CN115493932A - Method and system for acquiring fracture performance of aerospace thin-wall metal welding joint - Google Patents

Method and system for acquiring fracture performance of aerospace thin-wall metal welding joint Download PDF

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CN115493932A
CN115493932A CN202211128047.7A CN202211128047A CN115493932A CN 115493932 A CN115493932 A CN 115493932A CN 202211128047 A CN202211128047 A CN 202211128047A CN 115493932 A CN115493932 A CN 115493932A
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范凯
钟继如
赵和明
晏飞
邱卫东
沈俊
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East China University of Science and Technology
Shanghai Institute of Space Propulsion
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Shanghai Institute of Space Propulsion
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Abstract

The invention provides a method and a system for acquiring fracture performance of a spaceflight thin-wall metal welding joint, which comprises the following steps: preparing a typical position small-size thin slice sample; measuring a test load-displacement curve through a micro-tensile test, and calculating to obtain a true stress-true strain curve of the corresponding material; performing micro-stretching simulation based on a finite element method of a damage mechanics model, outputting a simulated load-displacement curve, and automatically adjusting material damage parameters by adopting an intelligent algorithm until a target function is met; according to the true stress-true strain curve and the optimal material damage parameter, performing bending/stretching test simulation according to a standard SENB/CT sample specified in the related standard of the current fracture toughness test, and calculating to obtain a crack propagation resistance curve cluster and fracture toughness distribution corresponding to each typical position of a welded joint. The method and the system can effectively solve the problem that the fracture performance of the aerospace thin-wall metal welded joint cannot be measured according to the existing standard specification, and meanwhile, the acquisition process is simple, convenient, reliable and low in cost.

Description

Method and system for acquiring fracture performance of aerospace thin-wall metal welding joint
Technical Field
The invention relates to the field of structural integrity of spacecraft metal components, in particular to a method and a system for acquiring fracture performance of a spacecraft thin-wall metal welding joint.
Background
The structural integrity of the spacecraft metal components is directly related to the successful launch and on-orbit safe operation of the spacecraft. With the development of low cost, high carrying capacity and long service life of the spacecraft, higher performance and lighter weight requirements are put forward on metal components. To meet this requirement, thin-walled metal welded structures are widely used. The welding joint area becomes a weak link of the anti-fracture failure because the microstructure and the mechanical property of the material are uneven and the welding joint area is sensitive to crack defects. Therefore, it is important to perform integrity assessment and damage tolerance design on this region.
In order to achieve accurate assessment and rational design, it is necessary to obtain the fracture properties (crack propagation resistance curve and fracture toughness) of this region. According to the current standard, the samples used for measuring the fracture performance parameters are SENB/CT samples with certain thicknesses. The aerospace thin-wall metal component is usually obtained by machining a thin plate and does not meet the thickness requirement of a standard SENB/CT sample. The material structure of each region of the thin-walled welded structure is not completely consistent with that of each region of the thick-walled welded structure. Therefore, the fracture performance measured by a sample prepared by adopting a plate with the thickness meeting the requirement cannot truly reflect the fracture performance of an actual thin-wall welding structure. Therefore, it is necessary to provide a method for obtaining the fracture performance of an aerospace thin-wall metal welded joint.
Patent document CN104062188B (application No. 201410293802.6) discloses a method for measuring fracture toughness JIC of each micro-zone of a heat affected zone of a weld joint. According to the method, the V-shaped groove is formed in the coarse grain area or the fine grain area of the heat affected zone of the welded sample, so that the crack propagation direction is effectively controlled, the crack is guaranteed to propagate in the coarse grain area or the fine grain area of the heat affected zone, and the fracture toughness of each micro-area of the heat affected zone of the welded joint is measured. The method is still based on a standard large-size SENB sample and cannot be applied to thin-wall welding joints.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method and a system for acquiring the fracture performance of a spaceflight thin-wall metal welding joint.
The method for acquiring the fracture performance of the aerospace thin-wall metal welding joint provided by the invention comprises the following steps:
step S1: typical position x of aerospace thin-wall metal welding joint to be acquired 1 、x 2 、...、x n Preparation of Small-size sheet sample S f1 、S f2 、...、S fn ；
Step S2: for the prepared small-sized thin sheet sample S f1 、S f2 、...、S fn Sequentially carrying out micro-tensile test TE 1 、TE 2 、...、TE n Measuring the test load-displacement curve
Figure BDA0003849767540000021
Calculating to obtain a true stress-true strain curve C of the local material at each position according to the test load-displacement curve and the sheet sample σε1 、C σε2 、...、C σεn ；
And step S3: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn Adopting finite element method based on damage mechanics model to carry out micro-tensile test TE 1 、TE 2 、...、TE n Carrying out simulation and outputting a simulated load-displacement curve
Figure BDA0003849767540000022
And step S4: establishing an objective function F (DP), and evaluating a simulated load-displacement curve by adopting an intelligent algorithm
Figure BDA0003849767540000023
And the measured test load-displacement curve
Figure BDA0003849767540000024
Automatically adjusting GTN damage parameters of the material until the GTN damage parameters meet the target function, and outputting the optimal material damage parameter DP 1 、DP 2 、...、DP n ；
Step S5: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn And material damage parameter DP 1 、DP 2 、...、DP n And different positions of the thin-wall metal welding joint to be obtained are determined according to the standard SENB/CT sample S specified in the related standard of the current fracture toughness test SENB1 、S SENB2 、...、S SENBn Performing bending/stretching test simulation, and outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni )；
Step S6: according to the obtained (P) 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni ) Calculating typical positions x of the welding joint 1 、x 2 、...、x n Corresponding crack propagation resistance curve C R1 、C R2 、...、C Rn And fracture toughness J IC1 、J IC2 、...、J ICn ；
Step S7: for n sets of data pairs (x) 1 ,J IC1 )、(x 2 ,J IC2 )、...、(x n ,J ICn ) Plotting to obtain the fracture toughness distribution of the aerospace thin-wall metal welding joint; for n sets of crack propagation resistance curves C R1 、C R2 、...、C Rn And drawing to obtain the aerospace thin-wall metal welding joint crack propagation resistance curve cluster.
Preferably, typical positions of the aerospace thin-wall metal welding joint comprise: weld fusion zone FZ, heat affected zone HAZ, near interface zone NIZ, and parent material zone BMZ.
Preferably, the thickness B of the small-sized thin sheet sample 1 Taking 0.3 mm-2 mm; width W of stretching section 1 Taking the length of 2 mm-5 mm 1 Taking 8 mm-12 mm.
Preferably, the step S2 employs:
step S2.1: in the test load-displacement curve
Figure BDA0003849767540000031
Selecting multiple sets of load displacement data pairs (p) 1 ,v 1 )、(p 2 ,v 2 )、...、(p n ,v n ) (ii) a Wherein p is n Representing the load, v n Represents a displacement;
step S2.2: based on each set of load displacement data pairs (p) i ,v i ) Calculating to obtain corresponding engineering stress
Figure BDA0003849767540000032
And engineering strain
Figure BDA0003849767540000033
Figure BDA0003849767540000034
Figure BDA0003849767540000035
Step S2.3: stress of engineering
Figure BDA0003849767540000036
And engineering strain
Figure BDA0003849767540000037
Conversion to true stress
Figure BDA0003849767540000038
And true strain
Figure BDA0003849767540000039
Figure BDA00038497675400000310
Figure BDA00038497675400000311
Step S2.4: all true stress true strain data pairs
Figure BDA00038497675400000312
Drawing to obtain a material true stress-true strain curve C σε 。
Preferably, the objective function F (DP) in step S4 adopts:
Figure BDA00038497675400000313
wherein N represents the number of the analog loads output in the displacement interval;
Figure BDA00038497675400000314
and
Figure BDA00038497675400000315
respectively, the simulated load and the test load at the displacement point j.
Preferably, the selection of the damage mechanics model is determined by a fracture mechanism of the weld joint material, and comprises: a Beremin injury mechanical model, a Rousseier injury mechanical model, or a Gurson-Tvergaard-Needleman injury mechanical model; the number and type of specific material damage parameters is determined by the damage mechanics model employed.
Preferably, said S4 employs:
step S4.1: determining the number m of comparison evaluation groups and the number k of data in each group according to the optimization capability of an intelligent algorithm;
step S4.2: setting a first set of displacements
Figure BDA0003849767540000083
Inputting initial material damage parameters to perform finite element simulation, and identifying corresponding load by using Python script
Figure DEST_PATH_1
And outputting the data to Matlab analysis software;
step S4.3: judging whether the target function F (DP) meets the requirements, if not, automatically adjusting the material damage parameters by the intelligent algorithm through a python script until the target function F (DP) meets the requirements; and repeating the triggering step S4.2 to the step S4.3 to sequentially carry out identification evaluation on the remaining m-1 groups until all load-displacement curve identification is completed.
Step S4.4: and outputting the final optimal material damage parameters.
Preferably, the step S5 adopts:
crack propagation length a per load step i The projected propagation length a of the crack on the initial crack plane is measured from the hole volume fraction cloud chart iVVF And the sum of a crack tip passivation effect correction value CTOD/2 before crack initiation:
a i ＝a iVVF +CTOD/2
wherein CTOD represents crack opening displacement.
Preferably, the step S6 employs:
step S6.1: calculating the corresponding response of each loading point iForce field intensity factor K i ；
Figure BDA0003849767540000041
Wherein S represents a span; w is a group of 2 Is the width of SENB specimen, B 2 Is the thickness of SENB specimen, B N Is the effective thickness of the SENB specimen, a i Is the crack length;
step S6.2: respectively calculating the elastic J integral J corresponding to the incremental step ei And plasticity J integral J pi ：
Figure BDA0003849767540000042
Figure BDA0003849767540000043
Wherein, K i Representing a stress field strength factor; b is a mixture of i-1 The length of the residual ligament corresponding to the displacement point i-1; a. The p The area of a plastic deformation part under a curve corresponding to each loading point on a load-displacement curve is represented, namely the energy absorbed by the plastic deformation of the sample; a. The pi -A p(i-1) Representing the difference value of the plastic part areas corresponding to the point i and the point i-1 on the load-displacement curve;
step S6.3: calculating the J integral J corresponding to the current loading point i ：
J i ＝J ei +J pi
Step S6.4: corresponding J integral J to each loading point i And crack propagation length a i Drawing to obtain a crack propagation resistance curve C R ；
Step S6.5: determination of the fracture toughness J of materials Using passivated lines IC ：
Figure BDA0003849767540000044
Wherein σ s Indicates the yield strength of the material; sigma b Represents the yield strength of the material; m represents a constraint coefficient.
The invention provides a system for acquiring fracture performance of a spaceflight thin-wall metal welding joint, which comprises:
a module M1: typical position x of aerospace thin-wall metal welding joint to be obtained 1 、x 2 、...、x n Preparation of Small-size sheet sample S f1 、S f2 、...、S fn ；
A module M2: for the prepared small-sized thin sheet sample S f1 、S f2 、...、S fn Sequentially carrying out micro-tensile test TE 1 、TE 2 、...、TE n Measuring the test load-displacement curve
Figure BDA0003849767540000051
Calculating to obtain a true stress-true strain curve C of the local material at each position according to the test load-displacement curve and the thin sheet sample σε1 、C σε2 、...、C σεn ；
A module M3: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn Adopting finite element method based on damage mechanics model to carry out micro-tensile test TE 1 、TE 2 、...、TE n Carrying out simulation and outputting a simulated load-displacement curve
Figure BDA0003849767540000052
A module M4: establishing an objective function F (DP), and evaluating a simulated load-displacement curve by adopting an intelligent algorithm
Figure BDA0003849767540000053
And measured test load-displacement curve
Figure BDA0003849767540000054
By automatically adjusting the material damage parameters until the target function is satisfied, and outputting the optimal material damageParameter DP 1 、DP 2 、...、DP n ；
A module M5: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn And material damage parameter DP 1 、DP 2 、...、DP n The different positions of the thin-wall metal welding joint to be obtained are measured according to the standard SENB/CT sample S specified in the related standard of the current fracture toughness test SENB/CT1 、S SENB/CT2 、...、S SENB/CTn Performing bending/stretching test simulation, and outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni )；
A module M6: according to the obtained (P) 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni ) Calculating typical positions x of the welding joint 1 、x 2 、...、x n Corresponding crack propagation resistance curve C R1 、C R2 、...、C Rn And fracture toughness J IC1 、J IC2 、...、J ICn ；
A module M7: for n groups of data pairs (x) 1 ,J IC1 )、(x 2 ,J IC2 )、...、(x n ,J ICn ) Plotting to obtain the fracture toughness distribution of the aerospace thin-wall metal welding joint; for n sets of crack propagation resistance curves C R1 、C R2 、...、C Rn And (5) drawing to obtain a space thin-wall metal welding joint crack propagation resistance curve cluster.
Compared with the prior art, the invention has the following beneficial effects:
1. the method provided by the invention effectively solves the problem that the aerospace thin-wall welded joint can not be subjected to fracture performance measurement based on a standard size sample by directly referring to the existing standard;
2. the invention realizes the acquisition of the material mechanical property and the fracture property of each typical position or continuous region of the thin-wall welding joint only through a small-size sheet sample, and simultaneously adopts an acquisition mode of intelligent algorithm plus finite element simulation to replace the existing test mode, thereby having simple, convenient and reliable process and low cost;
3. the method provided by the invention has wide application range, is suitable for all thin-wall metal welding structures in aerospace, and can be expanded to thick-wall metal welding structures.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a flow chart of a method for obtaining fracture performance of a spaceflight thin-wall metal welding joint.
FIG. 2 is a schematic diagram of an aerospace thin-wall 316L stainless steel argon arc welding joint according to one embodiment of the invention.
Fig. 3 is a schematic view of a small-sized sheet sample according to an embodiment of the present invention.
Fig. 4 is a test load-displacement curve for each position according to one embodiment of the present invention.
Fig. 5 is a local material true stress-true strain curve at each location in accordance with one embodiment of the present invention.
FIG. 6 is a micro-stretching simulation model according to one embodiment of the invention.
FIG. 7 is a test and simulated load-displacement curve evaluation process according to one embodiment of the invention.
Figure 8 is a full simulation model of a standard SENB specimen, in accordance with one embodiment of the present invention.
FIG. 9 is a cluster of crack propagation resistance curves according to one embodiment of the present invention.
FIG. 10 is a fracture toughness distribution according to one embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will aid those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any manner. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the invention.
Example 1
According to the method for acquiring the fracture performance of the thin-wall metal welding joint, as shown in figure 1, the method comprises the following steps:
step 1: typical position x of aerospace thin-wall metal welding joint to be acquired 1 、x 2 、…、x n Preparation of Small-size sheet sample S f1 、S f2 、…、S fn ；
Typical positions of the aerospace thin-wall metal welding joint comprise a welding Fusion Zone (FZ), a Heat Affected Zone (HAZ), a Near Interface Zone (NIZ) and a Base Metal Zone (BMZ); thickness B of small-sized thin sheet sample 1 Taking 0.3 mm-2 mm; width W of stretching section 1 Taking 2 mm-5 mm, length L 1 Taking 8-12 mm;
and 2, step: for the small-sized thin sheet sample S prepared in step 1 1 、S 2 、…、S n Sequentially carrying out a micro-tensile test TE 1 、 TE 2 、…、TE n Measuring the test load-displacement curve
Figure BDA0003849767540000071
Calculating to obtain a true stress-true strain curve C of the local material at each position according to the test load-displacement curve and the slice sample geometry σε1 、C σε2 、…、C σεn ；
The calculation process of the true stress-true strain curve of the local material at each position of the welding joint comprises the following steps:
step 2.1: in the test load-displacement curve
Figure BDA00038497675400000717
Selecting a plurality of groups of load displacement data pairs (p) 1 ，v 1 )、(p 2 ， v 2 )、…、(p n ，v n )；
Step 2.2: for each set of load displacement data pairs (p) i ，v i ) Calculating corresponding engineering stress according to the formula (1) and the formula (2)
Figure BDA0003849767540000072
And engineering strain
Figure BDA0003849767540000073
Figure BDA0003849767540000074
Figure BDA0003849767540000075
Step 2.3: applying the engineering stress according to the formula (3) and the formula (4)
Figure BDA0003849767540000076
And engineering strain
Figure BDA0003849767540000077
Conversion to true stress
Figure BDA0003849767540000078
And true strain
Figure BDA0003849767540000079
Figure BDA00038497675400000710
Figure BDA00038497675400000711
Step 2.4: all true stress true strain data pairs
Figure BDA00038497675400000712
Drawing to obtain a material true stress-true strain curve C σε ；
And 3, step 3: obtaining a true stress-true strain curve C according to the step 2 σε1 、C σε2 、…、C σεn Applying finite element method based on damage mechanics model to the micro-tensile test TE 1 、TE 2 、…、TE n Carrying out simulation and outputting a simulated load-displacement curve
Figure BDA00038497675400000713
Establishing an objective function F (DP), and estimating a simulated load-displacement curve by adopting an intelligent algorithm
Figure BDA00038497675400000714
And step 2, measuring a test load-displacement curve
Figure BDA00038497675400000715
By automatically adjusting the material damage parameter until the target function is satisfied, and outputting the optimal material damage parameter DP 1 、DP 2 、…、DP n ；
The objective function F (DP) is specifically as in equation (5):
Figure BDA00038497675400000716
wherein,
Figure BDA0003849767540000081
and
Figure BDA0003849767540000082
respectively representing the simulation load and the test load at a displacement point j, and N is the number of the simulation loads output in a displacement interval;
the selection of the damage mechanical model is determined by the fracture mechanism of the welding joint material, and generally comprises a Beremin damage mechanical model, a Rousseier damage mechanical model, a Gurson-Tvergaard-Needleman damage mechanical model and the like. The number and type of specific material damage parameters is determined by the damage mechanics model employed.
Wherein, step 3 includes:
step 3.1: determining the number m of comparison evaluation groups and the number k of data in each group according to the optimization capability of an intelligent algorithm;
step 3.2: setting a first set of displacements
Figure BDA0003849767540000083
Inputting a set of initial material damage parameters q 1 ，q 2 ，f 0 ，f c ，f F ，f N ，ε N ，S N ]Carrying out finite element simulation, and identifying corresponding load by utilizing Matlab
Figure BDA0003849767540000084
Step 3.3: judging whether the target function F (DP) meets the requirements, if not, automatically adjusting the material damage parameter set by the intelligent algorithm through a python script until the target function F (DP) meets the requirements;
step 3.4: and repeating the steps 3.2 and 3.3 to sequentially perform identification evaluation on the remaining m-1 groups until all load-displacement curves are identified.
Step 3.5: inputting a final optimal material damage parameter group [ q 1 ，q 2 ，f 0 ，f c ，f F ，f N ，ε N ，S N ]；
Specifically, the crack length a of each load step in the step 4 i The projected propagation length a of the crack on the initial crack plane is measured from the hole volume fraction cloud chart iVVF And the sum of the corrected value CTOD/2 of the passivation effect of the crack tip before crack initiation is as follows:
a i ＝a iVVF +CTOD/2 (6)
wherein CTOD is crack opening displacement.
And 4, step 4: obtaining a true stress-true strain curve C according to the step 2 σε1 、C σε2 、…、C σεn And the material damage parameter DP obtained in the step 3 1 、DP 2 、…、DP n Welding of thin-walled metal to be obtainedThe joints are positioned according to the SENB/CT sample S specified in the relevant standards of the current fracture toughness test SENB/CT1 、S SENB/CT2 、…、S SENB/CTn Performing bending/stretching test simulation, and outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ，V 1i ，a 1i )、(P 2i ，V 2i ，a 2i )、…、(P ni ，V ni ，a ni )；
And 5: obtained according to step 4 (P) 1i ，V 1i ，a 1i )、(P 2i ，V 2i ，a 2i )、…、(P ni ，V ni ， a ni ) Calculating typical positions x of the welding joint 1 、x 2 、…、x n Corresponding crack propagation resistance curve C R1 、 C R2 、…、C Rn And fracture toughness J IC1 、J IC2 、…、J ICn ；
For n groups of data pairs (x) 1 ，J IC1 )、(x 2 ，J IC2 )、…、(x n ，J Icn ) Plotting to obtain the fracture toughness distribution of the aerospace thin-wall metal welding joint; for n sets of crack propagation resistance curves C R1 、C R2 、…、C Rn Drawing to obtain a space thin-wall metal welding joint crack propagation resistance curve cluster;
wherein, the crack propagation resistance curve C in the step 5 R And fracture toughness J IC The calculation process of (2) comprises:
step 5.1: firstly, calculating a stress field intensity factor K corresponding to each loading point i according to the formula (7) i ：
Figure BDA0003849767540000091
Wherein S is span, W 2 Is the width of SENB specimen, B 2 Is the thickness of SENB specimen, B N Is the effective thickness of the SENB specimen, a i Is the crack length;
step 5.2: push buttonThe equations (8) and (9) respectively calculate the elastic J integral J corresponding to the incremental step ei And plasticity J integral J pi ：
Figure BDA0003849767540000092
Figure BDA0003849767540000093
Wherein, K i Calculated by formula (7); b is a mixture of i-1 The length of the remaining ligament corresponding to the displacement point i-1 is equal to W-a i ；A p The area of the plastic deformation part under the curve corresponding to each loading point on the load-displacement curve, namely the energy absorbed by the plastic deformation of the sample; a. The pi -A pi-1 The difference value of the plastic part areas corresponding to the point i and the point i-1 on the load-displacement curve is referred to.
Step 5.3: the J integral J corresponding to the loading point is calculated according to the formula (10) i ：
J i ＝J ei +J pi (10)
Step 5.4: corresponding J integral J to each loading point i And crack propagation length a i Drawing to obtain a crack propagation resistance curve C R ；
Step 5.5: determination of the fracture toughness J of materials Using passivated lines IC The formula is as follows:
Figure BDA0003849767540000094
wherein σ s Is the yield strength of the material; sigma b Is the yield strength of the material; m is a constraint coefficient.
The invention provides a thin-wall metal welding joint fracture performance acquisition system, which comprises:
a module M1: typical position x of aerospace thin-wall metal welding joint to be obtained 1 、x 2 、...、x n Preparation of Small-size sheet sample S f1 、S f2 、...、S fn ；
A module M2: for the prepared small-sized thin sheet sample S f1 、S f2 、...、S fn Sequentially carrying out a micro-tensile test TE 1 、TE 2 、...、TE n Measuring the test load-displacement curve
Figure BDA0003849767540000101
Calculating to obtain a true stress-true strain curve C of the local material at each position according to the test load-displacement curve and the thin sheet sample σε1 、C σε2 、...、C σεn ；
A module M3: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn Adopting finite element method based on damage mechanics model to carry out micro-tensile test TE 1 、TE 2 、...、TE n Carrying out simulation and outputting a simulated load-displacement curve
Figure BDA0003849767540000102
A module M4: establishing an objective function F (DP), and evaluating a simulated load-displacement curve by adopting an intelligent algorithm
Figure BDA0003849767540000103
And the measured test load-displacement curve
Figure BDA0003849767540000104
By automatically adjusting the material damage parameter until the target function is satisfied, and outputting the optimal material damage parameter DP 1 、DP 2 、...、DP n ；
A module M5: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn And material damage parameter DP 1 、DP 2 、...、DP n The different positions of the thin-wall metal welding joint to be obtained are measured according to the standard SENB/CT sample S specified in the related standard of the current fracture toughness test SENB/CT1 、S SENB/CT2 、...、S SENB/CTn Performing bending/stretching test simulation, and outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni )；
A module M6: according to the obtained (P) 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni ) Calculating typical positions x of the welding joint 1 、x 2 、...、x n Corresponding crack propagation resistance curve C R1 、C R2 、...、C Rn And fracture toughness J IC1 、J IC2 、...、J ICn ；
A module M7: for n groups of data pairs (x) 1 ,J IC1 )、(x 2 ,J IC2 )、...、(x n ,J ICn ) Drawing to obtain the fracture toughness distribution of the aerospace thin-wall metal welding joint; for n sets of crack propagation resistance curves C R1 、C R2 、...、C Rn And drawing to obtain the aerospace thin-wall metal welding joint crack propagation resistance curve cluster.
Example 2
Example 2 is a preferred example of example 1
An embodiment of the invention is given below by taking stainless steel 316L argon arc welding joint as an example, and specifically illustrates a method for obtaining fracture performance of an aerospace thin-wall metal welding joint and a result.
Step 1: typical position fusion zone (x) for aerospace thin-wall 316L stainless steel electron beam welding joint of FIG. 2 3 =0 mm), heat affected zone (x) 2 =2 mm), near interface region (x) 4 =2 mm), base material region (x) 1 ＝-5mm、x 5 =5 mm), small-sized sheet samples S were prepared respectively f1 、S f2 、S f3 、S f4 、S f5 (ii) a Thickness B of the sample 1 =0.5mm, stretch width W 1 Length of stretched length of =2mmL 1 =9mm, the specific geometry is shown in fig. 3;
step 2: for the small-sized thin sheet sample S prepared in step 1 1 、S 2 、S 3 、S 4 、S 5 Sequentially carrying out a micro-tensile test TE 1 、TE 2 、TE 3 、TE 4 、TE 5 Measuring the test load-displacement curve
Figure BDA0003849767540000105
As shown in fig. 4;
step 2.1: respectively in the above test load-displacement curve C EPV 100 sets of load displacement data pairs (p) are selected 1 ， v 1 )、(p 2 ，v 2 )、…、(p 100 ，v 100 )；
Step 2.2: for each set of load displacement data pairs (p) i ，v i ) Calculating corresponding engineering stress according to the formula (1) and the formula (2)
Figure BDA0003849767540000111
And engineering strain
Figure BDA0003849767540000112
Figure BDA0003849767540000113
Figure BDA0003849767540000114
Step 2.3: the engineering stress is expressed according to the formula (3) and the formula (4)
Figure BDA0003849767540000115
And engineering strain
Figure BDA0003849767540000116
Conversion to true stress
Figure BDA0003849767540000117
And true strain
Figure BDA0003849767540000118
Figure BDA0003849767540000119
Figure BDA00038497675400001110
Step 2.4: all true stress true strain data pairs
Figure BDA00038497675400001111
Drawing to obtain a local material true stress-true strain curve C of 5 typical positions of the thin-wall 316L stainless steel argon arc welding joint σε1 、C σε2 、C σε3 、C σε4 、C σε5 As shown in fig. 5;
and 3, step 3: small-size thin-walled test specimens S using ABAQUS commercial finite element analysis software 1 、S 2 、S 3 、S 4 、S 5 Performing full-scale modeling, wherein the material performance is represented by the true stress-true strain curve C obtained in the step 2 σε1 、C σε2 、C σε3 、C σε4 、 C σε5 Determining; selecting a Gurson-Tvergaard-Needleman injury mechanical model, wherein the material injury parameters of the Gurson-Tvergaard-Needleman injury mechanical model totally comprise 8: material monomer cell hole growth coefficient q 1 And q is 2 Initial pore volume fraction f 0 Critical pore volume fraction f during pore polymerization c Critical pore volume fraction f at material failure F Volume fraction f of nucleatable inclusions or nucleation second phase N 50% of the nucleation particles are broken and the average equivalent plastic strain ε N And standard deviation of nucleation strain S N (ii) a Inputting initial material damage parameter group q 1 ＝1.5，q 2 ＝1，f 0 ＝0.0001，f c ＝0.01，f F ＝0.05，f N ＝0.1，ε N ＝0.3，S N ＝0.1](ii) a Setting boundary conditions (U1 = U2= U3= UR1= UR2= UR3= 0) at the left end of the sample, and setting boundary conditions (U2 = U3= UR1= UR2= UR3= 0) at the right end; applying a horizontal rightward displacement load U1=20mm at the right end; selecting an 8-node reduction integral unit (C3D 8R) for the grid type, and carrying out finite element simulation on the stretching process, wherein a finite element model is shown in FIG. 6;
the embodiment is based on a mixed ion group algorithm, and the number of comparison evaluation groups m =10 and the number of data per group k =6 are determined according to the optimization capability of the mixed ion group algorithm;
establishing an objective function F (DP), as shown in formula (5):
Figure BDA0003849767540000121
identifying a first set of displacements via Python scripts
Figure BDA0003849767540000122
Corresponding load
Figure BDA0003849767540000123
And outputting the parameters to Matlab, and automatically adjusting the material damage parameter set through a python script until the target function F (DP) meets the requirement, wherein the identification process is shown in FIG. 7.
Repeating steps 3B and 3C to sequentially shift V for the remaining 9 groups 2 、V 3 、V 4 、V 5 、V 6 、V 7 、V 8 、V 9 Corresponding load P 2 、P 3 、P 4 、P 5 、P 6 、P 7 、P 8 、P 9 And performing identification evaluation until all load-displacement curve identification is completed.
Finally, the optimal GTN damage parameters of local materials at 5 typical positions are output, and are shown in the following table.
q 1 q 2 f 0 f c f F f N ε N S N
DP 1 1.5 1 0.000001 0.04 0.25 0.002 0.3 0.1
DP 2 1.5 1 0.00005 0.02 0.21 0.002 0.3 0.1
DP 3 1.5 1 0.0002 0.01 0.18 0.002 0.3 0.1
DP 4 1.5 1 0.00001 0.015 0.2 0.002 0.3 0.1
DP 5 1.5 1 0.000001 0.035 0.23 0.002 0.3 0.1
And 4, step 4: obtaining a true stress-true strain curve C according to the step 2 σε1 、C σε2 、C σε3 、C σε4 、C σε5 And the material damage parameter DP obtained in the step 3 1 、DP 2 、DP 3 、DP 4 、DP 5 The SENB sample S to be obtained at different positions of the thin-wall metal welding joint according to the standard specified in the related standard of the current fracture toughness test SENB1 、S SENB2 、S SENB3 、 S SENB4 、S SENB5 A bending test simulation was performed with the sample geometry as shown in fig. 8;
outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ，V 1i ，a 1i )、 (P 2i ，V 2i ，a 2i )、…、(P ni ，V ni ，a ni )；
And 5: firstly, calculating a stress field intensity factor K corresponding to each loading point i according to a formula (7) i ：
Figure BDA0003849767540000124
Wherein the span S =57.6mm and the SENB sample width W 2 =14.4mm, SENB sample thickness B 2 =7.2mm, effective thickness B of SENB specimen N ＝7.2mm，a i Is the crack length;
the elastic J integral J corresponding to the increment step is respectively calculated according to the formula (8) and the formula (9) ei And plasticity J integral J pi ：
Figure BDA0003849767540000125
Figure BDA0003849767540000131
Wherein, K i Calculated by formula (7); b i-1 The length of the remaining ligament corresponding to the displacement point i-1 is equal to W-a i ；A p For each load point on the load-displacement curveThe area of the plastic deformation part under the corresponding curve, namely the energy absorbed by the plastic deformation of the sample; a. The pi -A pi-1 The difference value of the plastic part areas corresponding to the point i and the point i-1 on the load-displacement curve is referred to.
The J integral J corresponding to the loading point is calculated according to the formula (10) i ：
J i ＝J ei +J pi (10)
Corresponding J integral J to each loading point i And crack propagation length a i Drawing to obtain a crack propagation resistance curve C of each typical position of the welding joint R1 、C R2 、C R3 、C R4 、C R5 As shown in fig. 9;
determination of the fracture toughness J of materials Using passivated lines IC1 、J IC2 、J IC3 、J IC4 、J IC5 The formula is as follows:
Figure BDA0003849767540000132
wherein σ s Is the yield strength of the material; sigma b Is the yield strength of the material; m is a constraint coefficient.
J IC1 J IC2 J IC3 J IC4 J IC5
1602 1356 1123 1244 1590
For 5 sets of data pairs (x) 1 ，J IC1 )、(x 2 ，J IC2 )、(x 3 ，J IC3 )、(x 4 ，J IC4 )、(x 5 ，J IC5 ) Plotting to obtain the fracture toughness distribution of the aerospace thin-wall metal welded joint, as shown in FIG. 10; for 5 sets of crack propagation resistance curve C R1 、C R2 、C R3 、C R4 、C R5 And (4) drawing to obtain a spaceflight thin-wall metal welding joint crack propagation resistance curve cluster, as shown in figure 8.
It is known to those skilled in the art that, in addition to implementing the system, apparatus and its various modules provided by the present invention in pure computer readable program code, the system, apparatus and its various modules provided by the present invention can be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like by completely programming the method steps. Therefore, the system, the apparatus, and the modules thereof provided by the present invention may be considered as a hardware component, and the modules included in the system, the apparatus, and the modules for implementing various programs may also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (10)

1. A method for acquiring fracture performance of a spaceflight thin-wall metal welding joint is characterized by comprising the following steps:
step S1: typical position x of aerospace thin-wall metal welding joint to be acquired 1 、x 2 、...、x n Preparation of Small-size sheet sample S f1 、S f2 、...、S fn ；
Step S2: for the prepared small-sized thin sheet sample S f1 、S f2 、...、S fn Sequentially carrying out a micro-tensile test TE 1 、TE 2 、...、TE n Measuring the test load-displacement curve
Figure FDA0003849767530000011
Calculating to obtain a true stress-true strain curve C of the local material at each position according to the test load-displacement curve and the sheet sample σε1 、C σε2 、...、C σεn ；
And step S3: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn Adopting finite element method based on damage mechanics model to carry out micro-tensile test TE 1 、TE 2 、...、TE n Carrying out simulation and outputting a simulated load-displacement curve
Figure FDA0003849767530000012
And step S4: establishing an objective function F (DP), and estimating a simulated load-displacement curve by adopting an intelligent algorithm
Figure FDA0003849767530000013
And the measured test load-displacement curve
Figure FDA0003849767530000014
By automatically adjusting the material damage parameter until the target function is satisfied, and outputting the optimal material damage parameter DP 1 、DP 2 、...、DP n ；
Step S5: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn And material damage parameter DP 1 、DP 2 、...、DP n The different positions of the thin-wall metal welding joint to be obtained are measured according to the standard SENB/CT sample S specified in the related standard of the current fracture toughness test SENB/CT1 、S SENB/CT2 、...、S SENB/CTn Performing bending/stretching test simulation, and outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni )；
Step S6: according to the obtained (P) 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni ) Calculating typical positions x of the welding joint 1 、x 2 、...、x n Corresponding crack propagation resistance curve C R1 、C R2 、...、C Rn And fracture toughness J IC1 、J IC2 、...、J ICn ；
Step S7: for n groups of data pairs (x) 1 ,J IC1 )、(x 2 ,J IC2 )、...、(x n ,J ICn ) Plotting to obtain the fracture toughness distribution of the aerospace thin-wall metal welding joint; for n sets of crack propagation resistance curves C R1 、C R2 、...、C Rn And drawing to obtain the aerospace thin-wall metal welding joint crack propagation resistance curve cluster.
2. The method for acquiring the fracture performance of the aerospace thin-wall metal weld joint as claimed in claim 1, wherein the typical positions of the aerospace thin-wall metal weld joint comprise: weld fusion zone FZ, heat affected zone HAZ, near interface zone NIZ, and parent material zone BMZ.
3. The method for obtaining fracture performance of aerospace thin-walled metal weld joints according to claim 1, wherein the mini-tabs are formed from a metal alloy having a high thermal conductivityThickness B of size sheet sample 1 Taking 0.3 mm-2 mm; width W of stretching section 1 Taking 2 mm-5 mm, length L 1 Taking the diameter of 8 mm-12 mm.
4. The method for acquiring the fracture performance of the spaceflight thin-wall metal welding joint as claimed in claim 1, wherein the step S2 adopts:
step S2.1: in the test load-displacement curve
Figure FDA0003849767530000021
Selecting multiple sets of load displacement data pairs (p) 1 ,v 1 )、(p 2 ,v 2 )、...、(p n ,v n ) (ii) a Wherein p is n Representing the load, v n Represents a displacement;
step S2.2: based on each set of load displacement data pairs (p) i ,v i ) Calculating to obtain corresponding engineering stress
Figure FDA0003849767530000022
And engineering strain
Figure FDA0003849767530000023
Figure FDA0003849767530000024
Figure FDA0003849767530000025
Step S2.3: stress of engineering
Figure FDA0003849767530000026
And engineering strain
Figure FDA0003849767530000027
Conversion to true stress
Figure FDA0003849767530000028
And true strain
Figure FDA0003849767530000029
Figure FDA00038497675300000210
Figure FDA00038497675300000211
Step S2.4: all true stress true strain data pairs
Figure FDA00038497675300000212
Drawing to obtain a material true stress-true strain curve C σε 。
5. The method for acquiring the fracture performance of the spaceflight thin-wall metal welding joint as claimed in claim 1, wherein the objective function F (DP) in the step S4 is as follows:
Figure FDA00038497675300000213
wherein N represents the number of the analog loads output in the displacement interval;
Figure FDA00038497675300000214
and
Figure FDA00038497675300000215
respectively, the simulated load and the test load at the displacement point j.
6. The method for acquiring the fracture performance of the aerospace thin-wall metal welded joint as claimed in claim 1, wherein the selection of the damage mechanics model is determined by the fracture mechanism of the welded joint material, and includes: a Beremin injury mechanical model, a Rousseier injury mechanical model, or a Gurson-Tvergaard-Needleman injury mechanical model; the number and type of specific material damage parameters is determined by the damage mechanics model employed.
7. The method for acquiring the fracture performance of the aerospace thin-wall metal welded joint as claimed in claim 1, wherein the S4 comprises:
step S4.1: determining the number m of comparison evaluation groups and the number k of data in each group according to the optimization capability of an intelligent algorithm;
step S4.2: setting a first set of displacements
Figure DEST_PATH_BDA0003849767540000083
Inputting initial material damage parameters to perform finite element simulation, and identifying corresponding load by using Python script
Figure 1
And outputting the data to Matlab analysis software;
step S4.3: judging whether the target function F (DP) meets the requirement, if not, automatically adjusting the material damage parameter by the intelligent algorithm through the python script until the target function F (DP) meets the requirement; and repeating the triggering step S4.2 to the step S4.3 to sequentially carry out identification evaluation on the remaining m-1 groups until all load-displacement curve identification is completed.
Step S4.4: and outputting the final optimal material damage parameters.
8. The method for acquiring the fracture performance of the aerospace thin-wall metal welded joint according to claim 1, wherein the step S5 is implemented by:
crack propagation length a per load step i The projected propagation length a of the crack on the initial crack plane is measured from the hole volume fraction cloud chart iVVF And the sum of the corrected value CTOD/2 of the passivation effect of the crack tip before crack initiation:
a i ＝a iVVF +CTOD/2
wherein CTOD represents crack opening displacement.
9. The method for acquiring the fracture performance of the aerospace thin-wall metal welded joint according to claim 1, wherein the step S6 is performed by:
step S6.1: calculating stress field intensity factor K corresponding to each loading point i i ；
Figure FDA0003849767530000033
Wherein S represents a span; w 2 Width of SENB sample, B 2 Thickness of SENB sample, B N Is the effective thickness of the SENB specimen, a i Is the crack length;
step S6.2: respectively calculating the elastic J integral J corresponding to the incremental step ei And plasticity J integral J pi ：
Figure FDA0003849767530000034
Figure FDA0003849767530000035
Wherein, K i Representing a stress field strength factor; b i-1 The length of the residual ligament corresponding to the displacement point i-1; a. The p The area of a plastic deformation part under a curve corresponding to each loading point on a load-displacement curve is represented, namely the energy absorbed by the plastic deformation of the sample; a. The pi -A p(i-1) Representing the difference value of the plastic part areas corresponding to the point i and the point i-1 on the load-displacement curve;
step S6.3: calculating J integral J corresponding to current loading point i ：
J i ＝J ei +J pi
Step S6.4: each loading point pairCorresponding J integral J i And crack propagation length a i Drawing to obtain a crack propagation resistance curve C R ；
Step S6.5: determination of the fracture toughness J of materials Using passivated lines IC ：
Figure FDA0003849767530000041
Wherein σ s Indicates the yield strength of the material; sigma b Indicates the yield strength of the material; m represents a constraint coefficient.
10. A spaceflight thin-wall metal welding joint fracture performance obtaining system is characterized by comprising:
a module M1: typical position x of aerospace thin-wall metal welding joint to be obtained 1 、x 2 、...、x n Preparation of Small-size sheet sample S f1 、S f2 、...、S fn ；
A module M2: for the prepared small-sized thin sheet sample S f1 、S f2 、...、S fn Sequentially carrying out a micro-tensile test TE 1 、TE 2 、...、TE n Measuring the test load-displacement curve
Figure FDA0003849767530000042
Calculating to obtain a true stress-true strain curve C of the local material at each position according to the test load-displacement curve and the sheet sample σε1 、C σε2 、...、C σεn ；
A module M3: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn Adopting finite element method based on damage mechanics model to carry out micro-tensile test TE 1 、TE 2 、...、TE n Carrying out simulation and outputting a simulated load-displacement curve
Figure FDA0003849767530000043
A module M4: establishing an objective function F (DP), and estimating a simulated load-displacement curve by adopting an intelligent algorithm
Figure FDA0003849767530000044
And the measured test load-displacement curve
Figure FDA0003849767530000045
Automatically adjusting GTN damage parameters of the material until the GTN damage parameters meet the target function, and outputting the optimal material damage parameter DP 1 、DP 2 、...、DP n ；
A module M5: according to the obtained true stress-true strain curve C σε1 、C σε2 、...、C σεn And material damage parameter DP 1 、DP 2 、...、DP n The different positions of the thin-wall metal welding joint to be obtained are measured according to the standard SENB/CT sample S specified in the related standard of the current fracture toughness test SENB/CT1 、S SENB/CT2 、...、S SENB/CTn Performing bending/stretching test simulation, and outputting the load, displacement and crack propagation length (P) corresponding to each loading point i in each group of tests 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni )；
A module M6: according to the obtained (P) 1i ,V 1i ,a 1i )、(P 2i ,V 2i ,a 2i )、...、(P ni ,V ni ,a ni ) Calculating typical positions x of the welded joint 1 、x 2 、...、x n Corresponding crack propagation resistance curve C R1 、C R2 、...、C Rn And fracture toughness J IC1 、J IC2 、...、J ICn ；
A module M7: for n groups of data pairs (x) 1 ,J IC1 )、(x 2 ,J IC2 )、...、(x n ,J ICn ) Plotting to obtain the fracture toughness distribution of the aerospace thin-wall metal welding joint; for n sets of crack propagation resistance curves C R1 、C R2 、...、C Rn And (5) drawing to obtain a space thin-wall metal welding joint crack propagation resistance curve cluster.
CN202211128047.7A 2022-09-16 2022-09-16 Method and system for acquiring fracture performance of aerospace thin-wall metal welding joint Pending CN115493932A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117433990A (en) * 2023-12-18 2024-01-23 中国汽车技术研究中心有限公司 Method, system and equipment for determining interlayer shear strength of composite material laminated plate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117433990A (en) * 2023-12-18 2024-01-23 中国汽车技术研究中心有限公司 Method, system and equipment for determining interlayer shear strength of composite material laminated plate
CN117433990B (en) * 2023-12-18 2024-02-23 中国汽车技术研究中心有限公司 Method, system and equipment for determining interlayer shear strength of composite material laminated plate

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