Design method of rotor vibration external transmission coefficient based on support dynamic strain test data

Abstract

The present invention provides a method for designing the rotor vibration external transmission coefficient based on the test data of the support dynamic strain, including: Step 1, calculating the deformation of the support structure considering bolt connection; Step 2, calculating the deformation of the support structure with rigid connection; Step 3, obtaining the connection stiffness correction coefficient according to Step 1 and Step 2; Step 4, obtaining the calculation result of the average stress at the patch according to the connection stiffness correction coefficient; Step 5, obtaining the measurement result of the average stress at the patch and the measured data of the external vibration of the engine according to the result of Step 4; Step 6, obtaining the vibration load of the rotor support structure; Step 7, calculating the rotor vibration external transmission coefficient according to the vibration load of the rotor support structure. The present invention establishes the mathematical relationship between the vibration load borne by the rotor support and the vibration response of the external engine casing, and can provide a technical approach for the quantitative evaluation of the safety of the engine support structure and the quantitative prediction of the external vibration response, which has practical engineering significance for the safety design of aeroengines.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and particularly relates to a design method for a rotor vibration external transmission coefficient based on support dynamic strain test data. Background Art

[0002] Aero-engines are characterized by high load, high speed and light weight. When encountering severe working conditions such as blade loss and foreign object damage, the safety problem of the support structure becomes the key to determining the survival ability of aero-engines. Under the extreme state of blade loss, the rotor system of an aero-engine bears impact loads and large unbalanced loads. The loads are transmitted to the support structure through the rotor structure, causing serious damage to the support structure and seriously threatening the bearing capacity of the support structure. Therefore, it is necessary to study the safety problem of the support structure of the aero-engine bearing-support structure under extreme loads.

[0003] At present, there are few related studies on the quantitative evaluation of the safety of the support structure. The difficulty lies in that due to space limitations, it is usually difficult to obtain the loads of the engine support structure. For an aero-engine, loads such as unbalanced excitation during the operation of the rotor are transmitted to the external casing, mounting joints, etc. through the rotor fulcrum and the load-bearing frame, and vibration sensors are usually installed at the vibration response at the casing, which is easy to obtain. However, the internal vibration loads of the rotor support structure are difficult to obtain under the whole-machine state. This article provides a method for evaluating the rotor vibration external transmission coefficient based on support dynamic strain test data. Using this method, on the one hand, the rotor support load can be obtained by back-calculating the easily measured external vibration of the casing, so as to conduct a quantitative evaluation of the safety of the support structure; on the other hand, the external vibration response of the engine can be predicted through the measured load of the rotor support structure or the simulation data of the rotor unbalanced response, which has practical engineering significance for the safety design of the aero-engine support structure. Summary of the Invention

[0004] In view of this, the present invention provides a design method for a rotor vibration external transmission coefficient based on support dynamic strain test data, so as to provide technical support for the quantitative evaluation of the safety of the engine support structure and the quantitative evaluation and prediction of the external vibration response.

[0005] The present invention provides the following technical solutions: A method for designing the rotor vibration external transmission coefficient based on the measured data of the support dynamic strain, including: Step 1, performing the deformation calculation of the support structure considering bolt connection; Step 2, performing the deformation calculation of the support structure with rigid connection; Step 3, obtaining the connection stiffness correction coefficient according to Step 1 and Step 2; Step 4, obtaining the calculation result of the average stress at the patch position according to the connection stiffness correction coefficient; Step 5, obtaining the measurement result of the average stress at the patch position and the measured data of the external vibration of the engine according to the result of Step 4; Step 6, obtaining the vibration load of the rotor support structure; Step 7, calculating the rotor vibration external transmission coefficient according to the vibration load of the rotor support structure.

[0006] Further, Step 1 is specifically as follows:

[0007] Establish a finite element model of the support structure with bolt connection;

[0008] Apply a load to the finite element model of the support structure with bolt connection for static strength calculation, obtain the first deformation result of the support structure, and obtain the first deformation amount S far from the load application position and the displacement constraint position 1 .

[0009] Further, Step 2 is specifically as follows:

[0010] Replace the bolt connection with a rigid connection and establish a finite element model of the support structure with rigid connection;

[0011] Apply a load to the finite element model of the support structure with rigid connection for static strength calculation, obtain the second deformation result of the support structure, and obtain the second deformation amount S far from the load application position and the displacement constraint position 2 and the initial elastic modulus of the material at the rigid connection position .

[0012] Further, Step 3 is specifically as follows:

[0013] Change the elastic modulus at the rigid connection position, apply a load for static strength iterative calculation until , obtain the elastic modulus of the material at the rigid connection position at this time ;

[0014] Obtain the connection stiffness correction coefficient through the formula .

[0015] Further, Step 4 is specifically as follows:

[0016] Considering the connection stiffness correction coefficient, correct the elastic modulus of the material at the bolt connection position, and establish a finite element model of the rigid connection of the support structure at different fulcrum positions;

[0017] Apply the rotor lateral vibration load F for simulation calculation to obtain the stress distribution results of the support structure;

[0018] According to the stress distribution results of the support structure, select the finite element nodes within the grid wire range of the strain gauge patch position;

[0019] The average stress of the finite element nodes to obtain the average stress calculation results at the patch of the support structure .

[0020] Furthermore, step 5 is specifically as follows:

[0021] Measure the actual vibration response data of the casing through the vibration test equipment ;

[0022] Through the formula , obtain the average stress measurement results at the patch, where is the dynamic strain data of the support, and E is the mechanical property data of the material.

[0023] Furthermore, step 6 is specifically as follows:

[0024] According to the formula , obtain the vibration load of the rotor support structure , where F is the rotor lateral vibration load.

[0025] Furthermore, step 6 is specifically as follows:

[0026] Through the formula obtain the single - time rotor vibration transmission coefficient ;

[0027] Through the formula , obtain the final rotor vibration transmission coefficient .

[0028] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above - mentioned technical solutions adopted in the present invention at least include: The present invention establishes a mathematical relationship between the vibration load borne by the rotor support and the vibration response of the engine external casing, which can provide a technical approach for the quantitative evaluation of the safety of the engine support structure and the quantitative prediction of the external vibration response, and has practical engineering significance for the safety design of aero - engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] ​Figure 1 It is a schematic flowchart of an embodiment of the present invention.

[0031] Figure 2 It is a schematic diagram of the chip placement position of an embodiment of the present invention. Detailed implementation manners

[0032] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0033] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0034] As Figure 1 shown, an embodiment of the present invention provides a design method for the rotor vibration external transmission coefficient based on the test data of the support dynamic strain, which specifically includes the following steps:

[0035] Step 1: Calculate the deformation of the support structure considering the bolt connection. Considering the influence of the bolt connection on the rigidity of the engine casing, establish a finite element model of the support structure with bolt connection. Apply a load of magnitude F 0 to the rotor support structure model for static strength calculation, obtain the deformation result of the support structure, and record the deformation amount at the position far from the load application position and the displacement constraint position in the calculation model 0 of F. .

[0036] Among them, the original geometric model of the bolt entity needs to remove the thread and chamfer to simplify the bolt; in the finite element model, the screw and the connecting piece, the nut and the connecting piece, and the nut and the screw are connected rigidly, and the contact surfaces of the connecting pieces are in frictional contact.

[0037] Step 2: Calculate the deformation of the support structure with rigid connection. Remove the bolts and replace the bolt connection with a rigid connection to establish a finite element model of the support structure with rigid connection. Apply a load of magnitude F 0 to the rotor support structure model for static strength calculation, obtain the deformation result of the support structure, and record the deformation amount at the same position as in Step 1 and the initial elastic modulus of the material at the rigid connection position .

[0038] Step 3: Calculate the connection stiffness correction coefficient. For the finite element model of the support structure with rigid connection, change the elastic modulus of the connection part, apply a load of magnitude F 0 for iterative calculation until , record the elastic modulus of the material at the rigid connection position at this time . The connection stiffness correction coefficient .

[0039] Step 4 Obtain the average stress calculation result at the strain gauge patch. Considering the connection stiffness correction factor, correct the material elastic modulus at the bolt connection position, and establish a rigid connection finite element model of the support structure at different fulcrums. Then apply the rotor lateral vibration load F for simulation calculation to obtain the stress distribution result of the support structure. According to the finite element simulation stress distribution result of the support structure, select the finite element nodes within the grid wire range of the strain gauge patch position, calculate the average stress of these finite element nodes in these areas, and obtain the average stress calculation result at the strain gauge patch of the support structure .

[0040] Step 5 Obtain the average stress measurement result at the strain gauge patch and the measured data of the external vibration of the engine. Paste strain gauges on the support structure at the rotor fulcrum, and measure the dynamic strain data of the support through the strain test equipment . Install vibration sensors on the engine casing, and measure the measured vibration response data of the casing through the vibration test equipment . According to the dynamic strain test result of the support structure and the material mechanics performance data, use the stress-strain theoretical formula to obtain the average stress measurement result at the strain gauge patch , where E is the material mechanics performance data.

[0041] Step 6 Obtain the vibration load of the rotor support structure. According to the stress measurement result at the support strain gauge patch and the support deformation simulation calculation result, calculate the vibration load of the rotor support structure , and the calculation formula is , where F is the rotor lateral vibration load.

[0042] Step 7 Calculate the rotor vibration transmission coefficient. According to the vibration load of the rotor support structure , and the corresponding measured vibration response data of the casing , calculate the single-time rotor vibration transmission coefficient , and the calculation formula is , as specifically shown in Table 1 below. Perform a mathematical average on the rotor vibration transmission coefficients during multiple tests at multiple measurement points to obtain the final rotor vibration transmission coefficient , and the calculation formula is .

[0043] Table 1 Calculation results of rotor vibration transmission coefficient

[0044]

[0045] The above are only specific embodiments of the present invention, and the scope of the invention cannot be limited thereby. Therefore, the replacement of equivalent components or equivalent changes and modifications made according to the scope of protection of the present invention should still fall within the scope covered by this patent. In addition, the technical features, the technical features and the technical solutions, and the technical solutions and the technical solutions in the present invention can be freely combined and used.

Claims

1. A method for designing rotor vibration transmission coefficient based on support dynamic strain test data, characterized in that: include: Step 1, perform deformation calculation of the supporting structure considering bolt connection; Step 2, calculating the deformation of the rigidly connected supporting structure; Step 3, obtaining the connection stiffness correction coefficient according to step 1 and step 2; Step 4: Considering the connection stiffness correction coefficient, the material elastic modulus at the bolt connection position is corrected, and a rigid connection finite element model of the supporting structure at different fulcrums is established; Apply the rotor lateral vibration load F to perform simulation calculations to obtain the stress distribution results of the supporting structure; select the finite element nodes within the range of the strain gauge patch position grid according to the stress distribution results of the supporting structure; The average stress calculation result at the support structure patch is obtained based on the average stress of all finite element nodes within the grid wire of the strain gauge patch position ; Step 5: Measure the actual vibration response data of the casing through the vibration test equipment ; Through the formula , get the average stress measurement result at the patch ,in, is the dynamic strain data of the support, and E is the mechanical property data of the material; Step 6, obtaining the vibration load of the rotor support structure; Step 7: Calculate the rotor vibration transmission coefficient based on the vibration load of the rotor support structure.

2. The rotor vibration transmission coefficient design method based on support dynamic strain test data according to claim 1 is characterized in that: The step 1 is specifically as follows: Establish a finite element model of the supporting structure with bolted connections; A load is applied to the finite element model of the support structure with bolt connection to perform static strength calculation, thereby obtaining a first deformation result of the support structure and a first deformation amount S1 away from the load application position and the displacement constraint position.

3. The rotor vibration transmission coefficient design method based on support dynamic strain test data according to claim 2 is characterized in that: The step 2 is specifically as follows: Use rigid connection to replace bolt connection and establish finite element model of rigid connection supporting structure; Apply load to the finite element model of the rigidly connected support structure to perform static strength calculation, obtain the second deformation result of the support structure, and obtain the second deformation S2 away from the load application position and the displacement constraint position and the initial elastic modulus of the material at the rigid connection position .

4. The rotor vibration transmission coefficient design method based on support dynamic strain test data according to claim 3 is characterized in that: The step 3 is specifically as follows: Change the elastic modulus of the rigid connection position, apply the load and perform static strength iteration calculation until , obtain the material elastic modulus of the rigid connection position at this time ; By formula Get the connection stiffness correction factor .

5. The rotor vibration transmission coefficient design method based on support dynamic strain test data according to claim 1 is characterized in that: The step 6 is specifically as follows: According to the formula , obtain the vibration load of the rotor support structure , where F is the rotor lateral vibration load.

6. The rotor vibration transmission coefficient design method based on support dynamic strain test data according to claim 5 is characterized in that: The step 7 is specifically as follows: By formula Get the single rotor vibration transmission coefficient ; By formula , and the final rotor vibration transmission coefficient is obtained .

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