Wood compression testing apparatus and wood compression testing method

Abstract

To perform a compression test of wood by one testing device for wood test pieces different in various conditions.SOLUTION: According to an aspect of the present invention, there is provided a compression testing device for wood, including a test chamber including two pairs of a fixed wall and a movable wall facing the fixed wall, wherein a wood test piece and a periphery simulation wood test piece for simulating a state in which wood is combined are installed in the test chamber so as to surround the wood test piece, and the movable wall includes a movable wall load cell for measuring a contact pressure between the wood test piece installed in the test chamber and the movable wall. A slide mechanism capable of adjusting a distance between the movable wall and the fixed wall facing the movable wall is provided, and the distance between the movable wall and the peripheral simulated wood test piece can be adjusted by sliding the movable wall by the slide mechanism.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wood compression test device and a wood compression test method, and more particularly to a wood compression test device and a wood compression test method suitable for carrying out a compression test to measure the strength of wood. [Background technology]

[0002] Conventionally, methods for measuring the strength of wood, such as testing methods for bending, tension, compression, and other loads, have been prescribed in the Japanese Industrial Standards (JIS) Z 2101 (Non-Patent Document 1). In particular, for compression tests, JIS Z 2101 stipulates that a rectangular parallelepiped test piece should be compressed in the longitudinal direction, or only partially compressed in the longitudinal direction, and that measurements should not be taken up to the point of fracture.

[0003] On the other hand, an example of using wood as a buffer against a drop impact is when it is used as a buffer for metal casks used to transport spent fuel in nuclear power plants.

[0004] In this case, a buffer is made by combining multiple pieces of wood, and when the metal cask falls, the buffer absorbs energy by compressing the wooden pieces, thereby reducing the impact load applied to the metal cask body and its contents, the spent fuel.

[0005] When measuring the strength of wood for such uses, using the method of compressing a rectangular parallelepiped test piece in the longitudinal direction, as in the JIS standard mentioned above, is not suitable because there is no wood to combine adjacent to the test piece, making the test piece more likely to buckle and resulting in an underestimation of the compressive load compared to when the wood pieces are combined.Similarly, with partial compression tests, the test is not carried out to failure, making it difficult to evaluate the actual capacity of the buffer.

[0006] For this reason, the Central Research Institute of Electric Power Industry's Central Research Institute of Electric Power Industry Report No. 8074, June 2009 (Non-Patent Document 2) describes inserting a cylindrical test piece into a circular tubular wooden restraining jig and compressing the test piece. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Japanese Industrial Standard JIS Z 2101 [Non-patent document 2] Central Research Institute of Electric Power Industry Report No. 8074, June 2009 Summary of the Invention [Problem to be solved by the invention]

[0008] However, it is difficult to adjust the fit of the cylindrical wood restraint jig to the test specimen as described in Non-Patent Document 2. For example, if you want to conduct a test under conditions where the wood specimen is deteriorated or the moisture content is changed, the dimensions of the wood can easily change depending on these conditions.

[0009] For this reason, it may be impossible to insert a wood test piece into a cylindrical wood restraint jig that does not take into account dimensional changes in wood, or even if the wood test piece can be inserted into the cylindrical wood restraint jig, a gap may occur. If a gap occurs between the wood test piece and the cylindrical wood restraint jig, it may be impossible to perform tests that correspond to conditions in which the wood test piece is deteriorated or the moisture content is changed.

[0010] Ultimately, the compressive load required for wood compression testing varies depending on the surrounding restraint conditions, so the inability to control changing conditions during testing is a problem.

[0011] The buffer body of the metal cask mentioned above may be made by combining pieces of wood, but since it is difficult to make the spacing between the pieces of wood constant, the spacing between the pieces of wood is allowed within a certain tolerance range.

[0012] Because the compression load varies depending on the amount of gap between the pieces of wood, when conducting compression tests on wood, it is necessary to adjust the test conditions, including the gap.However, there was a problem in that such adjustments could not be made with conventional standard cylindrical wood restraint jigs.

[0013] The present invention has been made in consideration of the above points, and its object is to provide a wood compression testing device and compression testing method that can perform wood compression tests on wood test pieces under various conditions using a single testing device. [Means for solving the problem]

[0014] In order to achieve the above-mentioned object, the wood compression testing device of the present invention has a test chamber formed by two pairs of fixed walls and movable walls opposite the fixed walls, and the movable walls are equipped with a movable wall load cell that measures the contact pressure between the movable walls and wood test pieces installed in the test chamber, and are also equipped with a sliding mechanism that can adjust the distance between the movable walls and the fixed walls opposite them, and the distance between the movable walls and the wood test pieces can be adjusted by sliding the movable walls with the sliding mechanism.

[0015] More specifically, the test chamber is formed by two pairs of fixed walls and movable walls opposite the fixed walls, and within the test chamber, a wood test piece and a surrounding mock wood test piece are installed to simulate a state in which wood is combined so as to surround the wood test piece, and the movable wall is equipped with a movable wall load cell that measures the contact pressure between the wood test piece installed in the test chamber and the movable wall, and is also equipped with a sliding mechanism that can adjust the distance between the movable wall and the fixed wall opposite it, and the distance between the movable wall and the surrounding mock wood test piece can be adjusted by sliding the movable wall with the sliding mechanism.

[0016] Furthermore, in order to achieve the above-mentioned object, the wood compression testing method of the present invention is characterized in that a test chamber is constructed with two pairs of fixed walls and movable walls facing the fixed walls, the movable walls are equipped with a movable wall load cell that measures the contact pressure between the movable wall and a wood test piece installed in the test chamber, and are equipped with a sliding mechanism that can adjust the distance between the movable wall and the fixed wall facing the movable wall, and the distance between the movable wall and the wood test piece is adjusted by sliding the movable wall with the sliding mechanism.

[0017] More specifically, the test chamber is configured with two pairs of fixed walls and movable walls facing the fixed walls, and within the test chamber, a wood test piece and a surrounding simulated wood test piece are installed so as to surround the wood test piece and simulate a state in which wood pieces are assembled together, The movable wall is equipped with a load cell for the movable wall that measures the contact pressure between the wood test piece installed in the test chamber and the movable wall, and is also equipped with a sliding mechanism that can adjust the distance between the movable wall and the opposing fixed wall, and the distance between the movable wall and the surrounding simulated wood test piece can be adjusted by sliding the movable wall with the sliding mechanism. [Effects of the Invention]

[0018] According to the present invention, when performing compression tests on wood, wood test pieces under various different conditions can be tested using a single testing device. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a longitudinal sectional view schematically showing a first embodiment of a compression testing device for wood according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA′ in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes the compression testing device and method for wood of the present invention based on the illustrated embodiment. Note that the same reference numerals are used for the same components in each drawing. [Example]

[0021] 1 and 2 show a schematic configuration of a wood compression testing device according to the present invention.

[0022] As shown in the figure, the wood compression testing device 1 of this embodiment has two pairs of a first fixed wall 4a and a second fixed wall 4b, and a first movable wall 5a and a second movable wall 5b that face the first fixed wall 4a and the second fixed wall 4b, forming a test chamber 10. Inside this test chamber 10, a wood test piece 2 with a square cross section and four surrounding simulated wood test pieces 3a, 3b, 3c, and 3d are placed around the square cross section wood test piece 2 to simulate a state in which wood is combined together.

[0023] The first movable wall 5a and the second movable wall 5b are equipped with a load cell 7a for the first movable wall and a load cell 7b for the second movable wall that measure the contact pressure between the wood test piece 2 installed in the test chamber 10 and the first movable wall 5a and the second movable wall 5b, and are also equipped with a first slide mechanism 6a and a second slide mechanism 6b that can adjust the distance between the first movable wall 5a and the second movable wall 5b and the opposing first fixed wall 4a and second fixed wall 4b.

[0024] In this embodiment, the first movable wall 5a and the second movable wall 5b are slid by the first sliding mechanism 6a and the second sliding mechanism 6b, so that the distances L1 and L2 between the first movable wall 5a and the second movable wall 5b and the third surrounding simulated wood test piece 3c and the second surrounding simulated wood test piece 3b closest to the first movable wall 5a and the second movable wall 5b can be adjusted.

[0025] The first movable wall load cell 7a is integrated with the first slide mechanism 6a, and the second movable wall load cell 7b is integrated with the second slide mechanism 6b.

[0026] In addition, the first movable wall 5a is connected to a first reaction wall 8a via a first slide mechanism 6a, and the second movable wall 5b is connected to a second reaction wall (not shown) via a second slide mechanism 6b.

[0027] In addition, the wood compression testing device 1 of this embodiment further includes a compression jig 11 that compresses the wood test piece 2, and this compression jig 11 incorporates a compression jig load cell 12 that measures the compression force of the compression jig 11, and further incorporates a displacement meter 14 that measures the compression displacement.

[0028] An auxiliary jig 13 is placed between the compression jig 11 and the wood test piece 2. It is preferable that the surface of this auxiliary jig 13 that comes into contact with the wood test piece 2 has the same shape as the wood test piece 2.

[0029] More specifically, the wood compression testing device 1 of this embodiment has a test chamber 10 formed by a first fixed wall 4a, a second fixed wall 4b, and a first movable wall 5a, a second movable wall 5b, and the test chamber 10 is surrounded by the first fixed wall 4a and the second fixed wall 4b, which are side walls that are appropriately fixed, and the first movable wall 5a that can slide laterally (in the direction of arrow A in Figures 1 and 2) and the second movable wall 5b that can slide laterally (in the direction of arrow B in Figure 2). The first fixed wall 4a and the second fixed wall 4b and the first movable wall 5a and the second movable wall 5b are arranged to face each other.

[0030] The wood test piece 2 is formed in a rectangular parallelepiped, cubic, spherical or other shape, and in this embodiment, a rectangular parallelepiped wood test piece 2 with a square cross section is used and placed in the test chamber 10.

[0031] In addition, four surrounding simulated wood specimens, namely, a first surrounding simulated wood specimen 3a, a second surrounding simulated wood specimen 3b, a third surrounding simulated wood specimen 3c and a fourth surrounding simulated wood specimen 3d, are placed around the wood specimen 2 to simulate the state in which the wood is combined.

[0032] In addition, the first movable wall 5a and the second movable wall 5b are provided with a first sliding mechanism 6a and a second sliding mechanism 6b so that the distances L1 and L2 between the first movable wall 5a and the second movable wall 5b and the nearest third surrounding simulated wood test piece 3c and second surrounding simulated wood test piece 3b, i.e., the distances determined by the tolerance of the spacing when the wood is combined, can be adjusted.

[0033] In addition, the first movable wall 5a and the second movable wall 5b are connected to the first reaction wall 8a and the second reaction wall (not shown) through the first slide mechanism 6a and the second slide mechanism 6b, and the first slide mechanism 6a and the second slide mechanism 6b are provided with a load cell 7a for the first movable wall and a load cell 7b for the second movable wall.

[0034] In addition, the first fixed wall 4a and the second fixed wall 4b, the wood test piece 2 and the first surrounding simulated wood test piece 3a, the second surrounding simulated wood test piece 3b, the third surrounding simulated wood test piece 3c and the fourth surrounding simulated wood test piece 3d are placed on a base plate 9.

[0035] In this example, the wood test piece 2 is compressed by a compression jig 11, which is equipped with a load cell 12 for the compression jig.

[0036] In the wood compression testing device 1 of this embodiment configured as described above, the wood test piece 2 is bounded by four simulated wood test pieces: the first simulated wood test piece 3a, the second simulated wood test piece 3b, the third simulated wood test piece 3c, and the fourth simulated wood test piece 3d, making it possible to simulate the compression conditions when wood is combined and compressed from above with the compression jig 11. Furthermore, by adjusting the distances L1 and L2 between the first movable wall 5a and the second movable wall 5b and the nearest third simulated wood test piece 3c and second simulated wood test piece 3b before the test, it is possible to reproduce test conditions corresponding to the tolerance of the spacing between the combined wood test pieces 2.

[0037] In addition, the first movable wall 5a and the second movable wall 5b may be equipped with a distance measuring device (not shown) that measures the distance between them and the third surrounding simulated wood test piece 3c and the second surrounding simulated wood test piece 3b.

[0038] In addition, the first movable wall 5a and the second movable wall 5b can be moved toward or away from the opposing first fixed wall 4a and second fixed wall 4b by the first slide mechanism 6a and the second slide mechanism 6b.

[0039] The first slide mechanism 6a and the second slide mechanism 6b are supported by a first reaction wall 8a and a second reaction wall (not shown) and are configured to support the lateral expansion force generated by compression of the wood test piece 2.

[0040] In this example, the wood test piece 2 is compressed by a compression jig 11, which incorporates a compression jig load cell 12 to measure the compression force (compression load) of the compression jig 11. Furthermore, the compression jig 11 incorporates a displacement meter 14 to measure the compression displacement of the compression jig 11.

[0041] The compressive stress-compressive strain relationship can be obtained from the measurement results of the compressive load measured by the compression jig load cell 12 and the compressive displacement measured by the displacement meter 14. The compressive stress-compressive strain relationship can be used in analyses such as finite element analysis, making it possible to design wooden buffers based on the analysis results.

[0042] An auxiliary jig 13 may be interposed between the compression jig 11 and the wood test piece 2. Stable compression is possible by making the surface of this auxiliary jig 13 that comes into contact with the wood test piece 2 the same shape as the wood test piece 2. Furthermore, if the position or size of the wood test piece 2 is different, it is sufficient to prepare a corresponding auxiliary jig 13, eliminating the need to move the compression device that operates the compression jig 11.

[0043] Furthermore, a first movable wall load cell 7a and a second movable wall load cell 7b are installed on the first slide mechanism 6a and the second slide mechanism 6b.

[0044] When the wood test piece 2 is compressed, it expands laterally, but because the sides of the wood test piece 2 are restrained by the four first surrounding simulated wood test piece 3a, second surrounding simulated wood test piece 3b, third surrounding simulated wood test piece 3c, and fourth surrounding simulated wood test piece 3d, the first fixed wall 4a, the second fixed wall 4b, the first movable wall 5a, and the second movable wall 5b, a restraining force is generated on the sides of the wood test piece 2. This lateral restraining force on the wood test piece 2 can be measured by the first movable wall load cell 7a and the second movable wall load cell 7b.

[0045] This makes it possible to measure stress occurring not only in the compression direction, but also in two directions on the sides of the wood test piece 2. Because stress on the sides of the wood test piece 2 deforms the other pieces of wood it is combined with, this information is important for predicting deformation of the combined wood as a whole.

[0046] Furthermore, the magnitude of the reaction force in the lateral direction due to compression of the wood test piece 2 is affected by the degree of peripheral restraint.

[0047] The wood compression testing device 1 of this embodiment is capable of adjusting the initial gap using the first movable wall 5a and the second movable wall 5b, making it possible to perform tests according to the gap tolerance of the combination of wood buffer bodies.

[0048] This makes it possible to collect basic data on wood to evaluate the relationship between the size of the voids and the cushioning performance of wooden buffers.

[0049] Furthermore, the first movable wall 5a and the second movable wall 5b may be in contact with the nearest third surrounding simulated wood test piece 3c and second surrounding simulated wood test piece 3b before the test. The first sliding mechanism 6a and the second sliding mechanism 6b installed on the first movable wall 5a and the second movable wall 5b are equipped with the first movable wall load cell 7a and the second movable wall load cell 7b, so that the test can be performed with the side surfaces compressed as the initial state.

[0050] Furthermore, the moisture content of the wood test piece 2 is easily affected by the surrounding environment. This affects the dimensions of the wood test piece 2, so there is a risk that a compression test cannot be carried out using a fixed-size peripheral restraint jig as in conventional testing methods.

[0051] In contrast, in the wood compression testing device 1 of this embodiment, the first movable wall 5a and the second movable wall 5b can be slid, so it can flexibly respond even if the moisture content changes depending on the surrounding environment and the dimensions of the wood test piece 2 change.

[0052] Furthermore, since the strength of the wood test piece 2 also varies depending on the moisture content, when the moisture content is used as a parameter for the test condition, by using the wood compression testing device 1 of this embodiment, it is possible to test under many conditions for each test piece dimension of the wood test piece 2 without adjusting the dimensions of the restraint jig.

[0053] Furthermore, the wood test piece 2 is a material whose strength and dimensions are likely to change even when subjected to thermal history for a long period of time. Therefore, when testing to obtain the effect of thermal history on compressive strength, the wood compression testing device 1 of this embodiment makes it possible to perform tests that respond to dimensional changes in the wood test piece 2 under various test piece conditions.

[0054] In addition, using the wood compression testing device 1 of this embodiment, the compression load of the wood test piece 2 is measured using the load cell 12 for the compression jig and the compression displacement is measured using the displacement meter 13, and the reaction force on the side of the wood test piece 2 is measured via the first movable wall 5a and the second movable wall 5b using the load cell 7a for the first movable wall and the load cell 7b for the second movable wall, thereby making it possible to evaluate the compression behavior when the wood is combined.

[0055] In addition, by simultaneously inserting into the test chamber 10 the first surrounding simulated wood test piece 3a, the second surrounding simulated wood test piece 3b, the third surrounding simulated wood test piece 3c, and the fourth surrounding simulated wood test piece 3d, which restrain the periphery, in addition to the wood test piece 2 to be compressed, the interference effect between pieces of wood when they are combined can be reproduced.

[0056] With the wood compression testing device 1 of this embodiment, the reaction force behavior when the wood test piece 2 is compressed can be measured under conditions where the lateral constraint conditions of the wood test piece 2 are changed, and the stress-strain relationship that represents the wood compression behavior when the wood test pieces 2 are combined can be determined in a state where the gaps between the pieces of wood in the combined wood are reproduced.

[0057] Therefore, according to this embodiment, when carrying out a compression test on a wood test piece 2, it is possible to carry out the test on a single wood test piece 2 for wood test pieces 2 under various different conditions.

[0058] In this embodiment, the wood compression test apparatus 1 is configured using the first surrounding simulated wood test piece 3a, the second surrounding simulated wood test piece 3b, the third surrounding simulated wood test piece 3c, and the fourth surrounding simulated wood test piece 3d. However, the first surrounding simulated wood test piece 3a, the second surrounding simulated wood test piece 3b, the third surrounding simulated wood test piece 3c, and the fourth surrounding simulated wood test piece 3d are not necessarily required components of the wood compression test apparatus of the present invention. Even without the first surrounding simulated wood test piece 3a, the second surrounding simulated wood test piece 3b, the third surrounding simulated wood test piece 3c, and the fourth surrounding simulated wood test piece 3d, the same effect as in the above-described embodiment can be obtained (in this case, the distance between the first movable wall 5a and the second movable wall 5b and the wood test piece 2 can be adjusted).

[0059] Furthermore, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0060] 1...wood compression test apparatus, 2...wood test piece, 3a...first ambient simulated wood test piece, 3b...second ambient simulated wood test piece, 3c...third ambient simulated wood test piece, 3d...fourth ambient simulated wood test piece, 4a...first fixed wall, 4b...second fixed wall, 5a...first movable wall, 5b...second movable wall, 6a...first sliding mechanism, 6b...second sliding mechanism, 7a...load cell for first movable wall, 7b...load cell for second movable wall, 8a...first reaction wall, 9...surface plate, 10...test chamber, 11...compression jig, 12...load cell for compression jig, 13...auxiliary jig, 14...displacement meter.

Claims

1. A wood compression testing device comprising: a test chamber having two pairs of fixed walls and movable walls facing the fixed walls; the movable walls each equipped with a load cell for the movable walls that measures the contact pressure between the movable walls and wood test pieces installed in the test chamber; and a sliding mechanism that can adjust the distance between the movable walls and the fixed walls facing the movable walls; the distance between the movable walls and the wood test pieces can be adjusted by sliding the movable walls with the sliding mechanism.

2. A test chamber is formed by two pairs of fixed walls and movable walls facing the fixed walls, and a wood test piece and a surrounding simulated wood test piece are installed in the test chamber so as to surround the wood test piece and simulate a state in which wood pieces are assembled together, The movable wall is equipped with a load cell for the movable wall that measures the contact pressure between the wood test piece installed in the test chamber and the movable wall, and is also equipped with a sliding mechanism that can adjust the distance between the movable wall and the opposing fixed wall, and the distance between the movable wall and the surrounding simulated wood test piece can be adjusted by sliding the movable wall with the sliding mechanism.

3. The wood compression testing device according to claim 2, the fixed wall is made up of first and second fixed walls, and the movable wall is made up of first and second movable walls facing the first and second fixed walls, respectively, and the first and second fixed walls and the first and second movable walls form a test chamber; The first and second movable walls are equipped with first and second movable wall load cells that measure the contact pressure between the first and second movable walls and the wood test pieces installed in the test chamber, respectively, and are also equipped with first and second sliding mechanisms that can adjust the distance between the first and second movable walls and the first and second fixed walls that face them, respectively, and the distance between the first and second movable walls and the surrounding simulated wood test pieces can be adjusted by sliding the first and second movable walls with the first and second sliding mechanisms, respectively.

4. The wood compression testing device according to claim 3, A wood compression testing device characterized in that the load cell for the first movable wall is integrated with the first slide mechanism, and the load cell for the second movable wall is integrated with the second slide mechanism.

5. The wood compression testing device according to claim 4, The first movable wall is connected to the first reaction wall via the first slide mechanism, and the second movable wall is connected to the second reaction wall via the second slide mechanism.

6. The wood compression testing device according to claim 5, A wood compression testing device further comprising a compression jig for compressing the wood test piece, wherein the compression jig incorporates a compression jig load cell for measuring the compressive force of the compression jig.

7. The wood compression testing device according to claim 6, A wood compression testing device characterized in that the compression jig has a displacement meter built in to measure compression displacement.

8. The wood compression testing device according to claim 7, 1. A wood compression testing device, comprising: an auxiliary jig disposed between the compression jig and the wood test piece;

9. The wood compression testing device according to claim 8, 10. A wood compression testing device, wherein the auxiliary jig has a surface that comes into contact with the wood test piece and has the same shape as the wood test piece.

10. A method for wood compression testing, characterized in that a test chamber is constructed having two pairs of fixed walls and movable walls facing the fixed walls, the movable walls are equipped with a movable wall load cell that measures the contact pressure between the movable walls and wood test pieces installed in the test chamber, and are equipped with a sliding mechanism that can adjust the distance between the movable walls and the fixed walls facing the movable walls, and the distance between the movable walls and the wood test pieces is adjusted by sliding the movable walls with the sliding mechanism.

11. A test chamber is configured with two pairs of fixed walls and movable walls facing the fixed walls, and a wood test piece and a surrounding simulated wood test piece are installed in the test chamber so as to surround the wood test piece and simulate a state in which wood pieces are assembled together, The movable wall is equipped with a load cell for the movable wall that measures the contact pressure between the wood test piece installed in the test chamber and the movable wall, and is also equipped with a sliding mechanism that can adjust the distance between the movable wall and the opposing fixed wall, and the distance between the movable wall and the surrounding simulated wood test piece is adjusted by sliding the movable wall with the sliding mechanism.

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