CN109960819A - Consider the incubation period prediction technique of contained center cracked tension sample - Google Patents
Consider the incubation period prediction technique of contained center cracked tension sample Download PDFInfo
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Abstract
The invention discloses a kind of incubation period prediction model and method for considering contained center cracked tension sample, the present invention utilizes a large amount of analogue datas, and fitting formula proposes the incubation period prediction technique of center cracked tension sample.The beneficial effects of the present invention are: simplifying the incubation period prediction technique of center cracked tension sample, and consider to restrain parameter, prediction data is more accurate and reliable.
Description
Technical field
The present invention relates to consider restrain influence center cracked tension sample (MT) incubation period predictive engine critical evaluation,
Alternatively, being exactly to determine that center cracked tension sample (MT) when under containing crackle, evaluates the incubation period of this center cracked tension sample.
Background technique
The components/devices being on active service under hot environment can inevitably generate various defects during production and military service.Creep
The germinating and extension of crackle are a dominant failure mechanism of the high-temperature component containing defect, and cause it in the slip of projected life
Effect.And the incubation period of creeping crack occupies very big specific gravity in the service life of high-temperature component, in order to ensure being taken under hot environment
The reliability of the component of labour also just seems further important to the research of creeping crack incubation period.Creep germinating is defined as micro- split
Line (or hole) connects the time for forming main crackle for the first time.And the generation of hole and micro-flaw and connection procedure of growing up are known as
Damage.It is a large amount of theoretical and it is demonstrated experimentally that creeping crack germinating and extension are the main reason for causing military service pipeline failure.
Foreign scholar proposes based on the improved incubation period prediction model of toughness dissipation model, which considers not
With the creep germinating occurred under stress state.But the application of the prediction model is related to large amount of complex calculating process and with one
Determine conservative, the application of actual component is limited to there are also certain.And influence of the contained effect of structure to incubation period is simultaneously
It is not studied；Scientific research personnel had carried out a large amount of research for restraining influence of the effect to On Creep Crack Growth in recent years.
Contained effect widely exists in the high-temperature component of processing and manufacturing, and causes significant impact to the service life of component.
So needing to propose that effective calculates considers to restrain the incubation period prediction model influenced in high temperature different component, with simplification
Engineer application.
Summary of the invention
Contained middle heart shake is considered in view of the technical drawbacks of the prior art, it is an object of the present invention to provide a kind of
The incubation period prediction technique of line tensile sample.
The technical solution adopted to achieve the purpose of the present invention is:
The incubation period prediction technique of the contained center cracked tension sample of consideration of the invention, comprising the following steps:
Step 1: determining contained parameter Q*, the stress strength factor K of center cracked tension sample, in which: Q* is dimensionless
Parameter, the unit of K are MPamm1/2；
Step 2: Q*, K in step 1 being substituted into following relational expression formulas (I), incubation period t is calculatedi, wherein ti
Unit be h:
(I) in: A2=21236356K-3.43846
(I) in: B2=0.000108629+0.0000117577K.
Preferably, the center cracked tension sample is 600~700 DEG C, preferably 650 DEG C.
Compared with prior art, the beneficial effects of the present invention are:
The invention discloses a kind of incubation period prediction model and method for considering contained center cracked tension sample, this hairs
Bright to utilize a large amount of analogue datas, fitting formula proposes the incubation period prediction technique of center cracked tension sample.Of the invention has
Beneficial effect is: simplifying the incubation period prediction technique of center cracked tension sample, and considers to restrain parameter, prediction data is more
Accurately and reliably.
Detailed description of the invention
Fig. 1 show the structural schematic diagram of the creep incubation period prediction model of center cracked tension sample of the invention.
Wherein: 1- sample ontology, the upper hole 2-, 3- lower opening, 4- precrack.
Fig. 2 show the FEM model schematic diagram of center cracked tension sample of the invention.Fig. 2 is structure in Fig. 1
A quarter.
Specific embodiment
The present invention is described in further detail below in conjunction with the drawings and specific embodiments.It should be appreciated that described herein
Specific embodiment be only used to explain the present invention, be not intended to limit the present invention.The present embodiment chooses P92 high-temperature refractory steel.
The incubation period prediction technique of the contained center cracked tension sample of consideration of the invention, comprising the following steps:
S1: the creep incubation period prediction model of center cracked tension sample is established, the model includes rectangular parallelepiped structure
The upper and lower ends of center cracked tension sample ontology 1, the sample ontology are symmetrically arranged with hole 2 and lower opening 3；In the sample sheet
It is inserted into precrack 4 in the middle part of the plane of symmetry of body, applies constant pressure load inside upper hole 2 and lower opening 3,
S2: establishing finite element model and see Fig. 2, obtains the change of impairment value at any time by the custom variable in post-processing
Change, as incubation period when the impairment value ω of the crackle advanced position d (mm) studied reaches 1；D (mm) is to determine creep
Creep impairment reaches 1 distance extended, the i.e. critical distance of creep germinating generation point is split in germinating when occurring before；
S3: the incubation period of the center cracked tension sample containing crackle can be obtained by finite element modelling；Different several
Under what size and load-up condition, the specific of acquisition restrains parameter and incubation period Data Data；
(1) different contained parameter Q*, stress strength factor K (MPamm1/2) in the case of incubation period ti(h) data；
(2) incubation period t is established according to data in step (1)iBecome about difference contained parameter Q* and stress strength factor K etc.
The function of amount；
(I) in: A2=21236356K-3.43846
(I) in: B2=0.000108629+0.0000117577K
Preferably, d takes the crystallite dimension of research material, takes 0.05mm, r to take crack tip passivation region size, takes
0.2mm。
Preferably, using different crack depths ratio a/W, (wherein a (mm) is crack depth, W (mm) in the step S3
Different contained parameter Q* can be obtained for specimen width (see Fig. 1), sample thickness B (mm)；
(II) in:It is the opening stress value at the crackle forward position obtained using FEM calculation, unit is
Mpa, σ0It is the yield strength of material, unit is MPa, referring to document: (Zhao L, Xu L, Han Y, Jing H.Two-
parameter charaSENTerization of constraint effeSENT induced by specimen size
on creep crack growth.Engng FraSENT Mech 2012；96:251–66.)；
σ22(r, 0) is the opening stress value in the crackle forward position obtained using steady state creep stress field calculation, and unit is Mpa；
(III) in: C* integral is the high temperature fracture parameter obtained using FEM calculation, and unit is MPamm (h)-1, r
It is the position apart from crackle forward position, unit is mm, and θ is crack tip angle,It is creep strain change rate, unit h-1, with
Material at high temperature creep attribute is related, n be nondimensional creep stress hardenability value, n andReferring to document: (Zhao L, Jing
H,Xu L,Han Y,Xiu J.Evaluation of constraint effeSENTs on creep crack growth
by experimental investigation and numerical simulation.EngngFraSENT Mech
2012；96:251-66.), InIt is dimensionless function related with n,It is dimensionless function related with θ and n, specifically
Value can be obtained with consulting literatures: Shih, C.F..1983.Tables of Hutchinson-Rice-Rosengren
Singular Field Quantities.Brown University Technical Report,MRL E-147.；
The C*,tiFinite element modelling the following steps are included:
(1) first, in accordance with size, the finite element model of center cracked tension sample is established, is arranged in material properties module
Resilient plastic parameter, is arranged compressive load and contained condition in payload module, the contained condition include symmetric condition and
Rigid condition sets output parameter in analysis step module: impairment value ω, in mesh module grid division, wherein Crack Tip
The grid dividing at end is even closer, as shown in Figure 2；
(2) task computation is submitted in operation module, obtains and contains creep stretching experiment calculated result, in destination file, from
Fracture parameter C* is obtained in historical variable, obtains stress value in field variable
(3) it obtains impairment value by the custom variable in post-processing to change with time, when the crackle forward position studied
As incubation period when the impairment value ω of position d reaches 1.
It is specific:
The present embodiment chooses P92 high-temperature refractory steel, with Q*=-1.3, K=20MPamm1/2, center cracked tension sample
As research object.Its main material attribute see the table below:
A2=21236356K-3.43846=713.7405944
B2=0.000108629+0.0000117577K=0.000344
The above is only a preferred embodiment of the present invention, it is noted that for the common skill of the art
For art personnel, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications
Also it should be regarded as protection scope of the present invention.
Claims (2)
1. considering the incubation period prediction technique of contained center cracked tension sample, which comprises the following steps:
Step 1: determining the contained parameter Q* and stress strength factor K of center cracked tension sample, in which: Q* is dimensionless ginseng
Number, the unit of K are MPamm1/2；
Step 2: by the Q* and the following relational expression formulas (I) of K substitution substitution in step 1, incubation period t is calculatedi, wherein ti's
Unit is h:
(I) in: A2=21236356K-3.43846；
(I) in: B2=0.000108629+0.0000117577K.
2. the incubation period prediction technique as described in claim 1 for considering contained center cracked tension sample, which is characterized in that
The center cracked tension sample is 600~700 DEG C.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111539144A (en) * | 2020-04-20 | 2020-08-14 | 中车青岛四方机车车辆股份有限公司 | Fracture toughness calculation method and system for crack-containing structural part |
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2017
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111539144A (en) * | 2020-04-20 | 2020-08-14 | 中车青岛四方机车车辆股份有限公司 | Fracture toughness calculation method and system for crack-containing structural part |
| CN111539144B (en) * | 2020-04-20 | 2023-09-22 | 中车青岛四方机车车辆股份有限公司 | Fracture toughness calculation method and system for structural member containing cracks |
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Application publication date: 20190702 |