specified conditions according to the reliability test specifications. When using rapid simulation tests, it is necessary to determine the equivalent relationship between the simulation test and the actual use of the user. 5.2.3 User survey
Conduct a survey among the users of the product to obtain reliability data of the actual use of the product. 5
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