JPH10146689A - Estimation system for residual welding stress and residual deformation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system to efficiently estimate residual stress and residual deformation of a structure with weld zone. SOLUTION: The structure including weld zone is divided into a plurality of substructures and classified into groups by shape. Regarding all the substructures, pertaining groups are registered on the data file 113. The substructures of each of the groups are divided into finite elements and are recorded on data file 114 with residual stress and residual deformation calculated. The individual finite element having distribution of residual stress and residual deformation recorded on the data file 114 is formed every group, which is used to estimate the residual stress and residual deformation of the whole structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for predicting residual stress and residual deformation of a welded structure.

[0002]

2. Description of the Related Art In a structure having a welded portion, if the residual stress and residual deformation due to welding exceed a specified value when the structure is completed, if the structure cannot be used as a structure or to remove the residual stress and residual deformation. In some cases, great effort is required. In order to avoid this, a means for predicting the residual stress and residual deformation of the welded portion is required in advance, and calculations using the finite element method are widely performed.

[0003] In welding, heat input is performed in a short period of time concentrated on the welded portion. Thus, the material is locally quenched to a high temperature and then quenched from the melting temperature. In the prediction of residual stress and residual deformation during welding by the finite element method, the history of temperature distribution in the structure during the entire welding process is taken into account in the heat transfer analysis in order to consider such a rapid temperature change process. Determined by the finite element method. Next, based on the calculated history of the temperature distribution in the structure, residual stress and residual deformation caused by welding heat input are calculated by a finite element method of stress analysis.

In addition, physical property values related to heat conduction analysis such as thermal conductivity, specific heat, density, and heat transfer coefficient of materials and physical property values related to stress analysis such as yield stress, elastic coefficient, and linear expansion coefficient have properties that depend on temperature. Have. It affects the values of residual stress and residual deformation at the end of welding. In order to incorporate the temperature dependence of the physical property value into the calculation, the relationship between the physical property value and the temperature in the above heat conduction analysis and stress analysis is measured by an experiment, and the value may be used.

[0005] Further, in the welded portion, a change in the structure of the material accompanies a change in temperature, and at a temperature higher than the melting temperature, the material changes from a solid to a liquid state. The temperature dependence of the material structure has been measured by experiments, and residual stress and residual deformation have been predicted using the measurement results.

A method of predicting residual stress and residual deformation by calculating a temperature distribution history in advance by temperature analysis and performing stress analysis with reference to the temperature distribution is described in Hyundai Welding Technology Daikei Vol. Publishing). A method for predicting residual stress and residual deformation in consideration of the process of structural change of a material is described in Tatsuo Inoue, Journal of the Japan Society of Mechanical Engineers (A), vol. 50, No. 451 (March 1984), pages 285-290. Papers (mechanical behavior and coupling effects of metallic materials with phase transformation), and Transactions of the Japan Society of Mechanical Engineers (A), vol. 50,
No. 459 (November 1984), pp. 1900-19
In 08, a paper published by Shigeo Wang et al. (Constitutive formula of viscoplastic body considering melting and analysis of welding process using it), and Transactions of the Japan Society of Mechanical Engineers (A), Vol. 51, No. 467 (1985) (July), page 1858-1863, based on the description of a paper (analysis of butt-welding process of plates using constitutive formula of viscoplastic body) published by Shige Wang et al.

[0007]

The above-described calculation method is a precise calculation for sequentially tracking the welding process. However, since a real structure has many welding lines, a large amount of calculation time is required.

According to the present invention, the prediction of residual stress and residual deformation of a material to be welded at the time of welding is performed to calculate the temperature change of rapid heating or rapid cooling of a welded part and the temperature dependence of physical property values related to heat conduction analysis and stress analysis. It is an object of the present invention to provide an apparatus for estimating residual stress and residual deformation in consideration of the case and with less calculation time than the conventional method.

[0009]

In order to achieve the above object, according to the present invention, the shape data of the entire structure having a welded portion and the structure are divided so that one or more sets of identical substructures exist. The substructure shape data is read from the storage means.

Next, for all substructures,
The same substructures belong to the same group, and the substructures are classified into groups, and the group number to which the substructure belongs is recorded in the storage unit.

Next, a finite element is generated for each group inside the substructure belonging to the group, and the substructure is subjected to a numerical analysis using the finite element method, thereby obtaining a distribution of residual stress and residual deformation in the substructure. Is calculated and recorded in the storage means.

Next, a structural element having the same shape as the substructure, which has the distribution of the residual stress and the residual deformation in the substructure independently, is generated. For all the substructures that make up the structure, the structure is reconstructed using structural elements representing the group to which the substructure belongs, and residual stress and residual deformation of the structure are predicted.

Further, in order to improve the similarity accuracy regarding the shape of the substructure, a triangular substructure, a quadrilateral substructure or a polyhedral substructure is used depending on the shape of the structure.

The following advantages can be obtained by dividing the structure into sub-structures and replacing the sub-structures with the structural elements described above and using the means for reconstructing the structure.

In calculating the residual stress and residual deformation of the structure,
For a partial structure belonging to the same group, a structural element generated once can be used. Therefore, when it is possible to generate a plurality of structural elements of the same group in the shape of the entire structure, it is possible to reduce the time required for analysis as compared with the case where element division is performed on the structure.

When calculating the distribution of residual stress and residual deformation in the substructure, the inside of the substructure is divided into finite elements, and the history of temperature distribution is calculated by the finite element method of heat conduction analysis. Next, based on the calculated history of the temperature distribution in the substructure, the distribution of residual stress and residual deformation caused by welding heat input is calculated by the finite element method of stress analysis.

[0017]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of hardware according to the present embodiment. In FIG. 1, a display device 10 is connected via a common bus 100.
1, an input device 102, a CPU 103, a RAM 104, a disk device 110, and a database 120 are provided.
The CPU 103 is a central processing unit when the operation program 111 stored in the disk device 110 is executed by the RAM 104. The disk device 110 has a structure shape data file 112 of the structure to be analyzed.
, A substructure shape data file 113 created by executing the operation program 111, a substructure analysis result data file 114, and a structure analysis result data file 115 are also stored at the same time. Frequently used substructure residual stress and residual deformation data recorded in the substructure analysis result data file 114 are recorded in the database 120.

FIG. 2 shows a plate-shaped structure A obtained by butt-welding four flat plates. In the figure, a double line W represents a welding line. Also, the broken line is an example of dividing into a partial structure of a quadrilateral flat plate. That is, a region surrounded by a broken line is one substructure. FIG. 3 shows an example of division by a quadrilateral substructure in a region including the welding line W. The area surrounded by the broken line in the figure is a substructure, and SUB1, SUB2,
SUB3 and SUB4 are serial numbers of the substructure. Also, one side of the quadrilateral substructure is weld line W
Are classified into a group GRP, a group GRP in which two sides are welding lines, and a group GRP3 in which the substructure does not include a welding line.

The operation flow of this embodiment will be described with reference to FIG. First, when the operation program 111 of the present apparatus is started, the processing of the STP 10 is performed in the main routine, and the contents of the entire structural shape data file 112 are read. The structure shape data read from the structure shape data file 112 includes the dimensions of the structure, the position of the weld line in the structure, the dimensions of the substructure, and the substructure of all the substructures constituting the structure. , The position of the welding line in the substructure, the welding conditions, and the position in the structure where the substructure exists.

Next, the processing shifts to a substructure setting routine of STP20, and a substructure setting routine STP20 shown in FIG. 5 is executed. First, STP21
, A serial number is automatically assigned to the substructure as a substructure number. Next, the process proceeds to STP22, in which group numbers are set for all substructures. The group number is determined as if the same substructures belong to the same group. Here, the same substructure means that the dimensions of the substructure, the material of the substructure, the position of the welding line in the substructure, and the welding conditions are the same among the substructures.

Next, the processing shifts to STP23, in which the element division in the substructure is automatically performed for all groups in order to calculate the distribution of residual stress and residual deformation in the substructure by the finite element method. . In the finite element generated in the substructure, the coordinates of the node in the substructure and the substructure analysis condition including the node data constituting the finite element are set. As a condition for the heat conduction analysis, for a finite element in the substructure and an element including a welding line, the heat input is set from the welding conditions. In addition, a heat transfer boundary condition is set on a surface that is in contact with the atmosphere during welding. As a condition for stress analysis, displacement of a node on the boundary of the substructure is restricted.
The processing shifts to STP24, where the substructure numbers of all the substructures, the group numbers of the substructures, and the substructure analysis conditions set in STP23 for all the groups are recorded in the substructure shape data file 113, The process returns to the main routine.

Next, the processing shifts to STP30 in FIG. 4, and the substructure stress analysis routine ST shown in FIG.
P30 is executed. In the substructure stress analysis routine, the substructure analysis conditions recorded in the substructure shape data file 113 in STP31 are read. Next, in STP32, the history of the temperature distribution in the substructure due to the heat input during welding is calculated for all the groups by the finite element method. The residual stress and residual deformation resulting from rapid heating and rapid cooling due to welding heat input to the welded portion are calculated from the obtained history data of the temperature distribution in the substructure. Next, in STP33, the values of the residual stress and residual deformation calculated for each group are recorded in the substructure analysis result data file 114, and the process returns to the main routine.

Next, the processing shifts to STP40 in FIG. 4, and the structure restructuring routine STP40 shown in FIG. 7 is executed. In this routine, the sub-structure analysis result data file 114 is read in STP41. Next, in STP42, a process of replacing a substructure including a plurality of finite elements with a single finite element is performed. Elements generated by the STP 42 will be referred to as structural elements in this embodiment. Specifically, the processing for generating the structural element is achieved by distributing the residual stress and residual deformation calculated by the substructure stress analysis routine in the structural element. By the processing in this step, for example, in a structural element including a welding line, a residual stress and residual deformation due to welding heat input are applied to the structural element in advance. Next, STP4
In step 3, the structure is reconstructed using the structural elements with reference to the corresponding data of the substructure number and the group number recorded in the substructure shape data file 113. Then, in STP 44, the reconstructed structure is calculated using the finite element method, and the distribution of residual stress and residual deformation in the structure is calculated. In the next STP45, the calculated analysis result is transferred to the entire structure analysis result data file 11.
Write 5 In STP46, the distribution data of the residual stress and residual deformation in the structure calculated in STP44 is displayed on the output device 101 as a contour map. When the process of STP46 ends, the process returns to the main routine, and all processes end.

As described above, according to this embodiment, in a structure having a welded portion, the residual stress existing in the substructure is calculated in advance, and a structural element having the calculated residual stress and residual strain is generated. For substructures belonging to the same group, structural elements generated once can be used. Therefore, when a plurality of structural elements of the same group can be generated with the same shape of the structure, the time required for analysis can be reduced as compared with the case where the structure is divided into elements.

FIG. 8 shows a different embodiment of the present invention. FIG.
When the main routine 200 is started, the processing of the STP 210 is performed, and the contents of the structure shape data file 112 are read. The structure shape data read from the structure shape data file 112 according to the present embodiment includes the dimensions of the structure and all the partial structures constituting the structure.
The size of the substructure, the number of the corresponding structural element recorded in the database 120, and the position in the structure where the substructure exists are recorded.

Next, the processing shifts to STP220 in FIG.
The substructure setting routine STP220 in FIG. 9 is executed. First, a serial number is assigned to a substructure as a substructure number in STP221. Next, the process proceeds to STP 222, and sets a group number for all substructures. As the group number in the STP 222, the number of the corresponding structural element recorded in the database 120 is used.

Next, the processing shifts to STP 230 in FIG.
The structure restructuring routine STP230 of FIG. 10 is executed. In this routine, the database 1 is
From 20, the data of the structural element corresponding to the substructure is read. Next, in STP232, the structure is reconfigured using the structural elements with reference to the substructure number and the group number. Then, in STP233, a calculation using the finite element method is performed on the reconstructed structure, and the distribution of residual stress and residual deformation in the structure is calculated. Next STP2
At 34, the calculated analysis result is written to the structure analysis result data file 115. In STP235, STP2
The distribution data of the residual stress and residual deformation in the structure calculated in 34 is displayed on the output device 101 as a contour map. When the processing of STP 235 ends, the process returns to the main routine, and all the processing ends.

FIG. 11 shows an embodiment in which the periphery of a welding line is divided using a triangular substructure. W in the figure represents a welding line. A triangular area surrounded by a broken line in the figure is a partial structure, and among the triangular substructures, groups GRP1, two sides of which are welding lines W, GRP2 and GRP3, one side of which is a welding line W, and two vertices. It is classified as GRP4 existing on the welding line W.

FIG. 12 shows an embodiment in which the periphery of a welding line is divided using a polyhedral substructure. W in the figure represents a weld. The hexahedron in the figure is a substructure, which is a hexahedron substructure, GRP1 having one surface shared by the welding portion W, GRP2 having two surfaces shared by the welding portion W, and welding in the substructure. Classified as GRP3 that does not include section W.

[0030]

According to the present invention, the substructure shape data stored in the storage means, the data in which the substructure numbers correspond to the group numbers, the residual stress and residual deformation data calculated for each group, The calculation of the structure is performed by the structural element reflecting the residual stress and residual deformation data for each. The same structural element can be used for partial structures belonging to the same group. Therefore, the calculation time can be reduced as compared with the case where the structure is divided into elements by the finite elements of the dimensions used for the analysis of the substructure and the analysis is performed. Further, when the structural elements used for the calculation of the structure are recorded in the database, it is not necessary to generate the structural elements again, so that the calculation time can be further reduced as compared with the above.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of hardware in one embodiment of the present invention.

FIG. 2 is an explanatory view of a structure in one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing division of a structure by a quadrilateral substructure in one embodiment of the present invention.

FIG. 4 is a flowchart of a main routine in one embodiment of the present invention.

FIG. 5 is a flowchart of a substructure setting routine in one embodiment of the present invention.

FIG. 6 is a flowchart of a substructure stress analysis routine in one embodiment of the present invention.

FIG. 7 is a flowchart of a structure reconstruction routine according to an embodiment of the present invention.

FIG. 8 is a flowchart of a main routine in a second embodiment of the present invention.

FIG. 9 is a flowchart of a substructure setting routine according to a second embodiment of the present invention.

FIG. 10 is a flowchart of a structure reconstruction routine according to a second embodiment of the present invention.

FIG. 11 is an explanatory diagram showing division of a structure by triangular substructures according to a third embodiment of the present invention.

FIG. 12 is an explanatory view showing division of a structure by a hexahedral substructure in a third embodiment of the present invention.

[Explanation of symbols]

101: display device, 102: input device, 103: CP
U, 104 RAM, 110 disk device, 120
Database.

Claims (1)

[Claims] An apparatus for predicting a residual stress and a residual deformation of a structure having a welded portion, wherein a shape of the structure and one or more sets of substructures having the same shape exist in the structure. Storage means for storing the shapes of the divided substructures; classifying the substructures into groups according to their shapes; generating finite elements inside the substructures belonging to the group for each group; A substructure setting device for setting a substructure analysis condition for performing a numerical analysis using, receiving the substructure analysis condition from the substructure setting device, performing a numerical analysis by a finite element method,
Calculating a distribution of residual stress and residual deformation inside the substructure and recording it in a substructure analysis result; receiving the substructure stress analysis result from the substructure analysis device; A means for generating an element having the same shape as a substructure having a distribution of stress and residual deformation alone therein, a structural reconstruction apparatus for calculating residual stress and residual deformation of a structure using structural elements, and An apparatus for predicting welding residual stress and residual deformation, comprising: