CN102680258B - Method for estimating structure fatigue state of in-service mechanical equipment - Google Patents
Method for estimating structure fatigue state of in-service mechanical equipment Download PDFInfo
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- CN102680258B CN102680258B CN201110414705.4A CN201110414705A CN102680258B CN 102680258 B CN102680258 B CN 102680258B CN 201110414705 A CN201110414705 A CN 201110414705A CN 102680258 B CN102680258 B CN 102680258B
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- 238000005259 measurement Methods 0.000 claims abstract description 11
- 239000000463 material Substances 0.000 claims description 8
- 230000035772 mutation Effects 0.000 claims description 3
- 238000013112 stability test Methods 0.000 claims description 3
- 238000012512 characterization method Methods 0.000 claims description 2
- 238000010276 construction Methods 0.000 description 11
- 238000011156 evaluation Methods 0.000 description 8
- 230000006378 damage Effects 0.000 description 4
- 230000036962 time dependent Effects 0.000 description 4
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Abstract
The invention relates to a method for estimating structure fatigue state of in-service mechanical equipment. The method comprises the steps of constructing a generalized load F which is not changed in statistic significance using statistic knowledge, wherein the statistic quantity S (F) of the constructed generalized load F has a corresponding relationship with a statistic quantity S (sigma) of a mechanical structure key part stress sigma; and obtaining a measuring data sequence of the key part strain epsilon through practical measurement; obtaining a strain statistic quantity of the key part by using the method provided by the invention; investigating a change situation of an elasticity modulus E of the statistic significance by using the relationship of the stress and the strain; and evaluating the fatigue state of the key part of the structure of the in-service mechanical equipment according to the change of the E. The method provided by the invention is simple; and the fatigue state of the structure of the in-service mechanical equipment can be estimated effectively.
Description
Technical field
The present invention relates to a kind of in-service mechanized equipment structural fatigue state estimating method, belong to mechanical strength test technical field.
Background technology
In engineering application, the damage that cyclic loading causes is so that destruction is one of major reason of structural failure.Under Cyclic Load, can there is fatigure failure in physical construction, and the essence of fatigure failure is an accumulated damage process.Randomness due to the intrinsic discreteness of the material property of physical construction and load, whether in-service mechanized equipment structure fatigure failure can occur is a uncertain event, so the fatigue state of physical construction is measured and assessment is very valuable from the angle of Probability & Statistics.At present, normally under laboratory condition, set up the fatigue damage rule that the controlled test unit of test condition and model carry out assessment material, still lack the evaluation method of effective in-service mechanized equipment structural fatigue state.
Summary of the invention
The object of the invention is for also there is no a kind of effective method that can estimate in-service mechanized equipment structural fatigue state at present, thereby propose a kind of in-service mechanized equipment structural fatigue state estimating method.
The present invention solves the problems of the technologies described above the evaluation method that proposes a kind of in-service mechanized equipment structural fatigue state, and the concrete steps of this evaluation method are as follows:
1) select to reflect the parameter of in-service mechanized equipment duty, as the generalized load F having on statistical significance, the statistic S (F) of this generalized load F and the statistic S (σ) of stress σ have corresponding relation;
2) determine the interval T of minimum statistics of this generalized load F
min, make the average E (F) of F and variance D (F) constant;
3) for the key position strain stress measurement data sequence corresponding with this generalized load, with the interval T of minimum statistics
mingenerate the equal value sequence U of one group of strain
ε;
4) calculate equivalent elastic modulus E
eqsequence, by equivalent elastic modulus E
eqthe variation of this place's elasticity modulus of materials of sequence characterization;
5) according to equivalent elastic modulus E
eqsequence, certainty equivalence elastic modulus slope of a curve;
6) utilize equivalent elastic modulus slope of a curve, estimate the fatigue state of this mechanized equipment structure.If equivalent elastic modulus slope of a curve is near 0 value, there is not fatigue in this mechanized equipment structure; If slope has exceeded the scope of setting, show that this mechanized equipment structure occurs tired, the time point that slope is undergone mutation is exactly that this in-service mechanized equipment structural key position starts to occur tired time point.
Described step 2) specifically comprise the steps:
A) according to certain time interval, generalized load is sampled, obtain generalized load sequence F={f
1, f
2..., f
i..., f
n;
B) according to two the new sequence U of generalized load sequence structure that obtain
fand S
f, U
fand S
fbe respectively equal value sequence and the variance sequence of generalized load sequence;
C) with t check and χ
2check is respectively to sequence U
fand S
faverage and variance do stability test, make sequence U
fand S
faverage and variance minimum value of T between stable Statistical Area all, thereby determine the interval T of minimum statistics
min.
The time interval of the key position strain stress measurement data sequence in described step 3) should be consistent with the time interval of generalized load sequence;
Described step 4) the equivalent elastic modulus E in
eqthe computing formula of sequence is: E
eq={ E
eq1, E
eq2..., E
eqi..., E
eqm}
m=n-Tmin, E
eqi=μ
fi/ μ
ε i, μ wherein
fifor the average of generalized load F, μ
ε iaverage for key position strain stress.
The described parameter that can reflect in-service mechanized equipment duty is power consumption, output, the power of operating load, equipment.
The invention has the beneficial effects as follows: the present invention is by setting up the incidence relation on statistical significance that has between the strain of physical construction key position and reflection mechanized equipment working status parameter, obtain the variation on statistical significance that has of physical construction elasticity modulus of materials, thereby realize the measurement of in-service physical construction fatigue state and evaluation.The inventive method is simple, can effectively estimate the fatigue state of in-service mechanized equipment structure.
Accompanying drawing explanation
Fig. 1 is a kind of in-service mechanized equipment structural fatigue state estimating method process flow diagram of the present invention;
Fig. 2 is certain equipment power of motor time history plot in the embodiment of the present invention;
Fig. 3 is the Mean curve figure that in the embodiment of the present invention, generalized load is power of motor;
Fig. 4 is the strain curve figure that in the embodiment of the present invention, certain equipment key point place is measured;
Fig. 5 is the Mean curve figure of strain in the embodiment of the present invention;
Fig. 6 is equivalent elastic modulus E in the embodiment of the present invention
eqthe time dependent course curve map of sequence.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described further.
As shown in Figure 1, the evaluation method of this in-service mechanized equipment structural fatigue state is by setting up the incidence relation on statistical significance that has between the strain of physical construction key position and reflection mechanized equipment working status parameter, obtain the variation on statistical significance that has of physical construction elasticity modulus of materials, realize the measurement of in-service physical construction fatigue state and evaluation.The present invention is based on measurement and the evaluation method of a kind of in-service mechanized equipment structural fatigue state of this thought proposition, in order to the monitoring and evaluation of in-service mechanized equipment structural fatigue state.Take certain plant equipment as example, and its concrete step is as follows:
Step 1 is determined generalized load
First select to reflect that the parameter of this mechanized equipment duty is power of motor, i.e. generalized load F, the statistic S (F) of this generalized load F and the statistic S (σ) of stress σ have corresponding relation.
Step 2 is determined the interval T of minimum statistics
min
By t, check and χ
2check, the interval T of minimum statistics of searching generalized load F
min, make average (mathematical expectation) E (F) of F and variance D (F) constant,
According to certain time interval, generalized load F is sampled, the time dependent curve of power of motor of this generalized load F as shown in Figure 2, obtains generalized load sequence (time series), establishes generalized load F={f
1, f
2..., f
i..., f
n, and construct two new sequence U with this
fand S
f,
U
f={ μ
f1, μ
f2..., μ
fi..., μ
fn, μ wherein
fifor the average (mathematical expectation) of generalized load F, the Mean curve of the power of motor of this generalized load F as shown in Figure 3, i.e. μ
fi=E[F]
t<n, T=2,3 ..., n-1,
S
f={ s
f1, s
f2..., s
fi..., s
fn, s wherein
fifor the variance of generalized load F, i.e. s
fi=D[F]
t<n, T=2,3 ..., n-1,
For T between given arbitrary Statistical Area, all can generate one group of sequence U
fand S
f, with t check and χ
2check is respectively to sequence U
fand S
faverage and variance do stability test.Make sequence U
fand S
faverage and variance minimum value of T between stable Statistical Area all, the interval T of the minimum statistics that will find exactly
min.
The equal value sequence of statistics of step 3 structure key position strain measurement data
Strain to this equipment key point place is measured, and resulting strain curve as shown in Figure 4, for the key position strain stress measurement data sequence (with the time interval of generalized load sequence consistent) corresponding with generalized load, is used the interval T of minimum statistics
mingenerate the equal value sequence U of one group of strain
ε,
U
ε={ μ
ε 1, μ
ε 2..., μ
ε i..., μ
ε m}
m=n-Tmin, μ wherein
ε ifor the average (mathematical expectation) of key position strain stress, i.e. μ
ε i=E[ε]
t=Tmi, the Mean curve of its key position strain stress as shown in Figure 5.
Step 4 is calculated equivalent elastic modulus E
eqsequence
Press formula E
eq={ E
eq1, E
eq2..., E
eqi..., E
eqm}
m=n-Tmin, E wherein
eqi=μ
fi/ μ
ε i, calculate equivalent elastic modulus E
eqsequence, equivalent elastic modulus E
eqnot the actual elastic modulus of key position measurement point material, but can characterize the variation of this place's elasticity modulus of materials.
Step 5 is judged the fatigue state of key position
Draw equivalent elastic modulus E
eqthe time dependent course curve of sequence, utilizes and to ask the method for functional derivative to draw equivalent elastic modulus slope of a curve, if there is not fatigue, and equivalent elastic modulus E so
eqfor constant, rate of curve, near 0 value, if slope exceeds certain scope, shows that fatigue has appearred in physical construction, and the time point that slope is undergone mutation is exactly that equipment key position starts to occur tired time point, according to equivalent elastic modulus E
eqthe amplitude declining, evaluates physical construction tired degree, i.e. fatigue state occurs.The E of this equipment
eqthe time dependent course curve of sequence as shown in Figure 6, as can be seen from Figure 6, equivalent elastic modulus E
eqat a time, some place starts to present downtrending, shows that this equipment starts to occur tired.
Claims (5)
1. an in-service mechanized equipment structural fatigue state estimating method, is characterized in that: the method specifically comprises the following steps:
1) select to reflect the parameter of in-service mechanized equipment duty, as the generalized load F having on statistical significance, the statistic S (F) of this generalized load F and the statistic S (σ) of stress σ have corresponding relation;
2) determine the interval T of minimum statistics of this generalized load F
min, make the average E (F) of F and variance D (F) constant;
3) for the key position strain stress measurement data sequence corresponding with this generalized load, with the interval T of minimum statistics
mingenerate the equal value sequence U of one group of strain
ε;
4) calculate equivalent elastic modulus E
eqsequence, by equivalent elastic modulus E
eqthe variation of this place's elasticity modulus of materials of sequence characterization;
5) according to equivalent elastic modulus E
eqsequence, certainty equivalence elastic modulus slope of a curve;
6) utilize equivalent elastic modulus slope of a curve, estimate the fatigue state of this mechanized equipment structure, if equivalent elastic modulus slope of a curve is near 0 value, there is not fatigue in this mechanized equipment structure, if slope has exceeded the scope of setting, show that this mechanized equipment structure occurs tired, the time point that slope is undergone mutation is exactly that this in-service mechanized equipment structural key position starts to occur tired time point.
2. in-service mechanized equipment structural fatigue state estimating method according to claim 1, is characterized in that: described step 2) specifically comprise the steps:
A) according to certain time interval, generalized load is sampled, obtain generalized load sequence F={f
1, f
2..., f
i..., f
n;
B) according to two the new sequence U of generalized load sequence structure that obtain
fand S
f, U
fand S
fbe respectively equal value sequence and the variance sequence of generalized load sequence;
C) with t check and χ
2check is respectively to sequence U
fand S
faverage and variance do stability test, make sequence U
fand S
faverage and variance minimum value of T between stable Statistical Area all, thereby determine the interval T of minimum statistics
min.
3. in-service mechanized equipment structural fatigue state estimating method according to claim 1, is characterized in that: the time interval of the key position strain stress measurement data sequence in described step 3) should be consistent with the time interval of generalized load sequence.
4. in-service mechanized equipment structural fatigue state estimating method according to claim 1, is characterized in that: the equivalent elastic modulus E described step 4)
eqthe computing formula of sequence is: E
eq={ E
eq1,e
eq2..., E
eqi..., E
eqm}
m=n-Tmin, E
eqi=μ
fi/ μ
ε i, μ wherein
fifor the average of generalized load F, μ
ε iaverage for key position strain stress.
5. in-service mechanized equipment structural fatigue state estimating method according to claim 1, is characterized in that: the described parameter that can reflect in-service mechanized equipment duty is power consumption, output, the power of operating load, equipment.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61277034A (en) * | 1985-06-03 | 1986-12-08 | Hitachi Ltd | Method for evaluating residual life of machine structure |
| CN1854706A (en) * | 2005-04-21 | 2006-11-01 | 通用电气公司 | Methods and systems for diagnosing machinery |
| CN100552409C (en) * | 2008-07-23 | 2009-10-21 | 北京交通大学 | Determine the method in locomotive overhaul cycle fatigue lifetime by the estimation diesel locomotive |
| CN102129512A (en) * | 2011-02-24 | 2011-07-20 | 西北工业大学 | Fatigue life analyzing method based on Paris formula |
-
2011
- 2011-12-13 CN CN201110414705.4A patent/CN102680258B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61277034A (en) * | 1985-06-03 | 1986-12-08 | Hitachi Ltd | Method for evaluating residual life of machine structure |
| CN1854706A (en) * | 2005-04-21 | 2006-11-01 | 通用电气公司 | Methods and systems for diagnosing machinery |
| CN100552409C (en) * | 2008-07-23 | 2009-10-21 | 北京交通大学 | Determine the method in locomotive overhaul cycle fatigue lifetime by the estimation diesel locomotive |
| CN102129512A (en) * | 2011-02-24 | 2011-07-20 | 西北工业大学 | Fatigue life analyzing method based on Paris formula |
Non-Patent Citations (2)
| Title |
|---|
| 《TC11材料高低周复合疲劳试验研究》;刘红彬等;《燃气涡轮试验与研究》;20110531;第24卷(第2期);第23-26、57页 * |
| 刘红彬等.《TC11材料高低周复合疲劳试验研究》.《燃气涡轮试验与研究》.2011,第24卷(第2期), |
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Application publication date: 20120919 Assignee: Luoyang Huaci Technology Co.,Ltd. Assignor: Henan University of Science and Technology Contract record no.: X2019980000425 Denomination of invention: Method for estimating structure fatigue state of in-service mechanical equipment Granted publication date: 20140416 License type: Common License Record date: 20191101 |
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Granted publication date: 20140416 |