Method for predicting service life of aviation dynamic sealing ring based on gap leakage analysis

Abstract

The invention belongs to the technical field of rubber sealing tests, and relates to a gap leakage analysis-based aviation dynamic sealing ring service life prediction method, which comprises the following steps: S1, carrying out an aviation dynamic sealing ring service life pre-test, carrying out sealing ring service life exploration, and determining a sealing ring failure criterion; s2, carrying out an aviation dynamic sealing ring service life model correction test, and recording service life correction parameters in the test process; s3, according to Archard adhesion wear analysis and gap leakage analysis, obtaining a wear loss variable of the aviation dynamic sealing ring; s4, the abrasion loss of the aviation movable sealing ring is calculated, a standard equation for judging the sealing state of the aviation movable sealing ring is established, and the working state is determined; and S5, establishing an aviation dynamic sealing ring aging prediction model of the target working condition, and completing service life prediction evaluation. According to the invention, traditional sealing ring size measurement is replaced by the leakage amount, so that a complex sealing ring dismounting experiment is avoided, non-experimental wear of the sealing ring is reduced, and an accurate service life prediction model is established.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation sealing ring life prediction, and in particular relates to a method for predicting the service life of an aviation dynamic sealing ring based on gap leakage analysis. Background Art

[0002] In aircraft hydraulic systems, seals are often used as a common external dynamic seal and are often used in the actuators of aircraft actuation systems. During the working process, due to the dual effects of pre-compression and oil pressure, the contact surface will inevitably wear. With the continuous loss of seal material, the sealing effect will decrease and the leakage will increase. Severe leakage will cause system failure and even affect flight safety. Therefore, the wear process of the seal and the life prediction method for the wear of the seal have important practical significance.

[0003] At present, the main failure criterion for predicting the life of the seal ring is the wear of the seal ring. This data acquisition requires measuring the size of the seal ring. Due to the complexity of the sealing device, frequent disassembly and assembly of the seal ring will increase the complexity of the test and affect its actual sealing performance. Frequent disassembly and assembly operations may also cause additional tensile and compressive stresses on the seal ring, causing additional damage to the seal ring, thereby increasing the error of the test.

[0004] To solve the above problems, the present invention proposes a dynamic seal life prediction method taking leakage into consideration. By measuring the leakage of hydraulic oil at different times, the leakage caused by the pressure difference flow can be known by analyzing the gap leakage. The mapping relationship between the leakage and the wear can be inferred from this theory, and the wear of the sealing ring at each test time can be obtained. The wear modulus is corrected, and the Archard model is established. The life of the sealing ring is predicted according to the failure criteria. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for predicting the service life of aviation dynamic seals based on gap leakage analysis. The leakage volume replaces the traditional seal size measurement to avoid complicated disassembly and assembly experiments of the seal, reduce non-experimental wear of the seal, and establish an accurate wear prediction model. The wear prediction model can accurately complete the life prediction within an acceptable error range. The wear prediction model has a high accuracy rate and is of positive significance for guiding product design, optimizing material selection and improving processes.

[0006] To achieve the above object, the present invention discloses a method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis, which comprises:

[0007] S1: Conduct a preliminary test on the service life of an aviation dynamic seal ring to determine the failure criterion of the seal ring; the failure criterion of the preliminary test on the service life of an aviation dynamic seal ring is set as the test time and wear amount when the aviation dynamic seal ring fails according to the leakage amount at the sealing point per minute;

[0008] S2: Conduct life model correction test of aviation dynamic seal ring, and record the life correction parameters during the test, including test leakage Q, test time T and dynamic seal ring friction F f ;

[0009] S3: Based on Archard adhesive wear analysis and gap leakage analysis, the wear variables of the aviation dynamic seal ring are obtained;

[0010] S31: Based on Archard adhesive wear analysis, a wear calculation model for aviation dynamic seals is established, and the total wear depth of aviation dynamic seals is obtained as follows:

[0011]

[0012] Among them, H z is the total wear depth at any time; h i is the wear amount of the i-th node at time t; Δt is the wear time variable; n is the total number of measurement nodes of the aviation dynamic seal ring; i is the measurement node number of the aviation dynamic seal ring;

[0013] S32: According to the gap leakage analysis, the mapping relationship between leakage and wear is determined, the leakage of the aviation dynamic seal ring is calculated, and the wear variable of the aviation dynamic seal ring is obtained as follows:

[0014]

[0015] Among them, ΔH is the wear variable of the aviation dynamic seal ring; H i is the wear depth at time t; H i-1 is the wear depth at time t; μ j is the fluid dynamic viscosity; L is the gap sealing length; Q is the leakage of the aviation dynamic seal ring; D is the diameter of the cylinder; Δp is the pressure difference at both ends of the gap;

[0016] S4: Calculate the wear amount of the aviation dynamic seal ring, establish the standard equation for judging the sealing state of the aviation dynamic seal ring, and determine the working state of the aviation dynamic seal ring;

[0017] S41: Map the relationship between the total wear depth of the aviation dynamic seal ring in step S31 and the wear amount variable of the aviation dynamic seal ring in step S32, calculate the wear modulus of the aviation dynamic seal ring, and obtain the wear amount of the aviation dynamic seal ring as:

[0018]

[0019] in, Predict wear of dynamic seals in aviation; is the weighted sum of wear modulus; p cis the seal roughness contact pressure; ν is the average speed of a single stroke; T is the test time of the aviation dynamic seal ring; I(t i ) is the wear modulus of the dynamic seal ring; t i is the time of the i-th measurement node;

[0020] S42: Based on the wear amount H of the aviation dynamic seal ring in step S31, a standard equation for judging the sealing state of the aviation dynamic seal ring is established based on the required threshold value to determine the working state S of the aviation dynamic seal ring. i ;

[0021] S5: Establish an aging prediction model for aviation dynamic seals under target working conditions and complete service life prediction evaluation;

[0022] When the working state of the aviation dynamic seal ring in step S42 is the normal sealing state S i =1, according to the aging prediction model of the aviation dynamic seal ring under the target working condition calculated in step S31, the service life prediction result of the aviation dynamic seal ring is obtained based on the wear amount:

[0023]

[0024] Among them, T0 is the prediction result of the service life of aviation dynamic seals; H0 is the demand judgment threshold of aviation dynamic seals.

[0025] Preferably, a preliminary test of the service life of aviation dynamic seals is performed in step S1, specifically: a group of aviation dynamic seals are installed, the test is stopped when one of the seals in the test device reaches the failure criterion, and the time of the test is recorded.

[0026] Preferably, in step S2, a life model correction test of an aviation dynamic seal ring is performed, specifically:

[0027] S21: Install a set of aviation dynamic seals; spread the aviation dynamic seals and place them into the installation slots of the test fixture, so that the aviation dynamic seals are placed reasonably without twisting or flipping, and the installation status is consistent;

[0028] S22: Raise the oil temperature in the aviation dynamic seal ring to the test temperature, run it for 1 hour under a stable medium pressure and measure and record the friction force;

[0029] S23: Wear life test is carried out according to the test speed, oil pressure and test temperature corresponding to this group of tests. The sensor collects and stores the friction force and oil leakage in real time. At the same time, the leakage needs to be observed and recorded every 2 hours.

[0030] Preferably, in step S31, the wear depth of the wear surface is obtained according to Archard adhesive wear analysis, specifically:

[0031] According to Archard adhesive wear analysis, the volume wear change rate of the aviation dynamic seal ring within time t is determined as:

[0032]

[0033] Where V is the wear volume; t is the wear time; K is the wear coefficient; F is the seal normal contact load; H d The material hardness of the aviation dynamic seal ring;

[0034] Wear modulus of aviation dynamic seal ring I = K / H d , then the wear volume of the aviation dynamic seal is:

[0035] dV=IFνdt

[0036] Divide both sides of the above formula by the wear area S, and the wear depth of the aviation dynamic seal ring is:

[0037] dh=Ip(t)νdt

[0038] Where, h is the wear depth of the aviation dynamic seal ring; p(t) is the contact pressure at time t;

[0039] When the wear modulus I and the average speed v of a single stroke are determined, the wear amount of the seal ring is positively correlated with the contact pressure of the seal contact surface; the wear depth of the i-th measurement node on the contact surface of the aviation dynamic seal ring at time t is:

[0040]

[0041] Due to the mutual influence between the wear amount and the contact pressure of the sealing contact surface, according to the calculated contact pressure at time t, the total wear depth of the aviation dynamic seal ring is obtained as follows:

[0042] h=Iν∫p(t)dt

[0043] According to the actual test data collection time, the wear amount needs to be discretized as follows:

[0044]

[0045] Among them, p(t i ) is t i contact pressure over time; Δt is the test time interval.

[0046] Preferably, in step S32, the leakage amount Q of the aviation dynamic seal ring is formed on the sealing surface due to the reciprocating motion of the piston rod of the aviation dynamic seal ring, and life prediction modeling and calculation are performed. The initial leakage change of the hydraulic rod seal is set to zero through conversion, and the leakage amount Q of the aviation dynamic seal ring is obtained as:

[0047] Q=Q0-q

[0048] Among them, Q0 is the actual measured piston seal leakage; q is the leakage at the initial stage of sealing operation.

[0049] Preferably, in step S32, a mapping relationship between leakage and wear is determined based on gap leakage analysis, and the leakage of the aviation dynamic seal ring is calculated, specifically:

[0050] Since differential pressure flow will cause leakage of aviation dynamic seals, the mapping relationship between leakage and wear is inferred through gap leakage analysis, and the leakage of aviation dynamic seals under differential pressure flow is obtained as follows:

[0051]

[0052] Where Q1 is the leakage of the aviation dynamic seal ring under pressure differential flow; D is the diameter of the cylinder; h is the wear depth; μ j is the dynamic viscosity of the fluid; Δp is the pressure difference at both ends of the gap; μ0 is the relative velocity of the inner and outer cylinders;

[0053] When the relative speed of the inner and outer cylinders of the aviation dynamic seal ring is μ0=0, that is, when there is no relative motion between the piston and the cylinder wall, the concentric ring gap flow rate is:

[0054]

[0055] Among them, Q2 is the leakage of the aviation dynamic seal ring in the pressure difference flow without relative velocity;

[0056] Due to the increase in the number of reciprocating motions between the piston and the cylinder wall, the aviation dynamic seal ring is worn during the reciprocating process, and the seal wear depth h changes; the seal gap of the aviation dynamic seal ring after wear is equivalent to the concentric annular gap, and the leakage of the aviation dynamic seal ring at the seal wear depth h is:

[0057]

[0058] Preferably, the wear modulus of the aviation dynamic seal ring in step S41 is:

[0059]

[0060] Among them, I(t i ) is the wear modulus of the aviation dynamic seal ring; p(t i ) is t i contact pressure of time;

[0061] In order to ensure the accuracy of the calculation of the wear modulus of the sealing ring, the average wear modulus of the sealing ring within a wear period is used to calculate its wear modulus.

[0062] Preferably, the t i The contact pressure p(t i )for:

[0063]

[0064] Among them, F f (t i ) is t i The friction force over time; μ is the dynamic friction coefficient.

[0065] Preferably, the standard equation for determining the sealing state of the aviation dynamic seal ring is established based on the required threshold in step S42, specifically:

[0066]

[0067] Among them, H0 is the threshold for determining the demand for aviation dynamic seals; S i For the working state of the aviation dynamic seal ring, S i =1 is the normal sealing state, S i =0 is the seal failure state. When the wear depth of the aviation dynamic seal ring exceeds the judgment threshold, it means that the seal has failed and a new aviation dynamic seal ring needs to be replaced.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] (1) The present invention avoids the complicated experimental steps of disassembling and assembling the sealing ring by measuring the leakage amount instead of the traditional sealing ring size measurement, reduces the non-experimental wear and performance change of the sealing ring, and increases the service life of the dynamic sealing ring.

[0070] (2) The present invention corrects the wear modulus based on the calculated wear amount of the dynamic seal ring, establishes the Archard model, and realizes the prediction of the dynamic seal ring seal life. It is of great significance for guiding the dynamic seal ring product design, optimizing the dynamic seal ring material selection and improving the dynamic seal ring production and manufacturing process.

[0071] (3) The wear prediction model established by the dynamic seal life prediction method considering the leakage amount proposed in the present invention has high accuracy and can accurately complete the life prediction of the dynamic seal ring within the acceptable error range. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a flow chart of the method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis of the present invention;

[0073] Figure 2 This is a flow chart of the dynamic seal life prediction test of the present invention;

[0074] Figure 3A geometrical dimension diagram of a nitrile seal ring used in the test of the present invention;

[0075] Figure 4 This is a data diagram of the dynamic seal life prediction test process of the present invention;

[0076] Figure 5 This is a verification effect diagram of the dynamic seal life prediction model of the present invention. DETAILED DESCRIPTION

[0077] The exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0078] The embodiment of the present invention provides a method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis. Figure 1 As shown, a preliminary test of the service life of the aviation dynamic seal ring is carried out to investigate the service life of the seal ring and determine the failure criterion of the seal ring; a correction test of the service life model of the aviation dynamic seal ring is carried out to record the service life correction parameters during the test; the wear amount variable of the aviation dynamic seal ring is obtained according to the Archard adhesive wear analysis and the gap leakage analysis; the wear amount of the aviation dynamic seal ring is calculated, and the standard equation for judging the sealing state of the aviation dynamic seal ring is established to determine the working state; an aging prediction model of the aviation dynamic seal ring under the target working condition is established to complete the service life prediction evaluation; it includes:

[0079] The material of the aviation dynamic seal ring of the embodiment of the present invention is nitrile rubber, the inner diameter of the seal ring is 28.2 mm, the cross-sectional diameter is 1.78 mm, and the Mooney-Rayling model coefficients of the material are C_10=-0.12 MPa, C_01=1.41 MPa. Figure 3 The figure shows the geometric dimensions of the nitrile seal ring used in the test of the present invention. The elastic modulus of the polytetrafluoroethylene seal ring is 225.15MPa, the surface roughness is 0.8607μm, the friction coefficient is 0.285, the wear modulus is 1.2×10^(-5)mm^3 / N·m, and the test oil is No. 15 aviation hydraulic oil, the density at room temperature is 839.3〖kg / m〗^3, and the viscosity is 9.6435m^2 / s. As an example, a wear prediction model is established to predict the product life, verify the accelerated life prediction evaluation and the failure consistency test. In order to verify the accuracy of the wear model, the piston rod speed is 20mm / s and the stroke is 50mm.

[0080] Step S1: Conduct a preliminary test on the service life of an aviation dynamic seal ring to investigate the service life of the seal ring and determine the failure criterion of the seal ring.

[0081] First, a test is conducted to determine the life of the seal ring. According to the failure criterion of the test: the leakage at the seal is 0.05g per minute. When this state is reached, the test time is recorded to find out the life of the seal ring, and the size of the dynamic seal ring when it fails is obtained, and the wear amount is calculated. The specific performance parameter data are shown in Table 1.

[0082] Table 1 Failure performance parameters of aviation dynamic seal rings

[0083] Time (h) Failure size (mm) Wear amount (mm) Wear rate 1095 1.0101 0.7698 43.2％

[0084] like Figure 2 The flow chart of the dynamic seal life prediction test of the present invention is shown; a preliminary test of the service life of an aviation dynamic seal ring is performed, a group of aviation dynamic seal rings are installed, and when one of the seal rings in the test device reaches the standard of the failure criterion, the test is stopped and the time of the test is recorded. The failure criterion of the preliminary test of the service life of the aviation dynamic seal ring is set as: the leakage at the seal is 0.05g per minute, and the test time and wear amount when the aviation dynamic seal ring fails are obtained.

[0085] Step S2: Performing an aviation dynamic seal ring life model correction test, specifically:

[0086] Step S21: Install a set of aviation dynamic seals; stretch the aviation dynamic seals and place them into the installation slots of the test fixture, so that the aviation dynamic seals are placed reasonably without twisting or flipping, and the installation state is consistent.

[0087] Step S22: Raise the oil temperature in the aviation dynamic seal ring to the test temperature, run it for 1 hour under a stable medium pressure, and measure and record the friction force.

[0088] Step S23: Perform the wear life test according to the test speed, oil pressure and test temperature corresponding to the test group. The sensor collects and stores the friction and oil leakage in real time. At the same time, the leakage needs to be observed and recorded every 2 hours. The life correction parameters recorded during the test include: test leakage Q, test time T and dynamic seal friction F f The wear test data are shown in Table 2.

[0089] Table 2 Partial data of friction and leakage of seal ring wear test

[0090]

[0091]

[0092] Step S3: According to Archard adhesive wear analysis and clearance leakage analysis, the wear amount variable of the aviation dynamic seal ring is obtained.

[0093] Step S31: According to Archard adhesive wear analysis, a wear calculation model for the aviation dynamic seal ring is established; according to Archard adhesive wear analysis, the wear depth of the wear surface is obtained, and the volume wear change rate of the aviation dynamic seal ring within time t is determined as:

[0094]

[0095] Where V is the wear volume; t is the wear time; K is the wear coefficient; F is the seal normal contact load; H d It is the material hardness of aviation dynamic seal.

[0096] Wear modulus of aviation dynamic seal ring I = K / H d , then the wear volume of the aviation dynamic seal is:

[0097] dV = IFνdt;

[0098] Divide both sides of the above formula by the wear area S, and the wear depth of the aviation dynamic seal ring is:

[0099] dh=Ip(t)νdt;

[0100] Where h is the wear depth of the aviation dynamic seal ring; p(t) is the contact pressure at time t.

[0101] When the wear modulus I and the average speed v of a single stroke are determined, the wear amount of the seal ring is positively correlated with the contact pressure of the seal contact surface; the wear depth of the i-th measurement node on the contact surface of the aviation dynamic seal ring at time t is:

[0102]

[0103] Due to the mutual influence between the wear amount and the contact pressure of the sealing contact surface, according to the calculated contact pressure at time t, the total wear depth of the aviation dynamic seal ring is obtained as follows:

[0104] h=Iν∫p(t)dt

[0105] Due to the limitations of real physical test conditions, the step size cannot be infinitely reduced like in simulation tests. Therefore, according to the actual test data collection time, the wear amount needs to be discretized as follows:

[0106]

[0107] Among them, p(t i ) is t i contact pressure over time; Δt is the test time interval.

[0108] The total wear depth of the aviation dynamic seal ring is obtained as follows:

[0109]

[0110] Among them, H z is the total wear depth at any time; h i is the wear amount of the i-th node at time t; Δt is the wear time variable; n is the total number of aviation dynamic seal measurement nodes; i is the measurement node number of aviation dynamic seal.

[0111] Step S32: Determine the mapping relationship between leakage and wear according to the gap leakage analysis, and calculate the leakage of the aviation dynamic seal ring, specifically:

[0112] Since differential pressure flow will cause leakage of aviation dynamic seals, the mapping relationship between leakage and wear is inferred through gap leakage analysis, and the leakage of aviation dynamic seals under differential pressure flow is obtained as follows:

[0113]

[0114] Where Q1 is the leakage of the aviation dynamic seal ring under pressure differential flow; D is the diameter of the cylinder; h is the wear depth; μ j is the dynamic viscosity of the fluid; Δp is the pressure difference at both ends of the gap; μ0 is the relative velocity of the inner and outer cylinders.

[0115] When the relative speed of the inner and outer cylinders of the aviation dynamic seal ring is μ0=0, that is, when there is no relative motion between the piston and the cylinder wall, the concentric ring gap flow rate is:

[0116]

[0117] Among them, Q2 is the leakage of the aviation dynamic seal ring in the pressure difference flow without relative velocity.

[0118] Due to the increase in the number of reciprocating motions between the piston and the cylinder wall, the aviation dynamic seal ring is worn during the reciprocating process, and the seal wear depth h changes; the seal gap of the aviation dynamic seal ring after wear is equivalent to the concentric annular gap, and the leakage of the aviation dynamic seal ring at the seal wear depth h is:

[0119]

[0120] The wear variable of the aviation dynamic seal ring is obtained as follows:

[0121]

[0122] Among them, ΔH is the wear variable of the aviation dynamic seal ring; H i is the wear depth at time t; H i-1 is the wear depth at time t; μ jis the fluid dynamic viscosity; L is the gap sealing length; Q is the leakage of the aviation dynamic seal ring; D is the diameter of the cylinder; Δp is the pressure difference at both ends of the gap.

[0123] The leakage amount Q of the aviation dynamic seal ring is due to the reciprocating motion of the piston rod of the aviation dynamic seal ring, forming a leakage channel on the sealing surface. The life prediction modeling and calculation are carried out. The initial leakage change of the hydraulic rod seal is set to zero through transformation, and the leakage amount Q of the aviation dynamic seal ring is obtained as follows:

[0124] Q = Q0-q;

[0125] Among them, Q0 is the actual measured piston seal leakage; q is the leakage at the initial stage of sealing operation.

[0126] like Figure 4 The figure shows the data of the dynamic seal life prediction test process of the present invention; the relationship between the wear amount and the leakage amount is deduced based on the above content, and the change of the seal ring wear depth within 200 hours is obtained in combination with the experimental data as shown in Table 3.

[0127] Table 3 Partial calculation results of seal ring wear

[0128]

[0129] Step S4: Calculate the wear amount of the aviation dynamic seal ring, establish a standard equation for judging the sealing state of the aviation dynamic seal ring, and determine the working state of the aviation dynamic seal ring.

[0130] Step S41: Map the relationship between the total wear depth of the aviation dynamic seal ring in step S31 and the wear amount variable of the aviation dynamic seal ring in step S32, and calculate the wear modulus of the aviation dynamic seal ring.

[0131] The wear amount of the aviation dynamic seal ring is obtained as follows:

[0132]

[0133] Among them, H is the wear amount of aviation dynamic seal ring; is the weighted sum of wear modulus; p c is the seal roughness contact pressure; ν is the average speed of a single stroke; T is the test time of the aviation dynamic seal ring; I(t i ) is the wear modulus of the dynamic seal ring; t i is the time of the i-th measurement node;

[0134] The wear modulus of aviation dynamic seal is:

[0135]

[0136] Among them, I(t i ) is the wear modulus of the aviation dynamic seal ring; p(ti ) is t i Time contact pressure.

[0137] t i The contact pressure p(t i )for:

[0138]

[0139] Among them, F f (t i ) is t i The friction force over time; μ is the dynamic friction coefficient.

[0140] The calculated instantaneous value of the seal ring wear modulus within 200 hours is shown in Table 4.

[0141] Table 4 Partial data table of calculation of seal ring wear modulus

[0142]

[0143] The average wear modulus in the first 200 hours is -1.385×10 -8 According to the Archard wear prediction model, the wear amount of the aviation dynamic seal ring is obtained as follows:

[0144] H=-1.555×10 -8 p c νT;

[0145] Step S42: Based on the wear amount H of the aviation dynamic seal ring in step S31, a standard equation for judging the sealing state of the aviation dynamic seal ring is established based on the required threshold, specifically:

[0146]

[0147] Among them, H0 is the threshold for determining the demand for aviation dynamic seals; S i For the working state of the aviation dynamic seal ring, S i =1 is the normal sealing state, S i =0 is the seal failure state. When the wear depth of the aviation dynamic seal ring exceeds the judgment threshold, it means that the seal has failed and a new aviation dynamic seal ring needs to be replaced.

[0148] Step S5: Establishing an aging prediction model for the aviation dynamic seal ring under the target working condition to complete the service life prediction evaluation;

[0149] When the working state of the aviation dynamic seal ring in step S42 is the normal sealing state S i =1, the aging prediction model of the aviation dynamic seal ring under the target working condition is obtained according to the calculation in step S31, and the service life prediction result of the aviation dynamic seal ring is obtained based on the wear amount:

[0150]

[0151] Among them, T0 is the prediction result of the service life of aviation dynamic seals; H0 is the demand judgment threshold of aviation dynamic seals.

[0152] like Figure 5 The figure shows the verification effect diagram of the dynamic seal life prediction model of the present invention. According to the seal ring life determination test, the wear amount = 0.77mm is taken as its failure threshold. It is estimated that when the piston rod speed is 20mm / s, the stroke is 50mm, the friction coefficient is 0.285, and the friction force is 200N, the seal ring life is: 980h. According to the experimental data, the model can be verified and it is found that the model accuracy rate reaches 89.50%. The specific results are shown in Table 5:

[0153] Table 5 Prediction results of service life of aviation dynamic seal ring

[0154] Predicted lifespan / h Actual lifespan / h Accuracy / % 980 1095 89.50

[0155] The beneficial effects of the present invention are as follows: the present invention provides a method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis. The present invention avoids the complicated experimental steps of disassembling and assembling the seal ring by measuring the leakage amount instead of the traditional seal ring size measurement, reduces the non-experimental wear and performance changes of the seal ring, corrects the wear modulus according to the calculated wear amount, establishes the Archard model, and realizes the prediction of the service life of the dynamic seal. The accuracy rate of the established wear prediction model is 89.5%, and the service life prediction is accurately completed within the acceptable error range, which is of great significance for guiding product design, optimizing material selection and improving processes.

[0156] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis, characterized in that: It includes: S1: Conduct preliminary test on the service life of aviation dynamic seal rings to determine the failure criteria of the seal rings; The failure criterion of the life pre-test of the aviation dynamic seal ring is set as the test time and wear amount when the aviation dynamic seal ring fails according to the leakage amount at the seal per minute; S2: Conduct life model correction test of aviation dynamic seal ring, and record the life correction parameters during the test, including test leakage Q, test time T and dynamic seal ring friction F f ; S3: Based on Archard adhesive wear analysis and gap leakage analysis, the wear variables of the aviation dynamic seal ring are obtained; S31: Based on Archard adhesive wear analysis, a wear calculation model for aviation dynamic seals is established, and the total wear depth of aviation dynamic seals is obtained as follows: Among them, H z is the total wear depth at any time; h i is the wear amount of the i-th node at time t; Δt is the wear time variable; n is the total number of measurement nodes of the aviation dynamic seal ring; i is the measurement node number of the aviation dynamic seal ring; S32: According to the gap leakage analysis, the mapping relationship between leakage and wear is determined, the leakage of the aviation dynamic seal ring is calculated, and the wear variable of the aviation dynamic seal ring is obtained as follows: Among them, ΔH is the wear variable of the aviation dynamic seal ring; H i is the wear depth at time t; H i-1 is the wear depth at time t; μ j is the fluid dynamic viscosity; L is the gap sealing length; Q is the leakage of the aviation dynamic seal ring; D is the diameter of the cylinder; Δp is the pressure difference at both ends of the gap; S4: Calculate the wear amount of the aviation dynamic seal ring, establish the standard equation for judging the sealing state of the aviation dynamic seal ring, and determine the working state of the aviation dynamic seal ring; S41: Map the relationship between the total wear depth of the aviation dynamic seal ring in step S31 and the wear amount variable of the aviation dynamic seal ring in step S32, calculate the wear modulus of the aviation dynamic seal ring, and obtain the wear amount of the aviation dynamic seal ring as: in, Predict wear of dynamic seals in aviation; is the weighted sum of wear modulus; p c is the seal roughness contact pressure; ν is the average speed of a single stroke; T is the test time of the aviation dynamic seal ring; I(t i ) is the wear modulus of the dynamic seal ring; t i is the time of the i-th measurement node; S42: Based on the wear amount H of the aviation dynamic seal ring in step S31, a standard equation for judging the sealing state of the aviation dynamic seal ring is established based on the required threshold value to determine the working state S of the aviation dynamic seal ring. i ; S5: Establish an aging prediction model for aviation dynamic seals under target working conditions and complete service life prediction evaluation; When the working state of the aviation dynamic seal ring in step S42 is the normal sealing state S i =1, according to the aging prediction model of the aviation dynamic seal ring under the target working condition calculated in step S31, the service life prediction result of the aviation dynamic seal ring is obtained based on the wear amount: Among them, T0 is the prediction result of the service life of aviation dynamic seals; H0 is the demand judgment threshold of aviation dynamic seals.

2. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1 is characterized in that: In step S1, a preliminary test of the service life of an aviation dynamic seal ring is performed, specifically: a group of aviation dynamic seal rings are installed, the test is stopped when one of the seal rings in the test device reaches the failure criterion standard, and the test time at this time is recorded.

3. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1 is characterized in that: In step S2, a life model correction test of an aviation dynamic seal ring is performed, specifically: S21: Install a set of aviation dynamic seals; spread the aviation dynamic seals and place them into the installation slots of the test fixture, so that the aviation dynamic seals are placed reasonably without twisting or flipping, and the installation status is consistent; S22: Raise the oil temperature in the aviation dynamic seal ring to the test temperature, run it for 1 hour under a stable medium pressure and measure and record the friction force; S23: Wear life test is carried out according to the test speed, oil pressure and test temperature corresponding to this group of tests. The sensor collects and stores the friction force and oil leakage in real time. At the same time, the leakage needs to be observed and recorded every 2 hours.

4. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1 is characterized in that: In step S31, the wear depth of the wear surface is obtained according to Archard adhesive wear analysis, specifically: According to Archard adhesive wear analysis, the volume wear change rate of the aviation dynamic seal ring within time t is determined as: Where V is the wear volume; t is the wear time; K is the wear coefficient; F is the seal normal contact load; H d The material hardness of the aviation dynamic seal ring; Wear modulus of aviation dynamic seal ring I = K / H d , then the wear volume of the aviation dynamic seal is: dV=IFνdt Divide both sides of the above formula by the wear area S, and the wear depth of the aviation dynamic seal ring is: dh=Ip(t)νdt Where, h is the wear depth of the aviation dynamic seal ring; p(t) is the contact pressure at time t; When the wear modulus I and the average speed v of a single stroke are determined, the wear amount of the seal ring is positively correlated with the contact pressure of the seal contact surface; the wear depth of the i-th measurement node on the contact surface of the aviation dynamic seal ring at time t is: Due to the mutual influence between the wear amount and the contact pressure of the sealing contact surface, according to the calculated contact pressure at time t, the total wear depth of the aviation dynamic seal ring is obtained as follows: h=Iν∫p(t)dt According to the actual test data collection time, the wear amount needs to be discretized as follows: Among them, p(t i ) is t i contact pressure over time; Δt is the test time interval.

5. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1 is characterized in that: In step S32, the leakage amount Q of the aviation dynamic seal ring is formed on the sealing surface due to the reciprocating motion of the piston rod of the aviation dynamic seal ring, and the life prediction modeling and calculation are performed. The initial leakage change of the hydraulic rod seal is set to zero through conversion, and the leakage amount Q of the aviation dynamic seal ring is obtained as: Q=Q0-q Among them, Q0 is the actual measured piston seal leakage; q is the leakage at the initial stage of sealing operation.

6. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1 is characterized in that: In step S32, the mapping relationship between leakage and wear is determined according to the gap leakage analysis, and the leakage of the aviation dynamic seal ring is calculated, specifically: Since differential pressure flow will cause leakage of aviation dynamic seals, the mapping relationship between leakage and wear is inferred through gap leakage analysis, and the leakage of aviation dynamic seals under differential pressure flow is obtained as follows: Where Q1 is the leakage of the aviation dynamic seal ring under pressure differential flow; D is the diameter of the cylinder; h is the wear depth; μ j is the dynamic viscosity of the fluid; Δp is the pressure difference at both ends of the gap; μ0 is the relative velocity of the inner and outer cylinders; When the relative speed of the inner and outer cylinders of the aviation dynamic seal ring is μ0=0, that is, when there is no relative motion between the piston and the cylinder wall, the concentric ring gap flow rate is: Among them, Q2 is the leakage of the aviation dynamic seal ring in the pressure difference flow without relative velocity; Due to the increase in the number of reciprocating motions between the piston and the cylinder wall, the aviation dynamic seal ring is worn during the reciprocating process, and the seal wear depth h changes; the seal gap of the aviation dynamic seal ring after wear is equivalent to the concentric annular gap, and the leakage of the aviation dynamic seal ring at the seal wear depth h is:

7. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1 is characterized in that: The wear modulus of the aviation dynamic seal ring in step S41 is: Among them, I(t i ) is the wear modulus of the aviation dynamic seal ring; p(t i ) is t i contact pressure of time; In order to ensure the accuracy of the calculation of the wear modulus of the sealing ring, the average wear modulus of the sealing ring within a wear period is used to calculate its wear modulus.

8. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 7 is characterized in that: The i The contact pressure p(t i )for: Among them, F f (t i ) is t i The friction force over time; μ is the dynamic friction coefficient.

9. The method for predicting the service life of an aviation dynamic seal ring based on gap leakage analysis according to claim 1, characterized in that: The standard equation for determining the sealing state of the aviation dynamic seal ring is established based on the required threshold in step S42, specifically: Among them, H0 is the threshold for determining the demand for aviation dynamic seals; S i is the working state of the aviation dynamic seal ring, S i =1 is the normal sealing state, S i =0 is the seal failure state. When the wear depth of the aviation dynamic seal ring exceeds the judgment threshold, it means that the seal has failed and a new aviation dynamic seal ring needs to be replaced.

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