JP6747410B2 - Elastic adhesive behavior analysis method - Google Patents

Description

The present invention relates to an elastic adhesive behavior analysis method for analyzing the strain/stress behavior of an elastic adhesive itself such as a mastic adhesive by a finite element method, and in particular, it is a technique characterized by setting conditions of the elastic adhesive. ..

A mastic adhesive, which is an elastic adhesive, is interposed so as to fill the gap between the two parts. Then, the two components are bonded (constrained) by the mastic adhesive.
Here, an elastic adhesive such as a mastic adhesive is a semi-solid substance in an unused state, but when a component bonded with the elastic adhesive is subjected to heat treatment, the elastic adhesive foams ( The elastic adhesive finally has a rubber-like property, that is, an elastic force, by being expanded and then cured and contracted by cooling. The elastic adhesive provided in this manner is important, for example, when the component bonded with the elastic adhesive receives an external force, the bonding position serves as a support point for the external force and suppresses the vibration of the component. Play an important role.

As a technique for analyzing the strain/stress behavior of such an elastic adhesive, for example, there is a technique described in Patent Document 1. Patent Document 1 describes that an elastic adhesive having different dimensions and physical property values can be easily and quickly modeled by modeling the elastic adhesive. Specifically, in Patent Document 1, as an FEM model of an elastic adhesive, elastic adhesives having different dimensions and physical property values are set in a rectangular parallelepiped shape model, and the shape model is divided into three in the height direction. A method of dividing into a plurality of rectangular parallelepiped solid elements divided into two in the width direction to form an FEM model is disclosed.

JP, 2007-179175, A

Patent Document 1 describes that a load acts on the elastic adhesive from the outside and the elastic adhesive is subjected to compressive deformation and shear deformation, but it is not possible to consider the stress generated by the elastic adhesive itself. It is enough.
The present invention has been made by paying attention to the above points, and more accurately considers the stress generated by the elastic adhesive itself, so that the strain/stress change behavior of the constrained elastic adhesive is more accurate. The purpose is to analyze well.

In order to solve the problem, according to one embodiment of the present invention, the strain/stress behavior of an elastic adhesive itself in a state of being restrained by two parts by joining the two parts is used to determine the strain/stress behavior using a computer. A method for analyzing the behavior of an elastic adhesive that is analyzed by the element method, wherein as the elastic adhesive model, a columnar shape model in which the contour shape of the bonding surface with each of the parts is a continuous arc shape is set together with The model is divided into a plurality of solid elements, and the elastic coefficient and the thermal expansion coefficient are set as the material conditions of the elastic adhesive.

According to one embodiment of the present invention, by setting the elastic coefficient and the thermal expansion coefficient as at least the material conditions of the elastic adhesive, the volume change of the elastic adhesive itself due to the temperature change and the accompanying strain of the elastic adhesive itself. It is also possible to consider stress.
At this time, the shape model of the elastic adhesive is changed to a behavior when the volume of the elastic adhesive itself changes by using a columnar shape model such as a cylindrical shape that does not have a steep curvature portion as the contour shape of the adhesive surface. It is possible to avoid that the analysis result of 1 shows the behavior different from the actual one.
As a result, according to one aspect of the present invention, it is possible to analyze the strain/stress change behavior of the constrained elastic adhesive itself with higher accuracy.

It is a figure explaining a processing composition. It is a figure explaining the example of FEM analysis flow (in the case of stress application). It is a figure explaining the example of the FEM analysis flow (in the case of temperature provision). It is a disassembled perspective view explaining the elastic-adhesive analysis model in an Example. It is a figure explaining the elastic-adhesive analysis model (side view) in an Example. It is the exploded perspective view explaining the elastic adhesive analysis model (mesh subdivision) in an example. It is a figure which shows the model of the elastic adhesive agent in an Example.

Next, an embodiment of the present invention will be described with reference to the drawings.
The structural analysis using the computer of this embodiment is CAE analysis using the finite element method. As in the conventional analysis method, as software (program), as shown in FIG. 1, CAD software 10 and analysis software 11 (preprocessor 11A, solver 11B, and postprocessor 11C) are provided. Known software may be adopted as the CAD software 10 and the analysis software 11.

The CAD software 10 sets, based on the input information, two parts that are arranged facing each other at a predetermined interval and the shape data information of the elastic adhesive provided between the two parts. The two parts consist of a first part and a second part.
As the elastic adhesive to be analyzed, an elastic adhesive having thermal deformability such as a mastic adhesive is suitable.
The preprocessor 11A creates an analysis model (FEM model) from the above-mentioned shape data information, mesh creation conditions, material definition, boundary conditions, constraint conditions (fixing method), load conditions, and other analysis conditions.

The shape model relating to the elastic adhesive in the FEM model for analyzing the strain/stress behavior of the elastic adhesive itself is a columnar shape model, and further, in the shape model, the bonding surface of the elastic adhesive to the first component is The outer peripheral contour is set to a curved contour having no sharp curvature portion. For example, the contour of the adhesive surface is set to a contour shape such as a circular shape or an elliptical shape formed of continuous arc shapes. The steep curvature portion is, for example, a portion that forms a corner. Similarly, the outer peripheral contour of the bonding surface of the elastic adhesive to the second component is also set to a curved contour having no steep curvature portion.

Here, the reason why the contour shape of the bonding surface is formed by a continuous arc shape is as follows. That is, when a shape model having a sharp curvature portion such as a rectangular cross section is adopted, for example, when the elastic adhesive is deformed so as to shrink, the retraction at the corner portion (the sharp curvature portion) is locally generated. This is because the strain becomes more severe and the strain/stress behavior of the elastic adhesive may be different from the actual behavior. In that case, the sensory confirmation by visual inspection may not match the result of the experiment.

For example, the shape model of the elastic adhesive is set to a cylindrical shape. The cylindrical shape also includes a barrel shape. When the cylindrical shape model is adopted, the above condition can be satisfied with a simple shape model.
The shape model of the elastic adhesive is set by a plurality of solid elements in consideration of the set thickness and the size of the bonding surface.
Further, in the present embodiment, at least the elastic coefficient and the thermal expansion coefficient are set as the material condition of the elastic adhesive. By using the shape model for FEM analysis having the above-described contour shape on the outer periphery of the adhesive surface as described above, the elastic adhesive expands outward with the temperature change, and the elastic adhesive expands to the central portion. It is possible to reproduce the behavior of the elastic adhesive itself that is close to the actual one, such as shrinking toward.

Here, the two parts serve as a constraint condition for constraining the adhesive surface of the elastic adhesive.
Further, as the temperature change condition during the FEM analysis, an estimated heat change condition and a heat change condition due to heat generation of the adhesive itself are set.
Then, the stress or strain that is estimated to occur in the elastic adhesive itself by restraining the strain (expansion and contraction) of the elastic adhesive itself according to the temperature change is analyzed, and the strain/stress of the elastic adhesive itself is analyzed. It is possible to analyze the behavior.

The solver 11B executes the analysis on the set analysis model (shape model for FEM analysis) in the set thermal change state. The analysis by the finite element method may be either an implicit method or an explicit method, but the static implicit method is preferable from the viewpoint of analysis accuracy.
The post processor 11C performs processing for displaying the analysis result of the strain/stress behavior of the elastic adhesive itself analyzed by the solver 11B. For example, a process of displaying a diagram of the stress distribution generated by the constrained elastic adhesive itself, the state of deformation, and the like in a three-dimensional model is performed.

A processing example of the analysis processing software is shown in FIGS.
The processing example shown in FIG. 2 is an example of an FEM analysis flow in the case of analysis in a thermal change state. In the example of FIG. 2, the preprocessor 11A sets the FEM model in step S10.
In step S20, if the solver 11B determines that the heating condition is heating at a predetermined temperature or higher, the tensile stress generated in the elastic adhesive itself when the expansion expected to occur in the elastic adhesive is restrained. And analysis of shape change (expansion).
In step S30, if the solver 11B determines that the cooling condition occurs, the compressive stress or the shape change (compression) that occurs in the elastic adhesive itself when the shrinkage generated in the elastic adhesive due to the cooling condition is restricted. Perform an analysis on.
In step S40, the post processor 11C executes a process of displaying the state of strain/stress behavior occurring in the elastic adhesive itself based on the analysis of the solver 11B.

The processing example shown in FIG. 3 is an example of an FEM analysis flow in the case of analysis in the second thermal change state. In the example of FIG. 3, in step S110, the preprocessor 11A sets the FEM model.
In step S120, when the solver 11B determines that the heating condition is heating at a predetermined temperature or higher, the temperature increase due to the heating is applied to the elastic adhesive, and the tensile stress or shape due to expansion generated in the elastic adhesive itself is applied. Perform analysis for changes (expansions).
In step S130, if the solver 11B determines that the cooling condition occurs, the solver 11B imparts a temperature drop corresponding to the cooling condition to the elastic adhesive, and the compressive stress or the shape change (contraction change) due to the contraction generated in the elastic adhesive itself ( Analyze for compression).
In step S140, the post processor 11C executes a process of displaying the state of strain/stress behavior occurring in the elastic adhesive itself based on the analysis of the solver 11B.

According to the present embodiment, by setting the elastic coefficient and the thermal expansion coefficient as the model information of the elastic adhesive, the behavior due to the deformation of the elastic adhesive itself is also taken into consideration, and the elastic adhesive itself due to the temperature change is detected. It is possible to consider the volume change and the accompanying stress.
At this time, by making the shape model of the elastic adhesive a shape that does not have a portion with a sharp curvature as a contour shape, it is possible to avoid that the behavior of the elastic adhesive itself in the volume change is different from the actual behavior. ing.
As a result, according to one aspect of the present invention, it becomes possible to analyze the strain/stress change behavior of the elastic adhesive itself with higher accuracy.
Regarding temperature change conditions, both temperature change conditions of expansion in the actual heating process and contraction in the cooling process may be considered, and depending on the purpose, analysis may be performed by considering temperature change conditions of only expansion or only contraction. But it doesn't matter.

Here, in the thermoelastic model, the eigenvalue of the elastic adhesive may be used as the coefficient of thermal expansion, but a value obtained by experiments or the like may be used as the coefficient of thermal expansion. The temperature change condition to be applied is preferably in the temperature range of −10 to 250° C. A more preferable temperature range is 20 to 180°C.
As described above, according to the present embodiment, if there is part shape data, shape data and strength data of the adherend side, and physical property value information of the elastic adhesive, the target product is restrained without being manufactured. It is possible to predict the behavior of the elastic adhesive itself.

Next, examples according to the present invention will be described.
As shown in FIGS. 4 and 5, the model is a model a, a model b simulating a frame, a model c constrained by the model b, and a model simulating an elastic adhesive connecting the models a and c. d and. In this example, a mastic adhesive was assumed as the elastic adhesive.
The model a is a flat plate-shaped adherend model having a rectangular shape of 286 mm square in projection (in plan view).
The model b is a rigid body. The model b was set as a frame body having a thickness of 12 mm and a 300 mm square.
The model c is a flat plate-like adherend model having a thickness of 2 mm and a rectangular shape of 286 mm square in projection (in plan view).

Here, the plate thickness of the model a was changed and 6 types were individually set and analyzed. By changing the plate thickness conditions, various constraint conditions in the plate thickness direction to the elastic adhesive by the model a were set, and the behavior analysis of the elastic adhesive itself was executed.
As the model d, the physical property value of the elastic adhesive is used, and in the present embodiment, a thermoelastic FEM model is used, and a predetermined thermal expansion coefficient and Young's modulus (elastic coefficient) according to expansion and contraction are set. .. At this time, the Young's modulus (elastic coefficient) when expanded was 100 MPa, and the Young's modulus (elastic coefficient) when contracted was 200 MPa. The shape model of the model d was set to a cylindrical shape of 20 mmφ×3 mmh.

Further, as shown in FIG. 6, the jig and each adherend were divided into meshes. The elastic adhesive was divided into a plurality of solid elements, as shown in FIG. The analysis uses the static implicit method.
In the solid element of the elastic adhesive, the behavior of the elastic adhesive itself was analyzed under the condition that the temperature load was applied by the temperature change of heating from 20° C. to 170° C. and then decreasing from 170° C. to 20° C. The change from temperature increase to temperature decrease was performed by a coupled analysis that inherits the shape of the adherend and the stress distribution.

For the purpose of verifying the analysis results, a test jig having the same size and configuration as this model was manufactured and an experiment was conducted. Then, the behavior change of the surface (side surface) of the elastic adhesive was visually observed.
It was confirmed by analysis that the behavior of the elastic adhesive itself was consistent with the results of visual observation in the experiment. This indicates that the FEM model based on the present invention is an effective method for predicting the behavior of the elastic adhesive itself.

10 CAD software 11 Analysis software 11A Preprocessor 11B Solver 11C Postprocessor a Adhesive model b Frame model c Adhesive model d Elastic adhesive model

Claims (2)

It is a method of analyzing the behavior of an elastic adhesive that analyzes the strain/stress behavior of the elastic adhesive itself in a state of being constrained by the two parts by joining the two parts by a finite element method using a computer. hand,
As a model of the elastic adhesive, the contour shape of the bonding surface with each of the parts is set as a columnar shape model consisting of a continuous arc shape, and the model is divided into a plurality of solid elements,
A behavior analysis method of an elastic adhesive, characterized in that an elastic coefficient and a thermal expansion coefficient are set as material conditions of the elastic adhesive. The behavior of the elastic adhesive according to claim 1, characterized in that the strain/stress behavior of the elastic adhesive itself is analyzed under a temperature condition in which a temperature change is applied to the elastic adhesive within a preset temperature range. analysis method.

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