CN110765692B - Rubber O-shaped ring static seal life prediction method - Google Patents
Rubber O-shaped ring static seal life prediction method Download PDFInfo
- Publication number
- CN110765692B CN110765692B CN201911118711.8A CN201911118711A CN110765692B CN 110765692 B CN110765692 B CN 110765692B CN 201911118711 A CN201911118711 A CN 201911118711A CN 110765692 B CN110765692 B CN 110765692B
- Authority
- CN
- China
- Prior art keywords
- sealing
- contact
- shaped ring
- aging
- seal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Abstract
The invention relates to a rubber O-shaped ring static seal life prediction method, which is based on microscopic seepage theory rough surface contact finite element analysis, determines a seal contact pressure critical value through seal probability, then establishes a relation between compression permanent deformation rate and contact pressure through O-shaped ring structure macroscopic contact finite element analysis by fitting, further determines a compression permanent deformation rate critical value, and solves the problem of lack of unified and strict seal critical value standard. The vibration disengaging clearance of the sealing structural member under the use condition is considered to obtain the correction value of the compression set critical value, so that the method has better practical application value. The method can more comprehensively establish the numerical relation between the seal life index and the design parameters and the use conditions of the seal structure, and provides guidance for predicting the life of the seal structure and improving the design of the seal reliability.
Description
Technical Field
The invention belongs to the technical field of seal life prediction, and particularly relates to a static seal life prediction method of a rubber O-shaped ring.
Background
O-ring seals are widely used as a common technique for mechanical seals in hydraulic and pneumatic components of engines for sealing oil, water and gas media. Because the engine has severe service conditions, high temperature and high load are often accompanied, so that the sealing of the O-shaped ring is invalid, and the problem of three leaks is caused. Therefore, an effective O-shaped ring static seal life prediction method is established, a numerical relation between the seal life and each influence factor is established, and the method has important guiding significance for predicting the seal structure life and improving the seal reliability design.
At present, most national standards and patents provide rubber sealing life prediction methods, which are based on Arrhenius (Arrhenius) equation and aging dynamics equation, a relation of P-T-T (performance change-temperature-time) is determined, aging test data are processed through a binary regression algorithm and a least square method, a coefficient to be determined in the equation is obtained, and then the corresponding service life can be obtained according to the critical value and the temperature of the performance change. However, neither the performance P nor the sealing criteria are used as performance thresholds, nor are they used as indicators for determining the sealing life. The descriptions of the critical values in the various documents are not the same, but are approximate data based on industry experience. As in GB/T20028-2005, 50% of the performance change value is recommended as the threshold value. GB/T27800-2011 does not provide a definite value as a performance critical value, and recommends to determine through an examination test for simulating the use condition of a static seal rubber product, and the cost is high. CN201510701743 uses the specified compression recovery height of the O-ring as a critical value, and does not describe the critical value determining method, and has no universality. CN201410461145 and CN201611174320 are used for judging the critical standard of product failure according to the failure definition of the O-shaped sealing ring, wherein the compression permanent deformation rate epsilon is more than or equal to 40% or the compression stress relaxation rate delta is less than or equal to 80%.
In summary, the critical values are set according to industry experience, and have no unified criteria, but have different dimensional parameters, different surface processing quality and different material characteristics for the actual sealing structure, and the sealing critical values are necessarily different. Inaccurate values of the critical value lead to low prediction accuracy of the sealing life. More importantly, the critical value is usually related to the design parameters of the sealing structure, and the critical value cannot be accurately positioned, which means that the accurate numerical relation between the sealing life index and the influencing factors, namely the design parameters of the sealing structure cannot be established. As such, seal reliability forward designs lack sufficient guidance basis.
Disclosure of Invention
The invention aims to provide a rubber O-shaped ring static seal life prediction method aiming at the defects of the prior art.
The invention aims at realizing the following technical scheme:
the static seal life prediction method for the rubber O-shaped ring is characterized by comprising the following steps of:
A. based on an Arrhenius equation and an aging dynamics equation, a P-T-T (compression set-temperature-time) relation is determined, and the undetermined coefficients in the equation are determined through fitting of an aging test.
A1, establishing a P-T-T relation of rubber O-shaped ring materials
Arrhenius equation expressing the relationship between the reaction temperature T and the chemical reaction rate K is
The aging dynamics equation commonly used at present is a derivative and improvement method of a Dakin life pushing algorithm, and many experiments prove that the accuracy of prediction can be remarkably improved by adding an index to the time t parameter. The adopted P-t relationship is shown in the formula (2),
lnt-T can be obtained from formulae (1) and (2) -1 The linear prediction model of (2) is shown in the formula (3).
In the above formula, K is the chemical reaction rate, the unit is 1/d, A is an exponential factor, the unit is 1/d, E is the activation energy, the unit is J/mol, R is the gas mole constant, the default value is 8.314, the unit is J/(mol.K), T is the reaction temperature, the unit is K, P is the ageing performance index, B is the test constant, T is the ageing time, w is the ageing constant, and the default value is between 0 and 1.
Wherein P is characterized by a compression set epsilon, p=1-epsilon.
Let lnt =y, T -1 ＝X 1 ，
Formula (3) can be expressed as
Y＝a 0 +a 1 X 1 +a 2 X 2 (4)
Wherein a is 0 ,a 1 ,a 2 Is a coefficient to be determined.
A2, performing O-ring aging test under simulation condition
In order to determine the coefficients of the rubber O-ring material P-T relationship, an aging test under simulated operating conditions is required for the O-ring, test method referring to method B in ASTM-D395-03 (R2008). The simulation working environment requires the same sealing structure size as shown in figure 3 as the actual working environment, including groove depth, broadband, O-ring diameter cutting and compression; meanwhile, the ageing medium environment where the O-shaped ring is located is kept, such as soaking in engine oil or air.
A21, measuring the actual section diameter of each sample to be measured, and taking the original section diameter of the sample as the initial height h 0 . The depth of the groove is taken as the height h of the O-shaped ring after the maximum compression deformation n 。
A22, respectively placing the compression clamps with the samples to be tested into an ageing box with simulated working environments at different temperatures for ageing tests, wherein the ageing temperatures are respectively set to be T1, T2, … and Tn from low to high in sequence, and n is a natural number more than or equal to 4. The number of samples under each set of temperature conditions is at least 3 to 5.
A23, accumulating for a period of time t at the aging temperature i After that, releaseCompression, after half an hour at room temperature, the final height h of the sample is measured i According to epsilon i ＝(h 0 -h i )/(h 0 -h n ) Calculating the compression set epsilon under the aging time i And test specimen hardness H i 。
A24, repeating A22 and A23 according to the requirement to obtain test results under different aging time, and aging time sequence t i According to the principle of first-dense and then-sparse, exponential multiplication is recommended.
A25, when the test data are enough, the aging coefficient of the sample can be accurately fitted, and the aging test is terminated. Recommended aging time series t i ，i≥5。
A3, solving the P-T-T relation coefficient to be determined
According to the test result of the aging test in A2, solving the coefficient a to be determined in (4) by using a binary linear regression algorithm 0 ,a 1 ,a 2 . In order to ensure the reliability of the seal life prediction model, the recommended fitting goodness R is more than or equal to 0.9, and if the fitting goodness is not up to the standard, the accuracy of a test method and data is checked, or the number of tests is increased to improve the fitting goodness.
B. And determining a sealing contact pressure critical value through sealing probability based on microscopic seepage theory rough surface contact finite element analysis.
The theory of percolation was first proposed by S.R.Broadbet and J.M.Hammerley in 1957 to study the movement of fluids in a random medium, and was the theory of clustering in a random environment. The seepage theory has phase transition or critical phenomenon, which is very similar to the sealing phenomenon between rough contact surfaces, and people explain the mechanical sealing mechanism and predict the sealing probability of the rough contact surfaces by using the seepage theory. For a mechanical seal, the sealing contact annulus isolates two spaces operating at different pressures, preventing fluid from flowing from one side to the other through the channel. The simplest sealing mechanism is to have the two objects in direct contact with each other, thus preventing the passage of liquid between the gaps. If the two contact surfaces have exactly the same ideal conditions, such as perfectly smooth, flat, it is not possible for liquid to leak through the interface of the contact surfaces. In practice, however, the presence of microscopic irregularities in the contact surface renders the sealing contact surface imperfect, with the result that liquid can find a way and form a leak between two different pressure spaces. According to the seepage theory, when the contact rate reaches a critical value, a sealing cluster penetrating through the sealing surface can be realized, as shown in fig. 4. The specific flow is shown in fig. 2.
B1, intercepting rubber and pressing plate contact infinitesimal, and establishing a microscopic contact model as shown in fig. 5. The contact model recommends regular hexahedron units, and the number of the contact surface units is more than or equal to 20 multiplied by 20 in order to ensure enough statistical samples and statistical credibility.
And B2, modifying the node position according to the rough model of the contact surface generated by simulation, and generating a rough contact surface model in the finite element model. Wherein the contact surface roughness model is generated as follows.
B21, scanning and testing the local roughness of the contact surface, wherein the surface produced by the same process has similar roughness, which is the basic theory of replacing the whole rough morphology with local.
And B22, counting the distribution duty ratio of the cloud height interval of the contact surface roughness test data points.
And B23, generating a random roughness model of the contact surface by utilizing random function combination point cloud height interval distribution ratio statistical data.
And B3, solving to obtain a finite element analysis result.
B4, counting different average specific pressures P n Contact Rate p under c P is established n -p c A relationship curve. The average specific pressure, the nominal contact pressure, is shown as (5) as the pressure F applied to the contact element divided by the contact element area A n . The contact ratio, i.e. the number of cells contacted in the rough contact surface, is the ratio of the total contact surface cell number.
And B5, calculating the relation between the contact rate and the sealing probability according to the seepage theory.
And B51, calculating the sealing length L and the sealing width W of the contact sealing belt according to the O-ring sealing structure, and planning the number of units in the sealing length L and the sealing width W direction according to the minimum unit size in the B1.
B52, control contact rate p c The contacted and non-contacted cells are randomly generated on the lxw contact surface using a random function.
B53, searching clusters formed by the contact unit according to eight-communication definition, judging whether the formed maximum cluster can cover the whole sealing length L, and judging that the sealing is satisfied if the maximum cluster can cover the whole sealing length L; if the cover is not covered, the seal is judged to be impossible.
B54, repeating the steps B52 and B53 for N times, selecting N according to the accuracy requirement of enterprises on the sealing probability, recommending N to be more than or equal to 1000, and counting the number N of the sealing in the N-time value test s Probability of sealing p s As shown in (6)
B55, repeating steps B52, B53 and B54 with different contact ratios to obtain p c -p s A relationship curve. P established in connection with step B4 n -p c The relation curve can obtain P n -p s A relationship curve.
And B6, determining critical contact pressure according to the target sealing probability set by the enterprise. Enterprises set target sealing probability, such as 0.999, namely, 1%o failure rate is allowed based on factors such as sealing failure severity, customer acceptance degree and cost, and the like according to P n -p s The relationship may yield a critical contact pressure. (it should be noted that, at the sealing probability p s Near 1, contact pressure P n With p s The requirements on structural bearing capacity and contact surface processing technology are very strict, the implementation cost is increased sharply, a sealing structure which is not extremely important is not suggested, and 100% sealing probability is not suggested to be designed. )
C. And (3) through macroscopic contact finite element analysis of the O-shaped ring structure, fitting and establishing the relation between the compression set and the contact pressure, and further determining the critical value of the compression set. The specific flow is as follows.
And C1, establishing an O-shaped ring structure macroscopic contact finite element analysis model.
And C2, correlating the compression set epsilon measured by an aging test in the step 1.2 with the hardness H, wherein the hardness influences the elastic coefficient of the rubber O-shaped ring material, and the compression set influences the equivalent compression depth of the O-shaped ring.
C3, taking different compression depths and related material elastic coefficients as design parameters of an O-shaped ring structure macroscopic contact finite element model, and performing DOE calculation to obtain contact pressure P n And compression set epsilon.
C4 critical contact pressure P obtained in step B6 n By P n -epsilon curve, resulting in critical compression set.
D. And (3) calculating the vibration disengaging gap of the sealing contact surface by vibration finite element analysis of the sealing structural member under the use condition, and obtaining the correction value of the compression set critical value.
And D1, establishing a contact dynamics calculation model of the sealing structure.
And D2, testing vibration excitation load of the sealing structural member under the working condition.
And D3, taking the tested vibration signal as a contact dynamics calculation model of the sealing structure to input load, and calculating the maximum release clearance of the sealing contact surface under the vibration load condition, wherein the clearance influences the actual equivalent compression depth of the O-shaped ring.
And D4, correcting the critical compression set.
E. Substituting the corrected compression set critical value and working temperature into the P-T-T relation to realize the prediction calculation of the static sealing life of the rubber O-shaped ring at different temperatures.
Compared with the prior art, the invention has the beneficial effects that:
according to the static seal life prediction method of the rubber O-shaped ring, based on microscopic seepage theory rough surface contact finite element analysis, the seal contact pressure critical value is determined through seal probability, then the relation between the compression permanent deformation rate and the contact pressure is built through fitting through O-shaped ring structure macroscopic contact finite element analysis, and then the compression permanent deformation rate critical value is determined, so that the problem of lack of unified and strict seal critical value standard is solved. The vibration disengaging clearance of the sealing structural member under the use condition is considered to obtain the correction value of the compression set critical value, so that the method has better practical application value. The method can more comprehensively establish the numerical relation between the seal life index and the design parameters and the use conditions of the seal structure, and provides guidance for predicting the life of the seal structure and improving the design of the seal reliability.
Drawings
FIG. 1 is a frame flow chart of a rubber O-ring static seal life prediction method of the invention;
FIG. 2 is a flow chart of the critical seal contact pressure calculation based on the microscopic seepage theory of the present invention;
FIG. 3 is a schematic illustration of an O-ring seal configuration;
FIG. 4 is a schematic view of a contact unit seal cluster based on seepage theory, L being the seal length of the contact seal strip and W being the seal width;
FIG. 5 is a schematic diagram of a microcontact finite element model;
FIG. 6 is P n -p c A relationship curve;
FIG. 7 is p c -p s A relationship curve;
FIG. 8 is P n -epsilon curve;
fig. 9 is a comparison of a damped versus undamped mount.
Detailed Description
The invention is further illustrated by the following examples:
the invention is based on microscopic seepage theory rough surface contact finite element analysis, a sealing contact pressure critical value is determined through sealing probability, then the relationship between compression set and contact pressure is established through fitting through O-shaped ring structure macroscopic contact finite element analysis, and further the compression set critical value is determined, and the vibration disengaging clearance of the sealing contact surface is calculated through vibration finite element analysis of the sealing structural member under the use condition, so that the correction value of the compression set critical value is obtained, and the problem that the prior art lacks unified and strict sealing critical value standard is solved; and then, the compression set epsilon is used as a performance change index, a relation of P-T-T (performance change-temperature-time) is determined based on an Arrhenius equation and an aging dynamics equation, a undetermined coefficient in the equation is determined through fitting of an aging test, and the corrected compression set critical value and working temperature are substituted into the P-T-T relation, so that the static sealing life prediction calculation of the rubber O-shaped ring is realized. The method establishes the numerical relation between the seal life index and the design parameters and the use conditions of the seal structure more comprehensively, and provides guidance for predicting the life of the seal structure and improving the design of the seal reliability.
The method for predicting static seal life of a rubber O-ring of the present invention is described in further detail below in connection with an example of a fluororubber O-ring.
Step S1: based on an Arrhenius equation and an aging dynamics equation, a P-T-T (compression set-temperature-time) relation is determined, and the undetermined coefficients in the equation are determined through fitting of an aging test.
1.1 building a fluororubber O-shaped ring material P-T-T relation.
Based on an Arrhenius equation and an aging dynamics equation, determining a relation of P-T-T,
wherein P is characterized by a compression set epsilon, p=1-epsilon.
Let lnt =y, T -1 ＝X 1 ，
Formula (3) can be expressed as
Y＝a 0 +a 1 X 1 +a 2 X (4)
Wherein a is 0 ,a 1 ,a 2 Is a coefficient to be determined.
1.2 ageing test of O-ring under simulation conditions
To determine the coefficients of the fluororubber O-ring material P-T-T relationship, an aging test under simulated operating conditions was performed on the fluororubber O-ring, test method referring to method B in ASTM-D395-03 (R2008). The simulated working environment and the actual working environment keep the same sealing structure dimensions as shown in figure 3, including groove depth, broadband, O-ring diameter cutting and compression; while maintaining the O-ring immersed in the engine oil.
1.2.1 measuring the actual section diameter of each sample to be measured, taking the original section diameter of the sample as the initial height h 0 . Original section diameter mean value h of sample 0 =2.7mm. The depth of the groove is taken as the height h of the O-shaped ring after the maximum compression deformation n ＝2.0mm。
1.2.2 placing compression clamps filled with samples to be tested into simulated working environment aging boxes with different temperatures respectively for aging test, wherein the aging temperatures are respectively set to be T1, T2, T3, T4, T5 and T6 from low to high in sequence, and are 90 ℃, 100 ℃, 115 ℃, 140 ℃, 175 ℃ and 200 ℃ in sequence. The number of samples under each set of temperature conditions is at least 3 to 5.
1.2.3 accumulation at aging temperature over a period of time t i After that, the compression is released, and after half an hour of standing at room temperature, the final height h of the sample is measured i According to epsilon i ＝(h 0 -h i )/(h 0 -h n ) Calculating the compression set epsilon under the aging time i And test specimen hardness H i 。
1.2.4 repeating 1.2.2 and 1.2.3 as required to obtain test results under different aging times, aging time sequence t i According to the principle of firstly dense and secondly sparse, the three-dimensional matrix is sequentially 1d, 2d, 4d, 8d, 16d and 32d according to the exponential multiplication t1 to t 6.
1.2.5 according to the above aging time series, the corresponding aging test is completed and terminated.
The test result record table is referred to as follows:
1.3 solving the P-T-T relation to the coefficient to be determined
According to the test result of the aging test in 1.2, solving the coefficient a to be determined in the formula (4) by using a binary linear regression algorithm 0 ＝-15.108，a 1 ＝8276.429，a 2 4.843, goodness of fit r=0.95.
Step S2: and determining a sealing contact pressure critical value through sealing probability based on microscopic seepage theory rough surface contact finite element analysis. The specific flow is shown in fig. 2.
2.1 intercepting rubber and pressing plate contact infinitesimal, and establishing a microscopic contact model as shown in fig. 5. The contact model recommends regular hexahedral units, and the number of contact surface units is 80×20 in order to ensure sufficient statistical samples and statistical reliability.
2.2 modifying the node position according to the rough model of the contact surface generated by simulation, and generating a rough contact surface model in the finite element model. Wherein the contact surface roughness model is generated as follows.
2.2.1 scanning test contact surface local roughness, the roughness grade of the O-shaped ring contact steel plate is Rz12.5.
2.2.2 statistics of the contact surface roughness test data point cloud height interval distribution duty ratio.
2.2.3 generating a random roughness model of the contact surface by utilizing the random function and the distributed proportion statistical data of the cloud height interval of the joint.
2.3 solving to obtain a finite element analysis result.
2.4 statistics of different average specific pressure P n Contact Rate p under c Repeating for 3 times to randomly generate a rough contact surface model, and establishing P n -p c The relationship is shown in FIG. 6, and P obtained by 3 tests n -p c Relation curveThe lines substantially coincide.
2.5, calculating the relation between the contact rate and the sealing probability according to the seepage theory.
2.5.1 calculating the sealing length L and the sealing width W of the contact sealing belt according to the O-ring sealing structure, and planning the number of units in the sealing length L and the sealing width W direction according to the minimum unit size in 2.1.
2.5.2 controlling the contact Rate p c The contacted and non-contacted cells are randomly generated on the lxw contact surface using a random function.
2.5.3 searching clusters which can be formed by the contact unit according to eight-connection definition, judging whether the formed maximum cluster can cover the whole sealing length L, and if so, judging that the sealing is satisfied; if the cover is not covered, the seal is judged to be impossible.
2.5.4 repeating the steps 2.5.2 and 2.5.3 for N times, selecting N=10000 according to the accuracy requirement of the enterprise on the sealing probability, and counting the number N of the sealing in the N times value test s Probability of sealing p s As shown in (6)
2.5.5 repeating steps 2.5.2, 2.5.3 and 2.5.4 to obtain p c -p s The relationship is shown in fig. 7. Combining P established in step 2.4 n -p c The relation curve can obtain P n -p s A relationship curve.
2.6, determining the critical contact pressure according to the target sealing probability set by the enterprise. Enterprises set the target sealing probability to be 0.9995 based on factors such as sealing failure severity, customer acceptance degree and cost, namely, the failure rate is allowed to be 0.5 per mill, and the method is based on P n -p s The critical contact pressure can be obtained by the relation curve, and the maximum value of the random test is 1.445MPa.
Step S3: and (3) through macroscopic contact finite element analysis of the O-shaped ring structure, fitting and establishing the relation between the compression set and the contact pressure, and further determining the critical value of the compression set. The specific flow is as follows.
3.1 establishing an O-shaped ring structure macroscopic contact finite element analysis model.
3.2, correlating the compression set epsilon measured by the aging test in the step 1.2 with the hardness H, wherein the hardness influences the elastic coefficient of the rubber O-shaped ring material, and the compression set influences the equivalent compression depth of the O-shaped ring.
3.3 taking different compression depths and related material elastic coefficients as design parameters of the macroscopic contact finite element model of the O-shaped ring structure, and performing DOE calculation to obtain contact pressure P n The relationship with compression set epsilon is shown in figure 8.
3.4 Critical contact pressure P from 2.6 step n By P n -epsilon curve, resulting in critical compression set.
Step S4: and (3) calculating the vibration disengaging gap of the sealing contact surface by vibration finite element analysis of the sealing structural member under the use condition, and obtaining the correction value of the compression set critical value.
4.1 establishing a contact dynamics calculation model of the sealing structure.
4.2 testing the vibration excitation load of the sealing structure under operating conditions.
And 4.3, taking the tested vibration signal as a contact dynamics calculation model input load of the sealing structure, calculating a maximum disengaging gap 0.0683mm of a sealing contact surface of the non-vibration-reduction support scheme under the vibration load condition, wherein the maximum disengaging gap of the vibration-reduction support scheme is 0.0300mm, and the gap influences the actual equivalent compression depth of the O-shaped ring.
4.4, correcting the critical compression set, and obtaining the correction value of the critical value of the compression set rate as 0.113.
Step S5: and substituting the corrected compression set critical value and the working temperature into the relation of P-T-T, wherein the maximum working temperature of the tested fluororubber O-shaped ring is 110 ℃. Therefore, the roughness grade of the contact steel plate is Rz12.5, the static sealing life of the fluororubber O-shaped ring under the vibration-damping-free support is 330d, and the static sealing life of the fluororubber O-shaped ring is estimated to be 780d after the vibration-damping support is implemented.
The change of the sequence of the steps of the method, such as S2-S3-S4-S1-S5, can also realize the prediction of the static sealing life of the rubber O-shaped ring.
Claims (5)
1. The static seal life prediction method for the rubber O-shaped ring is characterized by comprising the following steps of:
A. based on an Arrhenius equation and an aging dynamics equation, determining a P-T-T relation, and determining a coefficient to be determined in the equation through fitting an aging test;
a1, establishing a P-T-T relation of rubber O-shaped ring materials
Arrhenius equation expressing the relationship between the reaction temperature T and the chemical reaction rate K is
The P-t relation is shown as formula (2)
lnt-T can be obtained from formulae (1) and (2) -1 The linear prediction model of (2) is shown in the formula (3);
wherein K is chemical reaction rate, unit is 1/d, A is an exponential factor, unit is 1/d, E is activation energy, unit is J/mol, R is a gas mole constant, default value is 8.314, unit is J/(mol.K), T is reaction temperature, unit is K, P is aging performance index, B is test constant, T is aging time, w is aging constant, default value is 0-1;
wherein P is characterized by a compression set epsilon, p=1-epsilon;
let lnt =y, T -1 ＝X 1 ，
Formula (3) can be expressed as
Y＝a 0 +a 1 X 1 +a 2 X 2 (4)
Wherein a is 0 ,a 1 ,a 2 Is a coefficient to be determined;
a2, performing an O-shaped ring aging test under a simulation condition;
a3, solving the P-T-T relation coefficient to be determined
According to the test result of the aging test in A2, solving the coefficient a to be determined in (4) by using a binary linear regression algorithm 0 ,a 1 ,a 2 ；
B. Determining a sealing contact pressure critical value through sealing probability based on microscopic seepage theory rough surface contact finite element analysis;
b1, intercepting rubber and pressing plate contact infinitesimal, establishing a microscopic contact model, wherein the contact model adopts regular hexahedral units, and the number of contact surface units is more than or equal to 20 multiplied by 20 in order to ensure enough statistical samples and statistical credibility;
b2, modifying the node position according to the rough model of the contact surface generated by simulation, and generating a rough contact surface model in the finite element model;
b3, solving to obtain a finite element analysis result;
b4, counting different average specific pressures P n Contact Rate p under c P is established n -p c The relation curve, average specific pressure, i.e. nominal contact pressure, is shown as (5) as the pressure F exerted on the contact element divided by the contact element area A n The contact rate, i.e. the number of cells contacted in the rough contact surface, is the ratio of the total contact surface cell number;
b5, calculating the relation between the contact rate and the sealing probability according to the seepage theory;
b6, determining critical contact pressure according to target sealing probability set by enterprises;
C. the relation between the compression set and the contact pressure is built through the macroscopic contact finite element analysis of the O-shaped ring structure by fitting, and then the critical value of the compression set is determined;
c1, establishing an O-shaped ring structure macroscopic contact finite element analysis model;
c2, correlating the compression set epsilon measured by an aging test in the step A2 with the hardness H, wherein the hardness influences the elastic coefficient of the rubber O-shaped ring material, and the compression set influences the equivalent compression depth of the O-shaped ring;
c3, taking different compression depths and related material elastic coefficients as design parameters of an O-shaped ring structure macroscopic contact finite element model, and performing DOE calculation to obtain contact pressure P n A relationship with compression set epsilon;
c4 critical contact pressure P obtained in step B6 n By P n -epsilon curve to obtain critical compression set;
D. the vibration decoupling gap of the sealing contact surface is calculated through vibration finite element analysis of the sealing structural member under the use condition, and a correction value of the compression set critical value is obtained;
d1, establishing a contact dynamics calculation model of the sealing structure;
d2, testing vibration excitation load of the sealing structural member under the working condition;
d3, taking the tested vibration signal as a contact dynamics calculation model input load of the sealing structure, and calculating the maximum disengaging clearance of the sealing contact surface under the vibration load condition, wherein the clearance influences the actual equivalent compression depth of the O-shaped ring;
d4, correcting the critical compression set;
E. substituting the corrected compression set critical value and working temperature into the P-T-T relation to realize the prediction calculation of the static sealing life of the rubber O-shaped ring at different temperatures.
2. The method for predicting the static sealing life of a rubber O-ring according to claim 1, wherein the step A2 specifically comprises the steps of:
a21, measuring the actual section diameter of each sample to be measured, and taking the original section diameter of the sample as the initial height h 0； With groove depth as the maximum O-ringHeight h after compression deformation n ；
A22, respectively placing compression clamps with samples to be tested into an ageing box with simulated working environments at different temperatures for ageing tests, wherein the ageing temperatures are respectively set to be T1, T2, … and Tn from low to high in sequence, n is a natural number more than or equal to 4, and the number of the samples under each group of temperature conditions is at least 3-5;
a23, accumulating for a period of time t at the aging temperature i After that, the compression is released, and after half an hour of standing at room temperature, the final height h of the sample is measured i According to epsilon i ＝(h 0 -h i )/(h 0 -h n ) Calculating the compression set epsilon under the aging time i And test specimen hardness H i ；
A24, repeating A22 and A23 according to the requirement to obtain test results under different aging time, and aging time sequence t i According to the principle of firstly dense and secondly sparse, multiplying according to an index;
a25, when the test data are enough, the aging coefficient of the sample can be accurately fitted, and the aging test is terminated; aging time series t i ，i≥5。
3. The method for predicting the static sealing life of a rubber O-ring according to claim 1, wherein the contact surface roughness model is generated according to the following method:
b21, scanning and testing the local roughness of the contact surface, wherein the surfaces produced by the same process have similar roughness, which is the basic theory of replacing the whole rough morphology with local parts;
b22, counting the distribution duty ratio of the cloud height interval of the roughness test data points of the contact surface;
and B23, generating a random roughness model of the contact surface by utilizing random function combination point cloud height interval distribution ratio statistical data.
4. The method for predicting the static sealing life of a rubber O-ring according to claim 1, wherein the step B5 comprises the following steps:
b51, calculating the sealing length L and the sealing width W of the contact sealing belt according to the O-shaped ring sealing structure, and planning the number of units in the sealing length L and the sealing width W direction according to the minimum unit size in the B1;
b52, control contact rate p c Randomly generating a contact unit and an untouched unit on the L×W contact surface by using a random function;
b53, searching clusters formed by the contact unit according to eight-communication definition, judging whether the formed maximum cluster can cover the whole sealing length L, and judging that the sealing is satisfied if the maximum cluster can cover the whole sealing length L; if the cover is not covered, judging that the sealing is not carried out;
b54, repeating the steps B52 and B53 for N times, selecting N according to the accuracy requirement of the enterprise on the sealing probability, wherein N is more than or equal to 1000, and counting the number N of sealing in the N-time value test s Probability of sealing p s As shown in (6)
B55, repeating steps B52, B53 and B54 with different contact ratios to obtain p c -p s A relationship curve; p established in connection with step B4 n -p c The relation curve can obtain P n -p s A relationship curve.
5. The method for predicting the static sealing life of the rubber O-ring according to claim 1, wherein the method comprises the following steps: and establishing a numerical relation between the seal life index and the design parameters and the use conditions of the seal structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911118711.8A CN110765692B (en) | 2019-11-15 | 2019-11-15 | Rubber O-shaped ring static seal life prediction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911118711.8A CN110765692B (en) | 2019-11-15 | 2019-11-15 | Rubber O-shaped ring static seal life prediction method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110765692A CN110765692A (en) | 2020-02-07 |
| CN110765692B true CN110765692B (en) | 2023-05-12 |
Family
ID=69337904
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911118711.8A Active CN110765692B (en) | 2019-11-15 | 2019-11-15 | Rubber O-shaped ring static seal life prediction method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110765692B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111458225B (en) * | 2020-04-29 | 2021-09-03 | 同济大学 | Method for predicting service life of proton exchange membrane fuel cell sealing material |
| CN113340574B (en) * | 2021-03-23 | 2022-03-01 | 新兴河北工程技术有限公司 | Accurate prediction and calculation method for service life of rubber sealing product |
| CN113654978A (en) * | 2021-08-25 | 2021-11-16 | 全球能源互联网研究院有限公司 | Oil-immersed sound vibration suppression damping rubber sound insulation performance evaluation method and application thereof |
| CN113701957B (en) * | 2021-08-27 | 2023-08-25 | 重庆建设车用空调器有限责任公司 | Detection device for sealing performance of sealing ring |
| CN114964670B (en) * | 2022-08-01 | 2022-11-01 | 宇一精工科技(南通)有限公司 | Method for detecting defects of sealing rubber ring |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0343620B1 (en) * | 1987-05-29 | 1995-06-28 | IDE, Russell, D. | Bearings having beam mounted bearing pads and methods of making same |
| CN107014684A (en) * | 2017-04-12 | 2017-08-04 | 浙江大学 | A kind of sealing ring Young's modulus semi physical detection means and method |
| CN108470101A (en) * | 2018-03-21 | 2018-08-31 | 西北工业大学 | Mechatronic Systems Y type sealing structure reliability estimation methods based on agent model |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2166348A1 (en) * | 2007-07-12 | 2010-03-24 | National Institute Of Advanced Industrial Science | High-pressure tank damage detecting method and device therefor |
-
2019
- 2019-11-15 CN CN201911118711.8A patent/CN110765692B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0343620B1 (en) * | 1987-05-29 | 1995-06-28 | IDE, Russell, D. | Bearings having beam mounted bearing pads and methods of making same |
| CN107014684A (en) * | 2017-04-12 | 2017-08-04 | 浙江大学 | A kind of sealing ring Young's modulus semi physical detection means and method |
| CN108470101A (en) * | 2018-03-21 | 2018-08-31 | 西北工业大学 | Mechatronic Systems Y type sealing structure reliability estimation methods based on agent model |
Non-Patent Citations (4)
| Title |
|---|
| "Accelerated Aging Test and Study of Storage Life Prediction of NBR O-Ring";Jun Pan等;《Advanced Materials Research》;20111231;第415-517卷;第184-190页 * |
| 基于渗流模型的平面密封机理研究;崔彪等;《现代车用动力》;20170831(第03期);第34-37页 * |
| 复合材料密封环微观摩擦状态模拟与摩擦性能对比分析;宫燃等;《兵工学报》;20150331;第36卷(第03期);第421-426页 * |
| 橡胶材料加速老化试验与寿命预测方法研究进展;刘晓丹等;《合成材料老化与应用》;20140228;第43卷(第01期);第69-73页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110765692A (en) | 2020-02-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110765692B (en) | Rubber O-shaped ring static seal life prediction method | |
| CN110069860B (en) | Telescopic joint reliability fatigue life assessment method | |
| CN103630343B (en) | Accelerating test method for shelf lives of vibration isolators | |
| CN107436983B (en) | O-shaped rubber sealing ring service life prediction method based on multivariate sample difference | |
| CN107702905B (en) | Rubber ring reliable life prediction method based on Weibull distribution | |
| Guiraud et al. | A non-central version of the Birnbaum-Saunders distribution for reliability analysis | |
| CN110909413A (en) | Concrete panel rock-fill dam horizontal displacement prediction accuracy method and system | |
| CN111504816A (en) | Marine atmospheric environment-tensile load dynamic loading coupling test and evaluation method | |
| CN116994999B (en) | Mechanical arm suction adjusting method and system for ultra-clean environment | |
| CN110298765B (en) | Power distribution network power consumption abnormality detection method based on objective correlation factors | |
| Chen et al. | Accelerated life test for reliability evaluation of pneumatic cylinders | |
| Guo et al. | Modeling and analysis for degradation with an initiation time | |
| CN111222095A (en) | Gross error discrimination method, device and system in dam deformation monitoring | |
| CN109299553B (en) | Method for modeling random model of degradation of sealing performance of underwater connector | |
| CN110568337A (en) | Metal packaging power MOSFET storage reliability detection technology based on hidden degradation | |
| CN110895625A (en) | Method for simulating reliability confidence interval estimation value of performance degradation product | |
| CN110196026B (en) | Method for rapidly measuring and calculating relation between surface roughness and measurement scale | |
| CN113870955A (en) | Method for establishing prediction model of post-curing effect of rubber performance in natural environment | |
| CN113642183A (en) | Design method of EWMA control chart with variable sample volume residual error | |
| CN110737987A (en) | Method for evaluating expected life of LED lighting products | |
| CN111177863A (en) | Degradation life estimation method aiming at random characteristics of mechanical wear process | |
| CN112577450B (en) | Engineering rock mass structural surface roughness coefficient determination method based on multiple regression analysis | |
| CN109766582B (en) | Prediction method for tensile strength of metal material | |
| CN113340574B (en) | Accurate prediction and calculation method for service life of rubber sealing product | |
| CN112748005B (en) | Method for measuring and calculating weak position of aluminum alloy section |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |