Operation frequency confirmation method and system for reliability identification and acceptance test

Abstract

The invention relates to an operation frequency confirmation method and system for reliability identification and acceptance test. The operation frequency confirmation method for reliability identification and acceptance test comprises the following steps: selecting a proper statistical scheme, a sequential test statistical scheme, a fixed-time truncation test statistical scheme and a full-number test statistical scheme; determining a judgment risk; comprehensive environment determination: determining a comprehensive environment condition of a reliability verification test and a relation between the comprehensive environment condition and the number of times of the reliability verification test according to field use of a tested product and task environment characteristics; determining a test scheme according to test requirements, and drawing a test profile map according to the test scheme; different devices are selected according to different tests, and the requirements of the test devices are specified; and detecting items and qualification criteria of the tested product. According to the operation frequency confirmation method for reliability identification and acceptance test, a basis can be provided for reliability identification and acceptance test.

Description

Technical Field

[0001] The present invention relates to the technical field of reliability identification and acceptance test schemes, and in particular to a method and system for confirming the number of operations used in reliability identification and acceptance tests. Background Art

[0002] In modern industrial systems, product reliability has become a key indicator of performance and safety. This is especially true in high-risk sectors such as military, aerospace, and rail transit, where equipment reliability is directly linked to mission success and personnel safety. Reliability assessment and acceptance testing, as core components of reliability engineering, assess product reliability levels during the design and production stages through systematic testing, providing a scientific basis for quality decision-making.

[0003] Reliability qualification testing verifies whether a product meets specified reliability indicators, such as mean time between failures (MTBF) and failure rate. It serves as a pre-qualification threshold for product development. Key features include: the test subject is a prototype, representative of mass production; environmental conditions simulate extreme operating scenarios, such as high and low temperatures, humidity, and vibration; and a statistical test plan is employed, using probability models to determine design compliance. This statistical test plan design includes: exponential distribution models, non-exponential distribution processing; risk and confidence control; and environmental and stress profiles.

[0004] Currently, the relevant field only stipulates reliability assessment and acceptance for mean time between failures. However, there is a lack of reliability test protocols for the number of operation trainings, which can be applied to equipment such as operation training devices and simulators to determine whether the number of operation times meets reliability requirements. The existing GJB (national military standard) also does not include reliability assessment and acceptance test methods for the number of operation times. Therefore, it is urgent to develop a method and system for confirming the number of operation times for reliability assessment and acceptance testing to address the above issues. Summary of the Invention

[0005] The technical problem to be solved by the present invention is the lack of a reliability test scheme for the number of operation training in reliability identification and acceptance tests, so as to be applicable to operation training equipment, simulation trainers and other equipment to make reliability judgments on whether the number of operations meets the reliability requirements.

[0006] To solve the above technical problems, according to one aspect of the present invention, a method for confirming the number of operations for reliability evaluation and acceptance testing is provided, comprising the following steps: selecting a statistical scheme, selecting an appropriate statistical scheme, wherein the statistical schemes include a sequential test statistical scheme, a fixed-number truncation statistical scheme, and a full-number test statistical scheme. If the number of reliability verification times is not specified in advance and it is desired to make an acceptance or rejection decision on the mean time between failures (MNBF) as soon as possible, the sequential test statistical scheme is selected; if the contract or product specification requires a reliability verification test, provides a verification value for the mean time between failures (MNBF), and has a fixed cutoff number of tests, the fixed-number truncation statistical scheme is selected; if it is required that every product be tested in the reliability acceptance test, the full-number test statistical scheme is selected.

[0007] Among them, the statistical schemes for sequential tests and fixed-number truncation tests are divided into standard statistical schemes and high-risk statistical schemes. When the producer's risk α and the user's risk β are both within the normal range of 10% to 20%, the standard statistical scheme is adopted. If the producer's risk α and the user's risk β are both 30%, the high-risk statistical scheme is adopted, which shortens the number of tests, but both the producer and the user bear higher decision-making risks. Definitions: Standard sequential test statistical scheme query table 1, low-number high-risk sequential test statistical scheme query table 2, standard fixed-number test statistical scheme query table 3, high-risk fixed-number test statistical scheme query table 4:

[0008] Table 1 Summary of statistical scheme for standard sequential test

[0009]

[0010] Table 2 Summary of statistical plan for a small number of high-risk sequential trials

[0011]

[0012]

[0013] Table 3 Summary of statistical scheme for standard fixed-time test

[0014]

[0015] Table 4 Summary of statistical plan for high-risk fixed-time test

[0016]

[0017] Among them, if the sequential test statistical scheme is adopted, and the manufacturer's risk is set as α, the user's risk is set as β, the MNBF test lower limit is θ1, the MNBF test upper limit is θ0, and the discrimination ratio is d, for an exponential product with an unknown MNBF value θ, the probability of r failures within the cumulative number of working times n is:

[0018]

[0019] Sequential testing must demonstrate that θ is at least not less than the MNBF lower limit θ1. If the actual MNBF is equal to the lower limit θ1, then the probability of r failures occurring within n number of tests is:

[0020]

[0021] To construct a sequential test, we need to select an upper bound on the MNBF test, θ0. If the MNBF of a product is equal to the upper bound, θ0, then the probability of r failures occurring within n trials is:

[0022]

[0023] The probability ratio is:

[0024]

[0025] This ratio is calculated continuously during the test and compared with two predetermined constants A and B, using the decision criteria a) to c) as follows:

[0026] a) If P(r) becomes < B, accept and stop the test;

[0027] b) If P(r) becomes > A, reject and stop the test;

[0028] c) If B<P(r)<A, continue the test.

[0029] The constants A and B are:

[0030]

[0031] Where: α is the producer risk, β is the user risk, and d is the identification ratio.

[0032] Substitute to get A, B;

[0033] Follow the steps below to calculate the truncation point and check χ 2 Distribute (1-α) and the upper quantile of β until the following equation is true:

[0034]

[0035] The point distributed on both sides of θ1 / θ0 appears when the degree of freedom is 2r0. By referring to the table (Table 5) of the "National Military Standard of the People's Republic of China" GJB899-2009, we can obtain the (1-α) and β probabilities and get r0, where 2r0 is the degree of freedom and r0 is the number of responsible failures.

[0036] Thus, the number of truncated trials, that is, the longest number of trials, is obtained:

[0037]

[0038] Among them, for the test items and judgment steps described in the sequential test statistical plan, r failures occur when the number of tests is n, which is represented by r = f(n) in the plane coordinate. Suppose two straight lines r1 and r2, r1 = c + bn, r2 = a + bn, where the upper side of r1 is rejection and the lower side of r2 is acceptance. The area between r1 and r2 is continued testing. Determine the slope and ordinate intercept of the two parallel lines:

[0039]

[0040] Substituting the numerical values ​​into the equations, we can get the values ​​of a, b, and c. Then we can draw the acceptance / rejection distribution graph based on the linear equations: r1=c+bn, r2=a+bn.

[0041] If a fixed-number truncation test statistical scheme is adopted, then in the test items and judgment criteria steps, the standardized number of judgments multiplied by the lower limit of the MNBF test is the number of tests, where the acceptance and rejection of the judgment failure numbers are shown in Tables 3 and 4;

[0042] Determine the decision risk and select a statistical scheme with a lower decision risk. A statistical scheme with a lower decision risk requires more tests, but also has a lower probability of accepting unqualified products or rejecting qualified products. Select the discrimination ratio d, where d = θ0 / θ1. The larger the discrimination ratio, the faster the test will make a decision. Careful selection is necessary to prevent a too large discrimination ratio from causing the upper test limit θ0 to be too large, making the design difficult to implement, or a too small discrimination ratio from causing too many tests.

[0043] Comprehensive environment determination: determine the comprehensive environmental conditions of the reliability verification test and their relationship with the number of times based on the on-site use and mission environment characteristics of the tested product; determine the test plan based on the test requirements, and the test plan includes one or more of high temperature test, low temperature test, normal temperature test, relative humidity test, vibration shock, and electrical stress, and draw the test profile;

[0044] Test facilities and test equipment requirements, select different equipment according to different tests, and specify the requirements for test equipment;

[0045] Test items and criteria: Test items and qualification criteria for the test products. Test items for the test products are specified based on product performance and technical indicators. The qualification criteria determine whether the product is qualified or rejected based on the selected reliability test method.

[0046] According to an embodiment of the present invention, the method for confirming the number of operations for reliability identification and acceptance testing may also include the steps of: fault criteria and classification statistics, fault criteria, classification and statistical principles, wherein, fault criteria: during the test process, when any of the following conditions occurs, it should be determined that the test product has a fault: under specified conditions, the test product cannot work; under specified conditions, the performance test results of the test product do not meet the specified requirements; under specified conditions, the mechanical, structural parts or components of the test product become loose, cracked, broken or damaged; Fault classification: faults occurring during the reliability test can be divided into associated faults and non-associated faults, and associated faults can be further divided into responsible faults and non-responsible faults; Fault statistical principles: during the test process, only responsible faults can be used as the basis for determining whether the test product is qualified or not.

[0047] According to an embodiment of the present invention, the method for confirming the number of operations for reliability identification and acceptance testing may also include the following steps: fault reporting and handling requirements, which can be found in GJB 450A-2004 "General Requirements for Equipment Reliability Work": establishing a fault reporting, analysis and corrective measures system; and establishing a fault review organization.

[0048] According to an embodiment of the present invention, in the step of selecting a statistical scheme, the sample size of the statistical scheme is selected, and the number of tested products can be agreed upon by the contractor and the ordering party in accordance with the contract provisions; if the ordering party has no provisions on the statistical sample for the reliability acceptance test, at least two products in each batch of products shall be tested; the recommended sample size is 10% of each batch of products, but not more than 20 units, and full inspection is only used in special circumstances.

[0049] According to an embodiment of the present invention, in the step of determining the judgment risk, the production side risk can be α=10%, α=20% or α=30%; the user side risk can be β=10%, β=20% or β=30%; when selecting the discrimination ratio d, d=1.5, d=2.0 or d=3.0 is used; among which, the larger the discrimination ratio, the faster the test makes a judgment, and it must be selected carefully to prevent the discrimination ratio from being too large, resulting in an excessively large test upper limit θ0, making the design difficult to implement, and the discrimination ratio from being too small, resulting in an excessive number of tests.

[0050] According to an embodiment of the present invention, in the test facility and test equipment requirement steps, the accuracy of instruments and equipment may be implemented in accordance with the general requirements of GJB150A-2009.

[0051] According to another aspect of the present invention, there is provided a system for verifying the number of operations for reliability evaluation and acceptance testing, comprising:

[0052] The statistical scheme selection module is used to select an appropriate statistical scheme. Statistical schemes include sequential test statistical scheme, fixed-number truncation statistical scheme, and full-number test statistical scheme. If the number of reliability verification tests is not specified in advance and the MNBF acceptance or rejection decision is to be made as soon as possible, the sequential test statistical scheme is selected. If the contract or product specification requires reliability verification testing, providing MNBF verification values, and a fixed cutoff number of tests, the fixed-number truncation statistical scheme is selected. If every product is required to be tested in the reliability acceptance test, the full-number test statistical scheme is selected.

[0053] The decision risk module is used to select a decision risk. A statistical scheme with a lower decision risk requires more trials, but the probability of accepting unqualified products or rejecting qualified products is also lower. The discrimination ratio d is selected, where d = θ0 / θ1. The larger the discrimination ratio, the faster the test decision is made. It must be selected carefully to prevent the discrimination ratio from being too large, which will lead to an excessively large upper test limit θ0, making the design difficult to implement, and too small a discrimination ratio, which will lead to an excessive number of trials.

[0054] The comprehensive environment determination module is used to determine the comprehensive environmental conditions of the reliability verification test and their relationship with the number of times based on the field use and mission environment characteristics of the tested product; the test plan is determined according to the test requirements. The test plan includes one or more of high temperature test, low temperature test, normal temperature test, relative humidity test, vibration shock, and electrical stress, and the test profile is drawn;

[0055] Test facilities and test equipment requirements module, which is used to select different equipment according to different tests and specify the requirements for test equipment;

[0056] The test items and criteria module is used for the test items and qualification criteria of the test products. The test items of the test products are specified according to the product performance and technical indicators. The qualification criteria determine whether the product is qualified or rejected according to the selected reliability test method.

[0057] According to an embodiment of the present invention, the operation number confirmation system for reliability identification and acceptance test may also include: a fault judgment and classification statistics module, which is used for fault judgment, classification and statistical principles, wherein the fault judgment: during the test process, when any of the following conditions occurs, the test product should be judged to have a fault: under specified conditions, the test product cannot work; under specified conditions, the performance test results of the test product do not meet the specified requirements; under specified conditions, the mechanical, structural parts or components of the test product become loose, cracked, broken or damaged; Fault classification: faults occurring during the reliability test can be divided into associated faults and non-associated faults, and associated faults can be further divided into responsible faults and non-responsible faults; Fault statistical principle: during the test process, only responsible faults can be used as the basis for determining whether the test product is qualified or not.

[0058] According to an embodiment of the present invention, the operation number confirmation system for reliability identification and acceptance testing may also include: fault reporting and handling requirements, which can be found in GJB 450A-2004 "General Requirements for Equipment Reliability Work": establishing a fault reporting, analysis and corrective measures system; establishing a fault review organization.

[0059] Compared with the prior art, the technical solution provided by the embodiments of the present invention can achieve at least the following beneficial effects:

[0060] The present invention's method and system for determining the number of operations for reliability evaluation and acceptance testing uses the reliability metric (mean number of times between failures (MNBF) ≥ n times (θ1)) to design a corresponding reliability test plan. This solves a problem in reliability evaluation and acceptance testing methods related to the number of operations that is currently not addressed in the GJB (national military standard), providing reference and guidance for related fields and possessing significant significance and impact.

[0061] Currently, relevant fields only stipulate reliability evaluation and acceptance based on the mean time between failures. This invention patent can address reliability evaluation and acceptance test solutions for some equipment based on the number of operations. In the fields of national defense modernization and high-end equipment manufacturing, this technology system, combined with GJB, will cover all equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0063] Figure 1 is a flow chart showing a method for confirming the number of operations for reliability evaluation and acceptance testing according to an embodiment of the present invention;

[0064] Figure 2 is a straight line distribution diagram showing acceptance and rejection according to an embodiment of the present invention;

[0065] Figure 3 is a flowchart showing fault judgment criteria and classification statistics according to an embodiment of the present invention;

[0066] Figure 4a-4b 1 is a cross-sectional view showing an experiment according to an embodiment of the present invention. DETAILED DESCRIPTION

[0067] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by persons of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in the present patent application specification and claims do not denote any order, quantity, or importance, but are merely used to distinguish different components. Similarly, terms such as "a" or "an" do not denote a limitation of quantity, but rather denote the presence of at least one.

[0069] Figure 1 FIG. 1 is a flow chart illustrating a method for confirming the number of operations for reliability evaluation and acceptance testing according to an embodiment of the present invention.

[0070] like Figure 1 As shown in FIG, a method for confirming the number of operations for reliability identification and acceptance testing includes the following steps: 1) selecting an appropriate statistical scheme; 2) determining the judgment risk; 3) determining the comprehensive environment; 4) requirements for test facilities and test equipment; 5) test items and qualification criteria for the tested product; 6) fault judgment criteria, classification and statistical principles; 7) fault reporting and handling requirements.

[0071] Select a statistical scheme. Choose an appropriate statistical scheme. Statistical schemes include: sequential test statistical scheme, fixed-number truncation statistical scheme, and full-number test statistical scheme. If the number of reliability verifications is not specified in advance and it is hoped that the acceptance or rejection decision of the MNBF will be made as soon as possible, the sequential test statistical scheme should be selected. If the contract or product specification requires a reliability verification test, provides the verification value of the MNBF, and has a fixed cutoff number of tests, the fixed-number truncation statistical scheme should be selected. If it is required that every product be tested in the reliability acceptance test, the full-number test statistical scheme should be selected.

[0072] Among them, the statistical schemes for sequential tests and fixed-number truncation tests are divided into standard statistical schemes and high-risk statistical schemes. When the producer's risk α and the user's risk β are both within the normal range of 10% to 20%, the standard statistical scheme is adopted. If the producer's risk α and the user's risk β are both 30%, the high-risk statistical scheme is adopted, which shortens the number of tests, but both the producer and the user bear higher decision-making risks. Definitions: Standard sequential test statistical scheme query table 1, low-number high-risk sequential test statistical scheme query table 2, standard fixed-number test statistical scheme query table 3, high-risk fixed-number test statistical scheme query table 4:

[0073] Table 1 Summary of statistical scheme for standard sequential test

[0074]

[0075]

[0076] Table 2 Summary of statistical plan for a small number of high-risk sequential trials

[0077]

[0078] Table 3 Summary of statistical scheme for standard fixed-time test

[0079]

[0080] Table 4 Summary of statistical plan for high-risk fixed-time test

[0081]

[0082]

[0083] For an exponential product with an unknown MNBF value θ, the probability of r failures occurring within the cumulative number of operating times n is:

[0084]

[0085] The following is a further detailed description of this application in conjunction with an operation training device case.

[0086] 1. Example: Reliability technical indicators of operation training equipment: Mean number of times between failures (MNBF) ≥ 1200 times (θ1)

[0087] 1 Statistical plan

[0088] If the standard statistical scheme for sequential trials is used, the scheme No. 4 in the simplified table of standard statistical schemes in Table 1 is selected. The scheme is as follows:

[0089]

[0090] Note: 1) If the product's MNBF true value is no more than 1200 times, the probability of the product being accepted is at most 10%. If the product's MNBF true value is no less than 2400 times, the probability of the product being accepted is at least 90%.

[0091] 2) This experiment is a fixed-number experiment, and its statistical scheme is similar to scheme 4 in Table 1.

[0092] The lower limit of the MNBF test is θ1 = 1200 times, and the upper limit is θ0 = 2400 times. If the actual MNBF is equal to the lower limit of the test, then the probability of r failures occurring within the number of tests, n, is:

[0093]

[0094] If MNBF is the upper limit of the test θ0, then the probability of r failures occurring within the number of trials n is:

[0095]

[0096] The probability ratio is:

[0097]

[0098] This ratio is calculated continuously during the test and compared with two predetermined constants A and B, using the decision criteria a) to c) as follows:

[0099] a) If P(r) becomes < B, accept and stop the test;

[0100] b) If P(r) becomes > A, reject and stop the test;

[0101] c) If B<P(r)<A, continue the test.

[0102] The constants A and B are:

[0103]

[0104] Where: α—producer risk, β—user risk, d—identification ratio

[0105] Substituting the discrimination ratio d = θ0 / θ1 = 2, we obtain A = 3 and B = 0.25.

[0106] Follow the steps below to calculate the truncation point and check the upper quantiles (1-α) and β of the χ2 distribution until the following equation is true:

[0107]

[0108] Right now

[0109] The point distributed on both sides of 0.5 appears when the degree of freedom is 14, which is determined by χ2 The upper quantile table of the distribution gives (1-a) and β probabilities, see Table 5 of the GJB899-2009 standard of the National Military Standard of the People's Republic of China:

[0110] Table 5 2 Distribution upper quantile table

[0111]

[0112]

[0113]

[0114]

[0115]

[0116] Comparing (1-a) and β probability in the above table, we get:

[0117]

[0118] Therefore, we can get r0=7 (2r0 is the degree of freedom, r0 is the number of responsible failures)

[0119] Thus, the number of truncated trials, that is, the longest number of trials, is obtained:

[0120]

[0121] Therefore, the test can have a maximum of 7 failures, or a maximum number of trials of 11361. Figure 2 is a straight line distribution diagram showing acceptance and rejection according to an embodiment of the present invention.

[0122] like Figure 2 As shown in the test items and judgment steps, r failures occur when the number of tests is n, which is represented by r = f(n) in the plane coordinates. Suppose two straight lines r1 and r2, r1 = c + bn, r2 = a + bn, where the upper side of r1 is rejection and the lower side of r2 is acceptance. The area between r1 and r2 is continued testing. Determine the slope and ordinate intercept of the two parallel lines:

[0123]

[0124] Substituting the values ​​into the equation, we get: a = -2.32, b = 0.0006, c = 1.585, so the equation of the line is:

[0125] r1=1.585+0.0006n

[0126] r2=-2.32+0.0006n

[0127] Get as Figure 2 The straight line distribution diagram is shown.

[0128] From the figure, the acceptance / rejection judgment comparison table is shown in Table 6 below.

[0129] Table 6 Comparison table of qualified judgment

[0130]

[0131] During actual operation, taking into account the environmental conditions, it is generally required that the number of times the engineering prototype of the conduct training equipment has been operated since the first operation should be accumulated within the number of times of reliability test.

[0132] The test conditions include: temperature stress and relative humidity stress. When applying temperature stress, the temperature stabilization time of the test sample shall not be less than 4 hours.

[0133] a) Normal temperature test: The normal temperature test of the operation training equipment shall be carried out during the type test or the special reliability test, and the operation times shall account for no less than 70% of the total times.

[0134] b) High temperature test: Special test for reliability of operation training equipment. High temperature test is divided into two parts:

[0135] 1) The storage temperature is +65℃. After returning to the natural temperature, the operation test is carried out 50 times. After another 4 hours of heat preservation, the operation test is carried out 50 times. The cycle is completed after 200 times. The proportion of the operation times to the total times is not less than 5%.

[0136] 2) Operating temperature is +50℃, perform 50 operation tests, then keep warm for 4 hours, and then operate the test 50 times, and complete the cycle 200 times. The operation times should account for no less than 5% of the total times.

[0137] c) Low temperature test

[0138] Special reliability test of operation training equipment Low temperature test is divided into two parts:

[0139] 1) The storage temperature is -50℃. After returning to the natural temperature, the operation test is carried out 50 times. After another 4 hours of heat preservation, the operation test is carried out 50 times. The cycle is completed after 200 times. The proportion of the operation times to the total times is not less than 5%.

[0140] 2) The operating temperature is -40℃. After 50 tests, keep the temperature for 4 hours and then operate the test 50 times. The operation test is completed after 200 times. The operation times should account for no less than 5% of the total times.

[0141] Relative humidity stress: After the training equipment is stored in a hot and humid environment at a temperature of 35°C and a relative humidity of 95%±3% for 24 hours, an appearance surface inspection is performed and 387 operations are performed, with the number of operations accounting for no less than 10% of the total number of operations.

[0142] Figure 4a-4b The following are cross-sectional diagrams showing tests performed according to an embodiment of the present invention: a—low-temperature test (operating temperature); b—high-temperature test (operating temperature); c—low-temperature test (storage temperature); d—high-temperature test (storage temperature); e—relative humidity test; and f—natural temperature test.

[0143] Test cross-section diagram see Figure 4a .

[0144] If a fault occurs within 3866 times, determine whether the fault is a responsible fault or a non-responsible fault based on the actual situation. If it is a responsible fault, Figure 2 Determine whether to reject or continue the test according to Table 3. If it is a non-responsible failure, the test can be continued.

[0145] Test facility and test equipment requirements: The accuracy of instruments and equipment shall comply with the general requirements of GJB150A-2009.

[0146] Fault judgment criteria, classification and statistical principles.

[0147] Fault judgment criteria: During the test, if any of the following conditions occurs, the product under test shall be judged to have failed:

[0148] a) The product under test cannot work under the specified conditions;

[0149] b) Under the specified conditions, the performance test results of the tested product do not meet the specified requirements;

[0150] c) Under specified conditions, the mechanical or structural parts or components of the tested product become loose, cracked, broken or damaged.

[0151] Fault classification: Faults that occur during reliability testing can be divided into related faults and non-related faults. Related faults should be further divided into responsible faults and non-responsible faults. Fault classification is shown in Figure 3 .

[0152] During the test, only the following situations can be judged as non-responsible failures:

[0153] a) Failure of the test product caused by misoperation;

[0154] b) Failure of the tested product caused by failure of the test device and test instrument;

[0155] c) Failure of the tested product caused by environmental conditions and working conditions that exceed the product's operating limits;

[0156] d) Faults introduced during the repair process.

[0157] Except for faults that can be determined as non-responsible faults, all other faults are determined as responsible faults, such as:

[0158] a) Failure due to design defects or poor manufacturing process;

[0159] b) intermittent faults;

[0160] c) Adjustments beyond the normal range of technical specifications;

[0161] d) Replacement caused by any failure symptoms (not exceeding performance limits) during the test due to any non-dependent failure causes;

[0162] e) Unverifiable abnormal circumstances.

[0163] Failure statistics principle: During the test, only responsible failures can be used as the basis for judging whether the tested product is qualified or not. Responsible failures can be counted according to the following principles:

[0164] a) When it can be confirmed that multiple failure modes are caused by the same cause, the entire event is counted as one failure;

[0165] b) Intermittent failures that can be verified to be caused by the same reason, if analysis confirms that corrective measures taken and verified to be effective will not reoccur, then multiple failures will be aggregated into one failure;

[0166] c) If a fault occurs multiple times at the same location, with the same nature and the same cause, and analysis confirms that the fault will not reoccur after corrective measures are taken and verified to be effective, the multiple faults will be counted as one fault;

[0167] d) If a fault that has been reported and is caused by the same fault cause and reappears because it cannot be truly eliminated, it should be combined with the originally reported fault as one fault;

[0168] e) During fault detection and repair, if other faults are found in the tested product and cannot be determined to be caused by the original fault, they should be regarded as separate responsible faults for statistics.

[0169] Fault reporting and handling requirements: See GJB 450A-2004 "General Requirements for Equipment Reliability Work":

[0170] a) Establish a fault reporting, analysis and corrective action system;

[0171] b) Establish a fault review organization.

[0172] For example: Reliability technical indicators of operation training equipment: Mean number of times between failures (MNBF) ≥ 1200 times (θ+)

[0173] If a fixed-order truncation test statistical plan is used, the plan number 21 in the high-risk test statistical plan summary table in Table 4 should be selected.

[0174] The plan is as follows:

[0175]

[0176] Note: For other similar cases, see the test section diagram. Figure 4b If a fault occurs within 1320 times, determine whether the fault is a responsible fault or a non-responsible fault based on the actual situation. If it is a responsible fault, Figure 3 Confirm rejection. If it is a non-responsible failure, the test can continue.

[0177] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the appended claims.

Claims

1. A method for confirming the number of operations for reliability evaluation and acceptance testing, comprising the following steps: Select a statistical plan, and select an appropriate statistical plan, which includes: There are three types of statistical schemes: sequential test statistical scheme, fixed-number truncation statistical scheme, and full-number test statistical scheme. If the number of reliability verification tests is not specified in advance and it is hoped that the acceptance or rejection decision of the mean time between failures (MNBF) will be made as soon as possible, the sequential test statistical scheme should be selected. If the contract or product specification requires a reliability verification test and provides a verification value of the mean time between failures (MNBF) and there is a fixed cutoff number of tests, the fixed-number truncation statistical scheme should be selected. If it is required that each product be tested in the reliability acceptance test, the full-number test statistical scheme should be selected. Among them, the statistical schemes for sequential tests and fixed-number truncation tests are divided into standard statistical schemes and high-risk statistical schemes. When the producer's risk α and the user's risk β are both within the normal range of 10% to 20%, the standard statistical scheme is adopted. If the producer's risk α and the user's risk β are both 30%, the high-risk statistical scheme is adopted, which shortens the number of tests, but both the producer and the user bear higher decision-making risks. Definitions: Standard sequential test statistical scheme query table 1, low-number high-risk sequential test statistical scheme query table 2, standard fixed-number test statistical scheme query table 3, high-risk fixed-number test statistical scheme query table 4: Table 1 Summary of statistical scheme for standard sequential test Table 2 Summary of statistical plan for a small number of high-risk sequential trials Table 3 Summary of statistical scheme for standard fixed-time test Table 4 Summary of statistical plan for high-risk fixed-time test Among them, if the sequential test statistical scheme is adopted, the producer risk is set as α, the user risk is set as β, the lower limit of the MNBF test is θ1, the upper limit of the MNBF test is θ0, and the discrimination ratio is d, For an exponential product with an unknown MNBF value θ, the probability of r failures occurring within the cumulative number of operating times n is: Sequential testing must demonstrate that θ is at least not less than the MNBF lower limit θ1. If the actual MNBF is equal to the lower limit θ1, then the probability of r failures occurring within n number of tests is: To construct a sequential test, we need to select an upper bound on the MNBF test, θ0. If the MNBF of a product is equal to the upper bound, θ0, then the probability of r failures occurring within n trials is: The probability ratio is: This ratio is calculated continuously during the test and compared with two predetermined constants A and B, using the decision criteria a) to c) as follows: a) If P(r) becomes < B, accept and stop the test; b) If P(r) becomes > A, reject and stop the test; c) If B<P(r)<A, continue the test. The constants A and B are: Where: α is the producer risk, β is the user risk, and d is the identification ratio. Substitute to get A, B; Follow the steps below to calculate the truncation point and check χ 2 Distribute (1-α) and the upper quantile of β until the following equation is true: This point distributed on both sides of θ1 / θ0 appears when the degree of freedom is 2r0. By referring to the table of the "National Military Standard of the People's Republic of China" GJB899-2009 standard, we can obtain the (1-α) and β probabilities and get r0, where 2r0 is the degree of freedom and r0 is the number of responsible failures. Thus, the number of truncated trials, that is, the longest number of trials, is obtained: Among them, for the test items and judgment steps described in the sequential test statistical plan, r failures occur when the number of tests is n, which is represented by r = f(n) in the plane coordinate. Suppose two straight lines r1 and r2, r1 = c + bn, r2 = a + bn, where the upper side of r1 is rejection and the lower side of r2 is acceptance. The area between r1 and r2 is continued testing. Determine the slope and ordinate intercept of the two parallel lines: Substituting the numerical values ​​into the equations, we can get the values ​​of a, b, and c. Then we can draw the acceptance / rejection distribution graph based on the linear equations: r1=c+bn, r2=a+bn. If a fixed-number truncation test statistical scheme is adopted, then in the test items and judgment criteria steps, the standardized number of judgments multiplied by the lower limit of the MNBF test is the number of tests, where the acceptance and rejection of the judgment failure numbers are shown in Tables 3 and 4; Determine the decision risk and select a statistical scheme with a lower decision risk. A statistical scheme with a lower decision risk requires more tests, but also has a lower probability of accepting unqualified products or rejecting qualified products. Select the discrimination ratio d, where d = θ0 / θ1. The larger the discrimination ratio, the faster the test will make a decision. Careful selection is necessary to prevent a too large discrimination ratio from causing the upper test limit θ0 to be too large, making the design difficult to implement, or a too small discrimination ratio from causing too many tests. Comprehensive environment determination: determine the comprehensive environmental conditions of the reliability verification test and their relationship with the number of times based on the on-site use and mission environment characteristics of the tested product; determine the test plan based on the test requirements, and the test plan includes one or more of high temperature test, low temperature test, normal temperature test, relative humidity test, vibration shock, and electrical stress, and draw the test profile; Test facilities and test equipment requirements, select different equipment according to different tests, and specify the requirements for test equipment; Test items and criteria: Test items and qualification criteria for the test products. Test items for the test products are specified based on product performance and technical indicators. The qualification criteria determine whether the product is qualified or rejected based on the selected reliability test method.

2. The method for confirming the number of operations for reliability evaluation and acceptance test according to claim 1, further comprising the steps of: fault criteria and classification statistics, fault criteria, classification and statistical principles, wherein: Fault judgment criteria: During the test, if any of the following conditions occurs, the test product shall be judged to have failed: under the specified conditions, the test product cannot work; under the specified conditions, the performance test results of the test product do not meet the specified requirements; under the specified conditions, the mechanical, structural parts or components of the test product become loose, cracked, broken or damaged; Fault classification: Faults occurring during the reliability test can be divided into correlated faults and non-correlated faults, and correlated faults can be further divided into responsible faults and non-responsible faults; Fault statistics principle: During the test, only responsible faults can be used as the basis for determining whether the test product is qualified or not.

3. The method for confirming the number of operations for reliability identification and acceptance testing as described in claim 1 further includes the steps of: fault reporting and handling requirements, which are as follows: GJB450A-2004 "General Requirements for Equipment Reliability Work": establishing a fault reporting, analysis and corrective measures system; establishing a fault review organization.

4. The method for confirming the number of operations for reliability evaluation and acceptance testing according to claim 1, wherein: In the step of selecting the statistical plan, the sample size of the statistical plan shall be selected, and the number of tested products shall be determined by the contractor and the ordering party in accordance with the contract provisions; if the ordering party has no provisions for the statistical sample of the reliability acceptance test, at least two products in each batch shall be tested; the recommended sample size is 10% of each batch of products, but not more than 20 units.

5. The method for confirming the number of operations for reliability evaluation and acceptance testing according to claim 1, wherein: In the step of determining the judgment risk, the production side risk adopts α=10%, α=20% or α=30%; the user side risk adopts β=10%, β=20% or β=30%; when selecting the discrimination ratio d, d=1.5, d=2.0 or d=3.0 is adopted; among which, the larger the discrimination ratio, the faster the test makes a judgment, and it must be selected carefully to prevent the discrimination ratio from being too large, resulting in an excessively large test upper limit θ0, making the design difficult to implement, and the discrimination ratio from being too small, resulting in an excessive number of tests.

6. The method for confirming the number of operations for reliability evaluation and acceptance testing according to claim 1, wherein: In the test facilities and test equipment requirements steps, the accuracy of instruments and equipment shall be implemented in accordance with the general requirements of GJB150A-2009.

7. An operation number confirmation system for reliability evaluation and acceptance testing, comprising: The statistical scheme selection module is used to select an appropriate statistical scheme. The statistical schemes include sequential test statistical scheme, fixed-number truncation statistical scheme, and full-number test statistical scheme. If the number of reliability verification tests is not specified in advance and it is desired to make an acceptance or rejection decision on the MNBF as soon as possible, the sequential test statistical scheme is selected. If the contract or product specification requires reliability verification testing, providing MNBF verification values, and a fixed cutoff number of tests, the fixed-number truncation statistical scheme is selected. If it is required that every product be tested in the reliability acceptance test, the full-number test statistical scheme is selected. The decision risk module is used to select a decision risk. A statistical scheme with a lower decision risk requires more trials, but the probability of accepting unqualified products or rejecting qualified products is also lower. The discrimination ratio d is selected, where d = θ0 / θ1. The larger the discrimination ratio, the faster the test decision is made. It must be selected carefully to prevent the discrimination ratio from being too large, which will lead to an excessively large upper test limit θ0, making the design difficult to implement, and too small a discrimination ratio, which will lead to an excessive number of trials. The comprehensive environment determination module is used to determine the comprehensive environmental conditions of the reliability verification test and their relationship with the number of times based on the field use and mission environment characteristics of the tested product; the test plan is determined according to the test requirements. The test plan includes one or more of high temperature test, low temperature test, normal temperature test, relative humidity test, vibration shock, and electrical stress, and the test profile is drawn; Test facilities and test equipment requirements module, which is used to select different equipment according to different tests and specify the requirements for test equipment; The test items and criteria module is used for the test items and qualification criteria of the test products. The test items of the test products are specified according to the product performance and technical indicators. The qualification criteria determine whether the product is qualified or rejected according to the selected reliability test method.

8. The system for confirming the number of operations for reliability evaluation and acceptance testing according to claim 7, further comprising: The fault judgment and classification statistics module is used for fault judgment, classification and statistical principles. Among them, fault judgment criteria: during the test, when any of the following conditions occurs, the test product should be judged to have a fault: under the specified conditions, the test product cannot work; under the specified conditions, the performance test results of the test product do not meet the specified requirements; under the specified conditions, the mechanical, structural parts or components of the test product become loose, cracked, broken or damaged; fault classification: faults occurring during the reliability test can be divided into correlated faults and non-correlated faults, and correlated faults can be further divided into responsible faults and non-responsible faults; fault statistics principle: during the test, only responsible faults can be used as the basis for judging whether the test product is qualified or not.

9. The system for confirming the number of operations for reliability evaluation and acceptance testing according to claim 8, further comprising: Fault reporting and handling requirements. For fault reporting and handling requirements, see GJB450A-2004 General Requirements for Equipment Reliability Work: Establish a fault reporting, analysis and corrective action system; Establish a failure review organization.

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