A load design method for strength test of composite cascades for thrust reversers

Abstract

This application relates to the field of blade-type thrust reverser strength design and provides a method for designing a strength test load for composite blades used in thrust reversers. By first establishing test load design software, inputting basic composite blade parameters, and conducting comparative analysis of various blades under aerodynamic loads, the composite blade with the largest exhaust angle is selected for loading. This method enables more efficient load equivalence. When assessing the blade test position, the aerodynamic load on the blade is simplified, reducing the difficulty of test loading while still meeting the composite blade test requirements. Furthermore, comparative analysis of the equivalent blade strength analysis results is performed to ensure the effectiveness of aerodynamic load equivalence. This facilitates test loading and provides relatively accurate test results.

Description

Technical Field

[0001] The present application relates to the field of strength design of blade-type reverse thrust devices, and in particular to a method for designing a strength test load of composite blades of a reverse thrust device. Background Art

[0002] The cascade thrust reverser blocks the ducted exhaust flow through a baffle. The engine's ducted airflow is then rectified by a specially designed cascade before being discharged, causing its direction of motion to deflect by more than 90 degrees. This generates a thrust component opposite the aircraft's forward direction, enabling rapid deceleration. Due to its low flow losses, strong ability to control reverse exhaust flow, and high reverse thrust efficiency, it is widely used in high-bypass-ratio turbofan engines. The cascade, the core component of the cascade thrust reverser, uses composite materials instead of metal to reduce structural weight. To precisely control the direction of the reverse airflow, the cascade has varying curvature angles and a dense grid arrangement. The resulting complex structure and loads make test load design difficult.

[0003] In the past, load-bearing structures have undergone strength tests and have a certain test load design capability, but they are unable to solve the problem of strength test load design for full-size composite blades with dense grid arrangement of blade-type reverse thrust devices under complex aerodynamic loads at different spatial occupancy angles and different blade exhaust angles.

[0004] Therefore, how to design the blade strength test load under different space occupation angles and different blade exhaust angles is a problem that needs to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a thrust reverser composite cascade strength test load design method to solve the cascade load comparison problem under different space occupation angles and different cascade exhaust angles.

[0006] The technical solution of the present application is: a method for designing a strength test load for a composite material blade cascade of a thrust reverser, comprising: obtaining basic parameters of the composite material blade cascade; performing comparative analysis of aerodynamic loads corresponding to different parameters of the composite material blade cascade, and selecting the composite material blade cascade with the largest load at different exhaust angles; performing strength analysis of the blade cascade with the largest load at different exhaust angles for different load conditions, and obtaining a global strain layout of the blade cascade; selecting a test position of the composite material blade cascade according to the strain distribution in different areas of the global strain layout of the blade cascade; performing equivalent simplification on the aerodynamic load of the blade cascade, keeping the test load after equivalent consistent with the initial aerodynamic load force, performing strength analysis of the composite load blade cascade with the largest load at different exhaust angles after aerodynamic load equivalent, and obtaining a global strain distribution of the blade cascade after load equivalent; performing comparison of the blade strength analysis results before and after aerodynamic load equivalent to determine the validity of the aerodynamic load equivalence, and if valid, executing the next step; determining a test constraint method, and obtaining a test load.

[0007] Preferably, the method for equivalently simplifying the aerodynamic load of the blade cascade is: dividing the blade cascades at different positions into regions by columns, and calculating the total aerodynamic load of each column of the blade cascade as the equivalent aerodynamic load.

[0008] Preferably, the basic parameters of the blade cascade include the composite blade cascade environment and usage, the blade cascade space occupation angle, the blade cascade exhaust angle, the three-dimensional geometric model of the blade cascade, material performance data for strength analysis, composite blade cascade layup information, aerodynamic data and temperature data.

[0009] Preferably, after judging the validity of the starting load equivalence, the load magnification factor is set according to the difference in mechanical properties of the resin-based composite material in a normal temperature dry environment and a humid and hot environment, and the final test load is the equivalent aerodynamic load multiplied by the load magnification factor.

[0010] Preferably, ANSYS is used to perform strength analysis of the composite load cascade with the maximum load at different exhaust angles after aerodynamic load equivalence.

[0011] Preferably, a comparative analysis of aerodynamic loads is performed on different positions and occupancy angles of the thrust reverser corresponding to the composite material cascades.

[0012] This application discloses a thrust reverser composite cascade strength test load design method. By first establishing test load design software, inputting basic composite cascade parameters, and conducting comparative analysis of various cascades under aerodynamic loads, the composite cascade with the largest exhaust angle is selected for loading. This method enables more efficient load equivalence. When assessing the cascade at the test position, the cascade aerodynamic load is simplified, reducing the difficulty of test loading while still meeting the composite cascade assessment requirements. Furthermore, comparative analysis of the equivalent cascade strength analysis results is performed to ensure the effectiveness of aerodynamic load equivalence. This facilitates test loading and provides relatively accurate test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0014] Figure 1 This is a schematic diagram of the overall process of this application. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0016] A thrust reverser composite cascade strength test load design method is proposed, which effectively analyzes the complex loads in the cascade strength test by equivalently simplifying the test loads.

[0017] like Figure 1 As shown, the following steps are included:

[0018] Step S100, obtaining basic parameters of the composite material cascade;

[0019] Basic parameters of composite cascades include the composite cascade environment and usage, cascade spatial footprint, cascade exhaust angle, 3D geometric model, material performance data for strength analysis, composite cascade layup information, aerodynamic data, and temperature data. These data can be obtained through test data or test instructions.

[0020] Step S200 , performing comparative analysis of aerodynamic loads on composite blade cascades corresponding to different parameters, and selecting the composite blade cascade with the largest load at different exhaust angles;

[0021] A load comparison analysis is carried out on the different positions of the reverse thrust device and different blade space occupation angles corresponding to the composite blade cascades. Considering the influence of different exhaust angles of the composite materials, the composite blade cascade with the largest load at different exhaust angles is selected.

[0022] When the composite blade with the largest load can meet the test requirements, the blades in other parts will also be able to meet the design requirements.

[0023] Step S300 , performing a strength analysis of the cascade with the maximum load at different exhaust angles for different load conditions to obtain a global strain layout of the cascade;

[0024] According to different load conditions, ANSYS software is used to carry out strength analysis of composite blades with the maximum load at different exhaust angles to obtain the global strain distribution of the blades.

[0025] Step S400, selecting an assessment position of the composite material cascade according to the strain distribution of different regions in the global strain layout of the cascade;

[0026] Combined with the structural characteristics and manufacturing process characteristics of composite blade cascades, positions with higher strain and more prone to manufacturing defects in blade cascades with different exhaust angles are selected as assessment positions.

[0027] Step S500, performing equivalent simplification on the cascade aerodynamic load, maintaining the equivalent test load and the initial aerodynamic load force magnitude consistent, performing a composite load cascade strength analysis with the maximum load at different exhaust angles after aerodynamic load equivalent, and obtaining the global strain distribution of the cascade after load equivalent;

[0028] Due to different installation angles and airflow return positions, the aerodynamic loads on different grids of the composite blade are different. It is difficult to consider the detailed aerodynamic load differences in the full-scale blade strength test, and the test loads need to be equivalently simplified.

[0029] The method for equivalently simplifying the aerodynamic load of the blade cascade is as follows: the blade cascades at different locations are divided into regions by columns, and the total aerodynamic load of each column of blades is calculated as the equivalent aerodynamic load. In this way, the loads before and after the equivalent are the same, but the amount of calculation is greatly reduced, thereby effectively improving the test efficiency.

[0030] The principle of equivalent simplification of the aerodynamic load of the cascade is as follows: the test load after the aerodynamic load of the cascade is equivalent is consistent with the force magnitude and direction of the initial aerodynamic load; the force transmission path, stress strain and displacement distribution of the cascade under the test state are minimally different from those of the actual working state of the cascade; and the feasibility of the subsequent loading system must also be considered.

[0031] Step S600, comparing the cascade strength analysis results before and after aerodynamic load equivalence to determine the validity of the aerodynamic load equivalence. If the validity is determined, proceed to the next step.

[0032] For different load conditions, ANSYS software was used to carry out strength analysis of the composite blades with the maximum load at different exhaust angles after load equivalence. The global strain distribution of the blades after load equivalence was obtained and compared with the strength analysis results of the composite blades before load equivalence to determine the validity of the experimental load equivalence.

[0033] If it is determined that the aerodynamic load equivalence is invalid, the process returns to step S500 and performs composite material cascade load equivalence again until it is valid.

[0034] Step S700: Humid and hot environment correction

[0035] High temperatures, especially the combined effects of heat and humidity, significantly affect the mechanical properties of resin-based composites. Therefore, testing must consider the effects of a heat and humidity environment. Since the tests are conducted in a dry state at room temperature, corrections for heat and humidity are necessary. The corresponding load magnification factor can be determined by testing specimens, components, and assemblies. The experimental failure mode obtained using this method must be consistent with the environmental conditions.

[0036] Step S800: determine the test constraint mode and obtain the test load.

[0037] After considering the test equivalent simplification, the test constraint method is determined, and after considering the wet and hot environment correction, the test load is obtained.

[0038] When designing a composite cascade strength test, we first establish test load design software, input the basic parameters of the composite cascade, conduct comparative analysis of various cascades under aerodynamic loads, and select the composite cascade with the largest exhaust angle for loading. This allows for more efficient load equivalence. When assessing the cascade's test position, we simplify the cascade's aerodynamic load, reducing the difficulty of test loading while still meeting the composite cascade's test requirements. Furthermore, we conduct comparative analysis of the equivalent cascade strength analysis results to ensure the effectiveness of aerodynamic load equivalence. This facilitates test loading and yields relatively accurate test results.

[0039] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for designing the strength test load of a composite material cascade of a thrust reverser, characterized in that: include: Obtain basic parameters of composite cascade; Conduct comparative analysis of aerodynamic loads on composite blade cascades under different parameters, and select the composite blade cascade with the largest load under different exhaust angles; For different load conditions, the cascade strength analysis is performed at different exhaust angles with the maximum load, and the global strain layout of the cascade is obtained; According to the strain distribution in different areas of the cascade global strain layout, the assessment position of the composite material cascade is selected; The aerodynamic load of the cascade is simplified and equivalent, and the equivalent test load is kept consistent with the initial aerodynamic load. The strength analysis of the cascade with the maximum composite load at different exhaust angles after the aerodynamic load is equivalent is performed to obtain the global strain distribution of the cascade after the load is equivalent. Compare the blade cascade strength analysis results before and after aerodynamic load equivalence to determine the validity of aerodynamic load equivalence. If valid, proceed to the next step. Determine the test constraint method and obtain the test load; The method for equivalently simplifying the aerodynamic load of the blade cascade is as follows: dividing the blade cascades at different positions into regions by columns, and calculating the total aerodynamic load of each column of the blade cascade as the equivalent aerodynamic load.

2. The thrust reverser composite cascade strength test load design method according to claim 1, characterized in that: The basic parameters of the blade include the composite blade environment and usage, the blade space occupation angle, the blade exhaust angle, the three-dimensional geometric model of the blade, material performance data for strength analysis, composite blade layup information, aerodynamic data and temperature data.

3. The thrust reverser composite cascade strength test load design method according to claim 1, characterized in that: After judging the validity of the aerodynamic load equivalence, the load magnification factor is set according to the difference in mechanical properties of the resin-based composite material under normal temperature dry environment and humid heat environment. The final test load is the equivalent aerodynamic load multiplied by the load magnification factor.

4. The thrust reverser composite cascade strength test load design method according to claim 1, characterized in that: ANSYS is used to analyze the strength of the composite load cascade with the maximum load at different exhaust angles after aerodynamic load equivalence.

5. The thrust reverser composite cascade strength test load design method according to claim 1, characterized in that: A comparative analysis of aerodynamic loads is conducted on the different positions and occupancy angles of the reverse thrust device corresponding to the composite blade cascade.

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