Aero-engine blisk health monitoring method based on digital twinning

Abstract

The invention provides an aero-engine blisk health monitoring method based on digital twinning, and provides an on-line damage identification and real-time monitoring method for the fatigue damage problem of an aero-engine blisk in a service state, and the fatigue damage problem of the aero-engine blisk in the service state is solved by integrating the digital twinning technology, the model correction technology and the non-contact laser vibration measurement technology. The damage identification, positioning, quantification and early warning of the blisk in a service state are realized, and the health state of the blisk is evaluated. The method has the advantages that the precise digital twin model of the blisk obtained through model correction provides a reference model for damage identification of the blisk; by establishing a blisk health monitoring system, feedback iteration among an engine control state, a digital twin model and online measurement parameters is realized, so that whether structural damage occurs or not is judged, the damage position is positioned, the damage degree is calculated, an alarm is given when the damage amount exceeds a limit value, the repair cost is reduced, and the flight safety is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft engine health monitoring, and in particular to an aircraft engine integral blade disk health monitoring method based on digital twin. Background Art

[0002] Aircraft engines have been in service for a long time in a complex load environment of high temperature, high pressure and high speed, and their parts are very prone to various failure behaviors. As a new type of structural component of aircraft engines, the integral blade directly connects the rotating working blades and the wheel hub into one, which is beneficial for weight reduction and avoids the loss of tenon airflow. At present, the fans and compressors of aircraft engines all adopt the integral blade structure in large quantities. As a key component of aircraft engines, the integral blade is subject to multiple loads such as temperature, centrifugal force, aerodynamics, and vibration, and is prone to fatigue damage. If cracks occur and are not monitored and identified in time, it may affect the engine performance and safety of use, and even cause grade accidents.

[0003] The aircraft engine is a complex system. It is difficult to timely identify the specific damage location and degree of damage by monitoring the vibration characteristics of the whole machine under working conditions. The existing damage identification of aircraft engine rotors is generally post-detection. After the damage occurs, the flight parameter data is used to roughly determine whether structural damage may occur, the engine is disassembled for inspection, and the damage location and morphology are determined by optical detection. This post-detection method cannot monitor the structural health in real time, and cannot provide early warning of damage. If the number of disassembly inspections is increased, the maintenance and support costs will be greatly increased. The existing real-time online damage identification and health monitoring of aircraft engines have not yet involved specific structural parts, or have not taken into account the complex and changeable operating conditions of aircraft engines. For the integral blade disk, a new structural rotating key component, there is a lack of health monitoring methods that can be applied to complex service conditions. Therefore, it is of great significance to establish an aircraft engine integral blade disk health monitoring method based on digital twins to realize the damage identification, location, evaluation and warning of the integral blade disk under service conditions, which is of great significance to ensure flight safety and reduce repair costs. Summary of the invention

[0004] The purpose of the present invention is to provide an aero-engine integral blade health monitoring method based on digital twin, which can determine whether the integral blade is damaged, the damage location, and the damage degree in the service state, evaluate the health status of the integral blade, reduce the repair cost, and ensure flight safety.

[0005] The present invention provides an aero-engine blisk health monitoring method based on digital twins, which is characterized by: an aero-engine blisk health monitoring method based on digital twins, comprising the following steps:

[0006] Step 1: Establish an initial digital twin model of the overall blade disk structure, use the established model to perform simulation calculations, and obtain the simulated modal frequencies and vibration shapes of each order of the overall blade disk.

[0007] Step 2: According to the simulation analysis results, formulate the distribution plan of the integral blade disk modal test measurement points and the hammer head selection plan, establish the integral blade disk modal test system, measure the vibration parameters of each measurement point, and identify and obtain the integral blade disk test modal frequency and vibration type.

[0008] Step three, taking the test modal frequency as the target value and the material parameters of the integral blade disk as the variable, a sensitivity-based model correction method is used to correct the initial digital twin model of the integral blade disk, obtain the precise digital twin model of the integral blade disk, and extract the stiffness matrix of each unit.

[0009] Step 4: Assemble the local element stiffness matrix into the global vibration modal stiffness matrix.

[0010] Step five: Establish an online testing system for the integral blade disk, install a laser sensor on the aircraft engine, and use a non-contact laser tracking test method to measure the structural surface of the integral blade disk of the aircraft engine in operation and identify the vibration parameters of the integral blade disk.

[0011] Step six, establish an integral blade health monitoring system, which consists of an online test analysis module, a digital twin model module, and a data optimization feedback module. The system automatically extracts the control parameters of the integrated electronic regulator of the aircraft engine, gives the load condition of the integral blade digital twin model according to the control state, drives the calculation of the simulated vibration characteristics and modal strain energy, and at the same time, the system reads the integral blade online test vibration parameters in real time to calculate the modal strain energy. The change in modal strain energy calculated based on the test and simulation vibration parameters exceeds the threshold, indicating the presence of damage. The mean value of the unit modal strain energy is calculated, and the unit area with the largest difference between the test and simulation is the damage location.

[0012] MSE ij ={φ i} T (K j}{Φ i}

[0013] Among them, MSE ij is the modal strain energy, {Φ i} is the vibration mode matrix of the ith order, {K j} is the stiffness matrix of the jth unit. MSE ij is the i-th modal strain energy of the j-th element.

[0014] Step seven: In the health monitoring system, the goal is to minimize the difference between the vibration frequencies of each order test and the vibration frequencies calculated by the digital twin model, and the material parameters of the damaged unit are used as variables. The non-destructive digital twin model is corrected by the sensitivity method to obtain the damage model, identify the material parameters of the damaged unit after stiffness reduction, and calculate the modal strain energy of the digital twin model before and after correction, and then calculate the stiffness damage index. The stiffness damage index is used to characterize the degree of damage to the entire blade disk.

[0015]

[0016] in, is the stiffness damage index, MSE ij is the i-th modal strain energy of the j-th unit calculated by the accurate digital twin model, is the i-th modal strain energy of the j-th element calculated by the modified damage model.

[0017] Step 8: In the health monitoring system, extract the local vibration mode of the damaged unit, calculate the correlation coefficient between the test vibration mode and the corrected simulation vibration mode, that is, the modal confidence factor, and verify the accuracy of the identification result.

[0018]

[0019] Among them, MAC ij is the modal assurance criterion, is the i-th order vibration mode matrix obtained by online testing, is the j-order vibration mode matrix calculated by the modified damage model.

[0020] Step nine: When the damage amount exceeds the limit value, the system issues an alarm and displays the damage location and damage amount.

[0021] It is suitable for the health monitoring and damage identification of the integral blade disk of the aircraft engine in service. It comprehensively utilizes digital twin technology, model correction technology and non-contact laser vibration measurement technology to realize the damage identification and alarm of the integral blade disk of the aircraft engine in service.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The digital twin-based aero-engine blisk health monitoring method described in the present invention provides a reference model for blisk damage identification by obtaining an accurate digital twin model of the blisk through model correction; by establishing an overall blisk health monitoring system, feedback iteration among the engine control state, the digital twin model, and online measurement parameters is achieved, thereby determining whether structural damage has occurred, locating the damage position, and calculating the degree of damage. When the damage amount exceeds the limit value, an alarm is issued, thereby reducing repair costs and ensuring flight safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0025] Figure 1 Schematic diagram of the implementation method. DETAILED DESCRIPTION

[0026] The present invention will be further explained below in conjunction with specific implementation plans, but the present invention is not limited thereto. The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the restrictive conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0027] The present invention relates to a method for monitoring the health of an aero-engine blisk based on digital twins. The specific implementation manner of the present invention is described below.

[0028] Example:

[0029] The geometric model of the overall blade disk structure is established according to the nominal size, and the model is simplified. The geometric model is imported into the ANSYS finite element software, the geometric model is cut, the material parameters are given in the partitions, and the mesh is divided using 20-node hexahedral units. Given the working conditions, the initial digital twin model of the overall blade disk is established, and modal analysis is performed to obtain the first 10 displacement modes, and the modal frequency and vibration shape are output.

[0030] According to the simulation analysis of the modal vibration mode, the number of measuring points of the integral blade disk modal test, the position and direction of the excitation point and the response point are determined, the piezoelectric acceleration sensor is fixed on the surface of the integral blade disk, and the integral blade disk test model is established in the test analysis software. The hammer pulse excitation method is used to perform multi-point hammering. The acceleration of the vibration pickup point is measured by the acceleration sensor, and the modal frequency and vibration mode of the integral blade disk test are obtained through identification by the data acquisition system.

[0031] Taking the first seven test modal frequencies of the integral blade as the target values ​​and the elastic modulus of the integral blade as the variable, a sensitivity-based model correction method was adopted, and a program was written to correct the initial digital twin model of the integral blade. The precise digital twin model of the integral blade was obtained, and the stiffness matrix of each unit was extracted.

[0032] The local element stiffness matrix is ​​assembled into the global vibration modal stiffness matrix according to the node position.

[0033] An online testing system for the integral blade disk is established. A laser sensor is installed on the aircraft engine, with the head aimed at the integral blade disk. The surface parameters of the integral blade disk structure in service status are measured in real time, and the vibration frequency and vibration mode vector of the integral blade disk are identified.

[0034] Establish an integral blade health monitoring system, automatically extract the control parameters of the integrated electronic regulator of the aircraft engine, convert the integral blade load conditions according to the high and low pressure rotor speeds and the temperature before the turbine, set the load boundary conditions of the integral blade digital twin model, calculate the simulation vibration frequency, vibration mode, stiffness matrix and modal strain energy, and at the same time, the system reads the integral blade online test vibration parameters in real time, identifies the vibration frequency and vibration mode, and calculates the modal strain energy. If the modal strain energy index calculated by the online test vibration parameters is compared with the modal strain energy index calculated by the simulation analysis, the change exceeds the threshold, indicating that the integral blade is damaged, and the position with the maximum change in the mean value of the modal strain energy of each order of the unit is identified as the damaged part of the integral blade.

[0035] In the health monitoring system, the control parameters of the integrated electronic regulator of the aircraft engine are input into the digital twin model module for simulation calculation. The data optimization feedback module calls the calculation results of the digital twin model module and the identification results of the online test analysis module, and takes the minimum difference between the first 7 vibration frequencies of the two as the goal, takes the elastic modulus of the damaged unit as the variable, and corrects the model based on the sensitivity method to identify the elastic modulus of the damaged unit, calculates the modal strain energy and stiffness damage index of the model before and after the damage, and identifies the damage degree of the entire blade disk.

[0036] In the health monitoring system, the local test vibration mode and the corrected simulation vibration mode of the damaged unit are extracted, and the correlation coefficient between the two is calculated to verify the accuracy of the identification result.

[0037] When the damage amount output by the health monitoring system exceeds the limit value, the system alarm is automatically triggered and the damage location and damage amount are displayed. Matters not covered by the present invention are known technologies.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A digital twin-based aero-engine blisk health monitoring method, characterized by: The steps include: Step 1: Establish an initial digital twin model of the integral blade disk structure, use the established model to perform simulation calculations, and obtain the simulated modal frequencies and vibration shapes of each order of the integral blade disk; Step 2: According to the simulation analysis results, formulate the distribution plan of the integral blade disk modal test measurement points and the hammer head selection plan, establish the integral blade disk modal test system, measure the vibration parameters of each measurement point, and identify and obtain the integral blade disk test modal frequency and vibration type; Step 3: Taking the test modal frequency as the target value and the material parameters of the blade disk as the variable, a sensitivity-based model correction method is used to correct the initial digital twin model of the blade disk, obtain the precise digital twin model of the blade disk, and extract the stiffness matrix of each unit; Step 4, assemble the local unit stiffness matrix into the global vibration mode stiffness matrix; Step 5: Establishing an online testing system for the blisk; Step 6: Establish an integral blade health monitoring system, which consists of an online test analysis module, a digital twin model module, and a data optimization feedback module. The system automatically extracts the control parameters of the integrated electronic regulator of the aircraft engine, and gives the load condition of the integral blade digital twin model according to the control state, drives the calculation of simulated vibration characteristics and modal strain energy. At the same time, the system reads the integral blade online test vibration parameters in real time and calculates the modal strain energy. The change in modal strain energy calculated from the test and simulation vibration parameters exceeds the threshold, indicating the presence of damage; Calculate the mean value of the unit modal strain energy, and the unit area with the largest difference between the test and simulation is the damage location; MSE ij ={Φ i } T {K j }{Φ i } Among them, MSE ij is the modal strain energy, {Φ i } is the vibration mode matrix of the ith order, {K j } is the stiffness matrix of the jth unit; MSE ij is the i-th modal strain energy of the j-th element; Step 7: In the health monitoring system, the goal is to minimize the difference between the vibration frequencies of each order test and the vibration frequencies calculated by the digital twin model, and the material parameters of the damaged unit are used as variables. The non-destructive digital twin model is corrected by the sensitivity method to obtain the damage model, identify the material parameters of the damaged unit after stiffness reduction, calculate the modal strain energy of the digital twin model before and after correction, and then calculate the stiffness damage index. The stiffness damage index is used to characterize the damage degree of the entire blade disk; in, is the stiffness damage index, MSE ij is the i-th modal strain energy of the j-th element calculated by the accurate digital twin model, is the i-th modal strain energy of the j-th element calculated by the modified damage model; Step 8: In the health monitoring system, extract the local vibration mode of the damaged unit, calculate the correlation coefficient between the test vibration mode and the corrected simulation vibration mode, that is, the modal confidence factor, and verify the accuracy of the identification result; Among them, MAC ij is the modal assurance criterion, is the i-th order vibration mode matrix obtained by online testing, is the j-order vibration mode matrix calculated by the modified damage model; Step nine: When the damage amount exceeds the limit value, the system issues an alarm and displays the damage location and damage amount.

2. The digital twin-based aero-engine blisk health monitoring method according to claim 1, characterized in that: The step five is to establish an online testing system for the integral blade disk, specifically, to install a laser sensor on the aircraft engine, adopt a non-contact laser tracking test method to measure the surface of the integral blade disk structure of the aircraft engine in operation, and identify the vibration parameters of the integral blade disk.

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