JPH0727748A - Thermal stress destructive test method for plate material - Google Patents

Abstract

PURPOSE:To obtain the evaluation of destruction due to thermal stress equivalent to that of plate material of actual size by surrounding the edge of small- sized plate material for a test with a hollow sash, allowing a cooling medium to flow, heating the surface of the late material and providing a strain gage and an acoustic emission sensor at a suitable part of the plate material. CONSTITUTION:The edge of a foam glass material 1 of three-layer structure composed of a mounting fine glass layer 1a, an intermediate foam glass layer 1b and a base foam glass layer 1c is surrounded by a hollow sash 2, water 3, 3 is allowed to flow therethrough and the glass material 1 is cooled from the edge part by circulating water. Strain gages 4 and thermocouples 5, 5 are arranged on the front face and the rear face of the glass material 1, connected to recorders 6, 7 and the strain and temperature are recorded. In addition, an AE sensor 8 is mounted and the AE pulse and energy are recorded by another recorder 10 through an AE tester 9. Heating is performed on one face of the glass material 1 by means of infrared rays and auxiliary heating is conducted from the other face thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a thermal brittle plate material such as plate glass and foam glass material, and particularly to a thermal stress fracture test method for foam glass material used for lightweight building materials, heat insulating materials, etc. The present invention relates to a thermal stress fracture test method in which the evaluation equivalent to that of a large practical size plate material can be obtained.

[0002]

[Prior art and its problems] In measuring and evaluating the thermal stress fracture behavior of a plate material due to sunlight heat, etc., while disposing a strain gauge on a large-sized practical size plate material while cooling the edge part or local part of the plate material. It is known to irradiate a heat ray from one surface of a plate material and measure stress appropriately, and it is known to attach an acoustic emission sensor to the plate material and measure the frequency and energy of occurrence of acoustic emission.

However, in the thermal stress fracture test of a large-sized practical size plate material, there are many inconveniences such as large scale equipment, inconvenience in handling materials, inefficiency, and considerable cost. On the other hand, in order to obtain the same behavior with a small test plate material, even if the irradiation heat quantity is simply adjusted, the stress distribution in the length (or width) direction and the thickness direction of the plate material can be approximated to obtain an equivalent evaluation. Have difficulty.

In view of the above problems, the present invention provides a thermal stress fracture test method in which a small test plate material can be used to obtain an evaluation equivalent to a large practical size plate material, and in particular, a foam glass material or the like. The present invention provides a test method which can be suitably applied to thermal stress fracture of the thermally brittle plate material due to sunshine heat or the like.

[0005]

According to the present invention, the periphery of a small test plate material is surrounded by a hollow sash, and a cooling medium is flown, while heating is performed from the surface of the plate material by a heating control means, and a strain gauge and an acoustic emission are provided at appropriate positions of the plate material. (Sound emission)
Attaching a sensor, a method to evaluate the fracture behavior based on the thermal stress generation status, the acoustic emission generation status, by heating from one side of the plate material and auxiliary heating from the other surface, It consists of a thermal stress fracture test method of a plate material that obtains an equivalent evaluation to a test by similar one-sided heating, and further, in order to make the stress distribution of the large plate model similar to that of the small plate model by a thermal stress analysis simulation test in advance. The thermal environment conditions are selected, and in addition, the plate material is a foam glass material.

[0006] Taking a foam glass material as an example, from practically sized glass having a length or width of approximately 1000 mm to 20
Some can reach 00 mm. There are various thicknesses from around 10 mm to over 50 mm. As described above, there are many inconveniences such as the large equipment and the inconvenience of handling the materials for the thermal stress fracture test of these materials as they are.

In the present invention, a thermal stress fracture test is carried out using a small size having a length or width of several hundred mm to 400 to 500 mm or less to obtain an evaluation equivalent to that of the practical size, This aims to solve the above problems.

[0008]

EXAMPLES The present invention will be described below based on examples. The existing foam glass material was adopted as the test plate material. It is known that when the foam glass material is incorporated into the sash and the thermal stress fracture behavior due to sunlight etc. is observed, it often occurs mainly from the end portion of the foam glass material. In consideration of the fact, in the present invention, the large-sized foam glass material to be put into practical use is first incorporated into the sash, while heating with infrared heating means from one side of the foam glass material assuming solar radiation, the strain that occurs, and Acoustic emission (hereinafter referred to as AE) is measured to investigate and investigate the fracture behavior, and stress analysis by a simulation test of the same size model is also used to confirm the consistency with the above facts. In a model simulation test, set thermal environment conditions, that is, the amount of heat ray irradiation from one side and the other side, to obtain an approximate stress distribution, and conduct and confirm a thermal stress fracture test of a similar small-sized foam glass material. This is a procedure that has been devised.

[Thermal Stress Fracture Test on Large-sized Foam Glass Material] As shown in the schematic perspective view of FIG. 1, a surface-packed dense glass layer (surface layer) 1a, an intermediate foam glass layer (intermediate layer) 1b, a base foam glass layer (Base layer) Regarding the foam glass material 1 with a three-layer structure of 1c, its size is set to a practical size of 900 mm □ × 30 mm thickness, and the surrounding area is surrounded by a hollow sash 2, and water 3 and 3 are passed through it. , The peripheral part of the foam glass material 1 is cooled by circulating it, and the strain gauges 4 and thermocouples 5 and 5 are arranged on the front surface and the back surface of the foam glass material 1, respectively, as shown in the figure, and recorders 6 and 7 respectively. Strain and temperature were recorded by connecting to, and the AE sensor 8 was attached, and the generated AE was recorded via the AE tester 9 to the AE pulse and energy in the recorder 10.

An infrared lamp (not shown) irradiates a heat ray 11 of 780 kcal / m ² h from one surface (front surface) side of the foam glass material. This corresponds to the maximum amount of solar radiation incident on the vertical wall in Japan.

The samples consist of the three types shown in Table 1.

[0012]

[Table 1]

[0013] Figure 3 A, graph B, respectively large size foamed glass material in C (large size sample) A, B, and strain of the vicinity of the end portion of the C, and the relationship between dimensionless AE energy accumulated amount It was shown to. The left column of Table 2 shows the time taken to break each large sample,
Immediately before that, the maximum amount of strain of the sample end face is shown.

[0014]

[Table 2]

From these results, AE is frequently generated when the strain amount exceeds 100 με for all three large size samples, and macroscopic destruction occurs when the strain amount exceeds 300 με. It can be seen that there is no great difference in the amount of strain leading to destruction, but the heat irradiation time (durability time) is superior in the order of A <B <C.

[Simulation Test for Large-sized Foam Glass Material] Regarding the test of the large-sized foam glass material, thermal stress analysis was performed using general-purpose finite element method software COSMOS / M. The thermal stress simulation model uses a polar coordinate system for convenience of calculation, and has a radius of 500 mm as shown in the perspective view of FIG.
, A disk type with a thickness of 30 mm is assumed. The thermal boundary condition is that the heat amount 11 of 780 kcal / m ² h is incident on the surface imitating the test of the large-sized foam glass material. did. Table 3 shows basic physical property values used in the simulation.

[0017]

[Table 3]

FIG. 4 shows the results of thermal stress analysis at the time when the amount of strain at the surface end where the microscopic fracture frequently occurs is 150 με (about 12 MPa). The positive stress value is tensile. Note the stress distribution in the radial direction in FIG. 4 A, in FIG. 4 B shows the stress distribution in the thickness direction.

[0019] Looking at the stress distribution in the radial direction in FIG. 4 A, circumferential stress (Hoop Stress) is compressed in the vicinity of the center
At (about 2MPa), it suddenly turns into tension from the vicinity of the heat insulation area at the end and reaches the maximum at the end face. Radial Stres
s) is compressive in the central part like the stress in the circumferential direction, and the value is almost the same as the stress in the circumferential direction. However, it was 0 MPa at the end face.

The other stress component, the shear stress (Shear S
The stress and the axial stress (Axial Stress) were almost 0 MPa from the center to the end face. Thermal stress analysis results in the thickness direction of the circumferential edge of the sample surface stress is maximized in FIG 4 B. Other stress components except radial stress (Radial Stress, Shear Stre
ss, Axial Stress) can be ignored at almost 0 MPa.

The distribution of stress in the circumferential direction gradually decreases in the order of the surface layer, the intermediate layer and the base layer, which means that the Young's modulus becomes smaller in the order of the surface layer, the intermediate layer and the base layer.
This is because the temperature difference between the center part and the end part of the sample becomes smaller from the front surface to the back surface.

From the above, it is recalled that the fracture is caused by the tensile stress and is caused from the end face by the largest circumferential stress. However, when the fracture of the foam glass material is easily caused from the end face, the crack is perpendicular to the end face. It is also consistent with the fact that progresses to.

[Simulation Test on Small-Sized Foam Glass Material and Setting of Thermal Environmental Conditions] In order to reproduce the result of the large-sized model on the small-sized model, the same form as that of FIG. Was set to 100 mm and various heat irradiation amounts were set to analyze the stress distribution.

As a result, it was found that an approximate stress distribution can be obtained by performing heat irradiation from the front surface and the back surface (11 and 11 ') and appropriately selecting the irradiation amount respectively. 2, the irradiation amount of heat 11 from the surface 1560kcal / m ² h, at the time of large-size model similar strain amounts 150με when the irradiation amount of heat 11 'from the back side and 780 kcal / m ² h The thermal stress analysis result of is shown in FIG. Note the radial stress distribution of small size model in Figure 4 C, shows the stress distribution in the thickness direction in FIG. 4 D.

[0025] Figure 4 as apparent circumferential stress from C was about 7MPa in compressive strength at the central portion. In addition, the area of the heat insulating portion on the end face suddenly changes to tensile and becomes maximum at the end face. The radial stress at the center is almost the same as the circumferential stress and 0 MPa at the end face, which is in agreement with the stress distribution tendency of the large size model. Other stress components are 0MPa from the center to the end face as in the large size model.

Further, the stress distribution in the depth direction of FIG. 4 D is seen that is most consistent with the large size model. That is, it is clear that the stress distribution similar to that of the large size model can be obtained by setting the thermal environment conditions in the small size model, and is used as the base for the subsequent thermal stress fracture test of the small size foam glass material. Is.

[Thermal stress fracture test of small-sized foam glass material]
Based on the above results, a thermal stress fracture test of a small-sized foam glass material (small-sized sample) was carried out.

According to the test of the large size sample in FIG. 1, the size is 200 mm □ × 30 mm, and the thermal environment conditions selected in the simulation test, that is, the irradiation heat quantity (11) on the surface is 1560 kcal / m ² h. The irradiation heat amount (11 ') on the back surface was 780 kcal / m ² h.

The attachment of the hollow sash 2, the arrangement of the strain gauge 4, the AE sensor 8 and the like are the same as in the case of the large size sample.
The types of foam glass materials are A, B, and C, which are the same as those for large size samples.
There are three types (see Table 1).

The results are shown in the right column of FIG. 3 and Table 2. Figure 3
Shows the relationship between the strain amount of the small size sample and the integrated amount of AE energy (shown as dimensionless) in comparison with the large size sample. Microscopic fracture occurs remarkably when the strain exceeds approximately 100 με, and there is no difference between large size and small size in each sample in the increasing tendency. It should be noted that in Sample B, the starting point of microscopic destruction in the large size is about 30 με, and there is a difference of 150 με in the small size.
It is estimated to be the difference in the initial defects of the sample.

Further, all of the samples reached macroscopic fracture at a point exceeding about 300 με, and the results are similar to those of the large size sample. The right column of Table 2 shows the time to reach macroscopic fracture and the amount of strain of each small size sample. There is no remarkable difference in the strain amount between the samples, and the fracture time can be accelerated as compared with the test in the large size sample, and becomes longer in the order of A <B <C as in the large size sample.

As described above, by irradiating an appropriate amount of heat from the front surface and the back surface of the small size sample based on the simulation test result, the result equivalent to the large size sample can be obtained.

[0033]

According to the present invention, by irradiating heat from the front surface and the back surface of a small plate material and appropriately selecting each heat irradiation amount, the same result as that of the large plate material can be obtained. It is possible to reduce the size and size of the sample, improve the measurement efficiency, and reduce the cost.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a test apparatus.

FIG. 2 is a perspective view of a simulation model.

FIG. 3 shows the relationship between the amount of strain and the integrated amount of AE in comparison between a large (practical) size sample and a small size sample, where A is sample A, B is sample B and C is sample C.

FIG. 4 shows the results of thermal stress analysis in a simulation model, of which A and B are for a large size model.
A is the stress distribution in the radial direction, B is the stress distribution in the depth direction,
Further, C 1 and D 2 are for a small size model, where C is the stress distribution in the radial direction and D is the stress distribution in the depth direction.

[Explanation of symbols]

 1 ------ Foam glass material 2 ------ Hollow sash 4 ------ Strain gauge 5 ------ Thermocouple 8 ------ AE sensor

Front page continued (72) Inventor Toshiyuki Hashida 2-1-5 Olympics, Miyagino-ku, Sendai-shi, Miyagi (72) Inventor Kazushi Sato 16-11 Yagiyama Midoricho, Taihaku-ku, Sendai-shi, Miyagi (72) Inventor Shin Omi Tokyo Central Glass Co., Ltd. 1-7-3 Kandanishikicho, Chiyoda-ku, Tokyo

Claims (3)

[Claims] 1. A small test plate is surrounded by a hollow sash, and a cooling medium is allowed to flow through the plate. The heating control means heats the plate surface, and a strain gauge and an acoustic emission (acoustic emission) sensor are attached at appropriate positions. , A method of evaluating the fracture behavior based on the thermal stress occurrence status, the occurrence status of acoustic emission, characterized in that the plate material is heated from one side of the plate material and auxiliary heating from the other surface. Thermal stress fracture test method. 2. A sheet material according to claim 1, wherein a thermal environment condition is selected in advance by a thermal stress analysis simulation test so as to approximate the stress distribution of the large sheet material model to that of the small sheet material model. Thermal stress fracture test method. 3. The thermal stress fracture test method for a plate material according to claim 1, wherein the plate material is a foam glass material.