CN107066725B - Rotor structure dynamics reverse design method based on fault genes - Google Patents

Rotor structure dynamics reverse design method based on fault genes Download PDF

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CN107066725B
CN107066725B CN201710230765.8A CN201710230765A CN107066725B CN 107066725 B CN107066725 B CN 107066725B CN 201710230765 A CN201710230765 A CN 201710230765A CN 107066725 B CN107066725 B CN 107066725B
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王俨剀
廖明夫
王鑫
程盼
李波
邓炜坤
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Northwestern Polytechnical University
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Abstract

A rotor structure dynamics reverse design method based on fault genes is characterized in that an initial structure design of a rotor is carried out according to the design requirements of the rotating speed and the power function of the rotor, and the critical rotating speed and the vibration mode are obtained; carrying out fault gene screening, establishing a fault gene library of the rotor-supporting system, and determining dominant genes and expressions of the dominant genes of the initial structure of the rotor; and estimating the fault response of the dominant fault of the initial structure of the rotor, if the fault response is prominent, adjusting the structural parameters of the rotor according to the genetic factors, and estimating the fault response again until the requirements are met. The method can predict the potential vibration fault in the design process, and carry out structural adjustment and optimization aiming at the specific fault, thereby reducing the possibility of fault occurrence to the maximum extent, improving the capability of the aeroengine structural dynamics design result to accommodate typical faults, indicating the direction for the rotor dynamics characteristic optimization, shortening the development period of a rotor system and saving the development cost at the same time.

Description

Rotor structure dynamics reverse design method based on fault genes
Technical Field
The invention relates to the field of aeroengine dynamics design, in particular to a method for designing aeroengine rotor structure dynamics.
Technical Field
Structural dynamics design is an important part in the design of aircraft engines. If the design is improper, the vibration of the whole machine exceeds the standard, and the reliability problem of the aero-engine is brought. Even causing structural damage to parts and causing flight accidents.
The design of the structure dynamics of the prior aero-engine mainly adopts the idea of forward design, namely the design point is the normal working condition of a rotor. The current design flow is as follows: starting from the overall parameters of the engine, the rotor structure is preliminarily designed, and then the dynamic characteristics under normal conditions are calculated to obtain the critical rotating speed and the vibration mode of the engine. And (4) testing whether the requirement of the upper limit of the vibration of the whole machine is met or not through the manufacturing and the assembly of the prototype. If the vibration frequently exceeds the standard, the design of the rotor-supporting system is adjusted and modified. The conventional design concept does not consider the deviation generated in the manufacturing, assembling and operating processes completely in the calculation process. Resulting in zero tolerance of the design result to "failure", and the similarity of the vibration characteristics and the design result can only be guaranteed with high precision manufacturing and assembly. Minor manufacturing and assembly variations, or changes in conditions during operation, may cause the vibrations to be out of specification. The designed engine rotor system is easy to be disturbed by the exceeding of vibration, and the inherent defect is caused.
In european patent DE102005052819a1, a new type of connection is proposed for use in the construction of aircraft engines rotors. By adopting the design of the multi-piece connecting rod, the welding seam between each stage of compressor disk and turbine disk caused by the traditional welding is eliminated, the service life of the engine is prolonged, and the assembling and maintaining processes of the rotor are simplified. But does not relate to rotodynamic design.
Florjacic, Stefan S. in the Rotor design in induced gas turbines (ISSN:04021215) paper introduces several basic criteria for Rotor design, together with the strength and dynamics requirements at Rotor steady state and transient state. The differences of the load and the rotor dynamic performance of several existing rotors are discussed, and a specific method for designing the rotor structure dynamics is provided, but the design idea is a forward design.
In the domestic patent, the invention with the publication number of CN205538223U creates an aeroengine multi-factor coupling vibration control comprehensive experiment table. The aeroengine main body of the experiment table is formed by modifying a real aeroengine, the high-voltage rotor and the low-voltage rotor are respectively powered by the motor, and the vibration condition of the high-voltage and low-voltage double-rotor systems of the aeroengine under the maneuvering flight condition is reflected more truly. The invention can be used for measuring the influence of the coupling fault on the vibration of the high-voltage rotor and the low-voltage rotor. However, the rotor system adopts a forward design idea, and the sensitivity of the easy-to-fault to the size of the tester is not considered.
In the invention with the publication number of CN201410146849.X, the invention provides a design method of the rotor structure dynamics of an aircraft engine, and the thermal mode of a rotor system avoids the mode of the rotor when the support is absolutely rigid by optimizing the parameters of the rotor and the support, so that the rotor system meets the requirement of the vibration standard in the thermal mode. The core of the engine is to ensure that the rotor can work stably in the whole working rotating speed range of the engine. But in the modeling calculation process, the factor of the fault force is not considered.
Aiming at the problem that the current design method only considers the normal working condition, the invention provides a rotor structure dynamics reverse design method based on fault genes.
Disclosure of Invention
The invention provides a rotor structure dynamics reverse design method based on fault genes, aiming at solving the problem that the design condition is only normal working condition in the current aero-engine structure dynamics design method.
The specific process of the invention is as follows:
step 1, determining an initial structure of an aircraft engine rotor.
Step 2, determining the critical rotating speed and the vibration mode of the rotor-supporting system:
and (3) calculating the critical rotating speed and the vibration mode of the initial structure of the rotor by a transfer matrix method according to the initial design parameters of the rotor of the aircraft engine determined in the step (1).
Step 3, determining a fault gene library of the rotor-bearing system:
potential faults of the rotor-bearing system include unbalance faults and misalignment faults. Therefore, the established fault gene library comprises two fault genes. Each fault gene reflects rotor characteristics and fault information and comprises component information, rotor information, gene segments, fault representation, gene rules and genetic factors, and the form of the fault gene is that the name of the fault gene is < component information > < rotor information > < gene segments > < fault representation > < gene rules > < genetic factors >; the symbol "< >" is the specific content of the rotor characteristic and the fault information, and the respective "< >" are in parallel relation.
The component information refers to the specific structure reflecting the specific chain, namely the main carrier generating the fault.
The rotor information refers to unchangeable physical factors in the initial structure of the rotor.
The gene segment refers to a structural parameter which can be optimized and adjusted in the initial structure of the rotor.
The fault appearance refers to the fault characteristics of the specific chain under study in actual vibration.
The gene rule refers to the relationship between the established fault appearance and the fault degree.
The genetic factors reflect the sensitivity of the fault representation to structural parameters.
Step 4, determining dominant fault genes of the rotor-bearing system:
and (3) providing a dividing principle of dominant/invisible expression of fault genes of the rotor-bearing system, namely taking the fault occurrence rate and the fault association degree as dividing standards. Through the analysis of a typical fault mechanism of the rotor system, the fault type which has high fault occurrence rate and is easy to induce other types of faults to occur is classified as an explicit fault.
Step 5, determining the structural parameter sensitivity of the dominant fault gene:
and (4) screening dominant fault genes from the fault gene library determined in the step (3). The genetic factor of the dominant fault gene is analyzed by a mathematical method to obtain the rule of influence of the rotor structural parameters on vibration, so that the sensitivity of the dominant fault gene on the structural parameters is determined.
Step 6, determining a structural optimization scheme for reducing the fault risk:
the structural optimization scheme for determining and reducing the fault risk is to estimate the dominant fault characteristic frequency multiplication amplitude and optimize the structural parameters with high sensitivity according to the genetic factors so as to reduce the influence of the dominant fault characteristic frequency multiplication on the vibration amplitude.
The specific process for determining the structural optimization scheme for reducing the fault risk is as follows: and (3) estimating the characteristic frequency multiplication amplitude of the dominant fault by using the initial structure parameters of the rotor and substituting the genetic factors, optimizing the initial structure of the rotor according to the genetic factors, adjusting the structure parameters of the rotor, and calculating the critical rotating speed of the rotor again. According to default design criteria, the critical rotation variation caused by rotor structure adjustment should not exceed +/-5%, otherwise dynamic design needs to be carried out again.
The method can improve the capacity of the aeroengine structure dynamics design result to contain typical faults.
The invention provides an expression mode of a fault gene of an aeroengine. Each fault gene comprises information reflecting rotor faults and characteristics, and the form of the fault gene is that the name of the fault gene is < part information > < rotor information > < gene fragment > < fault representation > < gene rule > < genetic factor >. The gene comprises the following information on the hexagonal aspect: a. the part information refers to the specific structure reflecting the specific chain, i.e., the primary carrier that generated the problem. If an imbalance fault exists in the rotating structure of the rotor, misalignment of the coupling often causes misalignment fault of the rotor structure. b. The rotor information refers to unchangeable physical factors in the initial structure of the rotor, such as rotor mass, bearing rigidity and the like. c. The gene segment refers to a structural parameter which can be optimized and adjusted in the initial structure of the rotor. d. The fault appearance refers to the fault characteristics of the specific vibration of the studied special chain, such as unbalanced fault which usually represents the predominance of one frequency multiplication in the vibration amplitude, and unbalanced fault which usually represents the predominance of two frequency multiplication in the vibration amplitude. e. The gene rule establishes the relation between fault representation and fault degree, and if the fault is not centered, the gene rule is the relation between vibration frequency doubling amplitude and horizontal offset. f. The genetic factor reflects the sensitivity of the fault representation to the structural parameters, and if the fault is not centered, the vibration frequency doubling amplitude is influenced by the structural parameters such as the support span and the like.
The invention provides a dividing principle of dominant/invisible expression of fault genes of a rotor-bearing system. Namely, the fault occurrence rate and the fault association degree are used as division standards. Through the analysis of a typical fault mechanism of the rotor system, the fault type which has high fault occurrence rate and is easy to induce other types of faults to occur is classified as an explicit fault. If the capability of the rotor structure for accommodating the dominant faults can be improved, the method has important significance for reducing the incidence rate of related fault types and improving the reliability of the engine.
According to the design requirements of the rotating speed and the power function of the rotor, the initial structure design of the rotor is carried out, the dynamic characteristics of the rotor are calculated, and the critical rotating speed and the vibration mode are obtained; then carrying out fault gene screening, establishing a fault gene library of the rotor-supporting system, and determining dominant genes and expressions of the dominant genes of the initial structure of the rotor; and then estimating the fault response of the dominant fault of the initial structure of the rotor, if the fault response is prominent, adjusting the structural parameters of the rotor according to the genetic factors, and estimating the fault response again until the requirements are met. The method can predict the potential vibration fault in the design process, and carry out structural adjustment and optimization aiming at the specific fault, thereby reducing the possibility of fault occurrence to the maximum extent and improving the capacity of the aeroengine structural dynamics design result to typical faults.
The invention has the beneficial effects that:
for the traditional aeroengine rotor design concept, the deviation generated in the manufacturing, assembling and operating processes is not considered in the calculation process. If the vibration of the prototype frequently exceeds the standard, the rotor-supporting system is adjusted and modified. The design method provided by the invention considers the influence of the fault force on the rotor vibration in the design process, and the dynamic design result is specifically adjusted according to the fault gene expression, so that the direction is pointed for optimizing the rotor dynamic characteristics. The process of repeated adjustment in the traditional method is avoided, the development period of the rotor system is shortened, and the development cost is saved.
According to the reverse design step, faults are considered in the design process, and the tolerance degree of the faults is improved by estimating the fault response of the rotor and adjusting the structural parameters of the rotor. By means of the embodiment, for the guiding groove of the experiment table causing misalignment fault, the initial structure of the rotor is optimized by adopting the method of moving the support K2 by using the reverse design method, and the optimization result is shown in FIG. 10. The support K2 moves 0.1135m, two support spans l1The vibration frequency doubling amplitude A is adjusted from 0.7475m to 0.8610m2The fault tolerance is reduced from 110.99um to 87.58um, and the fault tolerance is improved by 21.09 percent after optimization. In the figure, curve 6 is the initial rotor configuration l10.7475m time double frequency amplitude curve, curve 7 is the optimized structural parameter10.8610m time double frequency amplitude curve.
Drawings
FIG. 1 is a schematic diagram of a reverse design method according to the present invention.
FIG. 2a is a top view of the laboratory bench; FIG. 2b is a side view of the laboratory bench.
FIG. 3 is a rotor dynamics model diagram.
FIG. 4a is a first order mode of vibration of the rotor system; fig. 4b shows the second order mode shape of the rotor system.
FIG. 5 is a schematic view of an imbalance fault dynamics model.
Fig. 6 shows the rotation locus of the coupling.
FIG. 7 is a misalignment fault geometry diagram.
FIG. 8 shows the frequency doubling amplitude of vibration with the structural parameter l1A trend graph of the change.
FIG. 9a is a first order mode shape of the optimized rotor system; FIG. 9b shows the second order mode shape of the optimized rotor system.
Fig. 10 is a graph of the initial structure of the rotor and the double frequency amplitude versus the optimized rotor.
FIG. 11 is a flow chart of the present invention.
In the figure: 1. a guide groove; 2. a support; 3. a disc; 4. a rotor shaft; 5. a motor; 6. initial rotor Structure10.7475m time double frequency amplitude curve; 7. structural parameter optimized10.8610m time double frequency amplitude curve; and 8, a coupler.
Detailed Description
The embodiment provides a rotor structure dynamics reverse design method based on fault genes for a certain engine rotor fault simulation tester, and the rotor tester is designed on an existing experiment table. As shown in fig. 2a and 2b, the guide groove 1 on the test bench is used for embedding the support 2, but it is difficult to precisely control the horizontal misalignment, and the generated horizontal offset can reach 10mm at most. The method is adopted to design the rotor so as to improve the capacity of the rotor to accommodate the misalignment fault. The specific process is as follows:
step 1, determining the initial structure of an aircraft engine rotor
And (3) preliminarily designing the mechanical characteristics of the initial structure of the rotor of the aircraft engine. Simplifying the rotor structure into a single-span double-disk rotor model shown in FIG. 3Where l is the length of the rotor shaft 4, l1Two spans of support 2,/2For supporting the distance K2 from the coupling, mp，rpRespectively the mass and the radius of the disc 3. The target power of the designed rotor system is 11kw, the target working rotating speed is 3500r/min, and the target working rotating speed is between the first-order critical rotating speed and the second-order critical rotating speed of the rotor. And the primary design of the single-span double-disc rotor is carried out by adopting a transfer matrix method. Preliminary design parameters for the rotor structure were obtained as shown in table 1.
TABLE 1 rotor design parameters
Figure GDA0001297581320000051
Step 2: determining critical speed and mode shape of rotor-bearing system
And (3) calculating the critical rotating speed and the vibration mode of the initial structure of the rotor by a transfer matrix method according to the initial design parameters of the rotor of the aircraft engine determined in the step (1).
In the embodiment, the first-order critical rotating speed of the initial structure of the rotor is 3060.5r/min, and the first-order vibration mode is a bending vibration mode; the second-order critical rotating speed is 8484.6r/min, and the second-order vibration mode is a pitching vibration mode. As shown in fig. 4a, 4 b.
Step 3, determining a fault gene library of the rotor-bearing system
Potential faults of the rotor-bearing system include unbalance faults and misalignment faults. Therefore, the established fault gene library comprises two fault genes. Each fault gene reflects rotor characteristics and fault information and comprises component information, geometric information, fault representation and genetic factors, and the form of the fault gene is that the name of the fault gene is < component information > < rotor information > < gene fragment > < fault representation > < gene rule > < genetic factor >; the symbol "< >" is the specific content of the rotor characteristic and the fault information, and the respective "< >" are in parallel relation.
The component information refers to the specific structure of the specific chain, i.e., the main carrier for generating the problem. If an imbalance fault exists in the rotating structure of the rotor, misalignment of the coupling often causes misalignment fault of the rotor structure.
The rotor information refers to unchangeable physical factors in the initial structure of the rotor, such as rotor mass, supporting rigidity and the like.
The gene segment refers to a structural parameter which can be optimized and adjusted in the initial structure of the rotor.
The fault expression refers to the fault characteristics of the specific tested specific chain in the actual vibration, for example, unbalanced fault usually represents a first frequency multiplication in the vibration amplitude, and unbalanced fault usually represents a second frequency multiplication in the vibration amplitude.
The gene rule refers to the relationship between the established fault appearance and the fault degree, and if the fault is not centered, the gene rule refers to the relationship between the vibration frequency doubling amplitude and the horizontal offset.
The genetic factor reflects the sensitivity of the fault representation to structural parameters, and if the fault is not centered, the vibration frequency doubling amplitude is influenced by the structural parameters such as the support span and the like.
Analyzing the cause of the unbalance fault existing in the rotor-bearing system fault and deducing the genetic factor of the unbalance fault:
imbalance faults of the rotor structure can be caused due to uneven rotor material, additional keys, corrosion and abrasion.
And (3) establishing a dynamic model for the unbalanced fault to analyze a fault mechanism, and determining a genetic factor of the unbalanced fault through deduction. The imbalance fault dynamics model is shown in fig. 5, where the rotor deflection is a, O is located on the bearing center line, O' is the geometric center of the disk 3, the geometric center motion coordinates are (x, y), the center of gravity is P, and the center of gravity coordinates are (x, y)p,yp) Initial phase of
Figure GDA0001297581320000071
The eccentricity of the rotor is epsilon and the rotating speed is omega.
Solving the differential equation of motion of the geometric center O' of the disc can obtain:
Figure GDA0001297581320000072
where ω is the critical speed of the rotor system and D is the damping ratio.
Vibration-frequency multiplication amplitude A1Is that
Figure GDA0001297581320000073
Order to
Figure GDA0001297581320000074
At this time
A1＝|C1ε| (4)
Formulas 3 and 4 are genetic factors and gene rules of the imbalance fault respectively.
Analyzing the cause of the misalignment fault of the rotor-bearing system fault and deducing the genetic factor of the misalignment fault:
in the experiment table, the horizontal centering degree of the rotor structure cannot be guaranteed by the guide groove 1, so that a misalignment fault is generated.
And (4) establishing a dynamic model for the misalignment fault to perform fault mechanism analysis, and determining a genetic factor of the misalignment fault. The rotation track of the coupler in the presence of misalignment of parallel deflection angles is shown in figure 6, wherein o1，o2The center of the two half couplings, o '(x, y) is the dynamic center of the coupling, omega is the rotor speed, omega' is the angular speed of the dynamic center of the set teeth, α, β are the initial phases, and B is the misalignment.
According to the deformation relation of the beam under the action of the load force F in the mechanics of materials:
Figure GDA0001297581320000075
where E is the modulus of elasticity, I is the moment of inertia, and l is the length of the rotor shaft 4.
As shown in fig. 7, the horizontal offset of the bearing is d, which is derived from the geometrical relationship:
Figure GDA0001297581320000076
the equation of motion for the rotor system is:
Figure GDA0001297581320000081
solving to obtain a vibration frequency doubling amplitude:
Figure GDA0001297581320000082
order to
Figure GDA0001297581320000083
Then
A2＝|C2d| (10)
Formulas 9 and 10 are genetic factors and gene rules for misalignment faults, respectively.
After genetic factors of potential faults of the rotor structure are obtained through derivation, fault information is summarized to form a fault gene library, and the fault gene library is shown in table 2.
TABLE 2 rotor-bearing System failure Gene library
Figure GDA0001297581320000084
Step 4, determining dominant fault genes of the rotor-bearing system
The invention provides a dividing principle of dominant/invisible expression of fault genes of a rotor-bearing system, namely, the dividing criterion is the fault occurrence rate and the fault association degree. Through the analysis of a typical fault mechanism of the rotor system, the fault type which has high fault occurrence rate and is easy to induce other types of faults to occur is classified as an explicit fault. If the capability of the rotor structure for accommodating the dominant faults can be improved, the method has important significance for reducing the incidence rate of related fault types and improving the reliability of the engine.
In the embodiment, in the construction of the rotor, the rotor is balanced by adopting the field dynamic balancing technology, and the influence of the unbalance amount can be controlled within an acceptable range. However, the guide groove of the experiment table can not ensure the centering degree of the rotor, and the misalignment fault is easily caused. The misalignment fault is determined to be the dominant fault in the rotor-bearing system when designing the rotor structure.
Step 5, determining the structural parameter sensitivity of dominant fault gene
And (4) screening dominant fault genes from the fault gene library determined in the step (3). The genetic factor of the dominant fault gene is analyzed by a mathematical method to obtain the rule of influence of the rotor structural parameters on vibration, so that the sensitivity of the dominant fault gene on the structural parameters is determined.
In this embodiment, the dominant fault gene is an misalignment fault gene. According to the description of step 3, the misalignment fault gene comprises component information, rotor information, gene segments, fault representations, gene rules and genetic factors. Wherein: the component information is the main carrier that causes this problem, in this embodiment the coupling; the rotor information refers to unchangeable physical factors in the initial structure of the rotor, and in the embodiment, the physical factors refer to rotor mass m, rotor shaft length l, supporting rigidity k and rotor rotating speed omega; the gene segment refers to the structural parameters of the initial structure of the rotor which can be optimized and adjusted, in this embodiment, the support span l1(ii) a Distance l from K2 to coupling2(ii) a The fault appearance refers to the fault characteristics of the specific chain under study in actual vibration, and in the embodiment, refers to vibration frequency doubling amplitude; the gene rule refers to the relationship between the fault appearance and fault degree, in this embodiment, the vibration frequency doubling amplitude A2In relation to the horizontal offset d, i.e. A2＝|C2d |; the genetic factor reflects the sensitivity of the fault representation to the structural parameters, in this embodiment, the vibration frequency doubling amplitude is measured by the structural parameter l1、l2The influence of (c). Namely, it is
Figure GDA0001297581320000091
In this example, the selected misalignment fault geneThe expression form is that the gene is not aligned<Coupling device><m、l、k、Ω＞＜l1、
Figure GDA0001297581320000092
In this example,/1＝747.5mm，l2249mm, 10mm, 33.09kg of rotor mass m, 1030mm of rotor shaft 4 length l, 1 × 10 of bearing stiffness k9N/m。
The structural parameter l of the vibration frequency doubling effect caused by the misalignment fault can be known from the genetic factor of the misalignment fault1、l2The influence of (c). The vibration frequency doubling is inversely proportional to the two support spans l1I.e. vibration doubling with two support spans l1Is increased or decreased with two support spans l1Decrease and increase; the vibration frequency doubling is proportional to the distance l between the support K2 and the coupling2I.e. vibration doubling with bearing K2 to coupling distance l2Increases with the increase of the bearing K2 to the coupling distance l2Is reduced.
To reduce the amplitude of the vibration double frequency, two optimization methods are known from genetic factors: moving the support K1 to one end of the rotor shaft to make the support K1 far away from one end of the coupler, or moving the support K2 to the other end of the rotor shaft to make the support K2 near one end of the coupler; let the support move a distance l in both methodsKAnd the two adjusted support spans are recorded as l'1Support K2 to coupling distance l'2The sensitivity of the vibration double frequency amplitude to the structural parameters is now determined based on the genetic factors.
L 'when moving support K1'1＝l1+lK,l′2＝l2The genetic factor is
Figure GDA0001297581320000101
C is to be2To lKDerivation
Figure GDA0001297581320000102
L 'when moving support K2'1＝l1+lK,l′2＝l2-lKThe genetic factor is
Figure GDA0001297581320000103
At this time, C is2To lKDerivation
Figure GDA0001297581320000104
It is evident from equations 11 and 12 that both optimization methods reduce the frequency of the vibration double, and the degree of reduction of the vibration double by the movable support K2 is that of the movable support K1
Figure GDA0001297581320000105
The moving support K2 is more significant in reducing the vibration frequency doubling.
Step 6, determining a structural optimization scheme for reducing fault risk
The structural optimization scheme for determining and reducing the fault risk is to estimate the dominant fault characteristic frequency multiplication amplitude and optimize the structural parameters with high sensitivity according to the genetic factors so as to reduce the influence of the dominant fault characteristic frequency multiplication on the vibration amplitude. The specific process is as follows: and (3) estimating the characteristic frequency multiplication amplitude of the dominant fault by using the initial structure parameters of the rotor and substituting the genetic factors, optimizing the initial structure of the rotor according to the genetic factors, adjusting the structure parameters of the rotor, and calculating the critical rotating speed of the rotor again. According to default design criteria, the critical rotation variation caused by rotor structure adjustment should not exceed +/-5%, otherwise dynamic design needs to be carried out again.
For the initial structure of the rotor in this embodiment, the rotor mass m is 33.09kg, EI is 1.6493 × 10 kg3Nm2L is 1.03m, D is 0.05, ω is 3060.5r/min, and Ω is 0.5 ω. The frequency doubling amplitude caused by misalignment is A2110.99 um. In this embodiment, horizontal misalignment is an overt fault characterized by a doubling of the rotor rotation frequency with outstanding amplitude. Therefore, it is necessary to couple the rotorsAnd structural parameters are optimized, the frequency doubling amplitude is inhibited, and the sensitivity of the rotor to misalignment faults is reduced. In conjunction with the analysis of the sensitivity in step 5, moving the support K2 closer to the coupler 8 is more beneficial in reducing the frequency doubling amplitude. Obtaining a frequency doubling amplitude value according to the genetic factor1As shown in fig. 8. Adjusting the support K2 to move by a distance lK0.1135m, so that two support spans l'1＝l1+lK0.8610m, K2 distance l 'to coupler 8'2＝l2-lK0.1355 m. The critical rotation speed and the vibration mode of the optimized rotor are calculated by using a transfer matrix method, as shown in fig. 9a and 9b, the first-order critical rotation speed is 2918.5r/min, the second-order critical rotation speed is 8178.2r/min, and the influence on the critical rotation speed is 4.64%. At this time, the double frequency amplitude caused by misalignment is estimated again, and the result is A2The adjusted double frequency amplitude decreased by 21.09% when 87.58um, as shown in fig. 10. Therefore, the sensitivity of the shaft system to the misalignment fault is reduced by optimizing the structural parameters, and the tolerance capability of the rotor structure to the misalignment fault is improved.

Claims (3)

1. A rotor structure dynamics reverse design method based on fault genes is characterized by comprising the following specific processes:
step 1, determining an initial structure of an aircraft engine rotor;
step 2, determining the critical rotating speed and the vibration mode of the rotor-supporting system:
according to the preliminary design parameters of the aircraft engine rotor determined in the step 1, calculating the critical rotating speed and the vibration mode of the initial structure of the rotor by a transfer matrix method;
step 3, determining a fault gene library of the rotor-bearing system:
potential faults of said rotor-support system include unbalance faults and misalignment faults; therefore, the established fault gene library comprises two fault genes; each fault gene reflects rotor characteristics and fault information and comprises component information, rotor information, gene segments, fault representation, gene rules and genetic factors, and the form of the fault gene is that the name of the fault gene is < component information > < rotor information > < gene segments > < fault representation > < gene rules > < genetic factors >;
the symbol "< >" is the specific content of the rotor characteristic and the fault information, and the symbols "< >" are in parallel relation;
step 4, determining dominant fault genes of the rotor-bearing system:
the dividing principle of dominant/invisible expression of fault genes of the rotor-support system is put forward, namely the dividing standard is that the fault occurrence rate and the fault association degree are taken as dividing standards; through typical fault mechanism analysis of a rotor system, fault types which have high fault occurrence rate and are easy to induce other types of faults to occur are classified as dominant faults;
step 5, determining the structural parameter sensitivity of the dominant fault gene:
screening dominant fault genes from the fault gene library determined in the step 3; analyzing the genetic factor of the dominant fault gene by a mathematical method to obtain the rule of influence of the structural parameters of the rotor on vibration, thereby determining the sensitivity of the dominant fault gene on the structural parameters;
step 6, determining a structural optimization scheme for reducing the fault risk:
the structural optimization scheme for determining and reducing the fault risk is to estimate the dominant fault characteristic frequency multiplication amplitude and optimize the structural parameters with high sensitivity according to the genetic factors so as to reduce the influence of the dominant fault characteristic frequency multiplication on the vibration amplitude.
2. The method of claim 1, wherein the rotor structure dynamics based on the failure gene is reverse designed,
the component information refers to a specific structure reflecting a specific chain, namely a main carrier generating the problem;
the rotor information refers to unchangeable physical factors in the initial structure of the rotor;
the gene segment refers to a structural parameter which can be optimized and adjusted in the initial structure of the rotor;
the fault expression refers to the fault characteristics of the specific chain under study in actual vibration;
the gene rule refers to the relationship between the established fault appearance and the fault degree;
the genetic factors reflect the sensitivity of the fault representation to structural parameters.
3. The method for reverse rotor structure dynamics design based on fault genes as claimed in claim 1, wherein the specific process of determining the structure optimization scheme for reducing the risk of faults is as follows: estimating the characteristic frequency multiplication amplitude of the dominant fault by using the initial structure parameters of the rotor and substituting the genetic factors, optimizing the initial structure of the rotor according to the genetic factors, adjusting the structural parameters of the rotor, and calculating the critical rotating speed of the rotor again; according to default design criteria, the critical rotation variation caused by rotor structure adjustment should not exceed +/-5%, otherwise dynamic design needs to be carried out again.
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