CN107122521B - A kind of two-dimensional random load acts on the calculation method of lower fatigue life - Google Patents
A kind of two-dimensional random load acts on the calculation method of lower fatigue life Download PDFInfo
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Abstract
The invention discloses the calculation method that a kind of two-dimensional random load acts on lower fatigue life, implementation steps include: to obtain both amplitude, mean value respective distribution character and the probability density function of load modal data through statistical analysis by carrying out test acquisition load modal data to target material；Extrapolate the probability density function of the equivalent load of load modal data；Using under random loading Miner rule and three parameter empirical equations obtain two-dimensional random load effect under accumulation of fatigue damage computation model；Calculation of Fatigue Life model when according to accumulation of fatigue damage computation model reverse accumulation of fatigue damage equal to 1；Fatigue life of the target material under the effect of two-dimensional random load is acquired according to Calculation of Fatigue Life model.The present invention rapidly, more accurately can predict fatigue life in the early period of Element Design, provide reference early period for the durability Design of part, the failure risk of components in the process of development is reduced, so as to shorten the development cycle of components.
Description
Technical field
The present invention relates to load spectral analysis technologies, and in particular to a kind of two-dimensional random load (consideration load amplitude and load
Mean value is stochastic variable) effect lower fatigue life calculation method.
Background technique
Load spectrum analysis is a key content in motor live time prediction and fatigue endurance design process.Carrying out fatigue
When durable research, generally there are two types of processing methods for the application of load, first is that applying cyclic loading, second is that applying random load.It adopts
The statistical property due to considering load is loaded with random load, than the reality for more meeting automobile using cyclic loading load
Border use condition.Random load generally obeys certain successional probability distribution, such as normal distribution, exponential distribution, logarithm are just
State distribution, the extreme value distribution and three-parameter Weibull distribution etc..The analysis of fatigue of random loading lower member should integrate fortune
With Probability Statistics Theory and mechanical analyzing method come the problems in relieving fatigue analysis and design.Automobile is under random loading
When work, the mean value and amplitude of load all change at random, and mean value and amplitude should be regarded as binary in loading spectrum and become at random
Amount.In most cases, load amplitude X obeys Weibull distribution, mean value Y Normal Distribution.Due to load amplitude and load
The variation of lotus mean value equally can all affect greatly the fatigue life of part, in order to make result of study more meet the reality of part
Border working condition, to more accurately predict the fatigue life of part, to being random based on load amplitude and mean value
Fatigue life under the two-dimensional random load effect of variable, which carries out further investigation, to be necessary.The effect of two-dimensional random load
The calculating of lower fatigue life has become a crucial technical problem urgently to be resolved.
Summary of the invention
The technical problem to be solved in the present invention: in view of the above problems in the prior art, one kind is provided and solves and need to examine simultaneously
The computational problem for considering load amplitude and the fatigue life under the respective statistical property of load mean value, can be in the early period of Element Design
Rapidly, more accurately fatigue life is predicted, provides reference early period for the durability Design of part, reduces components and exist
Failure risk in development process acts on the meter of lower fatigue life so as to shorten the two-dimensional random load of the development cycle of components
Calculation method.
In order to solve the above-mentioned technical problem, the technical solution adopted by the present invention are as follows:
A kind of two-dimensional random load acts on the calculation method of lower fatigue life, and implementation steps include:
1) by carrying out test acquisition load modal data to target material, the load modal data is obtained through statistical analysis
Amplitude, both mean values respective distribution character and probability density function；
2) the equivalent load S of the load modal data is extrapolatedeqProbability density function f (Seq)；
3) it utilizes shown in the Miner rule and formula (2) under random loading shown in formula (1) in entirely, long life range
Between three parameter empirical equations between fatigue life and load obtain the lower accumulation of fatigue damage calculating of two-dimensional random load effect
Model；
Nf(S-S0)β=α (2)
In formula (1) and formula (2), D indicates that the accumulation of fatigue damage of target material, N indicate that the circulation that target material is subject to carries
Lotus total quantity, f (S) indicate the probability density function of random load, NfIndicate tired longevity of the target material under load S effect
Life, S indicate the load that target material is subject to, S0It is expressed as the loading coefficient of constant, α, β are constant coefficient；
4) Calculation of Fatigue Life mould when according to the accumulation of fatigue damage computation model reverse accumulation of fatigue damage equal to 1
Type；
5) fatigue life of the target material under the effect of two-dimensional random load is acquired according to the Calculation of Fatigue Life model.
Preferably, the detailed step of step 2) includes:
2.1) the equivalent load S according to Goodman formula Chinese style (3)eqExpression formula in load amplitude SaProbability it is close
Degree function acquires Y=SaProbability density function fY(y), and according to load mean value SmProbability density function find out the drawing of material
Stretch intensity σbWith load mean value SmDifference divided by tensile strength σbQuotient X probability density function fX(x)；
In formula (3), σbIndicate the tensile strength of target material, SaIndicate load amplitude, SmIndicate load mean value；
2.2) it is solved according to formula (4) and obtains equivalent load SeqProbability density function f (Seq)；
In formula (4), fY/X(z) equivalent load S is indicatedeqProbability density function, fY(zx) probability density function of Y is indicated,
Variable Z, which is equal to Y, indicates the load amplitude S of target material divided by X, Ya, the tensile strength σ of X expression target materialbWith load mean value
SmDifference divided by tensile strength σbQuotient.
Preferably, step 2.2) solution obtains equivalent load SeqProbability density function f (Seq) as shown in formula (5)；
In formula (5), f (Seq) indicate equivalent load SeqProbability density function, the load of target material is load amplitude Sa
With load mean value SmAll meet normal distribution, and load amplitude SaWith load mean value SmMutually independent two-dimensional random load, wherein
Load amplitude SaObey N (μa,σa 2), load mean value SmObey N (μm,σm 2), μaIndicate load amplitude SaMean value, σa 2It indicates to carry
Lotus amplitude SaVariance, μmIndicate load mean value SmMean value, σm 2Indicate load mean value SmVariance, a, b, c, σ1、σ2、μ1、μ2
It is intermediate parameters, intermediate parameters μ2Value and load amplitude SaMean μaIt is identical, σ2 2Value and load amplitude SaSide
Poor σa 2It is identical, intermediate parameters μ1Value be μ1=-μm/σb+ 1, σbIndicate the tensile strength of target material, variable Z is removed equal to Y
The load amplitude S of target material is indicated with X, Ya, the tensile strength σ of X expression target materialbWith load mean value SmDifference divided by
Tensile strength σbQuotient, q is integration variable.
Preferably, shown in the accumulation of fatigue damage computation model such as formula (6) in step 3) under the effect of two-dimensional random load；
In formula (6), D indicates that the accumulation of fatigue damage of target material, N indicate the cyclic loading sum that target material is subject to
Amount, f (Seq) indicate equivalent load SeqProbability density function, S0It is expressed as the loading coefficient of constant, α, β are constant coefficient.
Preferably, shown in the Calculation of Fatigue Life model such as formula (7) in step 4)；
In formula (7), NfIndicate fatigue life, α, β are constant coefficient, f (Seq) indicate equivalent load SeqProbability density letter
Number, S0It is expressed as the loading coefficient of constant.
Preferably, the detailed step of step 5) includes: that the Calculation of Fatigue Life model is passed through Gauss-Legendre
Quadrature formula carries out integral operation, so that fatigue life of the target material under the effect of two-dimensional random load be calculated.
Preferably, the detailed step of step 5) includes: to calculate fatigue life corresponding equivalent load S according to formula (8)D, root
According to equivalent load SDAcquire fatigue life of the corresponding fatigue life as target material under the effect of two-dimensional random load；
In formula (8), SDIndicate fatigue life corresponding equivalent load, S0It is expressed as the loading coefficient of constant, NfIndicate fatigue
Service life, α, β are constant coefficient.
The calculation method that two-dimensional random load of the present invention acts on lower fatigue life has an advantage that calculating side of the invention
Method is due to having fully considered load amplitude and the respective statistical property of load mean value, so that the load of load more meets the reality of part
Border working condition, so as to more accurately calculate fatigue life.Using this method can Element Design early period it is fast
Fatigue life is more accurately predicted in fast ground, provides reference early period for the durability Design of part, reduces components and opening
Failure risk during hair, so as to shorten the development cycle of components.
Detailed description of the invention
Fig. 1 is the basic procedure schematic diagram of one method of the embodiment of the present invention.
Fig. 2 is parameter μ in the embodiment of the present invention one1Probability density function curve comparison figure under different distributions.
Fig. 3 is parameter σ in the embodiment of the present invention one1Probability density function curve comparison figure under different distributions.
Fig. 4 is parameter μ in the embodiment of the present invention one2Probability density function curve comparison figure under different distributions.
Fig. 5 is parameter σ in the embodiment of the present invention one2Probability density function curve comparison figure under different distributions.
Specific embodiment
Embodiment one:
As shown in Figure 1, the implementation steps for the calculation method that the present embodiment two-dimensional random load acts on lower fatigue life include:
1) by carrying out test acquisition load modal data to target material, the load modal data is obtained through statistical analysis
Amplitude, both mean values respective distribution character and probability density function；
2) the equivalent load S of the load modal data is extrapolatedeqProbability density function f (Seq)；
3) it utilizes shown in the Miner rule and formula (2) under random loading shown in formula (1) in entirely, long life range
Between three parameter empirical equations between fatigue life and load obtain the lower accumulation of fatigue damage calculating of two-dimensional random load effect
Model；
Nf(S-S0)β=α (2)
In formula (1) and formula (2), D indicates that the accumulation of fatigue damage of target material, N indicate that the circulation that target material is subject to carries
Lotus total quantity, f (S) indicate the probability density function of random load, NfIndicate tired longevity of the target material under load S effect
Life, S indicate the load that target material is subject to, S0It is expressed as the loading coefficient of constant, α, β are constant coefficient；
4) Calculation of Fatigue Life mould when according to the accumulation of fatigue damage computation model reverse accumulation of fatigue damage equal to 1
Type；
5) fatigue life of the target material under the effect of two-dimensional random load is acquired according to the Calculation of Fatigue Life model.
In the present embodiment, the detailed step of step 2) includes:
2.1) the equivalent load S according to Goodman formula Chinese style (3)eqExpression formula in load amplitude SaProbability it is close
Function is spent, Y=S is found outaProbability density function fY(y), and according to load mean value SmProbability density function find out the drawing of material
Stretch intensity σbWith load mean value SmDifference divided by tensile strength σbQuotient X probability density function fX(x)；
In formula (3), σbIndicate the tensile strength of target material, SaIndicate load amplitude, SmIndicate load mean value；
2.2) it is solved according to formula (4) and obtains equivalent load SeqProbability density function f (Seq)；
In formula (4), fY/X(z) equivalent load S is indicatedeqProbability density function, fY(zx) probability density function of Y is indicated,
Variable Z, which is equal to Y, indicates the load amplitude S of target material divided by X, Ya, the tensile strength σ of X expression target materialbWith load mean value
SmDifference divided by tensile strength σbQuotient.
In order to calculate the fatigue life under the effect of two-dimensional random load, load amplitude and load mean value are present embodiments provided
All meet the equivalent load S of the two-dimensional random load of normal distributioneqProbability density function f (Seq).In the present embodiment, step
2.2) it solves and obtains equivalent load SeqProbability density function f (Seq) as shown in formula (5)；
In formula (5), f (Seq) indicate equivalent load SeqProbability density function, the load of target material is load amplitude Sa
With load mean value SmAll meet normal distribution, and load amplitude SaWith load mean value SmMutually independent two-dimensional random load, wherein
Load amplitude SaObey N (μa,σa 2), load mean value SmObey N (μm,σm 2), μaIndicate load amplitude SaMean value, σa 2It indicates to carry
Lotus amplitude SaVariance, μmIndicate load mean value SmMean value, σm 2Indicate load mean value SmVariance, a, b, c, σ1、σ2、μ1、μ2
It is intermediate parameters, intermediate parameters μ2Value and load amplitude SaMean μaIt is identical, σ2 2Value and load amplitude SaSide
Poor σa 2It is identical, intermediate parameters μ1Value be μ1=-μm/σb+ 1, σbIndicate the tensile strength of target material, variable Z is removed equal to Y
The load amplitude S of target material is indicated with X, Ya, the tensile strength σ of X expression target materialbWith load mean value SmDifference divided by
Tensile strength σbQuotient, q is integration variable.
Accumulation of fatigue damage computation model such as formula (6) institute in the present embodiment, in step 3) under the effect of two-dimensional random load
Show；
In formula (6), D indicates that the accumulation of fatigue damage of target material, N indicate the cyclic loading sum that target material is subject to
Amount, f (Seq) indicate equivalent load SeqProbability density function, S0It is expressed as the loading coefficient of constant, α, β are constant coefficient.
In the present embodiment, shown in the Calculation of Fatigue Life model such as formula (7) in step 4)；
In formula (7), NfIndicate fatigue life, α, β are constant coefficient, f (Seq) indicate equivalent load SeqProbability density letter
Number, S0It is expressed as the loading coefficient of constant.
In the present embodiment, the detailed step of step 5) includes: that the Calculation of Fatigue Life model is passed through Gauss-
Legendre quadrature formula carries out integral operation, so that tired longevity of the target material under the effect of two-dimensional random load be calculated
Life.
In the present embodiment, it is directed to intermediate parameters σ respectively1、σ2、μ1、μ2Different values are carried out, and respectively by different intermediate ginsengs
Equivalent load S under number value conditioneqProbability density function f (Seq) (f is expressed as in figureZ(Z)) formation curve respectively obtains
Fig. 2, Fig. 3, Fig. 4, Fig. 5.Fig. 2 describes σ1Value 0.08, σ2Value 30, μ2In the case where value 190, μ1Value is respectively
0.5,0.75,1,1.25,1.5 when probability density function f (Seq) correlation curve.Fig. 3 describes σ2Value 30, μ1Value
0.75、μ2In the case where value 190, σ1Probability density function f when value is 0.05,0.06,0.07,0.08,0.09,0.1 respectively
(Seq) correlation curve.Fig. 4 describes σ1Value 0.08, σ2Value 30, μ1In the case where value 0.75, μ2Value is respectively
150,170,190,210,230,250 when probability density function f (Seq) correlation curve.Fig. 5 describes σ1Value 0.08, μ1It takes
Value 0.75, μ2In the case where value 190, σ2Probability density function f (S when value is 5,10,20,30,40,50 respectivelyeq) pair
Compare curve.Fig. 2~Fig. 5 is analyzed it follows that 1) fZ(z) function graft shape and normal distyribution function shape phase
Seemingly, predominantly following three points: a) functional value has peak point, and z is remoter from peak point, and functional value is smaller；B) function is in peak value
There are inflection point in point two sides；C) curve is using trunnion axis as asymptote.2) in the case where other three parameter constants, μ1Reduction,
σ1、μ2、σ2Increase reduce peak of function, while function curve shape flatten it is slow.3)μ2Increase so that peak point is moved right
It is dynamic, μ1And σ1Increase be moved to the left peak point, σ2Variation do not change peak point position.
Embodiment two:
It is basically the same as the first embodiment in the present embodiment, main distinction point are as follows: step 5) is according to the fatigue life gage
Calculate the method difference that model acquires fatigue life of the target material under the effect of two-dimensional random load.
In the present embodiment, it converts the research to fatigue life to the research of equivalent load.It is as follows to define equivalent load: from
From the point of view of total function and effect, the final result under random load and the effect of two class load of cyclic loading all will lead to the damage of component
Hurt state to reach critical value and fail, it is believed that corresponding Mr. Yu's random load process, certainly exist one it is equivalent with it
Constant amplitude loading so that component under identical original state, is damaged simultaneously by identical action time.Define the perseverance
Width load is the equivalent load of random load, uses SDIt indicates.The corresponding relationship formula of equivalent load and fatigue life are shown in that three parameters pass through
Test formula.
In the present embodiment, the detailed step of step 5) includes: to calculate fatigue life corresponding equivalent load according to formula (8)
SD, according to equivalent load SDAcquire fatigue life of the corresponding fatigue life as target material under the effect of two-dimensional random load；
In formula (8), SDIndicate fatigue life corresponding equivalent load, S0The theory fatigue that expression is indicated with equivalent stress width
The limit, NfIndicate fatigue life, α, β are constant coefficient.By taking 16Mn material as an example, according to existing research, α=3.95 × 108, S0
=261MPa, β=2.According to formula (7) and formula (8), equivalent load of the 16Mn material under the effect of two-dimensional random load are as follows:
In formula (10), SDIndicate fatigue life corresponding equivalent load, SeqIndicate equivalent load.
For under the statistical distribution parameter of different loads amplitude and load mean value, still use Gauss-Legendre quadrature public
Formula carries out integral operation to function, and part equivalent load data are calculated and are shown in Table 1~table 5, while in order to be compared, calculating
The equivalent load of one-dimensional random load is shown in Table 6.After obtaining equivalent load, push away that you can get it fatigue life according to formula (8) is counter.
Table 1: different μ1、σ1Equivalent load (MPa) (μ2=210, σ2=40).
| μ1\σ1 | 0.05 | 0.06 | 0.07 | 0.08 | 0.09 | 0.1 |
| 0.5 | >600 | >600 | >600 | >600 | >600 | >600 |
| 0.75 | 314 | 316 | 344 | 417 | 526 | >600 |
| 1 | 270 | 271 | 272 | 273 | 274 | 275 |
| 1.25 | 262 | 262 | 262 | 262 | 263 | 263 |
| 1.5 | 261 | 261 | 261 | 261 | 261 | 261 |
Table 2: different μ2、σ2Equivalent load (MPa) (μ1=0.75, σ1=0.05).
| σ2\μ2 | 150 | 170 | 190 | 210 | 230 | 250 |
| 10 | 262 | 265 | 274 | 291 | 314 | 340 |
| 20 | 264 | 270 | 281 | 298 | 319 | 343 |
| 30 | 269 | 277 | 289 | 306 | 325 | 348 |
| 40 | 276 | 285 | 298 | 314 | 333 | 354 |
| 50 | 283 | 294 | 307 | 323 | 341 | 362 |
Table 3: different μ2、σ2Equivalent load (MPa) (μ1=1, σ1=0.05).
| σ2\μ2 | 150 | 170 | 190 | 210 | 230 | 250 |
| 10 | 261 | 261 | 261 | 261 | 263 | 268 |
| 20 | 261 | 261 | 261 | 263 | 266 | 273 |
| 30 | 261 | 262 | 263 | 266 | 271 | 279 |
| 40 | 262 | 264 | 266 | 270 | 277 | 286 |
| 50 | 264 | 267 | 271 | 276 | 283 | 292 |
Table 4: different μ2、σ2Equivalent load (MPa) (μ1=1, σ1=0.1).
Table 5: different μ2、σ2Equivalent load (MPa) (μ1=1.25, σ1=0.1).
| σ2\μ2 | 150 | 170 | 190 | 210 | 230 | 250 |
| 10 | 261 | 261 | 261 | 261 | 261 | 262 |
| 20 | 261 | 261 | 261 | 261 | 262 | 263 |
| 30 | 261 | 261 | 261 | 262 | 263 | 264 |
| 40 | 261 | 261 | 262 | 263 | 264 | 267 |
| 50 | 262 | 262 | 263 | 265 | 267 | 270 |
Table 6: the equivalent load (MPa) of one-dimensional random load.
| σ\μ | 150 | 170 | 190 | 210 | 230 | 250 |
| 10 | 261 | 261 | 261 | 261 | 261 | 264 |
| 20 | 261 | 261 | 261 | 262 | 264 | 270 |
| 30 | 261 | 261 | 262 | 265 | 269 | 277 |
| 40 | 262 | 263 | 265 | 269 | 275 | 284 |
| 50 | 264 | 266 | 269 | 274 | 281 | 291 |
Based on the analysis results, load mean value has large effect to the equivalent load of two-dimentional normal state random load, in load
Mean value SmMean μmWhen less than 0, equivalent load is reduced rapidly the equivalent load of even lower than one-dimensional random load；Work as μmEqual to 0
When, consider that the equivalent load of load mean value is more slightly higher than the equivalent load for not considering load mean value；Work as μmWhen greater than 0, with μ2、σ2
Increase, the equivalent load of two-dimensional random load increases sharply, until being much larger than the equivalent load of one-dimensional random load.
The above is only a preferred embodiment of the present invention, protection scope of the present invention is not limited merely to above-mentioned implementation
Example, all technical solutions belonged under thinking of the present invention all belong to the scope of protection of the present invention.It should be pointed out that for the art
Those of ordinary skill for, several improvements and modifications without departing from the principles of the present invention, these improvements and modifications
It should be regarded as protection scope of the present invention.
Claims (6)
1. the calculation method that a kind of two-dimensional random load acts on lower fatigue life, it is characterised in that implementation steps include:
1) by carrying out test acquisition load modal data to target material, the width of the load modal data is obtained through statistical analysis
Both value, mean value respective distribution character and probability density function；
2) the equivalent load S of the load modal data is extrapolatedeqProbability density function f (Seq)；
3) it utilizes tired in entirely, between long life range shown in the Miner rule and formula (2) under random loading shown in formula (1)
Three parameter empirical equations between labor service life and load obtain the accumulation of fatigue damage computation model under the effect of two-dimensional random load,
And shown in the accumulation of fatigue damage computation model such as formula (6) under the effect of two-dimensional random load；
Nf(S-S0)β=α (2)
In formula (1) and formula (2), D indicates the accumulation of fatigue damage of target material, and the cyclic loading that N indicates that target material is subject to is total
Quantity, f (S) indicate the probability density function of random load, NfIndicate fatigue life of the target material under load S effect, S table
Show the load that target material is subject to, S0It is expressed as the loading coefficient of constant, α, β are constant coefficient；
In formula (6), D indicates that the accumulation of fatigue damage of target material, N indicate the cyclic loading total quantity that target material is subject to, f
(Seq) indicate equivalent load SeqProbability density function, S0It is expressed as the loading coefficient of constant, α, β are the constant system in formula (2)
Number；
4) Calculation of Fatigue Life model when according to the accumulation of fatigue damage computation model reverse accumulation of fatigue damage equal to 1；
5) fatigue life of the target material under the effect of two-dimensional random load is acquired according to the Calculation of Fatigue Life model.
2. the calculation method that two-dimensional random load according to claim 1 acts on lower fatigue life, which is characterized in that step
2) detailed step includes:
2.1) the equivalent load S according to Goodman formula Chinese style (3)eqExpression formula in load amplitude SaProbability density letter
Number acquires Y=SaProbability density function fY(y), and according to load mean value SmProbability density function find out material stretching it is strong
Spend σbWith load mean value SmDifference divided by tensile strength σbQuotient X probability density function fX(x)；
In formula (3), σbIndicate the tensile strength of target material, SaIndicate load amplitude, SmIndicate load mean value；
2.2) it is solved according to formula (4) and obtains equivalent load SeqProbability density function f (Seq)；
In formula (4), fY/X(z) equivalent load S is indicatedeqProbability density function, fY(zx) probability density function of Y, variable are indicated
Z, which is equal to Y, indicates the load amplitude S of target material divided by X, Ya, the tensile strength σ of X expression target materialbWith load mean value Sm's
Difference is divided by tensile strength σbQuotient.
3. the calculation method that two-dimensional random load according to claim 2 acts on lower fatigue life, which is characterized in that step
2.2) it solves and obtains equivalent load SeqProbability density function f (Seq) as shown in formula (5)；
In formula (5), f (Seq) indicate equivalent load SeqProbability density function, the load of target material is load amplitude SaAnd load
Lotus mean value SmAll meet normal distribution, and load amplitude SaWith load mean value SmMutually independent two-dimensional random load, wherein load
Amplitude SaObey N (μa,σa 2), load mean value SmObey N (μm,σm 2), μaIndicate load amplitude SaMean value, σa 2Indicate load width
Value SaVariance, μmIndicate load mean value SmMean value, σm 2Indicate load mean value SmVariance, a, b, c, σ1、σ2、μ1、μ2It is
Intermediate parameters, intermediate parameters μ2Value and load amplitude SaMean μaIt is identical, σ2 2Value and load amplitude SaVariances sigmaa 2
It is identical, intermediate parameters μ1Value be μ1=-μm/σb+ 1, σbIndicate the tensile strength of target material, variable Z is equal to Y divided by X, Y
Indicate the load amplitude S of target materiala, the tensile strength σ of X expression target materialbWith load mean value SmDifference it is strong divided by stretching
Spend σbQuotient, q is integration variable.
4. the calculation method that two-dimensional random load according to claim 3 acts on lower fatigue life, which is characterized in that step
4) shown in the Calculation of Fatigue Life model such as formula (7) in；
In formula (7), NfIndicate fatigue life, α, β are constant coefficient, f (Seq) indicate equivalent load SeqProbability density function, S0
It is expressed as the loading coefficient of constant.
5. two-dimensional random load described according to claim 1~any one of 4 acts on the calculation method of lower fatigue life,
It is characterized in that, the detailed step of step 5) includes: that the Calculation of Fatigue Life model is public by Gauss-Legendre quadrature
Formula carries out integral operation, so that fatigue life of the target material under the effect of two-dimensional random load be calculated.
6. two-dimensional random load described according to claim 1~any one of 4 acts on the calculation method of lower fatigue life,
It is characterized in that, the detailed step of step 5) includes: to calculate fatigue life corresponding equivalent load S according to formula (8)D, according to equivalent
Load SDAcquire fatigue life of the corresponding fatigue life as target material under the effect of two-dimensional random load；
In formula (8), SDIndicate fatigue life corresponding equivalent load, S0It is expressed as the loading coefficient of constant, NfIndicate the tired longevity
Life, α, β are constant coefficient.
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