This part assumes that the statistical distribution of the time between adjacent failures (for repairable equipment) or the time before failure (for non-repairable equipment) is exponentially distributed, that is, the failure rate is constant. GB 5080.7-1986 Equipment reliability test Failure rate and mean time between failures under the assumption of constant failure rate Verification test plan GB5080.7-1986 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Equipment reliability test
Compliance test plans for failure rateand mean time between failuresassuming constant fallure rate1Scope
UDC 621.3-192.001
.4:001.5
GB 5080.7-86
IEC 605- 7-1978
This standard assumes that the statistical distribution of the time between adjacent failures (for repairable equipment) or the time before failure (for non-repairable equipment) obeys an exponential distribution, that is, the failure rate is constant. Under the above conditions, the statistical test plans of this standard are applicable to reliability verification tests with mean time between failures, mean time before failure and failure rate as reliability characteristics.
This part is used in conjunction with GB5080·1-86 "General requirements for equipment reliability tests". This part is equivalent to IEC605-.7 "Equipment reliability test Part 7: Verification test plan for failure rate and mean time between failures under constant failure rate assumption". 2 Related reliability characteristics
The basic reliability characteristic of this part is the mean time between failures. Time refers to the cumulative relevant test time of all tested equipment. Time can be replaced by distance, number of cycles or other quantities or units applicable to the tested equipment. The number of failures refers to the cumulative number of relevant failures that occur during the test. Specific reliability tests should clearly define the relevant test time and relevant failure number that can be counted. The symbol "m" in the test plan represents the basic reliability characteristics. Reliability characteristics such as mean time before failure and failure rate are converted into mean time between failures according to the following rules. Therefore, the test plan of this part is fully applicable to these characteristics.
When the reliability characteristic is the mean time between failures MTBF: MTBF = m
When the reliability characteristic is the mean time before (first) failure m or MTTF: mp = MTTF = m
When the reliability characteristic is the failure rate:
3 Statistical test plan and general test procedure
3.1 Types of test plans
There are two types of test plans:
Truncation sequential test plan, see Chapter 4,
Timed (fixed number) truncation test plan, see Chapter 5. National Bureau of Standards 1986-11-19
1987-10-01
GB5080.7-86
Detailed reliability test specifications should indicate what type of test plan to use. GB5080.1-867.3.1 provides guidance on the selection of test plan types. The choice of type also depends on the technical conditions, such as the possibility of monitoring the performance of the tested product during the test (see 9.1 of GB5080·1-86) and the total time available for the test. Chapters 4 and 5 give various test plans, which are presented in the form of diagrams, and the corresponding operating characteristic curves (acceptance probability relative to the actual mean time between failures) and the expected relevant test time for making decisions are also given in the form of diagrams. 3.2 General test procedure
A specified number of devices are randomly selected from a given product population and put into the specified test process. The relevant test time and the number of relevant failures of all tested products are recorded and accumulated one by one in accordance with 9.5 and 9.2 of GB5080·1-86. When a repairable product fails, the failed product should be repaired and put into the test in accordance with 10.1 of GB5080·1-86. The calculation of the relevant test time is independent of the time (total time) experienced by the tested product. The relevant test time and the relevant failure number shall be accumulated until a judgment can be made according to the selected sequential test scheme, or until the truncation condition is reached according to the selected fixed-time constant-number truncation test scheme. The understanding of the cumulative relevant test time shall be based on GB318782 "Basic Terms and Definitions of Reliability". Its calculation method is shown in Section 3.3 of this part. 3.3 Calculation of Cumulative Related Test Time
When the relevant test time of each test product can be recorded by the respective timer on the test product, the cumulative relevant test time at the Kth failure shall be the sum of all timer readings. That is, T:
where: n
tk, m
-total number of test products,
-the reading of the relevant test time of the mth test product among the test products at the kth failure. The cumulative relevant test time T* when no failure occurs at the judgment point is: r*- r*
where: 1*—the reading of the relevant test time of the mth test product at the judgment point. If other methods are used to record the relevant test time, the cumulative relevant test time T at the kth failure shall be calculated using the following alternative formula. It includes the cumulative relevant test time to the k-1th failure and the cumulative relevant test time from the k-1th failure to the kth failure. Tk=Tk-- +Mt..
Where: n—total number of tested products
-the relevant test time of the jth cycle of the mth tested product among the tested products after the k-1th failure. The k-1th failure or other technical or management reasons may cause interruptions, and the number of interruptions for different tested products may be different. Figure 1 further illustrates the cycle numbering of the relevant test time. 392
Tested product
Product number
1st
GB5080.7-86
Figure 1 Cycle number of relevant test time
The cumulative relevant test time T* when no failure occurs at the decision point is: T*=
Where: Tr-
-Cumulative relevant test time at the last failure before the decision point; relevant test time
+ 1.1 +t 12
+ 21+t 2.2+t 2,3
Calendar time
Relevant test time of the ith cycle of the mth test product among the tested products after the last failure. The above formula is also applicable to the test product is an irreparable device, except that each test product has no relevant test time after the first failure.
4 Sequential Test Plans
This section describes the preferred truncated sequential test plans (including operating characteristic curves and the expected relevant test time for making decisions). 4.1 Characteristics of Sequential Test Plans
The characteristics of sequential test plans are expressed as follows: mo = specified acceptable mean time between failures, α - manufacturer's risk?
β = user's risk,
Dm = discrimination ratio of mean time between failures.
The manufacturer's risk α is the probability that the device will be rejected when the actual m = mo. The user's risk β is the probability that the device will be accepted when the actual m = m. Here ml is the unacceptable mean time between failures. The discrimination ratio of mean time between failures is defined here as: Dm - mo/ml. 4.2 Tables and Figures of Sequential Test Plans
The following table lists the sequential test plans given in this part. 393
Nominal value, %
GB 5080.7—86
Sequential test plan
m=moTime limit for making a decision
Multiple of no
Actual risk, %
Note: ① The deviation of actual risk α' and β' from nominal a and is due to approximation and truncation in the test plan. m=ml
② During the test or within the test period and monitoring interval (see GB5080.1-86 Articles 8.1 and 9.1), the cumulative relevant test time and the relevant failure number should be compared with the acceptance and rejection criteria frequently. 394
Relevant failure number
GB 5080.7—86
Continue
=m. When, the expected decision point
Cumulative test time
Test plan 4=1 (a=0.10, β=0.10, Dm=1.5) Table 2
Cumulative relevant test time (multiples of mo) Reject
(equal to or less than)
Note: The number of relevant failures is greater than or equal to 41,
(equal to or greater than)
The law rejects.
Test plan 4: 1
Relevant failure number
Cumulative relevant test time (multiples of mo) Reject
(equal to or less than)
(equal to or greater than)
14m.
GB5080.7—86
Figure 3 Test Scheme 4:1 Working characteristic curve
Figure 4 Test Scheme 4:1 Expected relevant test time Actual m
Actual m
Related failure number
GB5080.7—86
When m=m, expected decision point
10m. Cumulative relevant test time
5 Test Scheme 4:2 (a=0.10, β=0.10, Dm=2.0) Figure 5
Table 3 Test Scheme 4:2
Cumulative relevant test time
(equal to or less than)
Note: If the number of related failures is greater than or equal to 16, they will be rejected. (Multiple of mo)
(equal to or greater than)wwW.bzxz.Net
GB 5080.7—86
Figure 6 Test Scheme 4:2 Working characteristic curve
Figure 7 Test Scheme 4:2 Expected relevant test time Actual m
Actual m
Related failure number
GB5080.7—86
m Strict m. When, expected decision point
Cumulative relevant test time
Test Scheme 4:3 (a0.10, B=0.10, Dm=3.0) Table 4 Test Scheme 4:3
Cumulative relevant
Related test
(equal to or less than)
Note: If the related failure number is greater than or equal to 7,
the product shall be rejected.
multiples)
(equal to or greater than)
GB5080.7--86
Test Scheme 4: 3 Working characteristic curve
Figure 10 Test Scheme 4: 3 Expected relevant test time for judgment Actual m
Actual m
GB 5080.7-86
When m = mo, the plastic judgment point
Figure 11 Test Scheme 4: 4 (α=0.10, β=0.10, Dm=5.0) Table 5 Test Scheme 4: 4
Related failure number
Cumulative related
(equal to or less than)
Note: If the number of related failures is greater than or equal to 4, they will be rejected. Time
1.25m Cumulative relevant test time
(multiple of mo)
(equal to or greater than)
GB5080.786
Test scheme 4:4 Working characteristic curve
Figure 13 Test scheme 4:4 Expected relevant test time for determination Actual m
Actual m
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.