JPH01313731A - Member strength analyzing device - Google Patents

Abstract

PURPOSE:To shorten CPU processing time and to obtain the analysis accuracy of the same degree as a linear analysis by converting a stress-strain curve to a linear approximate expression consisting of plural lines, utilizing this data and a linear solver and executing a non-linear analysis of a material. CONSTITUTION:Plural points a1 to a6 on a stress-strain curve S-E derived by a test are set as nodal points, connected by straight lines 21a to 21f and a linear approximation is executed. By subtracting from a load and a displacement quantity, a new load or displacement quantity is obtained, and the foregoing and characteristic data obtained from an approximate straight line of the next section become input data. A linear analyzing part 4 executes an analysis from a Young's modulus derived from an approximate straight line 21a and the load or the displacement, and when the maximum stress value is larger than the stress value a1, the load or the displacement corresponding to a1 is derived, and the analysis is executed until the value becomes smaller than a1. Subsequently, the load or the displacement derived by the first analysis is subtracted from analysis input data, and by giving a Young's modulus derived from an approximate straight line 21b, the analysis is executed. Thereafter, when the analysis is executed in the same way, stress values of each nodal point are all added and become analysis output data.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a device for analyzing strain when stress is applied to a member. A means for performing linear approximation by using a plurality of points on a stress strain curve obtained by testing a sample as nodes and connecting each adjacent node with a straight line, and characteristic data regarding the material of the sample obtained from the linear approximation. , means for performing linear analysis using load or displacement and model data as analysis input data, and in the linear analysis, determining the load or displacement corresponding to the stress value on the approximate straight line of the target section, and calculating the value. Means for repeatedly performing an operation of subtracting the load or displacement amount from the analysis human data to obtain a new load or displacement amount, and giving this and characteristic data obtained from the approximate straight line of the next section as analysis input data. It is constituted by having the following.

[Industrial Field of Application] The present invention relates to a member strength analysis device, and more particularly to a member strength analysis device capable of performing nonlinear analysis of a member at high speed using linear analysis means.

[Prior art] Recently, analysis systems such as member strength analysis devices have become widely used as simulation methods to check the safety, functionality, economic efficiency, etc. of products. There is a need for an analytical method that is highly accurate and requires less CPU time.

In conventional member strength analysis devices, the sixth, rl!
Nonlinear analysis is performed using stress strain curves as shown in J. That is, in the same figure, a plurality of nodes 53-1 to 53-n are set on a stress curve 51 obtained experimentally for a sample made of the same material as the member to be analyzed, and tangents 54-1 to 54-n at the origin 52 and each node are set. 54-n, linear analysis is performed, and the Young's modulus Poisson's ratio of each section is determined.

[Problems to be Solved by the Invention] As mentioned above, nonlinear analysis in conventional member strength analysis devices calculates tangents at each node (starting point of a step) on a stress-strain curve. There was a problem in that the errors between the lines and the tangents accumulated, and eventually the accuracy deteriorated considerably.

Therefore, if each step is made smaller in an attempt to obtain high accuracy, the analysis process will be repeated many times, which poses the problem of requiring a large amount of time.

Furthermore, there was the problem that nonlinear analysis was not possible when only a linear solver was available.

SUMMARY OF THE INVENTION An object of the present invention is to provide a member strength analysis apparatus that can solve these conventional problems by using a bilinear solver and perform nonlinear analysis in a relatively short processing time.

[Means for Solving the Problems] According to the present invention, the above objects are achieved by the means described in the claims. That is, the present invention provides means for performing linear approximation by using a plurality of points on a stress strain curve obtained by testing a sample as nodes and connecting each adjacent node with a straight line, and Means for performing linear analysis using characteristic data related to the material, load or displacement amount, and model data as analytical human data, and in the linear analysis, load or displacement amount corresponding to the stress value on the approximate straight line of the target section. is calculated, that value is subtracted from the load or displacement amount of the analysis input data to obtain a new load or displacement amount, and this and the characteristic data obtained from the approximate straight line of the next section are given as analysis input data. This is a member strength analysis device that repeatedly performs the analysis until the maximum stress value of the analysis result is equal to or less than the stress value determined from the given approximate straight line, and is equipped with means for adding the stress values of each node for each analysis.

[Embodiments] Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

In the figure, 1 is a model creation section, 2 is a pre-processing section, and 3 is a model creation section.
4 represents an analysis input data file, 4 represents a linear analysis section, 5 represents a linear solver, 6 represents an analysis output data file, 7 represents a post processing section, and 8 represents a plotting section.

In the model creation section 1, for example, a model of the both end support beam 9 as shown in FIG.
．． (10゛ represents the fulcrum, and the arrow indicated by the letter A indicates the load or displacement) Create data.

The pre-processing unit 2 performs pre-processing including mesh division on the data to generate analytical human data.

An example of the analysis input data is shown in FIG. 11 is an analysis control card, 12 is a node definition card, and 13 is a node definition card.
is an element definition card, 14 is an element shape property card, 15 is a material property definition card, 16 is a constraint definition card, 17 is a load definition card, 18 is Young's modulus, 19 is Poisson's ratio, 2
0 represents the amount of displacement.

Here, the data in the node definition card 12 is the node number 22 given to the intersection of line segments that divide the object into a plurality of parts in the xSy and z directions, and the X of each node number.

YSZ coordinates (shown as 23 to 25 in the figure)
and a degree-of-freedom direction number 26 indicating the six-degree-of-freedom direction of each node.

In the element definition card 13, the data is element number 27,
Reference shape characteristic number 28, node number 2 that constitutes the element
Consists of 9.

The data on the element shape characteristic card 14 consists of a shape characteristic number, a material characteristic number 30, and a plate thickness 31 that resists bending.

The data of the material property definition card 15 consists of a material property number, Young's modulus of 18, and Poisson's ratio of 19.

The data of the constraint definition card 16 consists of a strong displacement set number 32, a node number 33, a constraint degree of freedom number 34, and a strong displacement amount. The data on the load definition card 17 includes a load case number 35, an overall scale filter 36, a scale filter 37 for the load set, and a forced displacement set number. For detailed explanation of each data above, please refer to
FACOM Manual 99AR-5470F [! It is stated in the MM manual "Structural analysis program using finite element method".

In the linear analysis section 4 of FIG. 1, analysis is performed by giving data obtained from a stress strain curve as shown in FIG. 4 to the above-mentioned analysis input data.

FIG. 4 is a diagram showing an example of a stress curve, and is a stress curve S-E obtained by performing a tensile test on a test piece of the material.
It shows. In the same figure, 21a to 21f are straight lines connecting nodes on the stress curve, and these straight lines 2
The stress curve SE is linearly approximated by 1a to 21f.

The linear analysis unit 4 shown in FIG. 1 performs the analysis by applying, for example, the initial Young's modulus and load or displacement obtained from the approximate straight line 21a shown in FIG. 4 to the analysis input data. As a result of the analysis, the maximum stress value is the stress value a1 in Figure 4.
If it is larger, the load or displacement corresponding to al is determined and a second analysis is performed. At this time, if the maximum stress value as a result of the analysis is smaller than al, the analysis of this part is ended.

Next, the load or displacement obtained in the first analysis is subtracted from the load or displacement of the analysis input data, and the approximate straight line 2 in Figure 4 is calculated.
Analysis is performed by giving the Young's modulus obtained from 1b.

Similarly, if the maximum stress value obtained as a result of the analysis is greater than the stress value determined in FIG. 4, the analysis is performed one after another by repeating the analysis.

In this way, the stress values at each node are all added together to form analysis output data.

In the example of analysis input data shown in FIG. 3, the material property definition card 15 and the constraint definition card (displacement amount) are changed for each analysis.

FIG. 5 shows the control related to the linear analysis described above as a flowchart.

[Effects of the Invention] As explained above, according to the present invention, a stress strain curve created in a tensile test is converted into a linear approximation formula consisting of a plurality of linear approximations, and this data and a linear solver are used to perform nonlinear analysis of the material. Since the analysis is performed using a nonlinear solver, there is an advantage that the CPU processing time is shorter and the analysis accuracy is comparable to that of linear analysis.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of an embodiment of the present invention, Figure 2 is a diagram showing a model of a beam supported at both ends, Figure 3 is a diagram showing an example of analysis input data, and Figure 4 is a diagram showing a stress curve. Diagram showing an example,
FIG. 5 is a flowchart showing analysis control, and FIG. 6 is a diagram explaining conventional nonlinear analysis. 1... Model creation section, 2... Buri processing section, 3... Analysis input data file, 4...
... Linear analysis section, 5 ... Linear solver, 6.
... Analysis output data file, 7 ... Post processing section, 8 ... Plot section, 9 ...
・Both end support beam, 10.10'...Fulcrum, 11
... Analysis control card, 12 ... Node definition card, 13 ... Element definition card, 14 ...
...Element shape property card, 15...Material property definition card, 16...Restraint definition card, 17
... Load definition card, 18 ... Young's modulus, 19 ... Poisson's ratio, 20 ... Displacement amount, 21a to 21f ... Approximation straight line, 22.2
9.33...Node number, 23...X coordinate, 24...Y coordinate, 25...Z coordinate, 26...Free Degree direction number, 27...
Element number, 28... Shape characteristic number, 30...
...Material property number, 31...Plate thickness, 32...
...Set number, 34...Degree of freedom number, 3
5...Load case number, 36.37...
・Scale filter

Claims (1)

[Claims] Means for linear approximation by using a plurality of points on a stress strain curve obtained by testing a sample as nodes and connecting each adjacent node with a straight line; Means for performing linear analysis using characteristic data related to material, load or displacement amount, and model data as input data for analysis, and in the linear analysis, load or displacement amount corresponding to stress value on the approximate straight line of the target section. is calculated, that value is subtracted from the load or displacement amount of the analysis input data to obtain a new load or displacement amount, and this and the characteristic data obtained from the approximate straight line of the next section are given as analysis input data. , a member strength analysis characterized by comprising a means for repeating the analysis until the maximum stress value of the analysis result becomes equal to or less than the stress value determined from a given approximate straight line, and adding the stress values of each node for each analysis. Device.