Aircraft engine hydraulic mechanical device case pressure cycle life compliance verification method

Abstract

The present invention relates to a method for verifying the compliance of the pressure cycle life of the shell of an aircraft engine hydraulic mechanical device, which includes: determining a standard load spectrum, performing a static analysis on a test piece, judging whether the pressure peak exceeds the design strength of the shell material of the test piece, determining an equivalent acceleration load spectrum, judging whether the pressure peak in the equivalent acceleration load spectrum exceeds the design strength, performing an acceleration test, determining an equivalent deceleration load spectrum, judging whether the pressure peak in the equivalent deceleration load spectrum exceeds the design strength, and performing a deceleration test. The present invention proposes a method for verifying the compliance of the pressure cycle life of the shell of an aircraft engine hydraulic mechanical device. A pressure cycle equivalent load spectrum determination method is provided by using a hydraulic mechanical device shell pressure cycle life prediction simulation model, which can be combined with the hydraulic mechanical device shell structural strength to determine the acceleration or deceleration life verification equivalent load spectrum, thereby improving the verification efficiency while ensuring the validity of the verification results.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic machinery, and in particular to a method for verifying the compliance of the pressure cycle life of a hydraulic machinery device housing of an aircraft engine. Background Art

[0002] In the actual operation of aircraft engines, affected by the take-off and landing of aircraft, hydraulic mechanical devices will be continuously subjected to pressure cycle loads when the aircraft engines are working. Each flight cycle will have at least one peak pressure during the take-off phase, and some models will have a second peak pressure during the reverse thrust phase during landing. During the life of the aircraft engine, the hydraulic mechanical device may suffer structural low-cycle fatigue failure due to the pressure cycle load. Once the hydraulic mechanical device fails structurally, it will lead to serious consequences such as fuel leakage and engine loss of control, seriously affecting flight safety.

[0003] Most of the existing hydraulic mechanical devices for aircraft engines only consider high-cycle fatigue loads such as vibration, and adopt the form of infinite fatigue life for conservative design. In the design stage, there is a lack of low-cycle fatigue design for pressure cycle loads and effective pressure cycle life compliance verification. A conservative design will increase the weight of the structure, and insufficient design strength will pose serious safety hazards.

[0004] The current standard has requirements for the pulse test method of aircraft hydraulic parts, and some of its contents can be used as a reference when conducting pressure cycle life compliance verification of hydraulic mechanical device shells. However, the load spectrum determination method in the current standard is too broad. When determining the pressure range, a fixed safety factor is used to amplify the maximum working pressure, and the number of pressure cycles is only distinguished by the type of hydraulic parts, which is not targeted. At the same time, the current standard does not provide a method for determining the equivalent load spectrum. Once the determined pressure range exceeds the structural strength, the test will not be able to be carried out. In addition, if the number of pressure cycles is too high, if the equivalent accelerated life load spectrum cannot be determined, the verification cycle will be too long.

[0005] Therefore, it is necessary to develop a hydraulic mechanical device housing pressure cycle life compliance verification method to specifically, effectively and efficiently assess its pressure cycle life compliance. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a method for verifying the pressure cycle life compliance of the casing of an aircraft engine hydraulic mechanical device, which can assess the ability to resist pressure cycle loads, ensure that there will be no structural failure due to pressure cycle loads during its entire life cycle, and improve flight safety.

[0007] According to the technical solution provided by the present invention, the method for verifying the compliance of the pressure cycle life of the housing of the hydraulic mechanical device of an aircraft engine comprises the following steps:

[0008] S1. Determine the standard load spectrum through the product technical documentation requirements of the aircraft engine hydraulic mechanical device housing;

[0009] S2, performing static analysis on the test piece using the pressure peak value in the standard load spectrum determined in step S1 to determine whether the pressure peak value in the standard load spectrum exceeds the design strength;

[0010] S3. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum does not exceed the design strength of the shell material of the test piece and no accelerated test is required, the verification is completed according to the standard load spectrum;

[0011] S4. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum does not exceed the design strength of the test piece shell material and an accelerated test is required, an equivalent accelerated load spectrum is determined by increasing the pressure amplitude and reducing the number of cycles;

[0012] S5, performing static analysis on the test piece using the pressure peak value in the equivalent acceleration load spectrum determined in step S4 to determine whether the pressure peak value in the equivalent acceleration load spectrum exceeds the design strength;

[0013] S6. If the analysis result of step S5 shows that the pressure peak in the equivalent acceleration load spectrum does not exceed the design strength of the test piece shell material, perform an accelerated test on the test piece shell;

[0014] S7, if the analysis result of step S5 shows that the pressure peak in the equivalent acceleration load spectrum has exceeded the design strength of the shell material of the test piece, return to step S4;

[0015] S8. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum has exceeded the design strength of the test piece shell material, then determine the equivalent deceleration load spectrum by reducing the pressure amplitude and increasing the number of cycles;

[0016] S9, performing static analysis on the test piece using the pressure peak value in the equivalent deceleration load spectrum determined in step S8 to determine whether the pressure peak value in the equivalent deceleration load spectrum exceeds the design strength;

[0017] S10, if the pressure peak value in the equivalent deceleration load spectrum determined in step S9 does not exceed the design strength, perform a deceleration test on the test piece shell;

[0018] S11 . If the pressure peak value in the equivalent deceleration load spectrum determined in step S9 exceeds the design strength, return to step S8 .

[0019] Preferably, in step S1, the pressure amplitude and the number of cycles must be determined to determine the standard load spectrum, wherein the pressure amplitude P is determined by the following formula: ,

[0020] Where Pw is the normal maximum working pressure; FSF is the fatigue cycle stress factor, which is used to describe the safety factor, and FSF is set to 1.5; FF is the fatigue cycle temperature factor, which is used to describe the effect of the difference between the test temperature and the working temperature on the fatigue performance of the material, and can be determined by the following formula: ,

[0021] The number of cycles is consistent with the product cycle life requirements.

[0022] Preferably, the equivalent load spectrum is determined according to the following steps:

[0023] First, the standard load theoretical fatigue life is calculated according to the standard load spectrum, and the fatigue life loss factor is calculated in combination with the life requirements of the product technical documents. The calculation method is as follows: ,

[0024] Then, determine the equivalent load pressure amplitude, perform equivalent load life calculation, and combine the obtained fatigue life loss factor to determine the equivalent load cycle number, which is determined according to the following formula: ;

[0025] Finally, the equivalent load spectrum is finally determined by combining the determined equivalent load pressure amplitude and the equivalent load cycle number.

[0026] Preferably, the standard load theoretical fatigue life is determined according to the following steps:

[0027] Complete static analysis through meshing, load application, and material property assignment in ANSYS finite element analysis software;

[0028] Import the static analysis results into nCode-Designlife fatigue life analysis software as input, and then complete the fatigue analysis by setting standard loads and fatigue parameters;

[0029] The final output is the theoretical fatigue life under standard load.

[0030] Preferably, the equivalent load theoretical fatigue life is determined according to the following steps:

[0031] Complete static analysis through meshing, load application, and material property assignment in ANSYS finite element analysis software;

[0032] Import the static analysis results as input into nCode-Designlife fatigue life analysis software, and then complete the fatigue analysis by setting equivalent loads and fatigue parameters;

[0033] The final output is the equivalent load theoretical fatigue life.

[0034] The present invention proposes a compliance verification method for pressure cycle life for aircraft engine hydraulic mechanical devices. A pressure cycle equivalent load spectrum determination method is provided by using a hydraulic mechanical device housing pressure cycle life prediction simulation model, which can be combined with the hydraulic mechanical device housing structural strength to determine the acceleration or deceleration life verification equivalent load spectrum, thereby improving the verification efficiency and ensuring the validity of the verification results. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the pressure cycle life compliance verification method of the present invention.

[0036] Figure 2 It is a flow chart of the method for determining the equivalent test load spectrum.

[0037] Figure 3 It is a flow chart of the method for determining theoretical fatigue life.

[0038] Figure 4 It is the structural principle diagram of the pressure cycle loading device;

[0039] Figure 5 It is the structural schematic diagram of the hydraulic station. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments.

[0041] A method for verifying the compliance of the pressure cycle life of a hydraulic mechanical device housing of an aircraft engine, the method comprising the following steps:

[0042] S1. Determine the standard load spectrum through the product technical documentation requirements of the aircraft engine hydraulic mechanical device housing;

[0043] S2, performing static analysis on the test piece using the pressure peak value in the standard load spectrum determined in step S1 to determine whether the pressure peak value in the standard load spectrum exceeds the design strength;

[0044] S3. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum does not exceed the design strength of the shell material of the test piece and no accelerated test is required, the verification is completed according to the standard load spectrum;

[0045] S4. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum does not exceed the design strength of the test piece shell material and an accelerated test is required, an equivalent accelerated load spectrum is determined by increasing the pressure amplitude and reducing the number of cycles;

[0046] S5, performing static analysis on the test piece using the pressure peak value in the equivalent acceleration load spectrum determined in step S4 to determine whether the pressure peak value in the equivalent acceleration load spectrum exceeds the design strength;

[0047] S6. If the analysis result of step S5 shows that the pressure peak in the equivalent acceleration load spectrum does not exceed the design strength of the test piece shell material, perform an accelerated test on the test piece shell;

[0048] S7, if the analysis result of step S5 shows that the pressure peak in the equivalent acceleration load spectrum has exceeded the design strength of the shell material of the test piece, return to step S4;

[0049] S8. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum has exceeded the design strength of the test piece shell material, then determine the equivalent deceleration load spectrum by reducing the pressure amplitude and increasing the number of cycles;

[0050] S9, performing static analysis on the test piece using the pressure peak value in the equivalent deceleration load spectrum determined in step S8 to determine whether the pressure peak value in the equivalent deceleration load spectrum exceeds the design strength;

[0051] S10, if the pressure peak value in the equivalent deceleration load spectrum determined in step S9 does not exceed the design strength, perform a deceleration test on the test piece shell;

[0052] S11 . If the pressure peak value in the equivalent deceleration load spectrum determined in step S9 exceeds the design strength, return to step S8 .

[0053] In the above step S1, the pressure amplitude and the number of cycles must be determined to determine the standard load spectrum, wherein the pressure amplitude P is determined by the following formula: ,

[0054] Where Pw is the normal maximum working pressure; FSF is the fatigue cycle stress factor, which is used to describe the safety factor, and FSF is set to 1.5; FF is the fatigue cycle temperature factor, which is used to describe the effect of the difference between the test temperature and the working temperature on the fatigue performance of the material, and can be determined by the following formula: ,

[0055] The number of cycles is consistent with the product cycle life requirements.

[0056] like Figure 2 As shown, the above equivalent acceleration load spectrum is determined according to the following steps:

[0057] First, the standard load theoretical fatigue life is calculated according to the standard load spectrum, and the fatigue life loss factor is calculated in combination with the life requirements of the product technical documents. The calculation method is as follows: ,

[0058] Then, determine the equivalent accelerated load pressure amplitude, perform equivalent accelerated load life calculation, and combine the obtained fatigue life loss factor to determine the equivalent accelerated load cycle number, which is determined according to the following formula: ;

[0059] Finally, the equivalent acceleration load spectrum is finally determined by combining the determined equivalent acceleration load pressure amplitude and the equivalent acceleration load cycle number.

[0060] Similarly, if Figure 2 As shown, the above equivalent deceleration load spectrum is determined according to the following steps:

[0061] First, the standard load theoretical fatigue life is calculated according to the standard load spectrum, and the fatigue life loss factor is calculated in combination with the life requirements of the product technical documents. The calculation method is as follows: ,

[0062] Then, determine the equivalent deceleration load pressure amplitude, perform equivalent deceleration load life calculation, and combine the obtained fatigue life loss factor to determine the equivalent deceleration load cycle number, which is determined according to the following formula: ;

[0063] Finally, the equivalent deceleration load spectrum is finally determined by combining the determined equivalent deceleration load pressure amplitude and the equivalent deceleration load cycle number.

[0064] like Figure 3 As shown, the above standard load theoretical fatigue life is determined according to the following steps:

[0065] Complete static analysis in ANSYS finite element analysis software by meshing, applying standard loads, and assigning material properties;

[0066] Import the static analysis results into nCode-Designlife fatigue life analysis software as input, and then complete the fatigue analysis by setting standard loads and fatigue parameters;

[0067] The final output is the theoretical fatigue life under standard load.

[0068] Similarly, if Figure 3 As shown, the equivalent accelerated load theoretical fatigue life is determined by the following steps:

[0069] Static analysis is completed in ANSYS finite element analysis software through meshing, application of equivalent acceleration loads, and assignment of material properties;

[0070] Import the static analysis results into nCode-Designlife fatigue life analysis software as input, and then complete the fatigue analysis by setting equivalent acceleration load and fatigue parameters;

[0071] The final output is the equivalent accelerated load theoretical fatigue life.

[0072] Similarly, if Figure 3 As shown, the equivalent deceleration load theoretical fatigue life is determined by the following steps:

[0073] Static analysis is completed in ANSYS finite element analysis software through meshing, application of equivalent deceleration loads, and assignment of material properties;

[0074] Import the static analysis results into nCode-Designlife fatigue life analysis software as input, and then complete the fatigue analysis by setting the equivalent deceleration load and fatigue parameters;

[0075] The final output is the theoretical fatigue life of the equivalent deceleration load.

[0076] The above-mentioned load application (including standard load application, equivalent acceleration load application and equivalent deceleration load application) is realized by a load application device, such as Figure 4 As shown, the load loading device is mainly composed of a hydraulic station 1, a servo loading device (including a driver 2, an electro-hydraulic servo valve 3 and a pressure sensor 4), a servo controller 5 and a host computer 6. The hydraulic station 1 provides high-pressure hydraulic oil for the loading system; the modulated high-pressure oil is supplied to the electro-hydraulic servo valve 3 on the servo loading device. The servo controller 5 collects the output signal of the pressure sensor 4, compares it with the load force given by the host computer 6, calculates the output through the control algorithm, adjusts the valve core opening of the electro-hydraulic servo valve 3, and controls the pressure output to the test piece. The control algorithm is downloaded to the servo controller 5 through the host computer 6, and the host computer 6 provides a real-time information monitoring interface for the loading system, and monitors the internal pressure of the test piece throughout the test.

[0077] The hydraulic station 1 is an oil source device for a pressure cycle load loading device. The structure of the hydraulic station 1 is as follows: Figure 5As shown, it is mainly composed of an electric motor and a hydraulic pump, which converts the rotational mechanical energy of the motor into fluid pressure energy of a certain flow rate and pressure through the hydraulic pump. When the hydraulic oil source is working, the hydraulic pump 1.3 sucks hydraulic oil from the oil tank 1.1 through the inlet suction filter 1.2, and the high-pressure hydraulic oil at the outlet of the hydraulic pump 1.3 is supplied to the servo loading actuator through the pump outlet oil filter 1.6 and the one-way valve 1.7. The pilot relief valve 1.10 is used to set the total oil supply pressure of the hydraulic oil source; the safety valve 1.9 is a direct-acting relief valve, which can set the maximum limited working pressure of the system. The pressure value is determined by the pressure value of the original component with the lowest pressure resistance level in the high-pressure oil circuit of the system (generally less than 10% to 20% of the pressure resistance value). The accumulator 1.8 is mainly used to eliminate the pressure and flow pulsation of the oil supply at the outlet of the high-pressure pump. The pressure sensor 1.5 collects the outlet pressure of the hydraulic pump 1.3 for monitoring by the host computer; the seismic pressure gauge 1.4 displays the outlet pressure of the hydraulic pump 1.3 on site for monitoring by the on-site operator.

Claims

1. A method for verifying the compliance of the pressure cycle life of the housing of an aircraft engine hydraulic mechanical device, characterized in that The method comprises the following steps: S1. Determine the standard load spectrum according to the product technical document requirements of the aircraft engine hydraulic mechanical device. In step S1, the pressure amplitude and the number of cycles must be determined to determine the standard load spectrum, wherein the pressure amplitude P is determined according to the following formula: ， Where Pw is the normal maximum working pressure; FSF is the fatigue cycle stress factor, which is used to describe the safety factor, and FSF is set to 1.5; FF is the fatigue cycle temperature factor, which is used to describe the effect of the difference between the test temperature and the working temperature on the fatigue performance of the material, and can be determined by the following formula: ， The number of cycles is consistent with the product cycle life requirements; S2, performing static analysis on the test piece using the pressure peak value in the standard load spectrum determined in step S1 to determine whether the pressure peak value in the standard load spectrum exceeds the design strength; S3. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum does not exceed the design strength of the shell material of the test piece and no accelerated test is required, the verification is completed according to the standard load spectrum; S4. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum does not exceed the design strength of the test piece shell material and an accelerated test is required, the equivalent accelerated load spectrum is determined by increasing the pressure amplitude and reducing the number of cycles. The equivalent accelerated load spectrum is determined according to the following steps: First, the standard load theoretical fatigue life is calculated according to the standard load spectrum, and the fatigue life loss factor is calculated in combination with the life requirements of the product technical documents. The calculation method is as follows: ， Then, determine the equivalent load pressure amplitude, perform equivalent load life calculation, and combine the obtained fatigue life loss factor to determine the equivalent load cycle number, which is determined according to the following formula: ， Finally, the equivalent acceleration load spectrum is finally determined by combining the determined equivalent load pressure amplitude and equivalent load cycle number; S5, performing static analysis on the test piece using the pressure peak value in the equivalent acceleration load spectrum determined in step S4 to determine whether the pressure peak value in the equivalent acceleration load spectrum exceeds the design strength; S6. If the analysis result of step S5 shows that the pressure peak in the equivalent acceleration load spectrum does not exceed the design strength of the test piece shell material, perform an accelerated test on the test piece shell; S7, if the analysis result of step S5 shows that the pressure peak in the equivalent acceleration load spectrum has exceeded the design strength of the shell material of the test piece, return to step S4; S8. If the analysis result of step S2 shows that the pressure peak in the standard load spectrum has exceeded the design strength of the test piece shell material, then determine the equivalent deceleration load spectrum by reducing the pressure amplitude and increasing the number of cycles; S9, performing static analysis on the test piece using the pressure peak value in the equivalent deceleration load spectrum determined in step S8 to determine whether the pressure peak value in the equivalent deceleration load spectrum exceeds the design strength; S10, if the pressure peak value in the equivalent deceleration load spectrum determined in step S9 does not exceed the design strength, perform a deceleration test on the test piece shell; S11 . If the pressure peak value in the equivalent deceleration load spectrum determined in step S9 exceeds the design strength, return to step S8 .

2. The method for verifying the compliance of the pressure cycle life of the aircraft engine hydraulic mechanical device housing according to claim 1 is characterized by: The theoretical fatigue life under standard load is determined by the following steps: Complete static analysis through meshing, load application, and material property assignment in ANSYS finite element analysis software; Import the static analysis results into nCode-Designlife fatigue life analysis software as input, and then complete the fatigue analysis by setting standard loads and fatigue parameters; The final output is the theoretical fatigue life under standard load.

3. The method for verifying the compliance of the pressure cycle life of the housing of the hydraulic mechanical device of an aircraft engine according to claim 1, characterized in that: The equivalent load theoretical fatigue life is determined by the following steps: Complete static analysis through meshing, load application, and material property assignment in ANSYS finite element analysis software; Import the static analysis results as input into nCode-Designlife fatigue life analysis software, and then complete the fatigue analysis by setting equivalent loads and fatigue parameters; The final output is the equivalent load theoretical fatigue life.

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