CN109918835A - A kind of binary criterion analysis design method for preventing plasticity from collapsing and being excessively plastically deformed - Google Patents
A kind of binary criterion analysis design method for preventing plasticity from collapsing and being excessively plastically deformed Download PDFInfo
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- CN109918835A CN109918835A CN201910224800.4A CN201910224800A CN109918835A CN 109918835 A CN109918835 A CN 109918835A CN 201910224800 A CN201910224800 A CN 201910224800A CN 109918835 A CN109918835 A CN 109918835A
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Abstract
The invention discloses a kind of binary criterion analysis design methods for preventing plasticity from collapsing and being excessively plastically deformed, the design criteria that the analysis design method is used to prevent a load condition flowering structure from placticity failure occurs includes criterion of strength and Deformation Criteria, design load should be less than structure maximum load-carrying capacity divided by safety coefficient, to guarantee that structure will not be destroyed during operation；Maximum distortion (or strain) amount of limiting structure simultaneously, to guarantee that in the case where design load acts on be not in excessive deformation.It is advantage in comprehensive ASME VIII-2 specification and 13445 standard of EN for the criterion, based on zero curvature load and uses for reference material allowable stress and propose.Double criterion are analyzed to plastic-elastic stress using load resistance coefficient design method to evaluate, it is more convenient simple.
Description
Technical field
The present invention relates to a kind of analysis design method fields of pressure vessel, in particular to for comprehensive in elastic-plastic analysis
Prevent moulding from collapsing and the binary criterion analysis method of overall plastic deformation.
Background technique
Failure under a load condition is the dominant failure mode of pressure vessel.For this failure mode, at present
There are two types of assessment method: first is that structural-load-carrying capacity (i.e. structure can bear maximum load) evaluation of ASME specification, referred to as anti-
Only plasticity collapses；Second is that the amount of plastic deformation (total deformation can be used when flexible deformation is much smaller than plastic deformation) of EN standard is commented
Determine, referred to as gross plastic deformation (GPD) design & check.
It is a criterion of strength that the overall criterion to collapse is prevented in ASME specification, it cannot prevent structure from excessive plasticity occur
Deformation, because the load flowering structure gross plastic deformation that collapses is very big.Then in addition ASME code requirement meets usage criteria,
This is a kind of Deformation Criteria.The specific detailed rules and regulations of the no clear stipulaties usage criteria of the specification and require user oneself determine, this gives
The application and implementation of specification bring certain uncertain and difficult.
EN standard only recommends Limit Analysis, and requires maximum main structure strain absolute value control within 5%, this is a change
Shape criterion ensure that be not in overall excessive plastic deformation.Limit Analysis is also required to suitably to introduce criterion of strength, otherwise
The relatively low situation of safety margin will appear to the higher material of yield tensile ratio.
For elastic-plastic analysis of the pressure vessel under a load condition, ASME VIII-2 specification and EN at present
The design criteria for preventing plasticity from collapsing and preventing gross plastic deformation is set forth in 13445 standards, but remains unchanged there are limitation,
The evaluation knot of limit load analysis and elastic-plastic analysis in the case of in the wrong for material-strong relatively low more significant with geometrical hardening effect
Fruit may differ by larger, because of a kind of new analysis (evaluation) criterion of the invention, can provide more reasonable half-way house, mention for user
For a kind of general use elastic-plastic analysis assessment criteria.
Summary of the invention
The invention solves assessment method problem be to overcome the shortcomings of in existing criterion, provide one kind can be used to pair
Pressure vessel, which carries out elastic-plastic analysis, to be prevented placticity failure and facilitates objective assessment criteria and method.
To solve the problems, such as the above method, solution of the invention is:
A kind of binary criterion analysis design method for preventing plasticity from collapsing and being excessively plastically deformed, the overall criterion of this method
Including the criterion of strength for preventing plasticity from collapsing and prevent the Deformation Criteria being excessively plastically deformed.And further by pressure vessel intensity
Criterion and Deformation Criteria synthesis are one " binary criterion ".
Pressure vessel load-deflection (displacement or strain) curve, abbreviation P-w curve, after describing pressure vessel carrying
Deformation characteristic.First yield point indicates the pure elastic stage of loss of structure, starts local plastic deformation occur.Followed by local plastic
The process that area constantly expands and load reassigns.To perfectl plastic material, when reach capacity the point of load when, the structure of pressure vessel
The gross plastic deformation that can not be limited occurs, deformation increases, and load does not change, and finally collapses.To strain hardening
Material, when reach capacity the point of load when structure also enter the gross plastic deformation stage, but due to there is material hardening effect and several
What strengthening effect makes structure that can also continue to carry, and deformation increases simultaneously with load, is finally reached the point of load that collapses, ultimate load point
Load be the pressure vessel Exact limiting load P considered after strain hardening and geometrical hardening effectp。
The criterion of strength for preventing plasticity from collapsing is: pressure vessel allowable design load paIt collapses load no more than pressure vessel
PCDivided by safety coefficient 2.4.
Excessive plastic deformation to occur before the structure of pressure vessel collapses, so also needing in addition to meeting criterion of strength
Meet the usage criteria for preventing excessive deformation.A kind of embodiment of general usage criteria is prevented based on Exact limiting load
Only structure enters gross plastic deformation state.Use the Deformation Criteria for preventing from being excessively plastically deformed as follows: allowable design load
PaNo more than Exact limiting load PpDivided by safety coefficient 1.5.
Pressure vessel is collapsed load pCWith Exact limiting load PpIntegrate, constitute one simultaneously prevent plasticity collapse and
The binary criterion being excessively plastically deformed, i.e. Pa≤min(Pp/1.5,PC/2.4)。
Exact limiting load selection has following two methods:
(1) zero curvature load: the curvature of transition region is reduced to zero at ultimate load point on load-deflection curve, the point
Referred to as zero curvature point, corresponding load are known as zero curvature load pZ, it is exactly standard when structure enters gross plastic deformation state
Ultimate load.
(2) strain limiting load: maximum total yield strains load value when reaching 5% in structure.
Compared with existing design method, the beneficial effects of the present invention are:
Deformation Criteria method proposed by the present invention based on Exact limiting load provides a kind of general usage criteria for user
Embodiment.A kind of objective assessment criteria of convenience and method are provided to carry out elastic-plastic analysis to pressure vessel.In addition to one
There is the equipment of particular/special requirement to deformation a bit, after meeting binary criterion, user need not mention usage criteria again.It is comprehensive for the present invention
Close ASMEVIII-2 specification and 13445 standard of EN in advantage, based on zero curvature load and use for reference material allowable stress propose
's.Double criterion are analyzed to plastic-elastic stress using load resistance coefficient design method to evaluate, it is more convenient simple.
Detailed description of the invention
Fig. 1 is the flow chart of the specific embodiment of the invention.
Specific embodiment
In order to which objects and advantages of the present invention are more clearly understood, the present invention is carried out with reference to embodiments further
It is described in detail.
As shown in Figure 1, detailed process of the embodiment of the present invention is as follows:
S1 determines design load according to the operating condition that pressure vessel is considered, is denoted as P；
S2 carries out elastic and plastic finite element analysis to pressure vessel, is gradually loaded into 2.4P.If calculating does not dissipate, intensity is quasi-
Then pass through.Otherwise, it designs unqualified；
S3 extracts the load-deflection curve data of pressure vessel from calculated result；
S4 determines Exact limiting load PZOr PSIf 1.5P≤PZOr PS, then Deformation Criteria passes through.Otherwise, it designs unqualified；
If S5 pressure vessel criterion of strength and Deformation Criteria can be transferred through, qualification is designed.
Claims (4)
1. a kind of binary criterion analysis design method for preventing plasticity from collapsing and being excessively plastically deformed, it is characterised in that:
The criterion of strength for preventing plasticity from collapsing is: pressure vessel allowable design load paIt collapses load p no more than pressure vesselCIt removes
With safety coefficient 2.4；
Excessive plastic deformation to occur before the structure of pressure vessel collapses, so in addition to meeting criterion of strength, it is also necessary to full
Foot prevents the usage criteria of excessive deformation；A kind of embodiment of general usage criteria is to prevent from tying based on Exact limiting load
Structure enters gross plastic deformation state；Use the Deformation Criteria for preventing from being excessively plastically deformed as follows: allowable design load paNo
Greater than Exact limiting load PpDivided by safety coefficient 1.5；
Pressure vessel is collapsed load pCWith Exact limiting load PpIt integrates, constitute one prevents plasticity from collapsing and excessively simultaneously
The binary criterion of plastic deformation, i.e. Pa≤min(Pp/1.5,PC/2.4)。
2. a kind of binary criterion analysis design side for preventing plasticity from collapsing and being excessively plastically deformed according to claim 1
Method, it is characterised in that:
The overall criterion of this method is the criterion of strength for preventing plasticity from collapsing；Use intensity criterion is provided by user, is to prevent from pressing
The Deformation Criteria of force container excessive deformation；This method proposes the Deformation Criteria based on Exact limiting load, provides for user a kind of logical
Usage criteria embodiment, and be further one " binary criterion " by pressure vessel intensity and Deformation Criteria synthesis；
Pressure vessel load-deflection is displaced or strain curve, abbreviation P-w curve, and the deformation after description pressure vessel carrying is special
Property；First yield point indicates the pure elastic stage of loss of structure, starts local plastic deformation occur；It is continuous followed by local plastic area
Expand the process reassigned with load；To perfectl plastic material, when reach capacity the point of load when, the structure of pressure vessel occurs not
The gross plastic deformation that can be limited, deformation increase, and load does not change, and finally collapses；To strain-hardening material, when
Reach capacity the point of load when structure also enter the gross plastic deformation stage, but due to there is material hardening effect and geometrical hardening effect
It should make structure that can also continue to carry, deformation increases simultaneously with load, is finally reached the point of load that collapses, the load of ultimate load point is
Pressure vessel Exact limiting load P after considering strain hardening and geometrical hardening effectp。
3. a kind of binary criterion analysis design side for preventing plasticity from collapsing and being excessively plastically deformed according to claim 1
Method, it is characterised in that: Exact limiting load selection has following two methods:
(1) zero curvature load: the curvature of transition region is reduced to zero at ultimate load point on load-deflection curve, which is known as
Zero curvature point, corresponding load are known as zero curvature load pZ, it is exactly quasi- limit when structure enters gross plastic deformation state
Load；
(2) strain limiting load: maximum total yield strains load value when reaching 5% in structure.
4. a kind of binary criterion analysis design side for preventing plasticity from collapsing and being excessively plastically deformed according to claim 1
Method, it is characterised in that:
S1 determines design load according to the operating condition that pressure vessel is considered, is denoted as P；
S2 carries out elastic and plastic finite element analysis to pressure vessel, is gradually loaded into 2.4P；If calculating does not dissipate, criterion of strength is logical
It crosses；Otherwise, it designs unqualified；
S3 extracts the load-deflection curve data of pressure vessel from calculated result；
S4 determines Exact limiting load PZOr PSIf 1.5P≤PZOr PS, then Deformation Criteria passes through；Otherwise, it designs unqualified；
If S5 pressure vessel criterion of strength and Deformation Criteria can be transferred through, qualification is designed.
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| CN201910224800.4A CN109918835A (en) | 2019-03-24 | 2019-03-24 | A kind of binary criterion analysis design method for preventing plasticity from collapsing and being excessively plastically deformed |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111611680A (en) * | 2020-03-30 | 2020-09-01 | 浙江大学 | Manufacturing method of internal pressure steel oval end socket designed based on failure mode |
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2019
- 2019-03-24 CN CN201910224800.4A patent/CN109918835A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111611680A (en) * | 2020-03-30 | 2020-09-01 | 浙江大学 | Manufacturing method of internal pressure steel oval end socket designed based on failure mode |
| CN111611680B (en) * | 2020-03-30 | 2024-02-09 | 浙江大学 | Manufacturing method of internal pressure steel elliptical head based on failure mode design |
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Application publication date: 20190621 |
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