CN116362074A - Method for calculating fatigue life of automobile rubber suspension under random load - Google Patents

Method for calculating fatigue life of automobile rubber suspension under random load Download PDF

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CN116362074A
CN116362074A CN202310220265.1A CN202310220265A CN116362074A CN 116362074 A CN116362074 A CN 116362074A CN 202310220265 A CN202310220265 A CN 202310220265A CN 116362074 A CN116362074 A CN 116362074A
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赵学智
王坤
上官文斌
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South China University of Technology SCUT
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Abstract

The invention discloses a method for calculating fatigue life of an automobile rubber suspension under random load, which comprises the following steps: collecting a suspension force load spectrum; obtaining a force displacement relation of suspension and strain results of different displacement loads of suspension through finite element analysis; converting the force load spectrum of the suspended reinforced pavement into a suspended displacement load spectrum; dividing the suspended displacement load spectrum into 2n displacement load component spectrum according to rigidity; carrying out fatigue tests of different R ratio working conditions to obtain fatigue life; obtaining effective tensile strain of the dumbbell test column under different R ratio working conditions through finite element analysis; an SN curve with uniform R ratio working conditions is established according to the effective tensile strain and the actual measured fatigue life; and converting the suspended displacement load spectrum into strain load spectrums on each point of the suspended finite element model, counting by rain flow, and calculating the fatigue life by combining with an SN curve of a unified R ratio working condition. The invention can obtain the SN curve of the uniform R ratio working condition of the rubber material, and can be used for predicting the rubber fatigue under the effect of random load.

Description

Method for calculating fatigue life of automobile rubber suspension under random load
Technical Field
The invention relates to the field of fatigue analysis of automobile parts, in particular to a calculation method based on an automobile rubber suspension displacement load spectrum and fatigue damage.
Background
In the running process of the automobile, the load born by the rubber vibration isolator is from two aspects, namely a low-frequency large-amplitude pavement load spectrum and periodic high-frequency small-amplitude vibration caused by torsion of an engine crankshaft, and the automobile rubber vibration isolator works under random load working conditions. Therefore, the fatigue life prediction for the rubber vibration isolator of the automobile should take into account the effect of random loads. The random load can generate dynamic stress, cause fatigue damage and form fatigue fracture. Therefore, the collection and processing of the road load spectrum provides reliable data support for the simulation analysis of engineers in laboratories and multi-body dynamics, so that the engineers can make predictions and judgments on the fatigue life of automobile parts.
Generally, the acquired road spectrum can be applied to simulation analysis and a laboratory through processing, so how to scientifically and truly process the road spectrum directly influences the consistency of test results and actual effects. Generally, there are two methods of processing the road spectrum: the first is a load-carrying value method, namely, according to load information in a road spectrum, a constant load-carrying value is selected by combining with personal experience of an engineer and is used for fatigue test of parts; the second is a road spectrum iterative simulation method, namely, the collected road spectrum is subjected to simple screening, and an iterative method is adopted to carry out fatigue test in a laboratory. Although the fatigue failure area can be found out quickly by the first method, the accuracy of the test is low, the personal experience factors are more, and the subjectivity is too strong; the second method can truly reflect the actual loading condition of the parts, but the test period is longer, more than one month is needed in one period generally, the cost is high, and the resource utilization rate is low.
Disclosure of Invention
In order to accurately obtain fatigue damage of the rubber suspension, the invention provides a method for calculating the fatigue life of the rubber suspension of an automobile under random load, and a suspension strain result and a suspension material SN curve with uniform R ratio working conditions are obtained through finite element analysis. And (3) converting the suspension reinforced pavement load spectrum obtained in the experimental field into a displacement load spectrum by analyzing the force displacement relation of the suspension. And segmenting the displacement load spectrum by combining the nonlinearity of the suspension stiffness, and fitting the strain load spectrum on each node in the suspension finite element model by combining the strain results of different suspension displacement loads. And (3) performing rain flow counting on the fitted strain load spectrum, and calculating fatigue damage of the suspension under the action of the pavement load spectrum by combining with an SN curve of the suspension material.
In order to achieve the purpose of the invention, the invention provides a method for calculating the fatigue life of an automobile rubber suspension under random load, which comprises the following steps:
(1) The durability test of the whole vehicle is carried out on the reinforced pavement of the test field, and the suspension force load time history (load spectrum) suitable for the bench test and the simulation analysis is collected;
(2) And establishing a suspension finite element model, analyzing the suspension finite element model, and further obtaining a suspension force-displacement relationship and a suspension displacement-strain relationship.
(3) And (3) converting the suspension force load spectrum into a suspension displacement load spectrum according to the force-displacement relation obtained in the step (2).
(4) Considering the nonlinearity of the suspension stiffness, the suspension displacement load spectrum is divided into 2n units displacement load component spectrums according to the stiffness.
(5) And (3) carrying out fatigue tests under the working conditions of R >0, R=0 and R <0, and obtaining fatigue life under the working conditions of different R ratios.
(6) And obtaining effective tensile strain of the dumbbell test column under different R ratio working conditions through finite element analysis. And fitting the effective tensile strain and the actually measured fatigue life by adopting a least square method, so as to establish an SN curve of the rubber material with uniform R ratio working condition.
(7) According to the strain result of the suspension displacement loading in the step (2), converting the suspended displacement load component spectrum in the step (4) into a suspended strain load spectrum
(8) The suspended strain load spectrum is converted into a plurality of Block load blocks by rain flow counting.
(9) According to the SN curve in the step (6), calculating the fatigue damage of the suspension under the Block load Block
In the step (3), the transformation of the suspension displacement load spectrum is required to be completed by combining the geometry of the suspension. The force load spectrum of the suspension reinforced pavement is acquired through an acceleration sensor, and the displacement load obtained through the conversion of the force displacement relation is not the actual displacement of the suspension inner pipe relative to the suspension outer pipe. The displacement of the center point of the suspended inner tube should be within a displacement travel range (e.g., between-10 mm and +15 mm) limited by the suspension structure. When the load exceeds this range, the force load is transferred to the suspended outer tube approximately as rigidly. And correcting the converted displacement load according to the limit to obtain a suspended displacement load spectrum.
The basis of dividing the displacement load spectrum in the step (4) is an inflection point between the linear section and the nonlinear section, and the inner pipe of the nonlinear section impacts the middle point of the limiting block.
And (3) obtaining effective tensile strain of the dumbbell type test column under different R ratio working conditions in the step (6) is divided into the following three steps.
The first step: and (3) establishing a dumbbell type test column finite element model, and respectively loading displacement loads under different R ratio working conditions. In a complete loading process, one point of the dumbbell test column is at the reference strain epsilon f And the current strain ε f 'cyclic loading between's, strain range delta epsilon=epsilon f '-ε f . Effective tensile strain ε t The criterion assumes that the damage is caused by stretching only, and the strain result when the displacement load is the valley value is saved as the reference strain epsilon for calculating the effective stretching strain through the secondary development of finite elements f . The strain in the displacement loading process is recorded as the current strain epsilon f The difference between the current strain and the reference strain is denoted as strain range delta epsilon. To be suitable for multiaxial stress conditions, effective tensile strain ε t By three equally weighted principal strains ε tm Definition of the definition
ε t ＝ε t1 +ε t2 +ε t3 ,ε tm ＞0,m＝1,2,3
Under the global coordinate system can be expressed as:
Figure BDA0004116327410000031
wherein [ epsilon ] ti ε tj ε tk ]For effective tensile strain ε t Coordinates in a global coordinate system.
And a second step of: by comparing the strain range components Deltaε m And the current strain component ε fm Determining the effective tensile strain components ε tm Is of a size of (a) and (b). Only deformations in the tensile range will cause damage, as defined by the effective tensile strain. The strain range component ε tm And the current strain component ε fm All should be in the tensile range and the strain range component ε tm And should also be limited by the current strain component.
Figure BDA0004116327410000032
And a third step of: effective tensile strain ε t The direction of (a) is consistent with the direction of the strain range delta epsilon. Projecting the strain range delta epsilon along the direction of the coordinate system to obtain a strain range component delta epsilon m And unitizing the strain matrix to obtain a direction matrix theta of the strain range delta epsilon, namely the direction matrix of the effective tensile strain. The strain range is a 3 x 3 tensor, calculated as:
Δε＝ε fm 'e m '-ε fm e m (1)
the expression form of the components is as follows:
Figure BDA0004116327410000033
wherein ε fm As the main logarithmic strain component, m=1, 2,3.e, e m Is a directional cosine matrix. Epsilon fm ' represents the principal logarithmic strain component during displacement loading, e m ' is the direction cosine corresponding to the principal logarithmic strain component during displacement loading.
Direction matrix of strain range delta epsilon
Figure BDA0004116327410000041
The components are as follows:
Figure BDA0004116327410000042
wherein the method comprises the steps of
Figure BDA0004116327410000043
Delta epsilon is the modulus of the strain range 1i For strain range component Deltaepsilon 1 Projected in the x-direction under a global coordinate system. Component of strain range
Δε 1 ＝ε' f1 -ε f1 (7)
The components are as follows:
Δε 1 ＝[||ε' f1 ||cosα′ 1 -||ε f1 ||cosα 1 ||ε' f1 ||cosβ′ 1 -||ε f1 ||cosβ 1 ||ε' f1 ||cosγ′ 1 -||ε f1 ||cosγ 1 ] (8)
and (7) establishing a load mapping channel by corresponding the 2n bit load transferring component spectrums obtained in the step (4) to the 2n bit load transferring strain results obtained in the step (2) one by one. And fitting the strain load spectrum at each point on the suspension finite element model by adopting a piecewise linear method, and simultaneously considering the influence of the pre-strain. Strain load spectrum calculation formula:
Figure BDA0004116327410000044
wherein U is k (t) is the strain load component spectrum, ε k,FEResult Is a displacement load U k,FE Strain results, epsilon, of the time suspension Base Is the pre-strain result of the suspension after diameter reduction.
Compared with the prior art, the invention has at least the following positive effects:
1) Through finite element secondary development, an SN curve of a uniform R ratio working condition of the rubber material is obtained, and the method can be used for predicting rubber fatigue under the action of random load.
2) And fitting the strain load spectrum on each suspension node by a piecewise fitting method, and using the fitted strain load spectrum for fatigue life analysis. The load division is based on the suspension stiffness curve, has universality, can calculate random load fatigue life of rear pull rod suspensions with different sizes and different shapes, and provides reference for the design of suspension systems.
3) The invention can retain the strain ratio information of random load, so that the calculated fatigue life is more accurate.
4) The invention adopts the effective tensile strain as the damage parameter, can simultaneously consider the influence of normal strain and tangential strain, is an accurate critical plane method, has simple calculation process, is beneficial to improving the calculation efficiency and shortens the calculation time.
Drawings
Fig. 1 is a flowchart of a method for calculating fatigue life of an automobile rubber suspension under random load according to an embodiment of the invention.
FIG. 2 is a cloud chart of effective tensile strain of a dumbbell test column in an embodiment of this invention.
FIG. 3 is a schematic diagram showing the SN curve of effective tensile strain in an embodiment of the present invention.
FIG. 4 is a cloud image of random load uniaxial fatigue damage of a Ncode rubber mount in an embodiment of the invention.
Detailed Description
The present invention will be described in further detail below with reference to the accompanying drawings and examples in order to make the objects, technical solutions and advantages of the present invention more clear and obvious.
Referring to fig. 1, the method for calculating the fatigue life of the automobile rubber suspension under random load provided by the invention comprises the following steps:
(1) Carrying out a durability test of the whole vehicle on the reinforced pavement of the test field, and collecting a suspension force load time course (load spectrum) suitable for a bench test and simulation analysis;
(2) And establishing a suspension finite element model, analyzing the suspension finite element model, and further obtaining a suspension force-displacement relationship and a suspension displacement-strain relationship.
(3) And (3) converting the suspension force load spectrum into a suspension displacement load spectrum according to the force-displacement relation obtained in the step (2).
(4) Considering the nonlinearity of the suspension stiffness, the suspension displacement load spectrum is divided into 2n units displacement load component spectrums according to the stiffness.
By fitting the nonlinearity through multiple-segment linearity, it is theoretically necessary to divide the force-displacement relationship curve sufficiently fine, i.e., segment the displacement load spectrum sufficiently much. Considering the feasibility of engineering, the selection of the segments should be limited by the inflection point positions with larger abrupt changes in stiffness. One to two points are taken in the linear section, more than two to three points are taken in the nonlinear section, and the same number of segmentation points are taken in the positive stroke and the negative stroke for ensuring symmetry, and the total segmentation number is 2n. In some embodiments of the present invention, the spectrum is divided into 6 bit-shifted payload component spectra.
(5) Fatigue tests are carried out under different strain ratio working conditions to obtain the strain ratio working conditions (R>0, r=0 and R<0) Fatigue life under strain ratio
Figure BDA0004116327410000051
(6) And obtaining effective tensile strain of the dumbbell test column under different R ratio working conditions through finite element analysis. And fitting the effective tensile strain and the actually measured fatigue life by adopting a least square method, so as to establish an SN curve of the rubber material with uniform R ratio working condition.
In some of the embodiments of the present invention, the resulting SN curve is shown in fig. 3.
(7) And (3) converting the suspended displacement load component spectrum in the step (4) into a suspended strain load spectrum according to the strain result of the suspension displacement loading in the step (2).
And (3) corresponding the 2n bit load transferring component spectrums in the step (4) to the 2n bit load transferring strain results obtained in the step (2) one by one, establishing a load mapping channel, fitting the strain load spectrums at each point on the suspension finite element model by adopting a piecewise linear method, and simultaneously considering the influence of the pre-strain.
(8) The suspended strain load spectrum is converted into a plurality of Block load blocks by a rain flow counting method.
(9) And (3) calculating the fatigue damage of the suspension under the Block load Block according to the SN curve in the step (6).
In some embodiments of the present invention, since the road spectrum is generally acquired by engineers in the field of the host factory, and the road spectrum acquired by different host factories has a certain difference, it is necessary to first check the acquired road spectrum to determine whether the input road spectrum is suitable for laboratory and simulation analysis.
In some embodiments of the invention, the transition of the suspension displacement load spectrum is accomplished in step (3) in combination with the geometry of the suspension. The force load spectrum of the suspension reinforced pavement is acquired through an acceleration sensor, and the displacement load obtained through the conversion of the force-displacement relationship is not the relative displacement of the suspension inner tube and the suspension outer tube. The displacement of the center point of the suspension inner tube is between-10 mm and +15mm limited by the suspension structure. When the load exceeds this range, the force load is approximately transferred rigidly to the suspension outer tube. And correcting the converted displacement load according to the limit to obtain a suspension displacement load spectrum.
In some embodiments of the present invention, the step (4) is based on dividing the displacement load spectrum into an inflection point between the linear segment and the nonlinear segment and a middle point where the inner tube of the nonlinear segment hits the stopper.
In some embodiments of the present invention, step (6) of obtaining effective tensile strain of the dumbbell test column under different R ratio conditions comprises the following three steps:
the first step: and (3) establishing a dumbbell type test column finite element model, and respectively loading displacement loads under different R ratio working conditions. In a complete loading process, one point of the dumbbell test column is at the reference strain epsilon f And the current strain ε f 'cyclic loading between's, strain range delta epsilon=epsilon f '-ε f . Effective tensile strain ε t The criterion assumes that the damage is caused by stretching only, and the strain result when the displacement load is the valley value is saved as the reference strain epsilon for calculating the effective stretching strain through the secondary development of finite elements f . The strain in the displacement loading process is recorded as the current strain epsilon f ' whenThe difference between the pre-strain and the reference strain is noted as the strain range delta epsilon. To be suitable for multiaxial stress conditions, effective tensile strain ε t By three equally weighted principal strains ε tm Definition of the definition
ε t ＝ε t1 +ε t2 +ε t3 ,ε tm ＞0,m＝1,2,3
Under the global coordinate system can be expressed as:
Figure BDA0004116327410000071
wherein [ epsilon ] ti ε tj ε tk ]For effective tensile strain ε t Coordinates in a global coordinate system. i represents the x-direction basis vector [ 10 ] of the global coordinate system] T J represents the y-direction basis vector [0 10 ] of the global coordinate system] T K represents the z-direction basis vector [ 0.1 ] of the global coordinate system] T 。
And a second step of: by comparing the strain range components Deltaε m And the current strain component ε fm Determining the effective tensile strain components ε tm Is of a size of (a) and (b). Only deformations in the tensile range will cause damage, as defined by the effective tensile strain. Thus varying the range component ε tm And the current strain component ε fm All should be in the tensile range and the strain range component ε tm And should also be limited by the current strain component.
Figure BDA0004116327410000072
And a third step of: effective tensile strain ε t The direction of (a) is consistent with the direction of the strain range delta epsilon. Projecting the strain range delta epsilon along the direction of the coordinate system to obtain a strain range component delta epsilon m And unitizing the strain matrix to obtain a direction matrix theta of the strain range delta epsilon, namely the direction matrix of the effective tensile strain. The strain range is a 3 x 3 tensor, calculated as:
Δε＝ε fm 'e m '-ε fm e m (1)
the expression form of the components is as follows:
Figure BDA0004116327410000073
wherein ε fm As the main logarithmic strain component e m ＝[cosα m cosβ m cosγ m ]M=1, 2,3 is the directional cosine corresponding to the principal logarithmic strain component. Epsilon fm ' represents the principal logarithmic strain component during displacement loading, e m '＝[cosα m ' cosβ m ' cosγ m ']Is the direction cosine corresponding to the main logarithmic strain component in the displacement loading process.
Direction matrix of strain range delta epsilon
Figure BDA0004116327410000081
The components are as follows:
Figure BDA0004116327410000082
wherein the method comprises the steps of
Figure BDA0004116327410000083
Delta epsilon is the modulus of the strain range 1i For strain range component Deltaepsilon 1 Projected in the x-direction under a global coordinate system. Component of strain range
Δε 1 ＝ε' f1 -ε f1 (7)
The components are as follows:
Δε 1 ＝[||ε' f1 ||cosα′ 1 -||ε f1 ||cosα 1 ||ε' f1 ||cosβ′ 1 -||ε f1 ||cosβ 1 ||ε' f1 ||cosγ′ 1 -||ε f1 ||cosγ 1 ] (8)
β′ 1 representing the current strain ε' f Is a first principal component epsilon' f1 Included angle with the Y-axis of the global coordinate system.
In the embodiment of the invention, the step (7) is to establish a load mapping channel by corresponding the 2n bit load transferring component spectrum obtained in the step (4) to the 2n displacement load strain results obtained in the step (2) one by one. And fitting the strain load spectrum at each point on the suspension finite element model by adopting a piecewise linear method, and simultaneously considering the influence of the pre-strain. Strain load spectrum calculation formula:
Figure BDA0004116327410000084
wherein U is k (t) is the strain load component spectrum, ε k,FEResult Is a displacement load U k,FE Strain results, epsilon, of the time suspension Base Is the pre-strain result of the suspension after diameter reduction.
In some embodiments of the invention, the radial indentation is-1.17 mm, the displacement load U k,FE The partial values of (2) are shown in Table 1. As shown in FIG. 4, the finally obtained fatigue damage is distributed near the rubber main spring and is consistent with the fatigue failure position of the suspension actual measurement, thereby illustrating the effectiveness of the method.
TABLE 1 Displacement load U k,FE Value taking
Figure BDA0004116327410000085
Figure BDA0004116327410000091
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The method for calculating the fatigue life of the automobile rubber suspension under the random load is characterized by comprising the following steps of:
(1) Carrying out a durability test of the whole vehicle on the reinforced pavement of the test field, and collecting a suspension force load spectrum suitable for a bench test and simulation analysis;
(2) Establishing a suspension finite element model, analyzing the suspension finite element model, and further obtaining a suspension force-displacement relationship and a suspension displacement-strain relationship;
(3) Converting the suspension force load spectrum into a suspension displacement load spectrum according to the force-displacement relationship obtained in the step (2);
(4) Considering the nonlinearity of the suspension stiffness, dividing the suspension displacement load spectrum into 2n displacement load component spectrums according to the stiffness;
(5) Carrying out fatigue tests under the working conditions of R >0, R=0 and R <0 to obtain fatigue life under the working conditions of different R ratios;
(6) Obtaining effective tensile strain of the dumbbell test column under different R ratio working conditions through finite element analysis, fitting the effective tensile strain and the actually measured fatigue life, and thus establishing an SN curve of the rubber material with uniform R ratio working conditions;
(7) According to the displacement-strain relation in the step (2), converting the suspended displacement load component spectrum in the step (4) into a suspended strain load spectrum in a piecewise fitting mode;
(8) Converting the suspended strain load spectrum into a plurality of Block load blocks;
(9) And (3) calculating the fatigue damage of the suspension under the Block load Block according to the SN curve in the step (6).
2. The method for calculating the fatigue life of the automobile rubber suspension under random load according to claim 1, wherein the suspension force load spectrum is acquired by an acceleration sensor.
3. The method for calculating the fatigue life of an automotive rubber suspension under random load according to claim 1, wherein in the step (3), the transition of the suspension displacement load spectrum is completed by combining the geometric dimensions of the suspension.
4. The method for calculating the fatigue life of an automobile rubber mount under a random load according to claim 1, wherein in the step (3), the displacement load obtained by the force-displacement relationship conversion is obtained; and correcting the displacement load obtained by transformation according to the suspension displacement travel range to obtain a suspension displacement load spectrum.
5. The method for calculating the fatigue life of the automobile rubber mount under random load according to claim 1, wherein in the step (4), the basis of dividing the displacement load spectrum is an inflection point between a linear section and a nonlinear section and a middle point of an inner pipe impact limit block in the nonlinear section.
6. The method for calculating the fatigue life of an automobile rubber mount under random load according to claim 1, wherein in the step (6), the effective tensile strain and the actually measured fatigue life are fitted by a least square method.
7. The method for calculating the fatigue life of the automobile rubber suspension under the random load according to claim 1, wherein the step (6) is characterized in that effective tensile strain of the dumbbell-shaped test column under different R ratio working conditions is obtained, and the method comprises the following three steps:
the first step: building a dumbbell type test column finite element model, and respectively loading displacement loads with different R ratio working conditions: in a complete loading process, one point of the dumbbell test column is at the reference strain epsilon f And the current strain ε f 'cyclic loading between's, strain range delta epsilon=epsilon f '-ε f Effective tensile strain ε t The criterion assumes that the damage is caused by stretching only, and the strain result when the displacement load is the valley value is saved as the reference strain epsilon for calculating the effective stretching strain through the secondary development of finite elements f Recording strain in displacement loading processFor the current strain epsilon f ' the difference between the current strain and the reference strain is noted as the strain range Δε, the effective tensile strain ε for the application of multiaxial stress conditions t By three equally weighted principal strains ε tm Definition of the definition
ε t ＝ε t1 +ε t2 +ε t3 ,ε tm ＞0,m＝1,2,3
Under the global coordinate system can be expressed as:
Figure FDA0004116327360000021
wherein [ epsilon ] ti ε tj ε tk ]For effective tensile strain ε t Coordinates in the global coordinate system, i represents the x-direction basis vector [ 10 ] of the global coordinate system] T J represents the y-direction basis vector [0 10 ] of the global coordinate system] T K represents the z-direction basis vector [ 0.1 ] of the global coordinate system] T ；
And a second step of: by comparing the strain range components Deltaε m And the current strain component ε fm Determining the effective tensile strain components ε tm Is the magnitude of the strain range component epsilon tm And the current strain component ε fm All should be in the tensile range and the strain range component ε tm Also limited by the current strain component:
Figure FDA0004116327360000022
and a third step of: effective tensile strain ε t The direction of the strain range delta epsilon is kept consistent with the direction of the strain range delta epsilon, and the strain range delta epsilon is projected along the direction of a coordinate system to obtain the strain range component delta epsilon m And unitizing the strain matrix to obtain a direction matrix theta of the strain range delta epsilon, namely the direction matrix of the effective tensile strain, wherein the calculation formula of the strain range is as follows:
Δε＝ε fm 'e m '-ε fm e m (1)
the expression form of the components is as follows:
Figure FDA0004116327360000031
wherein ε fm As the main logarithmic strain component e m ＝[cosα m cosβ m cosγ m ]M=1, 2,3 is the direction cosine, ε, corresponding to the principal logarithmic strain component fm ' represents the principal logarithmic strain component during displacement loading, e m '＝[cosα m ' cosβ m ' cosγ m ']Is the direction cosine corresponding to the main logarithmic strain component in the displacement loading process;
direction matrix of strain range delta epsilon
Figure FDA0004116327360000032
The components are as follows:
Figure FDA0004116327360000033
wherein the method comprises the steps of
Figure FDA0004116327360000034
Delta epsilon is the modulus of the strain range 1i For strain range component Deltaepsilon 1 Projection in x-direction under global coordinate system, strain range component
Δε 1 ＝ε' f1 -ε f1 (7)
The components are as follows:
Δε 1 ＝[||ε' f1 ||cosα′ 1 -||ε f1 ||cosα 1 ||ε' f1 ||cosβ′ 1 -||ε f1 ||cosβ 1 ||ε' f1 ||cosγ′ 1 -||ε f1 ||cosγ 1 ] (8)
β′ 1 representing the current strain ε' f Is a first principal component epsilon' f1 Included angle with the Y-axis of the global coordinate system.
8. The method for calculating the fatigue life of an automobile rubber suspension under random load according to claim 1, wherein in the step (8), the strain load spectrum of the suspension is converted into a plurality of Block load blocks by a rain flow counting method.
9. The method for calculating the fatigue life of the automobile rubber suspension under random load according to any one of claims 1 to 8, wherein the step (7) is to set up a load mapping channel by corresponding the 2n bit load transfer component spectrums in the step (4) to the 2n bit load transfer strain results obtained in the step (2) one by one, and fit the strain load spectrums at each point on the suspension finite element model by adopting a piecewise linear method while considering the influence of the pre-strain.
10. The method for calculating the fatigue life of the automobile rubber mount under random load according to claim 9, wherein the calculation formula of the strain load spectrum is:
Figure FDA0004116327360000041
wherein U is k (t) is the strain load component spectrum, ε k,FEResult Is a displacement load U k,FE Strain results, epsilon, of the time suspension Base Is the pre-strain result of the suspension after diameter reduction.
CN202310220265.1A 2023-03-07 2023-03-07 Method for calculating fatigue life of automobile rubber suspension under random load Pending CN116362074A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116933102A (en) * 2023-09-15 2023-10-24 成都数之联科技股份有限公司 Rubber quality inspection method, device, medium, equipment and program product

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116933102A (en) * 2023-09-15 2023-10-24 成都数之联科技股份有限公司 Rubber quality inspection method, device, medium, equipment and program product
CN116933102B (en) * 2023-09-15 2023-12-19 成都数之联科技股份有限公司 Rubber quality inspection method, device, medium, equipment and program product

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