JP7246631B2 - How to get parameters - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for acquiring parameters used for numerical analysis relating to single-sided shear of sand molds, and a single-sided shear test apparatus for sand molds.

Conventionally, in the field of civil engineering design, in order to determine the shear strength of soil and sand (sand mold), a single-sided shear test of sand molds is performed. In this single-sided shear test, a sand mold test piece is placed in a single-sided shear tester, and the shear strength of the sand mold is measured.

One of the above-mentioned single-sided shear test apparatuses includes, for example, a single-sided shear test apparatus having a storage box that is divided into upper and lower parts (see FIG. 4 of Patent Document 1). In this single-sided shear test apparatus, a sand mold test piece is stored in a storage box, and a shear stress is applied to the test piece by moving the upper storage box horizontally while a constant vertical load is applied to the upper storage box. act. At this time, the shear strength of the test piece can be measured by measuring the shear stress generated in the test piece with a load measuring instrument and measuring the vertical displacement and horizontal displacement of the upper storage box with a displacement measuring instrument. ing.

JP-A-8-226886

In designing the sand mold, numerical analysis such as FEM (Finite Element Method) analysis is used. In the FEM analysis, by creating an analysis model of the sand mold and inputting various parameters, it is possible to predict the dimensional change and the like of the sand mold during solidification and shrinkage. In order to perform such a numerical analysis, it is necessary to acquire various parameters such as shear stress and normal stress acting on the sand mold from the measurement results of the single shear test using the single shear test apparatus described above.

However, since the above-described single-sided shear test apparatus measures the shear strength of the sand mold at room temperature, there is a problem that the shear strength of the sand mold cannot be measured at high temperatures. For this reason, there is a problem that it is impossible to obtain the parameters used for the numerical analysis of the single-sided shear of the sand mold under high temperature.

One aspect of the present invention has been made in view of the above-described problems, and an object thereof is to obtain parameters used for numerical analysis relating to single-sided shear of a sand mold under high temperature. Another object of the present invention is to provide a single-sided shear test apparatus capable of performing a single-sided shear test on sand molds at high temperatures.

A method for obtaining parameters according to one aspect of the present invention, which has been made to solve the above problems, is a method for obtaining parameters used for numerical analysis related to single-sided shear of a sand mold, and includes settings including temperature and physical property values of the sand mold. Using a setting step for determining conditions and the setting conditions determined in the setting step, a single-sided shear test is performed on the sand mold test piece housed in a vertically divisible container under a plurality of temperatures. a testing step and parameter calculation for calculating the parameter by creating the strength envelope for each of a plurality of temperatures based on the measurement results obtained by the testing step, assuming that the sand mold conforms to a predetermined strength envelope; and a step.

According to the parameter acquisition method described above, the sand mold single-sided shear test is performed at a plurality of temperatures in the test process, and the parameters are calculated at a plurality of temperatures in the calculation process based on the measurement results obtained in the test process. By constructing the strength envelope in , we can obtain various parameters for numerical analysis of the single-sided shear of the sand mold at multiple temperatures.

Further, in the parameter acquisition method according to one aspect of the present invention, the setting conditions determined in the setting step include the magnitude of the load applied to the sand mold from the axial direction and the amount of shear displacement of the sand mold. The measurement results obtained in the test step include the shear stress of the sand mold, the vertical stress of the sand mold, and the amount of vertical displacement at a plurality of temperatures, and the above calculated in the parameter calculation step The parameters include the adhesion force of the sand mold, the internal friction angle of the sand mold, and the expansion angle of the sand mold for each temperature.

According to the parameter acquisition method described above, based on the measurement results of the shear stress of the sand mold, the vertical stress of the sand mold, and the amount of vertical displacement obtained at a plurality of temperatures in the test process, in the parameter calculation process, for each temperature can calculate the adhesion force of the sand mold, the internal friction angle of the sand mold, and the expansion angle of the sand mold. As a result, the adhesive force, internal friction angle, and expansion angle of the sand mold for each temperature can be input as parameters for numerical analysis of the single-sided shear of the sand mold, and good numerical analysis results can be obtained.

Further, in the parameter acquisition method according to an aspect of the present invention, the temperature of the sand mold under the setting conditions includes a high temperature of at least 100° C. or higher.

According to the parameter acquisition method described above, it is possible to numerically analyze the single-sided shear of a sand mold at a high temperature of 100° C. or higher, and to predict the strength of the sand mold at a high temperature with high accuracy.

Further, in the parameter acquisition method according to one aspect of the present invention, the intensity envelope created in the parameter calculation step is created by interpolating a non-measured portion from the measurement result obtained in the test step. It is characterized by

According to the parameter acquisition method described above, an intensity envelope can be created by complementing the range (non-measurement portion) not measured in the test process based on the measurement results obtained in the test process. . This reduces the number of single-sided shear tests in the test process required to obtain the parameters.

A sand mold single plane shear test apparatus according to an aspect of the present invention is a sand mold single plane shear test apparatus, comprising: a vertically dividable container for containing the sand mold test piece; and the test piece in the container. A heater that heats the test piece in the container, a first pressure unit that applies a load from the first direction to the test piece, and a state in which the load is applied to the first pressure unit. A second pressure unit that applies a load from a second direction orthogonal to the first direction to the test piece in the container on one side, and a load that is applied to the test piece by the first pressure unit A first load sensor for measurement, a second load sensor for measuring the shear stress generated in the test piece loaded by the second pressure unit, and the test loaded by the second pressure unit and a shear displacement sensor that measures the amount of shear displacement of the piece.

According to the above-described sand mold single-sided shear test apparatus, the load is applied to the test piece in the container from the first direction (axial direction) by the first pressure unit, and the second pressure unit causes the test piece in the container to By applying a load to the test piece from the second direction (lateral direction), it is possible to apply a desired shear stress to the test piece and perform a single-sided shear test of the sand mold. In particular, since the heater can heat the test piece in the container to a high temperature, it is possible to perform a direct shear test of the sand mold at a high temperature. This makes it possible to measure the shear strength of the sand mold under multiple temperatures including high temperatures.

According to the parameter acquisition method of one embodiment of the present invention, it is possible to acquire parameters used for numerical analysis of single-sided shear of a sand mold under high temperature.

In addition, according to the sand mold direct shear test apparatus of one embodiment of the present invention, a sand mold direct shear test can be performed at a high temperature.

1 is a schematic diagram of a direct shear test apparatus according to an embodiment of the present invention; FIG. It is a figure which shows an example of the strength envelope of the sand mold which concerns on embodiment. It is a conceptual diagram which shows the expansion angle of the sand mold which concerns on embodiment. 4 is a flowchart showing the flow of a parameter acquisition method according to the embodiment; It is a flowchart which shows the flow of the single-shear test by the single-shear test apparatus which concerns on embodiment. 4 is a graph showing the relationship between the amount of shear displacement and the stress measured by the load sensor in a direct shear test according to the embodiment. It is a graph which shows the relationship between the shear displacement amount and vertical displacement amount by the direct shear test which concerns on embodiment. It is a graph which shows an example of the strength envelope created based on the measurement result obtained by the direct shear test which concerns on embodiment. It is the figure which compared the analytical value and experimental value of the numerical analysis using the parameter calculated by the parameter acquisition method which concerns on embodiment.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. FIG.

[Direct shear test equipment]
First, a single plane shear test apparatus 1 for conducting a single plane shear test of a sand mold will be described with reference to FIG. FIG. 1 is a schematic diagram of a direct shear test apparatus 1 of this embodiment. As shown in FIG. 1, the single-sided shear test apparatus 1 includes a housing 100, a container 10, a first pressure member 21, a contact member 21a, a contact member 21b, and a second pressure member 22. , a first cylinder 31, a second cylinder 32, a first upper load sensor 41 (first load sensor), a first lower load sensor 42 (first load sensor), a second load sensor 43, and shear displacement A sensor 44 , heaters 51 and 52 and a guide 60 are provided.

In the one-sided shear test by this one-sided shear test apparatus 1, a sand mold test piece TP was accommodated in the container 10, and a load was applied to the test piece TP from the axial direction by the first pressure unit 21. It is a device that applies shear stress to the test piece TP by applying a load to the test piece TP from the side direction by the pressurizing part 22 . Hereinafter, for convenience of explanation, the bottom side of the housing 100 in FIG.

The housing 100 is a rectangular box-shaped member and is vertically partitioned by a partition plate 101 . A container 10 is arranged inside the housing 100 . The container 10 is a container for containing a predetermined amount of sand-shaped test pieces TP. As the test piece TP, for example, a cylinder having a diameter of 50 mm and a height of 50 mm is used. The size and shape of the container 10 can be appropriately changed in design according to the test piece TP.

The container 10 has an upper container 11 and a lower container 12 and is configured to be divisible into the upper container 11 and the lower container 12 . The upper container 11 is fixed to the partition plate 101 . The upper and lower sides of the upper container 11 are open. The top side of the lower container 12 is open and the bottom side is closed.

The upper container 11 and the lower container 12 are integrated before performing the above-described single-sided shear test. On the other hand, when conducting the one-sided shear test, the container is divided into two parts, the upper container 11 and the lower container 12 . The halved lower container 12 is pressurized by a second pressurizing unit 22 (to be described later) so as to be movable in the lateral left direction along the guide 60 . The guide 60 is fixed to the bottom surface of the housing 100 and slidably supports the contact member 21b described later.

Note that the container 10 does not have to be vertically divisible, and the design may be changed as appropriate as long as the container 10 is configured to apply shear stress to the test strips TP in the container 10 .

The first pressure member 21 is, for example, a rod-shaped member, and applies a load to the test piece TP in the container 10 from the axial direction (first direction) via the contact member 21a. A first cylinder 31 is provided above the first pressure member 21 . The first cylinder 31 axially moves the first pressure member 21 based on a control signal from a control device (not shown).

A contact member 21 b is provided between the lower container 12 and the guide 60 . The abutment member 21b is, for example, a rod-shaped member for connecting the lower container 12 and the guide 60 together. When a load is applied downward to the container 10 by the first pressure member 21, a load (reaction force) is applied from the guide 60 side to the lower container 12 via the contact member 21b.

The second pressurizing part 22 is a rod-shaped member and applies a load to the test piece TP in the lower container 12 from the lateral direction (second direction). A second cylinder 32 is provided on the right side of the second pressure unit 22 . The second cylinder 32 moves the second pressure member 22 leftward on the side surface based on the control signal from the control device.

As the first cylinder 31 and the second cylinder 32, for example, hydraulic, pneumatic, and electric cylinders can be used. Also, instead of the first cylinder 31 and the second cylinder 32, for example, an electric jack may be used.

In this embodiment, heaters 51 and 52 are provided for heating the test strips TP in the container 10 . The heater 51 is provided inside the upper container 11 . Also, the heater 52 is provided inside the lower container 12 . Note that the heaters 51 and 52 only need to be able to heat the test strips TP in the container 10, and the arrangement position and number of arrangement thereof may be changed as appropriate. For example, the heater 51 may be installed on the side surface of the upper container 11 and the heater 52 may be installed on the side surface of the lower container 12 .

A first upper load sensor 41 is provided in the first pressurizing section 21 . The first upper load sensor 41 is a sensor for measuring the load applied to the test piece TP in the container 10 by the first pressurizing section 21 .

A first lower load sensor 42 is provided on the contact member 21b. The first lower load sensor 42 is a sensor for measuring the load (reaction force) applied to the lower container 12 from the guide 60 side.

A second load sensor 43 is provided in the second pressurizing section 22 . The second load sensor 43 is a sensor for measuring the load applied to the test piece TP in the lower container 12 by the second pressurizing section 22 .

The first upper load sensor 41, the first lower load sensor 42, and the second load sensor 43 output electrical signals corresponding to the magnitude of the measured loads to a control device (not shown). As the first upper load sensor 41, the first lower load sensor 42, and the second load sensor 43, piezoelectric element type, strain gauge type, capacitance type, or other load cells can be used.

The shear displacement sensor 44 is provided near the side surface of the lower container 12 and is a sensor that measures the amount of shear displacement of the test piece TP in the lower container 12 to which the load is applied in the side direction by the second pressure member 22. . Although not shown, a vertical displacement sensor for measuring the amount of vertical displacement of the test piece TP in the lower container 12 is provided near the side surface of the lower container 12 .

By using the shear displacement sensor 44, the amount of shear displacement of the test piece TP in the lower container 12 can be continuously measured. Moreover, by using a vertical displacement sensor, the vertical displacement amount of the test piece TP in the lower container 12 can be continuously measured. A laser displacement meter, for example, can be used as the shear displacement sensor 44 and the vertical displacement sensor.

[How to get parameters]
Next, a method of acquiring parameters to be input to numerical analysis (FEM analysis) of a sand mold using the above-described single-sided shear testing apparatus 1 will be described with reference to FIGS. 2 to 8. FIG.

(Sand mold prerequisites)
First, in the present embodiment, it is assumed that the sand mold follows the Mohr-Coulomb strength envelope shown in FIG. The Mohr-Coulomb intensity envelope is shown in equation (1) below.

τ=c+σtan φ Expression (1)
Here, τ is the shear stress, c is the adhesive force, σ is the normal stress, and φ is the internal friction angle. In designing sand molds (soil and sand), it is important to determine the shear strength of the sand mold. In determining the shear strength, the Mohr-Coulomb strength envelope is used. The Mohr-Coulomb strength envelope is constructed by fitting the Mohr stress circle with the Coulomb failure criterion. This strength envelope indicates the stress state at the fracture surface where the sand mold breaks when shear stress is applied to the sand mold. That is, when the shear stress τ acting on the sand mold satisfies τ>c+σtanφ, the sand mold is broken. On the other hand, when τ<c+σtanφ, the sand mold is in a stable state.

Sand molds also have shear properties, as shown in FIG. That is, in a tightly packed sand mold, when a shear stress is applied, the sand mold expands as some sand particles ride on other sand particles. Therefore, the vertical displacement amount (volumetric strain) of sand increases as the shear displacement amount (shear strain) increases. The expansion angle ψ indicates the expansion angle of the sand mold. On the other hand, in a loosely packed sand mold, sand particles fall and shrink when a shear stress is applied. Therefore, the vertical displacement of sand decreases as the shear displacement increases.

In this embodiment, on the premise that the sand mold has the above-described characteristics, various parameters used for numerical analysis of the sand mold are obtained in the order of steps shown in FIG. That is, as shown in FIG. 4, parameters are obtained in the order of the setting step (S1), the testing step (S2), and the parameter calculation step (S3). Each step will be described in detail below.

(Setting step S1)
In the setting step S1, setting conditions for the temperature of the sand mold and the physical property values of the sand mold are determined. The physical properties of the sand mold include the type of sand mold, density, water content, active clay content, compactability, strength of the sand mold, and the like. Specifically, in the setting step S1, setting conditions such as physical property values and temperature of the sand mold were determined as follows. The type of sand mold is silica sand, and the physical properties of the sand mold are density 1.53 g/cm ³ , water content 3.2%, active clay content 7.6 wt%, compactability 38%, sand mold strength 20 N/cm ^{2 .} It was used as a piece TP.

The sand mold test piece TP was cylindrical with a diameter of 50 mm and a height of 50 mm. The set temperature of the sand mold was in the range from room temperature to 400°C. Also, the magnitude of the load applied from the axial direction by the first pressure member 21 was 0.5 MPa, 0.75 MPa, and 1.0 MPa. Further, the shear variation of the test piece TP in the lower container 12 was set to 10 mm when the lower container 12 was pressurized from the side direction by the second pressurizing part 22 . Moreover, the shear displacement rate was set to 1.0 mm/min.

(Test step S2)
Next, in the test step S2, under the setting conditions determined in the setting step S1, the sand mold is subjected to single-sided shear using the single-sided shear test apparatus 1 under a plurality of temperatures from room temperature to a high temperature of 400 ° C. Do the test multiple times. The flow of this single-sided shear test will be described with reference to the flow chart of FIG. Note that the flowchart shown in FIG. 5 is an example, and the present invention is not limited to this flowchart.

In the single-sided shear test performed in the test step S2, first, a sand mold test piece TP is accommodated in the container 10 (S21). Subsequently, by outputting a control signal from a control device (not shown), the first cylinder 31 is operated to move the first pressure member 21 toward the container 10 side. Thereby, a predetermined load is applied to the test piece TP in the container 10 from the axial direction (S22).

Next, a shear stress is applied to the test piece TP from the lateral direction while the load is applied to the test piece TP in the container 10 from the axial direction (S23). Specifically, by outputting a control signal from the control device, the second cylinder 32 is operated to move the second pressure member 22 toward the container 10 . Thereby, a load is applied to the test piece TP in the lower container 12 from the lateral direction. As a result, shear stress acts on the test piece TP in the container 10 .

Then, the test piece TP in the lower container 12 is sheared by a predetermined distance by moving the lower container 12 laterally (to the left in FIG. 1) along the guide 60 by a predetermined distance (S24). In this manner, the single-sided shear test is performed multiple times under the set conditions determined in the setting step S1.

During the single-sided shear test of the sand mold, the shear displacement sensor 44 and the vertical displacement sensor continuously measure the shear displacement amount and the vertical displacement amount of the test piece TP in the lower container 12 . Further, the first upper load sensor 41 continuously measures the load applied from the first pressure unit 21 to the test piece TP, and the first lower load sensor 42 detects the load from the guide 60 side to the lower container 12 . The load (reaction force) applied to the is continuously measured. Further, the second load sensor 43 continuously measures the shear stress generated in the test piece TP by being pressurized by the second pressurizing part 22 .

(Parameter calculation step S3)
Next, the parameter calculation step S3 will be described. In the parameter calculation step S3, each parameter is calculated by creating an intensity envelope, which will be described later, for each of a plurality of temperatures based on the measurement results obtained in the test step S2.

6 and 7 show part of the measurement results of the single-sided shear test. FIG. 6 is a graph showing the relationship between the amount of shear displacement obtained by the direct shear test and the stress measured by the load sensor. FIG. 7 is a graph showing the relationship between the amount of shear displacement and the amount of vertical displacement obtained by a single-sided shear test.

In the example shown in FIG. 6, the amount of shear displacement is 10 mm, the applied load (upper axial load) from the axial direction by the first pressure member 21 is 0.75 MPa, and the lower portion is A direct shear test was performed under the condition that the load (lower shaft load) applied to the container 12 was 0.4 MPa. At this time, the measurement result of the shear stress τ generated in the test piece TP in the lower container 12 was approximately 0.3 MPa, as shown in FIG.

<Calculation of adhesive force c and internal friction angle φ>
The upper axial load obtained from the measurement result in the test step S2 becomes the vertical stress σ applied to the test piece TP in the lower container 12. This normal stress σ and shear stress τ are plotted as shown in FIG.

Hereinafter, the same one-sided shear test is performed by changing the axial load (upper axial load) applied by the first pressure member 21 . If it is possible to plot at least three points, it is possible to create the intensity envelope shown in FIG. FIG. 8 shows an example plotted at nine locations.

In this way, by plotting the normal stress σ and the shear stress τ obtained based on the measurement results of the single-sided shear test, the Mohr-Coulomb strength envelope shown in the above formula (1) is created. be able to.

As shown in FIG. 8, if the Mohr-Coulomb strength envelope can be created, the adhesive force c can be calculated from the intercept of the strength envelope, and the internal friction angle φ can be calculated from the slope of the strength envelope. Furthermore, by creating the intensity envelope, the non-measured portion can be interpolated from the measurement result obtained in the test step S2, and each parameter can be efficiently calculated.

Then, in the setting step S1, the set temperature of the sand mold is changed from room temperature to 400° C., and the one-sided shear test is performed a plurality of times in the test step S2. , and the internal friction angle φ can be calculated.

<Calculation of Expansion Angle ψ>
Next, the expansion angle ψ is calculated from the relationship between the amount of shear displacement and the amount of vertical displacement shown in FIG. Specifically, the expansion angle ψ is calculated, for example, by determining the slope of the vertical displacement at the shear displacement amount of 5 mm where the strength envelope is stable. However, when the expansion angle ψ is a negative value, the expansion angle ψ may be set to 0 as a parameter used for numerical analysis.

Then, in the setting step S1, the set temperature of the sand mold is changed from room temperature to 400° C., and the one-sided shear test is performed a plurality of times in the testing step S2. can be calculated.

(result of numerical analysis)
Next, the results of numerical analysis (FEM analysis) of the sand mold by inputting various parameters obtained by the above parameter acquisition method will be described with reference to FIG. By the above parameter acquisition method, the adhesive force c of the sand mold, the internal friction angle φ of the sand mold, and the expansion angle ψ of the sand mold are calculated for each of a plurality of different temperatures including a high temperature of 100° C. or higher. FIG. 9 shows an example of an analysis result of numerical analysis (FEM analysis) of a sand mold by inputting these parameters. As shown in FIG. 9, when a numerical analysis was performed using the parameters obtained by this embodiment, the analytical values of the numerical analysis regarding the casting shrinkage of the sand mold were compared with the experimental values even at a high temperature of 100°C or higher. I was able to get close to it.

[Effects of Embodiment]
According to the parameter acquisition method of the present embodiment described above, the one-sided shear test is performed on the sand mold test piece TP accommodated in the vertically divisible container 10 at a plurality of temperatures in the test step S2. . Based on the measurement results, in the parameter calculation step S3, by creating a Mohr-Coulomb intensity envelope for each of a plurality of temperatures, each parameter necessary for numerical analysis (FEM analysis) for each of a plurality of temperatures can be obtained efficiently. As a result, in the numerical analysis of the single-sided shear of the sand mold, by inputting each of the above parameters, numerical analysis can be performed satisfactorily under multiple temperatures. It can be predicted with high accuracy.

Further, according to the parameter acquisition method described above, based on the measurement results of the shear stress τ of the sand mold, the normal stress σ of the sand mold, and the amount of vertical displacement at a plurality of temperatures obtained in the test step S2, the parameter calculation step At S3, the adhesive force c of the sand mold, the internal friction angle φ of the sand mold, and the expansion angle ψ of the sand mold for each temperature can be calculated. As a result, the adhesive force c, the internal friction angle φ, and the expansion angle ψ of the sand mold for each temperature can be input as parameters for numerical analysis of the single-sided shear of the sand mold, and good numerical analysis results can be obtained.

In addition, according to the parameter acquisition method described above, it is possible to acquire the parameters used in the numerical analysis of the single-sided shear of the sand mold at a high temperature of 100°C or higher, so the numerical analysis of the single-sided shear of the sand mold can be performed satisfactorily. This makes it possible to predict the shear strength of sand molds at high temperatures with high accuracy.

Further, according to the parameter acquisition method described above, based on the measurement results obtained in the test step S2, the range not measured in the test step S2 (non-measured portion) is complemented, and the Mohr-Coulomb strength Create an envelope. As a result, the number of single-sided shear tests required to obtain each parameter used for numerical analysis can be reduced, and each parameter can be efficiently obtained.

According to the above-described sand mold single-sided shear test apparatus 1, the load is applied to the test piece TP in the container 10 from the axial direction by the first pressure unit 21, and the second pressure unit 22 vertically moves the test piece TP. By applying a load from the lateral direction to the test piece TP in the lower container 12 on one side of the divided container 10, a desired shear stress is applied to the test piece TP to perform a sand mold single-sided shear test. can. As a result, by using the measurement results of the single-sided shear test, it is possible to obtain accurate values of the adhesive force c, the internal friction angle φ, and the expansion angle ψ in the Mohr-Coulomb equation (1). .

In particular, since the heaters 51 and 52 can heat the test piece TP in the container 10 to a high temperature of at least 100° C. or higher, the single-sided shear test of the sand mold can be performed at a high temperature. This makes it possible to measure the shear stress and the amount of shear displacement that occur when the sand mold is subjected to single-sided shearing under a plurality of temperatures including high temperatures.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be implemented by appropriately combining technical means disclosed in different embodiments. The form is also included in the technical scope of the present invention.

1 Single Shear Test Apparatus 10 Container 11 Upper Container 12 Lower Container 21 First Pressure Unit 22 Second Pressure Unit 41 First Upper Load Sensor (First Load Sensor)
42 first lower load sensor (first load sensor)
43 second load sensor 44 shear displacement sensor 51, 52 heater TP test piece S1 setting step S2 testing step S3 parameter calculation step

Claims (4)

A method for obtaining parameters used for numerical analysis related to single-sided shear of a sand mold, comprising:
a setting step of determining setting conditions including the temperature and physical properties of the sand mold;
A test step of performing a one-sided shear test on the sand mold test piece housed in a vertically divisible container under a plurality of temperatures using the set conditions determined by the setting step;
a parameter calculation step of calculating the parameters by creating the strength envelope for each of a plurality of temperatures based on the measurement results obtained in the testing step, assuming that the sand mold follows a predetermined strength envelope;
A parameter acquisition method comprising: The setting conditions determined in the setting step include the magnitude of the load applied to the sand mold from the axial direction and the amount of shear displacement of the sand mold,
The measurement results obtained in the test step include the shear stress of the sand mold, the vertical stress of the sand mold, and the amount of vertical displacement at a plurality of temperatures,
2. The method according to claim 1, wherein the parameters calculated in the parameter calculation step include an adhesive force of the sand mold, an internal friction angle of the sand mold, and an expansion angle of the sand mold for each temperature. How to get parameters. 3. The parameter acquisition method according to claim 1, wherein the temperature of the sand mold under the set conditions includes a high temperature of at least 100[deg.] C. or higher. 4. Any one of claims 1 to 3, wherein the intensity envelope created in the parameter calculation step is created by interpolating non-measured portions from the measurement results obtained in the test step. How to get parameters described in .

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