An aero-engine process characteristic analysis method based on logical decision

Abstract

A kind of aero-engine process characteristic analysis method based on logical decision-making, comprising the following steps: step S01: determining the process characteristics related to class I and class II failure mechanism based on failure mode, effects and criticality analysis with failure control as the core;Step S02: determining the process characteristic carrier based on process control link;Step S03: determining the acceptable class I and class II failure mode criticality;Step S04: dividing the necessity level of process characteristic quality control according to logical decision-making method;Step S05: determining the key parts and important parts.The present application combines characteristic analysis with failure mode, effects and criticality analysis work comprehensively, and establishes the correlation criterion of quality stability and quality cost of process such as manufacturing, assembly and testing, so that the characteristic analysis is streamlined and explicit, and the rationality and consistency of aero-engine and its accessory process characteristic determination and classification are guaranteed, which provides a basic basis for key parts and important parts process preparation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the general quality characteristic design method of aero-engine, and relates to a kind of aero-engine process characteristic analysis method based on logical decision-making, which is suitable for the determination and classification of process characteristics of different types of aero-engines and their accessories. BACKGROUND

[0002] As the core key product of an aircraft, an aero-engine has complex structure and precision. On the one hand, the stability of its manufacturing quality has a significant impact on the reliability and safety of the aircraft. On the other hand, the cost of key and important characteristic quality control has an important impact on the product manufacturing cost and production cycle. Therefore, manufacturing process characteristic related quality control must be carried out. In order to facilitate the aero-engine manufacturing process department to fully understand the design intent, distinguish the primary and secondary in formulating process procedures and quality inspection control, control the focus, effectively allocate inspection resources, ensure the stability and traceability of product quality, and facilitate the ordering party to implement inspection and supervision on product quality, process characteristic analysis work needs to be carried out. Through scientific and reasonable process characteristic determination and classification, the process characteristics can be effectively controlled in the manufacturing process, thereby ensuring the reliability and economy of the engine.

[0003] Due to the lack of process characteristic determination and classification methods available for engineering application in existing standards and specifications, on the one hand, the process characteristics of similar products formed are greatly different due to the influence of human differences such as engineering experience and technical level of engineering and technical personnel. On the other hand, the analysis results deviate from the basic needs of manufacturing quality control, and the quality instability caused by factors such as personnel, equipment and inspection methods in the manufacturing link is ignored, so that the classification of process characteristics is extremely unreasonable. SUMMARY

[0004] The main purpose of the present application is to propose a kind of aero-engine process characteristic analysis method based on logical decision-making, aiming at solving the above technical problems.

[0005] To achieve the above purpose, the present application proposes a kind of aero-engine process characteristic analysis method based on logical decision-making, comprising the following steps:

[0006] Step S01: determining the process characteristics related to the failure mechanism of type I and type II failures based on failure mode effect and criticality analysis with failure control as the core;

[0007] Step S02: determining the process characteristic carrier based on the process control link;

[0008] Step S03: determining the acceptable type I and type II failure mode criticality;

[0009] Step S04: dividing the necessity level of process characteristic quality control according to the logical decision-making method;

[0010] Step S05: Determine the key parts and important parts.

[0011] Preferably, in step S01, the failure control core includes design characteristics, process characteristics, and verification methods.

[0012] Further, the design characteristics include structural strength design, environmental resistance design, backup design, redundancy design, structural redundancy design, hyperstatic design, and protection design characteristics. The process characteristics are dimensional tolerance, surface roughness, surface strengthening treatment, forging, casting grade requirements, and flaw detection characteristics for controlling the quality of process manufacturing, assembly, welding, and inspection processes based on design characteristics for design defects and manufacturing defects in failure mechanism reasons. The verification methods include calculation analysis, simulation analysis, and test verification projects for verifying the effectiveness of design characteristics and process characteristics.

[0013] Preferably, in step S02, when the process characteristic type is blank quality characteristics, mechanical processing characteristics, or thermal surface treatment characteristics, the carrier should be a part-level design drawing.

[0014] When the process characteristic type is assembly characteristics, welding characteristics, combined processing characteristics, or combined inspection characteristics, the carrier should be a component-level and above-level design drawing.

[0015] Preferably, in step S03,

[0016] For the type I failure mode, the acceptable failure mode criticality CAI of the type I failure mode is calculated by formula (1) m :

[0017] CAI m = 0.001·λ Z ·0.1·t …………………… (1)

[0018] For the type II failure mode, the acceptable failure mode criticality CAII of the type II failure mode is calculated by formula (2) m :

[0019] CAII m = 0.01·λ Z ·0.5·t …………………… (2)

[0020] In the formula,

[0021] λ Z —The total failure probability of the aero-engine within the life cycle, which can be calculated by the reciprocal of the aero-engine MTBF;

[0022] t—The average mission working time of the aero-engine.

[0023] Preferably, in the failure mode effect and criticality analysis method based on the failure control, the quantitative criticality matrix analysis method is used to calculate the criticality C of the failure mode under different severities m ;

[0024] The quantitative criticality matrix analysis calculates the probability C of the failure mode in the working state to cause the final effect of the failure according to the failure rate, failure mode frequency ratio, failure mode influence probability and working state time of the analyzed object mj , as shown in formula (3):

[0025] C mj = α j · β i · λ p · t … … … (3)

[0026] In the formula:

[0027] α j is the failure mode frequency ratio, which is the ratio of the occurrence number of the jth failure mode of the analyzed object to the number of all possible failure modes of the working unit, j = 1, 2, …, n, and n is the total number of failure modes of the analyzed object;

[0028] β j is the failure mode influence probability, which is the conditional probability of causing the final effect of the engine under the condition of the occurrence of the jth failure mode of the analyzed object;

[0029] λ p is the failure rate of the analyzed object in the task stage, with the unit of 1 / h;

[0030] t is the working time of the analyzed object in the task stage, with the unit of h.

[0031] Preferably, for the type I failure mode, the acceptable failure mode occurrence probability P mj of the failure mode is required to reach an extremely low level, which is less than 0.1% of the total failure probability of the aero-engine, i.e. α j · λ p ≤ 0.001 · λ Z , and the failure influence probability needs to reach a negligible degree, i.e. β j < 0.1; the acceptable failure mode criticality CAⅠ m of the type I failure mode is calculated by formula (4):

[0032] C mj = α j · λ p · β j · t < CAⅠm = 0.001 · λ Z · 0.1 · t … … (4)

[0033] For the type II failure mode, in the case that the failure source cannot be completely eliminated, its acceptable failure mode occurrence probability P mj is required to reach a lower level, which is less than 1% of the total failure probability of the aero-engine, i.e. a j = 0.01 · λ p = 0.01 · λ Z , and its failure impact probability needs to reach the possible loss degree, i.e. 0.1 ≤ β j < 0.5, so the acceptable failure mode severity CAII of the type II failure mode is calculated by formula (5) m :

[0034] C mj = a j · λ p · β j · t < CAII m = 0.01 · λ Z · 0.5 · t … … (5)

[0035] In the formula:

[0036] λ Z — the total failure probability of the aero-engine in the life cycle, which can be calculated by the reciprocal of the MTBF of the aero-engine;

[0037] t— the average mission working time of the aero-engine.

[0038] Preferably, in step S4, the related process characteristics are preliminarily classified based on the severity categories and the severities of the type I and type II failure modes:

[0039] When the severity category of the failure mode related to the process characteristic is type I, the preliminary classification of the process characteristic level is performed according to formula (6) and (7):

[0040] When S = 1 and C m ≥ CAI m :

[0041] PCG i ' = 100 … … (6)

[0042] When S = 1 and C m < CAI m :

[0043] PCG i ' = 10 … … (7)

[0044] When the severity category of the failure mode related to the process characteristics is Class II, the preliminary classification of the process characteristic level is carried out according to equations (8) and (9):

[0045] When S = 2, and C m ≥CAⅡ m hour:

[0046] PCG i =10…………………………………(8)

[0047] When S = 2, and C m <CAⅡ m hour:

[0048] PCG i =PCG i =0……………………………(9)

[0049] In the formula:

[0050] S—Fault mode severity category, S=1, 2, corresponding to category I and category II respectively;

[0051] C m —The severity of failure modes corresponding to process characteristics;

[0052] CAI m —Acceptable Class I failure mode hazard;

[0053] CAⅡ m —Acceptable Type II failure mode hazard;

[0054] PCG i — The preliminary classification level value of the i-th process characteristic, PCG' = 100, 10, 0, which correspond to the key characteristic, important characteristic, and general characteristic in the preliminary classification, respectively;

[0055] PCG i —The final grade value of the i-th process characteristic, PCG=0 indicates a general characteristic.

[0056] Preferably, based on the final determination of the process characteristic level according to the preliminary level classification and necessity judgment, the level of the process characteristic is determined according to the calculation result of formula (10):

[0057]

[0058] In the formula:

[0059] Nj — The j-th necessary decision item is assigned a value, j = 1 to 7, corresponding to 7 decision items respectively;

[0060] PCG iThe preliminary classification grade value of the i th process characteristic is PCG = 100, 10, 0, corresponding to key characteristic, important characteristic, and general characteristic, respectively;

[0061] PCG i The final classification grade value of the i th process characteristic is PCG = 100, 10, 0, corresponding to key characteristic, important characteristic, and general characteristic, respectively. i When PCG ≥ 100, the i th process characteristic is determined as a key characteristic; when 10 ≤ PCG < 100, the i th process characteristic is determined as an important characteristic; and when PCG = 0, the i th process characteristic is determined as a general characteristic. i i

[0062] Preferably, in step S05, the part or component containing a key characteristic is determined as a key part; and the part or component not containing a key characteristic but containing an important characteristic is determined as an important part.

[0063] With the above technical solution, the present application has the following advantages: the logical decision flow of the present application is based on the system engineering method, and combines the characteristic analysis with the failure mode, effect, and criticality analysis, and establishes the correlation criterion of the characteristics and the quality stability and cost of the manufacturing, assembly, and testing processes, so that the characteristic analysis is flowable and explicit, and the rationality and consistency of the determination and classification of the process characteristics of the aero-engine and its components are ensured, the basic basis for the process preparation of the key parts and important parts is provided, the manufacturing quality of the process characteristics is effectively controlled, the manufacturing reliability and economy of the engine are ensured, and the scientificity, accuracy, and consistency of the characteristic analysis are greatly increased. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 The figure is the logical decision diagram of the process characteristic level in the present application. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0066] A process characteristic analysis method of an aero-engine based on logical decision, comprising the following steps:

[0067] Step S01: determining the process characteristics related to the failure mechanisms of the type I and type II based on the failure mode, effect, and criticality analysis.

[0068] ​​Fault Mode, Effect and Criticality Analysis (FMECA) is performed to determine the failure modes, failure effects, severity class S and criticality C of the structure unit m and the process characteristics aiming at reducing the failure probability are determined according to the mechanism of the failure mode.

[0069] the Fault Mode, Effect and Criticality Analysis (FMECA) with the core of failure control;

[0070] The traditional FMECA analysis only focuses on the identification of failure modes and failure effects, and lacks the design analysis process of the design scheme, design characteristics and verification method related to the failure mechanism control. Therefore, the FMECA analysis cannot be closely combined with the design process, and cannot effectively lead the design to the scheme design, engineering design and verification work aiming at reducing the failure probability and failure effect probability, which causes the disconnection between functional design and reliability design from the basic method.

[0071] The Fault Mode, Effect and Criticality Analysis with the core of failure control follows the principle of model-based system engineering, and is based on the mapping logic of "function-failure", "function requirement-failure criterion", "function transmission-failure effect transmission" and "failure mechanism reason-failure control". Therefore, the design characteristics, process characteristics and verification methods for failure control measures can effectively lead and support the design, analysis and test verification work at each stage such as the scheme stage, prototype design stage and final design stage. Through design compliance check, quality review and closed loop, the substantial integration of functional design and reliability design can be ensured, and the synchronous realization of functional and reliability requirements can be ensured.

[0072] The core measures of failure control include design characteristics, process characteristics and verification methods:

[0073] (a) The design characteristics mainly include structural strength design, environmental resistance design, backup design, redundancy design, structural redundancy design, statically indeterminate design and protection design, which are proposed for the two aspects of failure inducing factors and reducing failure effect probability in the failure mechanism reason;

[0074] (b) The process characteristics are the size tolerance, surface roughness, surface strengthening treatment, forging, casting grade requirement and flaw detection inspection, which are formulated to control the quality of process manufacturing, assembly, welding, inspection and other processes based on the design characteristics;

[0075] (c) The verification method is the calculation analysis, simulation analysis and test verification project formulated to verify the effectiveness of the design characteristics and process characteristics.

[0076] Step S02: determining the process characteristic carrier based on the process control link

[0077] Since the process characteristics developed for a certain structure unit failure mechanism may need to be controlled in the corresponding manufacturing, welding, assembly, etc. links, it is necessary to determine the process characteristic carrier in the part-level design drawing, assembly-level and above-level design drawings according to the type of the corresponding process characteristic and the control link.

[0078] (a) When the process characteristic is of the following types, its carrier should be the part-level design drawing:

[0079] 1) Blank quality characteristics, such as: forging, casting acceptance standards, bar specifications and standards, non-destructive testing requirements, etc.

[0080] 2) Machining characteristics, such as: size, tolerance, surface roughness, mass center control requirements, frequency correction requirements, flow check, etc.

[0081] 2) Heat treatment characteristics, such as: hardness, shot peening, surface passivation, chrome plating, etc.

[0082] (b) When the process characteristic is of the following types, its carrier should be the assembly-level and above-level design drawing:

[0083] 1) Assembly characteristics, such as: assembly size, fit tolerance, assembly flexibility check;

[0084] 2) Welding characteristics, such as: welding quality standards, post-weld heat treatment requirements, etc.

[0085] 3) Combined machining characteristics, such as: post-weld machining size, post-assembly machining size, etc.

[0086] 4) Combined inspection characteristics, such as: post-weld flow check, rotor balance check, sealing check, pressure test requirements, etc.

[0087] The determination of the process characteristic carrier: the implementation process of the work characteristic mainly considers the following two factors:

[0088] (a) Due to the limitation of manufacturing and assembly process technology level, as well as the demand for miniaturization and integration, there is a certain difference between the engineering design drawing and the architecture design model finally used for process manufacturing, mainly including:

[0089] 1) For the convenience of processing and manufacturing, the same work unit is split into several component drawings;

[0090] 2) To meet the demand for miniaturization and integration, multiple structure units are integrated into one assembly drawing;

[0091] 3) To meet the assembly demand, multiple assembly unit drawings are generated.

[0092] (b) Due to the failure mechanism, it is impossible to implement the characteristics in the independent working unit design, and it is necessary to control in the upper unit design. For example, the balance requirement of the rotor, the clearance control requirement between the rotor and the stator, etc.

[0093] Due to the above two reasons, the process characteristics determined by FMECA must be implemented into the relevant parts and upper assembly drawings through the implementation analysis process. The characteristic detail table proposed in the present application can explicit the analysis process of the characteristic implementation, and the correlation between the characteristics determined by FMECA analysis and the characteristics in the design drawings and other carriers can be determined, so as to ensure the traceability of the important characteristic analysis process.

[0094] Step S03: Determine the acceptable hazard degree of class I and class II failure modes.

[0095] (a) For class I failure modes, the acceptable hazard degree of class I failure modes CAI is calculated by formula (1) m :

[0096] CAI m = 0.001·λ Z ·0.1·t …………………… (1)

[0097] In the formula:

[0098] λ Z — The total failure probability of the aero-engine in the life cycle, which can be calculated by the reciprocal of the MTBF of the aero-engine;

[0099] t— The average mission working time of the aero-engine.

[0100] (b) For class II failure modes, the acceptable hazard degree of class II failure modes CAII is calculated by formula (2) m :

[0101] CAII m = 0.01·λ Z ·0.5·t …………………… (2)

[0102] According to the principle of reliability design, when the product adopts margin design (such as parallel reserve design), the design margin is large, and the influence of manufacturing quality on inherent reliability is relatively small, so the process characteristics grade can be appropriately reduced. The hazard degree C mThe design margin can directly reflect the influence on reliability, and can be used as a condition for reducing the characteristic level. Therefore, the acceptable hazard levels of the I and II failure modes need to be determined.

[0103] The quantitative hazard matrix analysis is based on the failure rate, failure mode frequency ratio, failure mode influence probability, and working state time to calculate the probability C of the failure mode in the working state leading to the final failure impact mj , as shown in equation (3):

[0104] C mj = α j · β i · λ p · t … … … (3)

[0105] In the equation:

[0106] α j is the failure mode frequency ratio, which is the ratio of the number of occurrences of the jth failure mode of the analyzed object to the number of all possible failure modes of the working unit, j = 1, 2, …, n, and n is the total number of failure modes of the analyzed object;

[0107] β j is the failure mode influence probability, which is the conditional probability of the occurrence of a certain severity of the engine final impact consequence under the condition that the jth failure mode of the analyzed object occurs;

[0108] λ p is the failure rate of the analyzed object in its task phase, with the unit of 1 / h.

[0109] t is the working time of the task phase of the analyzed object, with the unit of h.

[0110] The statistical data of the failure mode occurrence probability and the failure impact probability of the aero-engine at home and abroad show that the acceptable failure mode hazard level can be determined according to the total failure probability of the aero-engine:

[0111] (a) For the I-type failure mode, in the case that the failure source cannot be completely eliminated, the acceptable failure mode occurrence probability P mj is required to reach an extremely low level, and the failure mode occurrence probability needs to be less than 0.1% of the total failure probability of the aero-engine, i.e., α j · λ p ≤ 0.001 · λ Z . The failure impact probability needs to reach a negligible level, i.e., β j < 0.1. Therefore, the acceptable failure mode hazard CAI of the I-type failure mode is calculated by equation (4): m

[0112] C​mj = a j • λ p • β j • t < CAi m = 0.001 • λ Z • 0.1 • t (4)

[0113] In the formula:

[0114] λ Z The total failure probability of the aero-engine in the life cycle can be calculated by the reciprocal of the MTBF of the aero-engine;

[0115] t - the average mission working time of the aero-engine.

[0116] (b) For the failure mode of type II, when the failure source cannot be completely eliminated, the acceptable failure mode occurrence probability P mj is required to reach a lower level, which is less than 1% of the total failure probability of the aero-engine, i.e. a j • λ p ≤ 0.01 • λ Z The failure impact probability needs to reach the possible loss degree, i.e. 0.1 ≤ β j < 0.5, so the acceptable failure mode severity CAii of the failure mode of type II is calculated by formula (5) m :

[0117] C mj = a j • λ p • β j • t < CAii m = 0.01 • λ Z • 0.5 • t (5)

[0118] Step S04: Perform the characteristic level division according to the logical decision method, and determine the necessity of process characteristic quality control according to the logical decision method. The logical decision process is shown in Figure 1 .

[0119] 4.1 Preliminary level division of related process characteristics based on the severity category and severity of failure modes of type I and type II: according to the severity category and severity of failure modes related to process characteristics determined by failure mode, effect and criticality analysis (FMECA), preliminarily divide the critical characteristics, important characteristics, or classify as general characteristics.

[0120] (a) When the severity category of the failure mode related to the process characteristic is type I:

[0121] The severity category is Class I, when the system design measures of fault isolation, safety protection, health monitoring and life management taken by the aero-engine can greatly reduce the hazard degree Cm caused by the failure mode m When the hazard degree Cm m is less than the acceptable value of Class I failure mode CAI m , the failure mode can be preliminarily classified as an important characteristic based on the hazard degree reduction characteristics category, otherwise it should be preliminarily classified as a critical characteristic. For example, "the fan case adopts a fully containment design, which can greatly reduce the influence probability of the fan rotor blade fracture leading to Class I non-containment, and the calculated hazard degree Cm is 7.3 x 10 -9 , which is less than the acceptable value CAI m . The characteristics related to fan blade fracture should be preliminarily classified as important characteristics".

[0122] When the severity category of the failure mode related to the process characteristic is Class I, the preliminary classification of the process characteristic level is performed according to formulas (6) and (7):

[0123] When S = 1 and Cm m ≥ CAI m :

[0124] PCG i ' = 100 … … … … … (6)

[0125] When S = 1 and Cm m < CAI m :

[0126] PCG i ' = 10 … … … … … (7)

[0127] In the formulas:

[0128] S - the severity category of the failure mode, S = 1, 2, corresponding to Class I and Class II, respectively;

[0129] Cm m - the hazard degree of the failure mode corresponding to the process characteristic;

[0130] CAI m - the acceptable hazard degree of Class I failure mode;

[0131] PCG i ' - the preliminary classification level value of the i-th process characteristic, PCG' = 100, 10, 0, corresponding to the preliminary classification of critical characteristics, important characteristics and general characteristics, respectively.

[0132] (b) When the final impact severity category of the failure related to the characteristic is Class II:

[0133] The severity category is Level II, meaning that the systematic design measures implemented in the aero-engine, such as fault diagnosis and isolation, safety protection, health monitoring, and life management, can significantly reduce the severity C caused by this failure mode. m When the hazard level C m Fault modes smaller than Class II are acceptable (CA II). m If the severity of the failure mode is low, the characteristic level can be reduced and it can be directly classified as a general characteristic; otherwise, it should be initially classified as an important characteristic.

[0134] When the severity category of the failure mode related to the process characteristics is Class II, the preliminary classification of the process characteristic level is carried out according to equations (8) and (9):

[0135] When S = 2, and C m ≥CAⅡ m hour:

[0136] PCG i =10…………………………………(8)

[0137] When S = 2, and C m <CAⅡ m hour:

[0138] PCG i =PCG i =0……………………………(9)

[0139] In the formula:

[0140] S—Fault mode severity category, S=1, 2, corresponding to category I and category II respectively;

[0141] C m —The severity of failure modes corresponding to process characteristics;

[0142] CAⅡ m —Acceptable Type II failure mode hazard;

[0143] PCG i '—The preliminary classification level value of the i-th process characteristic, PCG' = 100, 10, 0, which correspond to the key characteristic, important characteristic, and general characteristic in the preliminary classification, respectively.

[0144] PCG i —The final grade value of the i-th process characteristic, PCG=0 indicates a general characteristic.

[0145] The relevant process characteristics are classified based on severity categories I and II.

[0146] According to the reliability design principle, the quality control level of design characteristics and process characteristics is related to the severity of the corresponding failure mode impact.

[0147] According to the definition of key characteristics and important characteristics:

[0148] Key characteristics: refers to the characteristics that may endanger flight safety, cause personnel death or complete failure of engine and aircraft function if there is a failure.

[0149] Important characteristics: refers to characteristics that cause serious injury to personnel or cause mission failure, serious damage to engines or aircraft.

[0150] According to the definition of I, II severity categories:

[0151] Class I (catastrophic): causing death of personnel or destruction of products (such as aircraft, tanks, missiles and ships, etc.), major environmental damage.

[0152] Class II (fatal): causing serious injury to personnel or major economic loss or causing mission failure, serious damage to products and serious environmental damage.

[0153] As can be seen from the above definitions, the failure impact in the definition of key characteristics is basically the same as the definition of class I severity, and the failure impact in the definition of important characteristics is basically the same as the definition of class II severity. Therefore, the class I and II failure mode severity categories determined by FMECA analysis can be used as the basis for dividing key characteristics and important characteristics. This method analyzes the characteristics related to failure modes of class I and II severity categories, which can greatly reduce the analysis workload of designers and increase the analysis efficiency.

[0154] 4.2 Determine the necessity of the impact criteria of quality stability and quality cost of manufacturing, assembly, testing and other processes based on characteristics.

[0155] (a) Is the characteristic a major factor affecting the service life or structural strength of an aero-engine, and does it use damage tolerance design or strength-stress interference design?

[0156] When the process characteristic is a major factor affecting the service life or structural strength of an aero-engine, and uses damage tolerance design or strength-stress design, etc., which is sensitive to the quality stability of machining and uses fine design methods, then the decision item N1=1, otherwise N1=0. Such as the size of the casing mounting edge determined by strength-stress interference method, the size tolerance of blade tenon determined by damage tolerance design method, etc.

[0157] (b) Is the characteristic a major factor affecting the life or structural strength of the aero-engine, and can the effect of the instability of the characteristic be ignored in the design margin of the safety life design or the redundant structure design?

[0158] When the characteristic is a major factor affecting the life or structural strength of the aero-engine, and the design margin (such as the safety factor, strength reserve factor) of the safety factor strength design or the redundant structure design is low and cannot accommodate the effect of the quality instability of the process characteristic, then the decision item N2 = 1, otherwise N2 = 0. For example, the diameter size tolerance of the transmission shaft designed by the safety factor strength design.

[0159] (c) Is the characteristic a major factor affecting the structural interchangeability of the aero-engine?

[0160] When the characteristic is a major factor affecting the structural interchangeability of the aero-engine, then the decision item N3 = 1, otherwise N3 = 0. The major factors affecting the interchangeability of the aero-engine include:

[0161] 1) Shape tolerance of assembly reference;

[0162] 2) Size and geometric tolerance of assembly fit surface;

[0163] 3) Meshing size and tolerance;

[0164] 4) Center of mass or mass moment of inertia;

[0165] 5) Mass.

[0166] (d) Does the characteristic meet the coordination requirements proposed by the assembly requirements of higher-level assembly units or field maintainable units?

[0167] When the characteristic does not have structural interchangeability and needs to be selected, adjusted or supplemented during assembly in higher-level assembly units or field maintainable units, then the decision item N4 = 1, otherwise N4 = 0.

[0168] (e) Is the most stringent level of manufacturing and inspection required to ensure the stability of the characteristic?

[0169] In order to ensure the stability of the characteristic and prevent inspection defects such as sampling inspection, inspection equipment, personnel inspection errors from causing the actual characteristic of the product to exceed the design characteristic requirements, it is necessary to determine the most stringent level of manufacturing and inspection, and require complete project traceable inspection records, then the decision item N5 = 1, otherwise N5 = 0. For example: "welds are required to be Class I according to XX standard", "Class I inspection is required according to XX forged piece specification". Or in order to prevent slow deformation caused by machining and welding residual stress, etc., re-inspection of the characteristic before storage and assembly is required and detailed records are required.

[0170] (f) Is the characteristic subject to special inspection or special test requirements?

[0171] When the characteristic needs to use special tooling, equipment, facilities for inspection test or special test project, and the quantitative test requirements and pass criteria are formulated, the test and detection project of this kind generally has higher detection cost and longer cycle, then the decision item N6 = 1, otherwise N6 = 0. These test and detection projects include but are not limited to:

[0172] 1) Casing pressure inspection test;

[0173] 2) Fuel, oil, air flow inspection test;

[0174] 3) Fuel, oil nozzle injection direction inspection test;

[0175] 4) Rotor balance inspection;

[0176] 5) Surface roughness microscopic inspection, including: stylus method inspection, light cutting method inspection, interference method inspection;

[0177] 6) Non-destructive testing, including: ultrasonic testing, X-ray inspection, eddy current testing, fluorescent penetrant testing;

[0178] 7) Batch sampling destructive inspection or detection project.

[0179] Routine external pipeline assembly, welding sealing inspection test, such as: "kerosene chalk method inspection", is not a special inspection test.

[0180] (g) Can the characteristic only be ensured by the process and tooling equipment parameters of the characteristic forming process?

[0181] When the characteristic cannot be detected after processing, but only through the process and tooling equipment parameters in the characteristic forming process, in order to ensure traceability, provide data basis for quality analysis and process improvement, the related parameters of the forming process must be detected and recorded, then the decision item N7 = 1, otherwise N7 = 0.

[0182] The process characteristic control necessity analysis, according to the past experience of aero-engine engineering, since the aero-engine is the "heart" of the aircraft, its failure mode has a serious impact on the flight safety and flight mission of the aircraft. The number of corresponding failure control characteristics is very large. Even after the preliminary classification of related characteristics based on the I, II severity categories, and the reduction of the characteristic category based on the failure mode hazard, there will still be a large number of characteristics that can be divided into key characteristics and important characteristics. This will greatly increase the quality control cost and production cycle of the manufacturing unit.

[0183] According to the key characteristics, the important characteristics, the main purpose determined by the key characteristics and the important characteristics, the quality control related regulations of the key parts and the important parts, the control requirements of the incoming inspection, the process establishment, the unqualified product review and other aspects, combined with the characteristics of the aero-engine design, manufacturing, assembly and inspection, the life, structural strength, structural interchangeability, assembly coordination, manufacturing inspection level, test and detection, process assurance parameters and other characteristic types which have greater influence on the quality stability and quality cost of the manufacturing, assembly and inspection processes are selected, and seven necessary determination criteria are summarized and determined.

[0184] 4.3 Based on the final determination of the process characteristics based on the preliminary classification and the necessity determination, the level of the process characteristics is determined according to the calculation results of formula (10):

[0185]

[0186] In the formula:

[0187] Nj— The jth necessity determination item value, j = 1 ~ 7, corresponding to the 7 determination items respectively;

[0188] PCG i '— The preliminary classification level value of the ith process characteristic, PCG' = 100, 10, 0, corresponding to the key characteristics, important characteristics, general characteristics of the preliminary classification respectively.

[0189] PCG i — The final determined level value of the ith process characteristic, when PCG i ≥ 100, the process characteristic should be determined as a key characteristic; when 10 ≤ PCG i < 100, the process characteristic should be determined as an important characteristic; when PCG i = 0, the process characteristic should be determined as a general characteristic.

[0190] Step S05: Determine the key parts and the important parts; based on the process characteristic analysis results, the key parts and the important parts are determined according to the key part and the important part determination principle.

[0191] (a) The parts or assemblies containing key characteristics should be determined as key parts;

[0192] (b) The parts or assemblies not containing key characteristics but containing important characteristics should be determined as important parts;

[0193] (c) When a part is determined as a key part or an important part, it only means that the part contains key characteristics or important characteristics which need to be controlled in the part blank manufacturing, machining, heat treatment and other links, and it does not mean that the assembly to which it belongs is a key part or an important part;

[0194] (d) When the higher-level assembly is determined as a critical component or an important component, only the critical characteristics or important characteristics contained in the assembly level drawing are represented, which need to be controlled in the assembly, welding, inspection and other links, and the contained sub-components are not represented as critical components or important components.

[0195] The critical component and important component determination principle is that, in the past, when determining the critical component and important component, the principle is not clear enough, and the problem of the upper assembly being a critical component when the part is a critical component often occurs, causing confusion in the quality control link. The core of the critical component and important component quality control is the critical characteristics or important characteristics carried by the part or assembly drawing. The specific carrier of the process characteristics is combined to clarify the critical component and important component determination principle: the critical component and important component are the parts or assemblies corresponding to the part or assembly drawing carrying the critical characteristics or important characteristics.

[0196] Specifically, the MTBF of a certain type of aero-engine is 180h, and the average mission time is 1h. The combustion chamber component characteristic analysis steps are as follows:

[0197] Step S01: Determine the I and II type failure modes based on failure mode, effect and criticality analysis, and determine the characteristics related to failure mechanism. The combustion chamber component FMECA analysis results are shown in Table 1.

[0198] Table 1 Failure mode, effect and criticality analysis table with failure control as the core

[0199]

[0200] Step S02: Determine the process characteristic carrier based on the process control link. The combustion chamber component process characteristic carrier analysis is shown in Table 2.

[0201] Table 2 Process characteristic carrier analysis table

[0202]

[0203] Step S03: Determine the acceptable I and II type failure mode criticality

[0204] According to formula (1), the I type failure mode criticality CAI is calculated m = 0.0556 x 10 -6 ;

[0205] According to formula (2), the II type failure mode criticality CAII is calculated m = 2.78 x 10 -6 .

[0206] Step S04: Divide the characteristic level according to the logical decision method

[0207] According to the logical decision method, the process characteristic grade value is determined according to formula (6), (7), (8), (9), (10), and the characteristic grade is determined. The process characteristic analysis process is shown in Table 3.

[0208] Table 3 Process characteristic analysis table

[0209]

[0210] Step S05: Determine the key parts and important parts.

[0211] According to the key part and important part determination principle, the determination result of the combustion chamber part key part and important part is shown in Table 4.

[0212] Table 4 Key characteristic and important characteristic statistical table

[0213]

[0214] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or use of the content of the present application specification and drawings within the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A method of logic-decision based aeroengine process property analysis, characterized by, It comprises the following steps: Step S01: determining the process characteristics related to the failure mechanism of the first and second failure modes based on the failure mode effect and criticality analysis with failure control as the core; Step S02: determining the process characteristic carrier based on the process control link; Step S03: determining the acceptable failure mode criticality of the first and second failure modes; Step S04: dividing the necessity level of process characteristic quality control according to the logical decision method; Step S05: determining the key parts and important parts; In step S01, the failure control core includes design characteristics, process characteristics, and verification methods. The design characteristics include structural strength design, environmental resistance design, backup design, redundancy design, structural redundancy design, superstatic design, and protection design characteristics. The process characteristics are the size tolerance, surface roughness, surface strengthening treatment, forging, casting level requirements, and flaw detection characteristics developed to control the quality of the process manufacturing, assembly, welding, and inspection process based on the design characteristics for design defects and manufacturing defects in the failure mechanism. The verification method includes the calculation analysis, simulation analysis, and test verification projects developed to verify the effectiveness of the design characteristics and process characteristics. In step S02, when the process characteristic type is blank quality characteristics, mechanical processing characteristics, or thermal surface treatment characteristics, the carrier should be the part-level design drawing. When the process characteristic type is assembly characteristics, welding characteristics, combined processing characteristics, or combined inspection characteristics, the carrier should be the component-level and above-level design drawing. In the step S03, for the type I failure mode, the type I failure mode acceptable failure mode criticality CAI is calculated by formula (1) m : CAI m = 0.001 · λ Z · 0.1 · t … … … (1) For the type II failure mode, the acceptable failure mode criticality CAII of the type II failure mode is calculated by formula (2) m : CA II m = 0.01 · λ Z · 0.5 · t … … … (2) In the formula: λ Z - The total probability of failure of the aeroengine over its lifetime, calculated by the inverse of the aeroengine MTBF; t is the average mission working time of the aero-engine; In the failure mode effect and criticality analysis method based on the core of failure control, the quantitative criticality matrix analysis method is used to calculate the criticality C of different severity degrees m ; The quantitative hazard matrix analysis calculates the probability C of the failure mode in the working state resulting in the final impact of the failure according to the failure rate of the analyzed object, the failure mode frequency ratio, the failure mode impact probability, and the working state time mj As shown in formula (3): C mj = a j · β j · λ p · t … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … In the formula: a j - failure mode frequency ratio, ratio of the number of occurrences of the jth failure mode of the object under analysis to the number of all possible failure modes of the work unit, j = 1, 2, …, n, n being the total number of failure modes of the object under analysis; β j - failure mode impact probability, the conditional probability that the analyzed object leads to the occurrence of an engine end impact consequence of a certain severity under the condition that the jth failure mode occurs; λ p - failure rate of the object under analysis in its mission phase, in 1 / h; t is the working time of the analyzed object in the mission stage, in hours; For the category I failure mode, in the case that the failure source cannot be completely eliminated, its acceptable failure mode occurrence probability P mj A very low level is required, and its failure mode occurrence probability needs to be less than 0.1% of the total failure probability of the aero-engine, i.e. a j · l p ≤ 0.001 · l Z ; The failure influence probability thereof needs to reach a negligible degree, i.e. β j <0.1; the failure mode hazard degree CAI of the failure mode of type I is calculated by formula (4) m : C mj = a j • λ p • β j • t < CAl m = 0.001 • λ Z • 0.1 • t... (4) For the category II failure mode, the acceptable failure mode occurrence probability P mj A lower level is required, with a failure mode occurrence probability less than 1% of the total failure probability of the aeroengine, i.e. a j · λ p ≤ 0.01 · λ Z ; The failure influence probability thereof needs to reach the possible loss degree, that is, 0.1≤β j <0.5, so the acceptable failure mode hazard degree CAII of the type II failure mode is calculated by formula (5) m : C mj = a j • λ p • β j • t < CA II m = 0.01 • λ Z • 0.5 • t... (5) In the formula: λ Z - The total probability of failure of the aeroengine over its lifetime, calculated by the inverse of the aeroengine MTBF; t is the average mission working time of the aero-engine; In step S4, the related process characteristics are preliminarily classified based on the severity category and criticality of the first and second failure modes: When the failure mode severity category related to the process characteristics is category I, the preliminary classification of the process characteristic level is performed according to formulas (6) and (7): When S = 1, and C m ≥ CAI m : PCG i = 100 …………………… (6) When S = 1, and C m <CAI m When S = 1, and C PCG i = 10 …………………… (7) When the failure mode severity category related to the process characteristics is category II, the preliminary classification of the process characteristic level is performed according to formulas (8) and (9): When S = 2, and C m ≥ CAII m : PCG i = 10 …………………… (8) When S = 2, and C m <CA II m when: PCG i = PCG i = 0 (9) In the formula: S is the failure mode severity category, S=1, 2, corresponding to categories I and II, respectively; C m — process property corresponding to the failure mode criticality; CAI m - Acceptable Class I failure mode hazard; CA II m - Acceptable Class II failure mode severity; PCG i the preliminary classification grade value of the i th process characteristic, PCG = 100, 10, 0, corresponding to the preliminary classification of key characteristics, important characteristics, general characteristics, respectively; PCG i - the final grade value of the i-th process characteristic, PCG = 0 indicates a general characteristic; Based on the preliminary level classification and necessity determination, the level of the process characteristic is finally determined, and the result is calculated according to formula (10) to determine the level of the process characteristic: PCG i = PCG i 'x (10) In the formula: Nj is the value of the jth necessity decision item, j=1-7, corresponding to 7 decision items; PCG i the preliminary classification grade value of the i th process characteristic, PCG = 100, 10, 0, corresponding to the preliminary classification of key characteristics, important characteristics, general characteristics, respectively; PCG i - the final determined grade value of the i-th process characteristic, when PCG i ≥ 100, the process characteristic should be determined as a critical characteristic; when 10 ≤ PCG i < 100, the process characteristic should be determined as an important characteristic; when PCG i = 0, the process characteristic should be determined as a general characteristic; In step S05, the parts or components containing key characteristics should be determined as key parts, and the parts or components not containing key characteristics but containing important characteristics should be determined as important parts.

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