JP2013217822A - Analyzing device, method and program for welding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique by which, by paying attention to affection of phase transformation of a material to inherent strain, inherent strain varying depending on a material condition or a welding condition is easily derived so as to analyze weld deformation and residual stress of a welding structure with high accuracy.SOLUTION: An analyzing device 10 for a welding structure 30 includes: a database 12 in which inherent strain in a combination of weld joints showing a basic shape is registered; a derivation unit 13 for deriving an inherent strain of the welding structure 30 on the basis of a first parameter P1 and the database 12; a correction unit 14 for correcting the inherent strain on the basis of a correction formula to which a second parameter P2 related to phase deformation of a weld joint 32 and/or a welded member 31 is input; a resilience calculation unit 16 for executing a resilience calculation on the basis of a finite element method by using inherent strain after the correction; and a result display unit 18 for displaying an analysis result on the basis of weld deformation or residual stress of the welding structure 30 derived via the resilience calculation.

Description

  The present invention relates to a technique for analyzing welding deformation and residual stress in a welded structure.

  Analysis of weld deformation and residual stress in a welded structure using computer simulation is performed by a thermoelastic-plastic analysis method using a finite element method or an intrinsic strain method. Among these, the thermo-elasto-plastic analysis method for performing nonlinear analysis of the welding phenomenon requires enormous calculation time and cost when calculating the welding deformation of a large structure. On the other hand, since the inherent strain method using elastic analysis is applied to linear analysis with a short calculation time, an analysis result can be obtained in a short time even for a complicated welded structure (for example, Patent Documents 1 to 3). ).

JP-A-6-180271 JP 2003-121273 A JP 2011-101900 A

In the analysis based on the inherent strain method, the inherent strain in the combination of the welded joints of the basic shape is obtained by experimental measurement or calculation and is made into a database.
In the technique disclosed in the above-mentioned patent document, the inherent strain distribution derived from this database is elastically calculated as it is to derive welding deformation and residual stress.
However, in this method, since the inherent strain generated depends on various conditions, it is necessary to create a database for each condition in order to obtain an accurate inherent strain.

  The present invention has been made in view of such circumstances, paying attention to the effect of the phase transformation phenomenon of the material on the inherent strain, and easily derived the inherent strain that changes depending on the material conditions and welding conditions, It is an object of the present invention to provide a technique for analyzing welding deformation and residual stress of a welded structure with high accuracy.

  The welded structure analyzing apparatus includes a database in which the inherent strain in a combination of welded joints showing a basic shape is registered, a derivation unit for deriving the inherent strain of the welded structure based on the first parameter and the database, and the welded joint And / or a correction unit that corrects the inherent strain based on a correction formula that inputs a second parameter related to the phase transformation of the welded member, and an elastic calculation based on a finite element method using the corrected inherent strain. And a result display unit for displaying an analysis result based on welding deformation or residual stress of the welded structure derived by the elasticity calculation.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which introduce | transduces the inherent distortion which changes depending on material conditions and welding conditions easily, and analyzes the welding deformation and residual stress of a welded structure with high precision is provided.

The block diagram which shows 1st Embodiment of the analysis apparatus of the welded structure which concerns on this invention. The block diagram of the natural distortion correction | amendment part applied to the analysis apparatus of the welded structure which concerns on each embodiment. The perspective view which shows the welded structure to which embodiment of this invention is applied. The graph which contrasted the natural strain distribution in the weld line direction (X-axis direction) of a welded structure by the presence or absence of correction | amendment. The graph which contrasted the corrected inherent strain distribution in the welding line orthogonal direction (Y-axis direction) of a welded structure with the inherent strain distribution by a thermoelastic-plastic analysis. The graph which contrasted the corrected inherent strain distribution in the weld line direction (X-axis direction) of a welded structure with the inherent strain distribution by a thermoelastic-plastic analysis. The block diagram which shows 2nd Embodiment of the analysis apparatus of the welded structure which concerns on this invention.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, the welded structure analysis apparatus 10 according to the first embodiment includes a database 12 in which inherent strains in combinations of welded joints 32 (FIG. 3) showing basic shapes are registered, a first parameter P1, and Based on the database 12, the derivation unit 13 for deriving the inherent strain of the welded structure 30 (FIG. 3) and the second parameter P2 related to the phase transformation of the welded joint 32 and / or the welded member 31 (FIG. 3) were input. The correction unit 14 that corrects the inherent strain based on the correction formula (FIG. 2: Formulas (1), (2), and (3)), and the elasticity that executes the elastic calculation based on the finite element method using the corrected inherent strain. The calculation part 16 and the result display part 18 which displays the analysis result based on the welding deformation or residual stress of the welded structure 30 derived | led-out by this elasticity calculation are provided.

As shown in FIG. 3, in the welded structure 30, a pair of weld joints 32 are joined to each other by a weld member 31 with their end sides abutting each other. The welded structure 30 is displayed as a three-dimensional model by the finite element method.
Residual stresses and deformations generated in the welded structure 30 through the joining work greatly affect the structure quality and design guidelines such as fatigue life and weld cracks.

  In the inherent strain method, welding deformation and residual stress are derived by elastic analysis from the distribution of the inherent strain quantified for each element of the modeled welded structure 30. For this reason, the accuracy of analysis of welding deformation and residual stress based on the inherent strain method largely depends on the accuracy of the obtained inherent strain.

As shown in FIG. 1, the input unit 11 is used by an operator to input a first parameter P1 necessary for derivation of the inherent strain and a second parameter P2 necessary for correcting the inherent strain in consideration of the phase transformation. .
Examples of the first parameter P1 include, but are not limited to, the material composition, material properties, joint shape, groove shape and plate thickness of the welded joint 32, and the material composition, material properties, and welding conditions of the welded member 31. It is not something. The second parameter P2 will be described later.

The database 12 regards the welded structure 30 as an aggregate of weld joints 32 having a basic shape, and for each combination of the weld joints 32 having the basic shape, the shape, restraint conditions, welding conditions, and inherent strain are stored. Accumulated as data.
The deriving unit 13 selects a weld joint 32 having a basic shape corresponding to the welded structure 30 from the database 12, and derives the inherent strain of the welded structure 30 based on the first parameter P1.

As shown in FIG. 2, the correction unit 14 inputs the second parameter P2 from the input unit 11 and uses the correction expressions (1), (2), and (3) registered in the registration unit 15 to correct the correction term Y _ij And an adder 14b that adds the correction term Y _ij to the inherent strain X _ij input from the derivation unit 13 and outputs the corrected inherent strain (X _ij + Y _ij ). Yes.

In the correction equations (1), (2), and (3), the second parameter P2 related to the volume change rate, the carbon equivalent, and the cooling rate associated with the phase transformation of the welded joint 32 and the welded member 31 can be substituted as variables. .
Here, examples of the phase transformation that greatly affects the welding deformation and residual stress of the welded structure 30 include, but are not limited to, martensitic transformation and bainite transformation.
Among these phase transformations, the generation ratio of martensite phase generated during cooling after welding has a great influence on welding deformation and residual stress.

The meanings of the parameters included in the correction equations (1) and (2) in FIG. 2 are as follows.
α: Volume change per unit volume or unit weight due to martensitic transformation.
β: The martensite volume ratio or weight ratio in the welded member 31.
K _A : Carbon equivalent of the material of the welded joint 32.
K _DB : Carbon equivalent of the material of the welding member 31.
x _A : the cooling rate of the material of the weld joint 32.
x _DB : the cooling rate of the material of the welding member 31.
c ₁ , c ₂ , c ₃ , n ₀ , n ₁ , n ₂ : constants.

Further, C, Mn, Ni, Cr, and Mo shown in the carbon equivalent K (K _A , K _DB ) shown in the correction formula (3) in FIG. 2 indicate the volume ratio or weight ratio in the alloy of each element. .
In the verification graphs (FIGS. 4 to 6) described later, constants n ₀ = 3, c ₁ = c ₂ = c ₃ = n ₁ = n ₂ = 1 were used. 30 depending on the restraint condition of the welding member 31 at 30.

By the way, the correction term Y _ij can be expressed in a tensor when there is anisotropy in the transformation amount of the martensite phase. Specifically, the case where anisotropy exists in the crystal grain shape or the case where anisotropy exists in the constraint condition of the welded member 31 in the welded structure 30 is a target.
As factors affecting the phase transformation behavior, attention was paid to the material composition, material properties, and welding conditions. When other factors such as joint shape and groove shape affect the phase transformation amount, a constant c _{1 for} each of these factors. , C ₂ , c ₃ , n ₀ , n ₁ , n ₂ can be set.

The adding unit 14b adds the correction term Y _ij to the inherent strain X _ij of the welded structure 30 and outputs the corrected inherent strain (X _ij + Y _ij ) in consideration of the phase transformation.
Note that the correction equation for calculating the correction term Y _ij and the second parameter P2 in the correction unit 14 are not limited to the above (1), (2), and (3).
The output of the correction unit 14 is not limited to the intrinsic strain X _ij input from the derivation unit 13 and the correction term Y _ij added thereto. To do.

With reference to the graphs of FIGS. 4 to 6, the effectiveness of correcting the intrinsic strain in consideration of the phase transformation will be verified.
The graph in FIG. 4 compares the inherent strain distribution in the weld line direction (X-axis direction) of the welded structure 30 with and without correction.

That is, the inherent strain of each element output from the deriving unit 13 is indicated by ◇, and the inherent strain of each element output from the correction unit 14 is indicated by ◆.
From the graph of FIG. 4, it can be seen that the inherent strain of each element in the weld line direction (X-axis direction) of the welding member 31 is increased by considering the phase transformation.

The graph of FIG. 5 contrasts the corrected inherent strain distribution in the weld line orthogonal direction (Y-axis direction) of the welded structure 30 with the inherent strain distribution of the thermoelastic-plastic analysis.
The graph of FIG. 6 contrasts the corrected inherent strain distribution in the weld line direction (X-axis direction) of the welded structure 30 with the inherent strain distribution of the thermoelastic-plastic analysis.

That is, the inherent strain of each element by thermoelastic-plastic analysis is indicated by ◯, and the inherent strain of each element output from the correction unit 14 is indicated by ◆.
From the graphs of FIG. 5 and FIG. 6, it can be seen that the inherent strain of each element corrected in consideration of the phase transformation agrees well with the result of the inherent strain by strict thermal elastic-plastic analysis although it takes time.

The elasticity calculation unit 16 illustrated in FIG. 1 performs elasticity calculation based on the finite element method using the corrected inherent strain output from the correction unit 14, and calculates welding deformation and residual stress in each element of the welded structure 30. Output.
Then, in the three-dimensional analysis unit 17, a three-dimensional image of the welded structure 30 is formed based on the welding deformation and residual stress in each element and displayed on the result display unit 18.
The result display unit 18 is not limited to displaying such a three-dimensional image, and also displays various analysis results based on welding deformation or residual stress derived from the elasticity calculation unit 16.

  As described above, in the first embodiment, the welding distortion and the residual stress in the welded structure are obtained by correcting the inherent strain obtained from the generally used inherent strain method in consideration of the phase transformation. This analysis can be performed in a short time and with high accuracy.

(Second Embodiment)
As shown in FIG. 7, the welded structure analysis apparatus 10 according to the second embodiment further includes a registration unit 21 for registering the allowable values of welding deformation and residual stress, and elasticity in addition to the configuration of the first embodiment. A parameter updating unit for updating parameters so that the welding deformation and residual stress of the welded structure 30 derived by the calculation satisfy this allowable value.
7 that have the same configuration or function as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

The registration unit 21 registers allowable values of welding deformation and residual stress in each element of the welded structure 30. These allowable values can be registered from the parameter input unit 11.
Then, the comparison unit 22 compares the welding deformation and residual stress of each element output from the elasticity calculation unit 16 with allowable values.
Then, when there is an element exceeding the allowable value, the parameter update unit 23 updates the parameter and performs recalculation in the elasticity calculation unit 16. Then, update of parameters and recalculation of elasticity calculation are repeated until the welding deformation and residual stress of each element of the welded structure 30 satisfy this allowable value.

Next, with reference to FIG. 7, the operation of the welded structure analysis apparatus 10 according to the second embodiment will be described.
In the database 12, the inherent strain in the combination of welded joints indicating the basic shape is registered. Then, the operator inputs the first parameter P1 (the material composition of the welded joint 32, the material physical property, the joint shape, the groove shape and the plate thickness in the welded structure 30 and the material composition of the welded member 31, the material physical property, and the welding) Necessary data such as conditions and the second parameter P2 (parameters related to phase transformation) are input. Further, the allowable values of welding deformation and residual stress in the welded structure 30 are registered in the allowable value registration unit 21.

Based on the input first parameter P1 and the database 12, the distribution of the inherent strain of the welded structure 30 is derived (reference numeral 13).
Further, the second parameter P2 is substituted into the correction formula acquired from the registration unit 15, and correction is performed on the inherent strain output from the derivation unit 13 (reference numeral 14).

Then, elastic calculation based on the finite element method is executed using the corrected intrinsic strain to obtain weld deformation and residual stress of the welded structure 30 (reference numeral 16).
The three-dimensional analysis of the welded structure 30 reflecting the obtained welding deformation and residual stress is executed and the analysis result is displayed (reference numerals 17 and 18).

  On the other hand, the welding deformation and residual stress obtained by the elastic calculation unit 16 are compared with registered allowable values (reference numerals 21 and 22). If the welding deformation and residual stress satisfy the allowable values, the process is terminated. If not, the first parameter P1 or the second parameter P2 is updated and re-input (reference numerals 23 and 11). .

Based on the updated first parameter P1 or second parameter P2, the processes of reference numerals 13, 14, 16, 22, and 23 are repeated until the welding deformation and the residual stress satisfy the allowable values.
Then, the first parameter P1 and the second parameter P2 when the welding deformation and the residual stress satisfy the allowable values are displayed on the result display unit 18.
As described above, in the second embodiment, iterative calculation for searching for the optimum parameter is possible, and the optimum conditions for the welding process can be obtained in a short time.

  According to the welded structure analyzing apparatus of at least one embodiment described above, the weld deformation and residual stress of the welded structure are analyzed with high accuracy and speed by adopting the inherent strain taking account of the phase transformation of the material. It becomes possible to do.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.
The components of the welded structure analysis apparatus can also be realized by a computer processor, and can be operated by a welded structure analysis program.

  DESCRIPTION OF SYMBOLS 10 ... Analyzing apparatus of welded structure, 11 ... Parameter input part (input part), 12 ... Intrinsic strain database, 13 ... Intrinsic strain derivation part (derivation part), 14 ... Intrinsic strain correction part (correction part), 14a ... Correction Term calculation unit (calculation unit), 14b ... addition unit, 15 ... correction formula registration unit, 16 ... elasticity calculation unit, 17 ... three-dimensional analysis unit, 18 ... result display unit, 21 ... allowable value registration unit, 22 ... comparison unit , 23 ... Parameter update unit, 30 ... Welded structure, 31 ... Welded member, 32 ... Welded joint, P1 ... First parameter, P2 ... Second parameter.

Claims (6)

A database in which the inherent strain in a combination of welded joints showing the basic shape is registered;
A deriving unit for deriving the inherent strain of the welded structure based on the first parameter and the database;
A correction unit that corrects the inherent strain based on a correction formula that inputs a second parameter related to the phase transformation of the weld joint and / or weld member;
An elastic calculation unit for performing elastic calculation based on the finite element method using the corrected intrinsic strain;
And a result display unit for displaying an analysis result based on welding deformation or residual stress of the welded structure derived by the elasticity calculation. In the welding structure analysis device according to claim 1,
The correction unit is
A calculation unit for calculating a correction term based on the correction formula;
And an adding unit that adds the correction term to the inherent strain of the welded structure and outputs the corrected inherent strain. In the welded structure analysis apparatus according to claim 1 or 2,
2. The weld structure analysis apparatus according to claim 1, wherein the correction formula inputs the second parameter related to a volume change rate, a carbon equivalent, and a cooling rate associated with the phase transformation. In the analysis device of the welded structure according to any one of claims 1 to 3,
A registration unit for registering an allowable value of the welding deformation and the residual stress;
A parameter updating unit for updating the first parameter and / or the second parameter so that welding deformation and residual stress of the welded structure derived by the elastic calculation satisfy the allowable value. A welded structure analysis device. Registering the inherent strain in the combination of welded joints showing the basic shape as a database;
Deriving the inherent strain of the welded structure based on the first parameter and the database;
Correcting the inherent strain based on a correction formula that inputs a second parameter related to the phase transformation of the weld joint and / or weld member;
Performing an elastic calculation based on the finite element method using the corrected intrinsic strain;
And displaying an analysis result based on welding deformation or residual stress of the welded structure derived by the elasticity calculation. On the computer,
A function to register the inherent strain in the welded joint combination showing the basic shape as a database,
A function of deriving the inherent strain of the welded structure based on the first parameter and the database;
A function of correcting the inherent strain based on a correction formula in which a second parameter related to the phase transformation of the weld joint and / or weld member is input;
A function of performing elasticity calculation based on the finite element method using the corrected inherent strain;
A function for displaying an analysis result based on welding deformation or residual stress of the welded structure derived by the elastic calculation is executed.

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