Balance load expansion method based on stress monitoring

Abstract

The invention discloses a balance load expansion method based on stress monitoring, and belongs to the field of industrial data analysis. The problem of short test period is relieved by increasing the range of the wind tunnel test model matching balance load. The method specifically comprises the following steps: S1, extracting a high-risk stress node from a balance finite element analysis result as a stress monitoring object, establishing a stress equation between a balance aerodynamic load and the stress node, and creating a load coefficient table; s2, determining a balance load expansion range through a load coefficient table; s3, under the assistance of a balance stress monitoring system, carrying out load expansion and calibration on the balance in a balance load expansion range to obtain an expanded balance load; and S4, carrying out accuracy, precision and uncertainty analysis on the calibration of the balance load expansion part. According to the invention, the balance load envelope is expanded on the basis of the original design load of the balance, so that the test efficiency and the calibration precision are improved.

Description

Technical Field

[0001] The invention relates to a balance load expansion method based on stress monitoring, and belongs to the field of industrial data analysis. Background Art

[0002] The design range of the strain gauge balance is determined based on the aerodynamic load acting on the model and the mass of the model. The load range of each component of the balance determines the range of the balance. At the beginning of the balance design, it is difficult for technicians to accurately estimate the dynamic load borne by the model based on experience, so the balance design must have sufficient safety factors to ensure the strength of the balance. The relatively conservative safety factor is required to be kept below the fatigue limit under any possible test conditions. The larger the safety factor reserved in the balance design, the smaller the load range of the same size balance will be. When the balance is calibrated, it will be loaded according to the design load range, that is, all the components of the balance are loaded to their respective ranges at the same time. However, according to the actual experience of wind tunnel tests of various aircraft, it is rare that all units of the balance are fully loaded. As a result of this design, the load range of some units of the balance will be too abundant, while the capacity of some units is slightly insufficient. The load matching of each unit of the balance is not just right, which loses the volume load ratio of the balance, thereby affecting the measurement range of the aerodynamic force of the balance. This is more obvious in some high-load compact hinge moment balances and variable pressure high Reynolds number wind tunnel test balances, which require a balance with a higher volume load ratio in a limited space. On the other hand, the wind tunnel test cycle of many aircraft models requires very tight time requirements, and it is difficult to have enough time to design, process and calibrate new balances. If you can choose a balance with a matching load range from the existing inventory balances, it will help shorten the tight design cycle of aircraft design units.

[0003] In order to further bring out the best performance of the existing balance, a balance load expansion method based on stress monitoring is designed to address the problems of insufficient balance volume and load ratio and tight aircraft wind tunnel test cycle. On the premise of ensuring the safety of the balance, the load range of the balance is further expanded, the test cycle is shortened, and the scope of the balance to obtain test data is expanded. Summary of the invention

[0004] A brief overview of the present invention is provided below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0005] Aiming at the problem of insufficient balance volume and load ratio and tight aircraft wind tunnel test cycle, the present invention proposes a balance load expansion method based on stress monitoring, comprising the following steps: S1. Extract high-risk stress nodes from the balance finite element analysis results as stress monitoring objects, establish stress equations between the balance aerodynamic loads and stress nodes, and create a load coefficient table; S2. Determine the load extension range of the balance through the load factor table; S3. With the assistance of the balance stress monitoring system, the balance load is extended and calibrated within the balance load extension range to obtain the extended balance load; S4. Perform accuracy, precision and uncertainty analysis on the calibration of the load extension of the balance.

[0006] Furthermore, S1 specifically includes: S11. Taking the design load of the balance as input condition, use ANSYS software to conduct detailed finite element analysis on the balance body, and determine the key structure and strain gauge stress nodes from the analysis results; S12. Within the load range {-Fmax; +Fmax} of each component of the balance, the strain gauge stress nodes that exceed their threshold at least once during the analysis are saved in a load coefficient file to create a load coefficient table.

[0007] Furthermore, S2 specifically includes: S21. Input the simulated six-component load of the balance in the load factor table; S22. Calculate the limit value of each node, the limit value includes: tensile strength limit, fatigue limit, steady-state stress value and dynamic stress value, the steady-state stress value is the average value of the node stress change, and the dynamic stress value is the difference between the maximum value and the minimum value of the node stress; S23. Determine the balance load extension range by simulating a load that does not exceed the limit value.

[0008] Furthermore, S3 specifically includes: S31. Install the balance on a static calibration platform for isolated loading. Each unit of the balance is loaded with equal spacing of more than 10 points, and loads and unloads in equal steps. The loading range covers the extended load part; S32. Repeat the loading process of S31 three or more times; S33. When the extended load is applied to each component, the ratio of the calibration residual of this component to the design load of each unit is calculated. If the ratio is within 0.3%, it is considered that the influence of this component on other units can be ignored when the extended load is applied. S34. The entire loading process must be carried out under the monitoring of the balance stress monitoring system. When the system detects that the steady-state stress value or dynamic stress value range of the stress node in the load coefficient table exceeds the limit value, the loading should be stopped.

[0009] Furthermore, S4 specifically includes: S41. Perform comprehensive loading calibration on the balance under extended load conditions, apply an extended calibration load to the balance, record the output value of each component, and obtain recorded data; S42. Identify and remove bad values ​​from the recorded data to obtain the recorded data after removing the bad values; S43. Process the recorded data after removing bad values, find the balance calibration coefficient, and calculate the balance calibration precision, accuracy and uncertainty; S44. Determine whether the balance calibration precision, accuracy and uncertainty meet the requirements of GJB2244-94 "Wind Tunnel Strain Balance Specifications". If they meet the requirements, the extended load of the balance can be used normally.

[0010] The beneficial effects of the present invention are as follows: (1) The selection of the balance before the wind tunnel test is no longer limited to the design load of the balance. The load range of the balance can be determined by stress monitoring and calibration of the balance, making the load matching of each element of the balance more reasonable. By expanding the balance load envelope, a wider range of force test data can be obtained for aircraft wind tunnel tests, including the test angle and wind speed of the aircraft test model. The expansion of the balance load envelope will translate into more information and reduce the risk of aircraft design.

[0011] (2) Providing more options for matching balances for wind tunnel tests of aircraft models, alleviating the problem of tight test cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 Flow chart of the expansion method for balance load; Figure 2 It is the high risk stress node diagram of the balance; In the figure: 1- balance structure stress node (red); 2- balance strain gauge stress node (blue). DETAILED DESCRIPTION

[0013] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0014] Example 1, reference Figure 1 This embodiment describes a balance load expansion method based on stress monitoring, comprising the following steps: S1. Extract high-risk stress nodes from the balance finite element analysis results as stress monitoring objects, establish stress equations between the balance aerodynamic loads and stress nodes, and create a load coefficient table; S2. Determine the load extension range of the balance through the load factor table; S3. With the assistance of the balance stress monitoring system, the balance load is extended and calibrated within the balance load extension range to obtain the extended balance load; S4. Perform accuracy, precision and uncertainty analysis on the calibration of the load extension of the balance.

[0015] S1 specifically includes: S11. Taking the design load of the balance as input condition, use ANSYS software to conduct detailed finite element analysis on the balance body, and determine the key structure and strain gauge stress nodes from the analysis results; S12. Within the load range {-Fmax; +Fmax} of each component of the balance, the strain gauge stress nodes that exceed their threshold at least once during the analysis are saved in a load coefficient file to create a load coefficient table.

[0016] Specifically, S11 combined Figure 2 It can be seen that this process involves the calculation of all stresses in the balance, not only for a single load case, but for all combined load cases.

[0017] Stress through: ; Obtain, among which, is the absolute stress, j is the number of nodes, i is the quantity of one of the six components of the scale, The original component i signal, is the corresponding balance load factor.

[0018] The load coefficients of each component of each stress node are obtained through the linear function relationship in the finite element calculation. The stress of each stress node is calculated through the aerodynamic load obtained by real-time measurement during the wind tunnel test. Similarly, the changes in balance stress can also be monitored during balance calibration.

[0019] S12 is used to avoid calculating the stress of unimportant nodes. This optimization reduces the number of unnecessary node monitoring. The reduction in the number of nodes increases the speed of sampling and calculation, and can better track the dynamic changes of high-risk stress nodes.

[0020] S2 specifically includes: S21. Input the simulated six-component load of the balance in the load factor table; S22. Calculate the limit value of each node, the limit value includes: tensile strength limit, fatigue limit, steady-state stress value and dynamic stress value, the steady-state stress value is the average value of the node stress change, and the dynamic stress value is the difference between the maximum value and the minimum value of the node stress; S23. Determine the balance load extension range by simulating a load that does not exceed the limit value.

[0021] Specifically, for example, if the material of the balance is 17-4PH, the tensile strength limit of the balance is 760MPa, the fatigue limit is 400MPa, the steady-state stress value of the balance is 760MPa, and the dynamic stress value is 400MPa. The loads of each unit simulated based on not exceeding the balance stress limit value are the load extension range of the balance, and the extension range is shown in Table 1.

[0022] Table 1 Balance calibration extended load range

[0023] S3 specifically includes: S31. Install the balance on a static calibration platform for isolated loading. Each unit of the balance is loaded with equal spacing of more than 10 points, and loads and unloads in equal steps. The loading range covers the extended load part; S32. Repeat the loading process of S31 three or more times; S33. When the extended load is applied to each component, the ratio of the calibration residual of this component to the design load of each unit is calculated. If the ratio is within 0.3%, it is considered that the influence of this component on other units can be ignored when the extended load is applied. S34. The entire loading process must be carried out under the monitoring of the balance stress monitoring system. When the system detects that the steady-state stress value or dynamic stress value range of the stress node in the load coefficient table exceeds the limit value, the loading should be stopped.

[0024] S4 specifically includes: S41. Perform comprehensive loading calibration on the balance under extended load conditions, apply an extended calibration load to the balance, record the output value of each component, and obtain recorded data; S42. Identify and remove bad values ​​from the recorded data to obtain the recorded data after removing the bad values; S43. Process the recorded data after removing bad values, find the balance calibration coefficient, and calculate the balance calibration precision, accuracy and uncertainty; S44. Determine whether the balance calibration precision, accuracy and uncertainty meet the requirements of GJB2244-94 "Wind Tunnel Strain Balance Specifications". If they meet the requirements, the extended load of the balance can be used normally.

Claims

1. A balance load expansion method based on stress monitoring, characterized in that: The following steps are involved: S1. Extract high-risk stress nodes from the balance finite element analysis results as stress monitoring objects, establish stress equations between the balance aerodynamic loads and stress nodes, and create a load coefficient table; S2. Determine the load extension range of the balance through the load factor table; S3. With the assistance of the balance stress monitoring system, the balance load is extended and calibrated within the balance load extension range to obtain the extended balance load; S4. Perform accuracy, precision and uncertainty analysis on the calibration of the load extension of the balance.

2. A balance load expansion method based on stress monitoring according to claim 1, characterized in that: S1 specifically includes: S11. Taking the design load of the balance as input condition, use ANSYS software to conduct detailed finite element analysis on the balance body, and determine the key structure and strain gauge stress nodes from the analysis results; S12. Within the load range {-Fmax; +Fmax} of each component of the balance, the strain gauge stress nodes that exceed their threshold at least once during the analysis are saved in a load coefficient file to create a load coefficient table.

3. The balance load expansion method based on stress monitoring according to claim 1 is characterized in that: S2 specifically includes: S21. Input the simulated six-component load of the balance in the load factor table; S22. Calculate the limit value of each node, the limit value includes: tensile strength limit, fatigue limit, steady-state stress value and dynamic stress value, the steady-state stress value is the average value of the node stress change, and the dynamic stress value is the difference between the maximum value and the minimum value of the node stress; S23. Determine the balance load extension range by simulating a load that does not exceed the limit value.

4. The balance load expansion method based on stress monitoring according to claim 1 is characterized in that: S3 specifically includes: S31. Install the balance on a static calibration platform for isolated loading. Each unit of the balance is loaded with equal spacing of more than 10 points, and loads and unloads in equal steps. The loading range covers the extended load part; S32. Repeat the loading process of S31 three or more times; S33. For each component, the ratio of the calibration residual of this component to the design load of each unit is calculated when the extended load is applied. If the ratio is within 0.3%, it is considered that the influence of this component on other units can be ignored when the extended load is applied. S34. The entire loading process must be carried out under the monitoring of the balance stress monitoring system. When the system detects that the steady-state stress value or dynamic stress value range of the stress node in the load coefficient table exceeds the limit value, the loading should be stopped.

5. The balance load expansion method based on stress monitoring according to claim 1 is characterized in that: S4 specifically includes: S41. Perform comprehensive loading calibration on the balance under extended load conditions, apply an extended calibration load to the balance, record the output value of each component, and obtain recorded data; S42. Identify and remove bad values ​​from the recorded data to obtain the recorded data after removing the bad values; S43. Process the recorded data after removing bad values, find the balance calibration coefficient, and calculate the balance calibration precision, accuracy and uncertainty; S44. Determine whether the balance calibration precision, accuracy and uncertainty meet the requirements of GJB2244-94 "Wind Tunnel Strain Balance Specifications". If they meet the requirements, the extended load of the balance can be used normally.

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