Fuel gear pump equivalent accelerated life test method based on wear failure

Abstract

The invention discloses a fuel gear pump equivalent accelerated life test method based on wear failure. The method comprises the following steps: 1, constructing an equivalent acceleration model under fatigue wear; 2, analyzing the stress of the fuel gear pump; 3, on the basis of the equivalent acceleration model in the step 1, calculating an equivalent acceleration life test load spectrum of the fuel gear pump in combination with the stress analysis in the step 2; and 4, verifying the equivalent acceleration model constructed in the step 1 through a test. By constructing the equivalent acceleration model and iteratively calculating the acceleration load spectrum, the fatigue damage failure mechanism of the fuel gear pump is accurately verified in a short time, so that the test efficiency and accuracy are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of equivalent accelerated life testing of aviation fuel gear pumps, and particularly relates to an equivalent accelerated life test method for fuel gear pumps based on wear failure. BACKGROUND

[0002] The aviation fuel gear pump is a core component of the fuel control system of an aero-engine, and its reliability directly affects the safety of the aero-engine. As a key component, the bearing is subjected to alternating loads for a long time and is prone to failure due to fatigue wear. The traditional life test method is long in cycle and high in cost, and it is difficult to meet the rapid development requirements. The existing accelerated life test method is mostly based on a single load condition, lacks verification of the equivalence of the fatigue damage mechanism under complex working conditions, and causes deviation between the test results and the actual life characteristics.

[0003] For example, Yang Yang and Liu Jie, Research on Accelerated Life Test Method of Gear Pump Wear [J]. Machine Tool and Hydraulic Pressure, 2014, 42(23): 204-206. only selects the particle number of abrasive particles in the oil as the acceleration stress, which cannot explore the influence of multiple load conditions on the fatigue damage mechanism and the accelerated life, and cannot adjust the acceleration ratio more flexibly. SUMMARY

[0004] In order to overcome the above technical problems, the purpose of the present application is to provide an equivalent accelerated life test method for fuel gear pumps based on wear failure, which accurately verifies the fatigue damage failure mechanism of the fuel gear pump in a short time by constructing an equivalent acceleration model and iteratively calculating the accelerated load spectrum, thereby improving the test efficiency and accuracy.

[0005] The technical solution adopted by the present application is: An equivalent accelerated life test method for fuel gear pumps based on wear failure, comprising the following steps: Step 1: Constructing an equivalent acceleration model under fatigue wear; Step 2: Force analysis of the fuel gear pump; Step 3: On the basis of the equivalent acceleration model in Step 1, combining the force analysis in Step 2, calculating the equivalent accelerated life test load spectrum of the fuel gear pump; Step 4: Verify the equivalent acceleration model constructed in Step 1 through testing.

[0006] The step 1 specifically comprises the following steps: 11) Contact fatigue principle According to the fatigue damage theory, the contact fatigue curve of the sliding bearing when working has the following inverse power relationship: In the formula, represents the number of cycles when the part reaches failure; , Represent the model parameters, determined by the material; Represent the cyclic stress; Represent the rotational speed, r / min; Represent the working life, h; The damage degree of the fuel gear pump in each cycle is The fatigue curves of the parts for the full life test and the accelerated life test are respectively: In the formula: Represent the number of cycles when the part reaches failure under the stress ; Represent the number of cycles when the part reaches failure under the stress ; 12) Linear cumulative damage theory The fatigue wear caused by each load is linearly cumulative; In the formula: Represent the number of cycles under the stress ; When the part is subjected to various cyclic stresses and the fatigue damage caused by the stress to the part accumulates to 1, the part will be damaged and failed, and the safety range of the part is set, that is: 13) Equivalent principle of full life test and accelerated life test Let the linear fatigue damage accumulation equations of the full life test and the accelerated life test be respectively: In the formula: Represent the number of cycles under the stress ; In the test process, the linear fatigue damage accumulation of the accelerated life test and the full life test needs to be equivalent, that is: After sorting, we get: The fatigue relationship in the full life test and the accelerated life test is sorted as: That is: 14) Cyclic stress equation The cyclic stress has the following relationship: In the formula: Represent the maximum stress of the contact point on the fatigue wear contact surface in the gear pump during the full life test, Pa; , And Related to the material, structure of the parts; further available: In the formula: represents the maximum stress of the contact point on the fatigue wear contact surface in the gear pump during the accelerated life test, Pa; 15) Equivalent acceleration model under fatigue wear Cycle number of the gear pump , in the formula is the rotation speed of the fuel gear pump, is the full life test time, is the time used for the change of the flight state of the aircraft engine in the full life test, and the stable working time of the fuel gear pump is , and thus the equivalent equation can be established: In the formula: represents the rotation speed of the fuel gear pump during the accelerated life test, r / min; represents the accelerated life test time, min; For steel or steel parts, take the constant , and thus the equivalent acceleration model of the fuel gear pump under fatigue wear can be simplified as: .

[0007] The step two of the force analysis on the fuel gear pump comprises the following steps: 21) Gear meshing force When the gear pump works, the high-pressure cavity, the low-pressure cavity and the gear slot are filled with fuel oil of a certain pressure, and the hydraulic pressure is transmitted to the gear through each tooth surface in contact with the gear; the tooth surface of the gear in contact with the oil in the high-pressure cavity is subjected to high pressure ; the tooth surface of the gear in contact with the oil in the low-pressure cavity is subjected to low pressure ; the tooth surface of the gear in contact with the oil in the transition area is subjected to a changing pressure, gradually increasing from pressure to pressure ; The resultant force of the hydraulic pressure on the two gears is , , and the direction thereof is approximately perpendicular to the line connecting the centers of the two gears and points to the low-pressure side; the resultant moment and , and of the hydraulic pressure on the driving gear and the driven gear are opposite to the direction of rotation of the gear, thereby hindering the rotation of the gear; For the driving gear, the effective hydraulic pressure force generating the moment at each moment only acts on a segment from the instantaneous meshing point to the addendum, and the value thereof is , and the action point of the resultant force is the center The distance is The torque generated is: Similarly, we can obtain for: In the formula: Represents the pressure difference between the high and low pressure chambers, with a value of [value missing]. Pa; Represents the gear tooth width, in meters (m). Represents the radius of the tooth tip circle, in meters (m). , The distance from the meshing point to the center of the driving and driven gears is represented in meters (m). Considering the geometric relationship between the meshing point and the gear center, the intersection of the line of action and the line connecting the centers of the two gears is the node. For two identical gears: The magnitude of the input torque pulsates with the position of the engagement point, reaching its maximum when the engagement point is at the nodal point; at this point, the meshing force... The direction is aligned with the line of action, pointing towards the inner normal direction at the point of contact on the tooth surface. The magnitude of the meshing force is: In the formula: This represents the perpendicular distance from the center of the gear to the line of meshing, equal to... ; Represents the engagement angle; 22) Hydraulic radial force When the pump is working, the oil pressure on the gears is inconsistent along the tip circle surface; the gears are subjected to low pressure in the oil suction chamber. Its function is to be under high pressure in the oil discharge chamber. The pressure gradually decreases in the transition zone between the suction and discharge chambers. Rise to Within the transition zone, the pressure is distributed in a stepped manner, with a sudden change at the tooth tip. This is because there is a gap between the tooth tip and the housing, and the oil leaks from the gap, resulting in a pressure drop. This is usually approximated as a linear change from low pressure to high pressure, which can be expressed as: when hour, ; when hour, ; when hour, As the gear rotates, the position of the meshing point changes, and the range of the oil discharge chamber and the transition zone also changes. The total radial force and direction of the oil pressure on the gear also change. Taking the position of the gear meshing at the node as the calculation point, the total radial force of the oil pressure needs to be integrated according to the above pressure distribution law. Take an included angle on the tooth tip circle as... Width area micro element The hydraulic pressure acting on it , its in The separations on the shaft are as follows: In the formula: the negative sign indicates that the direction is opposite to the coordinate axis. Performing three-part integrations on each of the two component forces yields: Will Substitute the two equations above and let have to: In the formula: Represents tooth width, in meters (m). Represents the radius of the tooth tip circle, in meters (m). This represents the pressure difference between the high and low chambers. Pa; , and Represents the wrap angle of the low-pressure chamber, transition zone, and high-pressure chamber, in rad; Pick have to: At this point, the total radial force generated by the hydraulic pressure is: And the direction of the radial force is The positive direction of the shaft, that is, perpendicular to the line connecting the centers of the two gears, points from the high-pressure chamber to the low-pressure chamber; 23) Total radial force In addition to the radial force formed by hydraulic pressure acting directly on the tooth surface In addition, there is the meshing force generated by hydraulic torque. ,generally Compare Small; The radial force generated by meshing, for the driving gear, is directed towards... negative axis direction and An obtuse angle is formed, reducing the resultant force; for the driven gear, it is towards... positive axis direction and parallel An acute angle is formed, increasing the net force; according to the law of cosines... and By combining the forces, the total radial force acting on the driving and driven gears can be obtained. , They are respectively: Obviously, Therefore, when the driving gear and driven gear have the same specifications, the bearing of the driven gear wears out faster and is more likely to be damaged first. The following approximate formula is used to calculate the radial force and serve as the basis for bearing design; In the formula: Represents the pressure difference between high and low pressure levels, expressed in Pa. Represents the gear tooth width, in meters (m). Represents the tip circle diameter, in meters (m).

[0008] Step three specifically involves: 31) Load spectrum of fuel gear pump full-life test; 32) Calculate the equivalent accelerated life test load spectrum of the fuel gear pump; Given speedup The following equation: Combined with equivalent acceleration model The rotational speed during accelerated life testing was obtained. and the pressure difference between import and export This allows for the determination of the equivalent accelerated life test load spectrum.

[0009] Step four specifically involves: 41) Full life test and equivalent accelerated life test Two fuel gear pumps with identical parameters were subjected to full-life and accelerated-life tests, respectively. Bearing wear was taken as a reference at the end of the tests. 42) Equivalent accelerated model correction factor. At the end of the test, the wear amount of the test components over their entire lifespan was obtained. Wear of the same component as in equivalent accelerated life test ,Appear At this point, a correction factor needs to be added to the equivalent acceleration model for modification, as shown below: In the formula: Represents the correction factor, by and Sure; Depend on Sure, , Given, therefore should be kept Unchanged, when The larger the load, the lower the equivalent accelerated life test load needs to be, i.e., the lower the load needs to be. and ,but The smaller; conversely The smaller, The larger.

[0010] The beneficial effects of this invention are: This invention proposes an equivalent accelerated life test method for fuel gear pumps based on wear failure. This method constructs an efficient equivalent accelerated life model by combining linear cumulative damage theory with the equivalent principle of bearing fatigue wear. This model can generate an accelerated load spectrum through iterative calculation based on the full-life test load spectrum of the fuel gear pump. In step one, an equivalent accelerated model is constructed based on fatigue wear. In step two, a stress analysis is performed on the fuel gear pump. Based on the equivalent accelerated model in step one, and combined with the stress analysis in step two, the equivalent accelerated life test load spectrum is calculated in step three. Finally, in step four, the equivalent accelerated model constructed in step one is verified through experiments. This achieves the equivalent accelerated life test verification of the bearing fatigue damage failure mechanism. This method can shorten the test cycle and effectively assess the life characteristics of the fuel gear pump in a shorter time, providing technical support for product reliability assessment, design, and optimization simulation. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating the technical steps of the present invention.

[0012] Figure 2 It is a contact fatigue curve.

[0013] Figure 3 It is the stress-intensity model SN curve.

[0014] Figure 4 It is a geometric diagram showing the relationship between the meshing point and the center of the gear.

[0015] Figure 5 This is a force analysis diagram of the gear shaft. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, an equivalent accelerated life test method for a fuel gear pump based on wear failure includes the following steps; Step 1: Construct an equivalent acceleration model under fatigue wear Specifically, the steps include the following: 11) Contact fatigue principle According to fatigue damage theory, the contact fatigue curve of a sliding bearing during operation has the following inverse power relationship: In the formula: This represents the number of cycles required for a component to reach failure. , Representative model parameters, determined by the materials; Represents cyclic stress; Represents rotational speed, in r / min; Represents working life, h; The degree of damage to the fuel gear pump in each cycle is as follows: The fatigue curves of the parts for full-life testing and accelerated life testing are as follows: In the formula: Representing the stress during full life testing The number of cycles required for a part to fail under the influence of the action; Representative of accelerated life testing under stress The number of cycles required for a part to fail under the influence of the action; 12) Linear cumulative damage theory The fatigue wear caused by each load is linearly cumulative; In the formula: Representing the stress during full life testing Number of cycles under the influence; When a part is subjected to various cyclic stresses and the fatigue damage caused by these stresses accumulates to 1, the part will fail. A safe range is set for the part, namely: 13) Equivalence principle between full life test and accelerated life test Let the linear fatigue damage accumulation equations for full-life testing and accelerated-life testing be as follows: In the formula: Representative of accelerated life testing under stress Number of cycles under the influence; During the testing process, the linear fatigue damage accumulation in accelerated life testing and full life testing must be equivalent, that is: After sorting, we can obtain: The fatigue relationships in full-life testing and accelerated life testing are summarized as follows: Right now: 14) Cyclic stress equation Cyclic stress has the following relationship: In the formula: The maximum stress, in Pa, represents the maximum stress at the contact point on the fatigue wear contact surface of the gear pump during a full-life test. , and It is related to the material and structure of the parts; further, we can conclude that: In the formula: The maximum stress, in Pa, represents the stress at the contact point on the fatigue wear contact surface of the gear pump during accelerated life testing. 15) Equivalent Acceleration Model under Fatigue Wear Number of cycles of the gear pump In the formula The rotational speed of the fuel gear pump. For the entire life cycle testing time, The stable operating time of the fuel gear pump can be calculated from the time required for changes in the flight state of the aircraft engine during a full life test. Therefore, an equivalent equation can be established: In the formula: The fuel gear pump speed during accelerated life testing is expressed in r / min. This represents the accelerated life test time, in minutes.

[0018] The values ​​of the exponents in the material fatigue curve equation are shown in Table 1.

[0019] Table 1. Material fatigue curve equation index For steel or steel parts, take a constant. Therefore, the equivalent acceleration model of fatigue wear in the fuel gear pump can be simplified as follows: .

[0020] Step 2: Force Analysis of Fuel Gear Pump The force analysis of a fuel gear pump includes the following steps: 21) Gear meshing force When the gear pump is working, the high-pressure chamber, low-pressure chamber, and gear teeth are filled with fuel at a certain pressure. The hydraulic pressure is transmitted to the gears through the tooth surfaces that contact the gears; the gear tooth surfaces that are in contact with the oil in the high-pressure chamber are subjected to high pressure. The function of the gear is to allow the gear tooth surface in contact with the low-pressure chamber oil to be subjected to low pressure. The function of the gear is to change the pressure on the gear tooth surface where it contacts the oil in the transition zone, gradually increasing from high pressure to low pressure. Rise to pressure .

[0021] The resultant force of the hydraulic pressure on the two gears is... , The direction is approximately perpendicular to the line connecting the centers of the two gears, pointing towards the low-pressure side; it exerts a resultant torque on both the driving and driven gears. and , and The direction of the [something] is opposite to the direction of gear rotation, thus hindering gear rotation.

[0022] For the driving gear, the effective hydraulic force that generates torque at each instant only acts on the segment from the instantaneous meshing point to the tooth tip, and its value is... The point of application of the resultant force is at the center of the driving gear. The distance is The torque generated is: Similarly, we can obtain for: In the formula: Represents the pressure difference between the high and low pressure chambers, with a value of [value missing]. Pa; Represents the gear tooth width, in meters (m). Represents the radius of the tooth tip circle, in meters (m). , The distance from the meshing point to the center of the driving and driven gears is represented in meters (m).

[0023] Considering the geometric relationship between the meshing point and the gear center, the intersection of the line of action and the line connecting the centers of the two gears is the node. For two identical gears: The magnitude of the input torque pulsates with the position of the engagement point, reaching its maximum when the engagement point is at the nodal point; at this point, the meshing force... The direction is aligned with the line of action, pointing towards the inner normal direction at the point of contact on the tooth surface. The magnitude of the meshing force is: In the formula: This represents the perpendicular distance from the center of the gear to the line of meshing, equal to... ; Represents the engagement angle.

[0024] 22) Hydraulic radial force When the pump is working, the oil pressure on the gears is inconsistent along the tip circle surface; the gears are subjected to low pressure in the oil suction chamber. Its function is to be under high pressure in the oil discharge chamber. The pressure gradually decreases in the transition zone between the suction and discharge chambers. Rise to Within the transition zone, the pressure is distributed in a stepped manner, with a sudden change at the tooth tip. This is because there is a gap between the tooth tip and the housing, and the oil leaks from the gap, resulting in a pressure drop. This is usually approximated as a linear change from low pressure to high pressure, which can be expressed as: when hour, ; when hour, ; when hour, As the gear rotates, the position of the meshing point changes, and the range of the oil discharge chamber and the transition zone also changes. The total radial force and direction of the oil pressure on the gear also change. Taking the position of the gear meshing at the node as the calculation point, the total radial force of the oil pressure needs to be integrated according to the above pressure distribution law.

[0025] Take an included angle on the tooth tip circle as... Width area micro element The hydraulic pressure acting on it , its in The separations on the shaft are as follows: In the formula: the negative sign indicates that the direction is opposite to the coordinate axis. Performing three-part integrations on each of the two component forces yields: Will Substitute the two equations above and let have to: In the formula: Represents tooth width, in meters (m). Represents the radius of the tooth tip circle, in meters (m). This represents the pressure difference between the high and low chambers. Pa; , and Represents the wrap angle of the low-pressure chamber, transition zone, and high-pressure chamber, in rad; Pick have to: At this point, the total radial force generated by the hydraulic pressure is: And the direction of the radial force is The positive direction of the shaft, that is, perpendicular to the line connecting the centers of the two gears, points from the high-pressure chamber to the low-pressure chamber; 23) Total radial force In addition to the radial force formed by hydraulic pressure acting directly on the tooth surface In addition, there is the meshing force generated by hydraulic torque. ,generally Compare Small; The radial force generated by meshing, for the driving gear, is directed towards... negative axis direction and An obtuse angle is formed, reducing the resultant force; for the driven gear, it is towards... positive axis direction and parallel An acute angle is formed, increasing the net force; according to the law of cosines... and By combining the forces, the total radial force acting on the driving and driven gears can be obtained. , They are respectively: Obviously, Therefore, when the driving gear and driven gear have the same specifications, the bearing of the driven gear wears out faster and is more likely to be damaged first. The following approximate formula is used to calculate the radial force and serve as the basis for bearing design; In the formula: Represents the pressure difference between high and low pressure levels, expressed in Pa. Represents the gear tooth width, in meters (m). Represents the tip circle diameter, in meters (m).

[0026] Step 3: Calculate the equivalent accelerated life test load spectrum of the fuel gear pump. 31) Load spectrum of fuel gear pump full life test Assume the service conditions of the fuel gear pump are as shown in the load spectrum in Table 2.

[0027] Table 2 Service Conditions of Fuel Gear Pumps 32) Calculate the equivalent accelerated life test load spectrum of the fuel gear pump. Given speedup The following equation: Combined with equivalent acceleration model The rotational speed during accelerated life testing was obtained. and the pressure difference between import and export Thus, the equivalent accelerated life test load spectrum was determined, as shown in Table 3: Table 3. Load spectrum of equivalent accelerated life test for fuel gear pumps

[0028] Step 4: Experimentally verify the equivalent acceleration model 41) Full life test and equivalent accelerated life test Two fuel gear pumps with identical parameters were subjected to full-life and accelerated-life tests, respectively. Bearing wear was taken as a reference at the end of the tests. 42) Equivalent accelerated model correction factor. At the end of the test, the wear amount of the test components over their entire lifespan was obtained. Wear of the same component as in equivalent accelerated life test ,Appear At this point, a correction factor needs to be added to the equivalent acceleration model for modification, as shown below: In the formula: Represents the correction factor, by and Sure; Depend on Sure, , Given, therefore should be kept Unchanged, when The larger the load, the lower the equivalent accelerated life test load needs to be, i.e., the lower the load needs to be. and ,but The smaller; conversely The smaller, The larger.

[0029] Experimental Example: The advantages of this invention can be further illustrated by the following experiments: Two fuel gear pumps of the same type with identical parameters were tested according to Tables 4 and 5 respectively.

[0030] Table 4. Load spectrum of full-lifetime experiments (normalized) Given speedup Take the equivalent accelerated life test load spectrum and When the following formula is used:

[0031]

[0032] Calculate the actual speedup ratio The given acceleration ratio is not met. Therefore, the engine speed needs to be increased. and inlet / outlet pressure difference The corrected equivalent accelerated life test load spectrum is shown in Table 5.

[0033] Table 5. Equivalent accelerated life test load spectrum (normalized) From the equivalent acceleration model It is concluded that, among them At this point, the actual acceleration meets the requirements as follows.

[0034]

[0035] At the end of the experiment, wear was measured at the same location on the same component of both fuel gear pumps; specifically, the wear of the inner bore of the floating drive bearing was measured. Wear during the entire lifespan experiment was also measured. Wear amount in equivalent accelerated life test . Therefore, a correction factor is required. .

[0036] From the appendix Figure 2 It can be seen that with the number of loops... Increase, cyclic stress The two decrease, and there is an inverse power relationship between them.

[0037] From the appendix Figure 3 It can be seen that when stress Less than critical stress It eventually reaches an unlimited fatigue lifespan.

[0038] From the appendix Figure 4 The geometric relationship between the driving wheel, driven wheel, and meshing point can be seen. , The centers of the driving and driven wheels are respectively. This is the engagement point.

[0039] From the appendix Figure 5 It can be seen from the analysis of the hydraulic radial force on the driving wheel and the driven wheel, , The centers of the driving and driven wheels are respectively. , The driving and driven wheels are subjected to hydraulic radial force.

Claims

1. A method for equivalent accelerated life testing of a fuel gear pump based on wear failure, characterized in that, Includes the following steps; Step 1: Construct an equivalent acceleration model under fatigue wear; Step 2: Force analysis of the fuel gear pump; Step 3: Based on the equivalent acceleration model in Step 1, and combined with the force analysis in Step 2, calculate the equivalent accelerated life test load spectrum of the fuel gear pump. Step 4: Verify the equivalent acceleration model constructed in Step 1 through experiments.

2. The method for equivalent accelerated life testing of a fuel gear pump based on wear failure according to claim 1, characterized in that, Step one specifically includes the following steps: 11) Contact fatigue principle The contact fatigue curve of a sliding bearing during operation has the following inverse power relationship: In the formula: This represents the number of cycles required for a component to reach failure. , Representative model parameters, determined by the materials; Represents cyclic stress; Represents rotational speed, in r / min; Represents working life, h; The degree of damage to the fuel gear pump in each cycle is as follows: The fatigue curves of the parts for full-life testing and accelerated life testing are as follows: In the formula: Representing the stress during full life testing The number of cycles required for a part to fail under the influence of the action; Representative of accelerated life testing under stress The number of cycles required for a part to fail under the influence of the action; 12) Linear cumulative damage theory The fatigue wear caused by each load is linearly cumulative; In the formula: Representing the stress during full life testing Number of cycles under the influence; When a part is subjected to various cyclic stresses and the fatigue damage caused by these stresses accumulates to 1, the part will fail. A safety range is set for the part, namely: 13) Equivalence principle between full life test and accelerated life test Let the linear fatigue damage accumulation equations for full-life testing and accelerated-life testing be as follows: In the formula: Representative of accelerated life testing under stress Number of cycles under the influence; During the testing process, the linear fatigue damage accumulation in accelerated life testing and full life testing must be equivalent, that is: After sorting, we can obtain: The fatigue relationships in full-life testing and accelerated life testing are summarized as follows: Right now: 14) Cyclic stress equation Cyclic stress has the following relationship: In the formula: The maximum stress, in Pa, represents the maximum stress at the contact point on the fatigue wear contact surface of the gear pump during a full-life test. , and It is related to the material and structure of the parts; further, we can conclude that: In the formula: The maximum stress, in Pa, represents the stress at the contact point on the fatigue wear contact surface of the gear pump during accelerated life testing. 15) Equivalent Acceleration Model under Fatigue Wear Number of cycles of the gear pump In the formula The rotational speed of the fuel gear pump. For the entire life cycle testing time, The stable operating time of the fuel gear pump can be calculated from the time required for changes in the flight state of the aircraft engine during a full life test. Therefore, an equivalent equation can be established: In the formula: The fuel gear pump speed during accelerated life testing is expressed in r / min. Represents the accelerated life test time, in minutes; For steel or steel parts, take a constant. Therefore, the equivalent acceleration model of fatigue wear in the fuel gear pump can be simplified as follows: 。 3. The method for equivalent accelerated life testing of a fuel gear pump based on wear failure according to claim 1, characterized in that, Step two, which involves stress analysis of the fuel gear pump, includes the following steps: 21) Gear meshing force When the gear pump is working, the high-pressure chamber, low-pressure chamber, and gear teeth are filled with fuel at a certain pressure. The hydraulic pressure is transmitted to the gears through the tooth surfaces that contact the gears; the gear tooth surfaces that are in contact with the oil in the high-pressure chamber are subjected to high pressure. The function of the gear is to allow the gear tooth surface in contact with the low-pressure chamber oil to be subjected to low pressure. The function of the gear is to change the pressure on the gear tooth surface where it contacts the oil in the transition zone, gradually increasing from high pressure to low pressure. Rise to pressure ; The resultant force of the hydraulic pressure on the two gears is... , The direction is approximately perpendicular to the line connecting the centers of the two gears, pointing towards the low-pressure side; it exerts a resultant torque on both the driving and driven gears. and , and The direction of the [something] is opposite to the direction of gear rotation, thus hindering gear rotation; For the driving gear, the effective hydraulic force that generates torque at each instant only acts on the segment from the instantaneous meshing point to the tooth tip, and its value is... The point of application of the resultant force is at the center of the driving gear. The distance is The torque generated is: Similarly, we can obtain for: In the formula: Represents the pressure difference between the high and low pressure chambers, with a value of [value missing]. Pa; Represents the gear tooth width, in meters (m). Represents the radius of the tooth tip circle, in meters (m). , The distance from the meshing point to the center of the driving and driven gears is represented in meters (m). Considering the geometric relationship between the meshing point and the gear center, the intersection of the line of action and the line connecting the centers of the two gears is the node. For two identical gears: The magnitude of the input torque fluctuates with the position of the meshing point, reaching its maximum when the meshing point is at the nodal point; at this point, the meshing force... The direction is aligned with the line of action, pointing towards the inner normal direction at the point of contact on the tooth surface. The magnitude of the meshing force is: In the formula: This represents the perpendicular distance from the center of the gear to the line of meshing, equal to... ; Represents the engagement angle; 22) Hydraulic radial force When the pump is working, the oil pressure on the gears is inconsistent along the tip circle surface; the gears are subjected to low pressure in the oil suction chamber. Its function is to be under high pressure in the oil discharge chamber. The pressure gradually decreases in the transition zone between the suction and discharge chambers. Rise to Within the transition zone, the pressure is distributed in a stepped manner, with a sudden change at the tooth tip. This is because there is a gap between the tooth tip and the housing, and the oil leaks from the gap, resulting in a pressure drop. This is usually approximated as a linear change from low pressure to high pressure, which can be expressed as: when hour, ; when hour, ; when hour, As the gear rotates, the position of the meshing point changes, and the range of the oil discharge chamber and the transition zone also changes. The total radial force and direction of the oil pressure on the gear also change. Taking the position of the gear meshing at the node as the calculation point, the total radial force of the oil pressure needs to be integrated according to the above pressure distribution law. Take an included angle on the tooth tip circle as... Width area micro element The hydraulic pressure acting on it , its in The separations on the shaft are as follows: In the formula: the negative sign indicates that the direction is opposite to the coordinate axis. Performing three-part integrations on each of the two component forces yields: Will Substitute the two equations above and let have to: In the formula: Represents tooth width, in meters (m). Represents the radius of the tooth tip circle, in meters (m). This represents the pressure difference between the high and low chambers. Pa; , and Represents the wrap angle of the low-pressure chamber, transition zone, and high-pressure chamber, in rad; Pick have to: At this point, the total radial force generated by the hydraulic pressure is: And the direction of the radial force is The positive direction of the shaft, that is, perpendicular to the line connecting the centers of the two gears, points from the high-pressure chamber to the low-pressure chamber; 23) Total radial force In addition to the radial force formed by hydraulic pressure acting directly on the tooth surface In addition, there is the meshing force generated by hydraulic torque. ,generally Compare Small; The radial force generated by meshing, for the driving gear, is directed towards... negative axis direction and An obtuse angle is formed, reducing the resultant force; for the driven gear, it is towards... positive axis direction and parallel An acute angle is formed, increasing the net force; according to the law of cosines... and By combining the forces, the total radial force acting on the driving and driven gears can be obtained. , They are respectively: Obviously, Therefore, when the driving gear and driven gear have the same specifications, the bearing of the driven gear wears out faster and is more likely to be damaged first. The following approximate formula is used to calculate the radial force and serve as the basis for bearing design; In the formula: Represents the pressure difference between high and low pressure levels, expressed in Pa. Represents the gear tooth width, in meters (m). Represents the tip circle diameter, in meters (m).

4. The method for equivalent accelerated life testing of a fuel gear pump based on wear failure according to claim 1, characterized in that, Step three specifically includes: 31) the full-life test load spectrum of the fuel gear pump; 32) calculating the equivalent accelerated life test load spectrum of the fuel gear pump; Given speedup The following equation: Combined with equivalent acceleration model The rotational speed during accelerated life testing was obtained. and the pressure difference between import and export This allows for the determination of the equivalent accelerated life test load spectrum.

5. The method for equivalent accelerated life testing of a fuel gear pump based on wear failure according to claim 1, characterized in that, Step four specifically includes: 41) Full life test and equivalent accelerated life test Two fuel gear pumps with identical parameters were subjected to full-life and accelerated-life tests, respectively. Bearing wear was taken as a reference at the end of the tests. 42) Equivalent accelerated model correction factor. At the end of the test, the wear amount of the test components over their entire lifespan was obtained. Wear of the same component as in equivalent accelerated life test ,Appear At this point, a correction factor needs to be added to the equivalent acceleration model for modification, as shown below: In the formula: Represents the correction factor, by and Sure; Depend on Sure, , Given, therefore should be kept Unchanged, when The larger the load, the lower the equivalent accelerated life test load needs to be, i.e., the lower the load needs to be. and ,but The smaller; conversely The smaller, The larger.

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