Restraining and fixing device for measuring elastic modulus of cylindrical wood test piece

Abstract

The utility model discloses a restraining and fixing device for measuring the elastic modulus of a cylindrical wood test piece, which comprises a base, and a mounting seat is formed on the base; the anti-instability sleeve forms a mounting channel in the length direction, and the mounting channel forms a plurality of mounting stations in the length direction; the multiple linear bearings are arranged on the multiple mounting stations correspondingly, and the axes of the multiple linear bearings are aligned with one another so as to be used for mounting the cylindrical wood; the number of the fixing sleeves is two, the fixing sleeves are symmetrically arranged at the two ends of the mounting pipe, the upper fixing sleeve and the lower fixing sleeve are used for being connected with a force measuring sensor and a base of a mechanical testing machine respectively, stress and deformation are measured through the function of the mechanical testing machine, and the rift-grain tensile elastic modulus and the rift-grain compressive elastic modulus can be measured on the same wood test piece; the test piece is simple in shape and does not depend on a strain gauge or an extensometer to measure deformation any more, and the difficulty and cost of test piece machining are greatly reduced.

Description

Technical Field

[0001] This utility model relates to the field of measurement technology, and more specifically to a constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens. Background Technology

[0002] Currently, dumbbell-shaped specimens are typically used to measure the tensile modulus of elasticity of wood along the grain to ensure force transfer, while short wooden column specimens are used to prevent bending during the measurement of the compressive modulus of elasticity. This means that the tensile and compressive moduli of elasticity cannot be measured using the same specimen. Strain gauges are required to detect deformation during loading. However, the base and adhesive layer of the strain gauge also constrain the object being measured during deformation, leading to underestimation of the strain measurement results. Furthermore, strain gauge measurements require the use of a strain gauge for each wood specimen, resulting in relatively high measurement costs. Using an extensometer instead of strain gauges is more complex and prone to errors due to improper operation; therefore, the measurement method needs improvement. Utility Model Content

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a constraint and fixing device for measuring the elastic modulus of wood using a slender cylindrical specimen. This device can measure both tensile and compressive elastic moduli using the same specimen and avoids the use of strain gauges and extensometers, thereby reducing testing difficulty and cost.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A constraint fixing device for measuring the elastic modulus of cylindrical wood specimens includes an anti-instability sleeve, wherein the anti-instability sleeve forms an installation channel along the length direction, and the installation channel forms multiple installation positions along the length direction;

[0006] Multiple linear bearings are respectively disposed at multiple installation stations, and the axes of the multiple linear bearings are aligned with each other for installing cylindrical timber.

[0007] Two fixed sleeves are symmetrically arranged at both ends of the anti-instability sleeve. The upper and lower fixed sleeves are used to connect the mechanical testing machine and the base, respectively.

[0008] As a further improvement of this utility model, the fixing sleeve includes two interlocking arc-shaped plates, which are connected by a hose clamp, and the hose clamp is provided with a tightening bolt for adjusting the tightness.

[0009] As a further improvement of this utility model, the anti-instability sleeve includes two plates that are joined together. The edges of the two plates extend outward to form a mounting surface. The mounting surface is provided with connecting holes and is connected to each other by bolts.

[0010] As a further improvement of this utility model, the anti-instability sleeve is provided with multiple detachable brackets along the axial direction, and the installation station is the gap formed between adjacent brackets corresponding to the installation channel.

[0011] As a further improvement of this utility model, the anti-instability sleeve is provided with a plurality of positioning holes along the length direction, and the card seat is provided with an installation part corresponding to the positioning hole and is engaged with the positioning hole.

[0012] As a further improvement of this utility model, positioning holes are arranged along the length of both plates, and the card holder includes two interlocking arc-shaped seats, which are respectively set for the two plates.

[0013] As a further improvement of this utility model, it also includes a bracket, wherein the anti-instability sleeve is fixed to the base by the bracket, the bracket includes a sleeve and connecting columns symmetrically arranged on the sleeve, the sleeve is used to fit the anti-instability sleeve, and the two ends of the connecting columns are respectively connected to the sleeve and the base.

[0014] As a further improvement of this utility model, each of the two fixed sleeves is provided with a pin hole at the end away from the anti-instability sleeve.

[0015] The beneficial effects of this utility model are:

[0016] 1. The method of fixing with anti-instability sleeve and fixed sleeve can be applied to long wood specimens, which makes the deformation of wood specimens larger during the elastic modulus measurement. Thus, the deformation can be directly measured by the sensor of the mechanical testing machine, eliminating the need to use strain gauges or extensometers and reducing experimental costs.

[0017] 2. By connecting the mechanical testing machine with the upper fixed sleeve, it is possible to measure the tensile modulus of elasticity and the compressive modulus of elasticity along the grain on the same wood specimen. Moreover, the specimen shape is simple, which greatly reduces the difficulty and cost of specimen processing.

[0018] 3. After the fixed sleeve is connected to the mechanical testing machine, the wood is constrained by the linear bearing to prevent the wood specimen from bending and deforming during the test, thereby ensuring the measurement accuracy. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall installation of the first embodiment of this utility model;

[0020] Figure 2 This is a schematic diagram of the linear bearing installation according to the first embodiment of this utility model;

[0021] Figure 3 This is a schematic diagram of the fixing sleeve in the first embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the card holder installation according to the second embodiment of this utility model.

[0023] Reference numerals: 1. Base; 2. Mounting seat; 3. Anti-instability sleeve; 4. Mounting channel; 5. Linear bearing; 6. Fixing sleeve; 7. Mechanical testing machine; 8. Curved plate; 9. Hose clamp; 10. Tightening bolt; 11. Plate; 12. Mounting surface; 13. Connecting hole; 14. Card holder; 15. Positioning hole; 16. Mounting part; 17. Curved seat; 18. Bracket; 19. Sleeve; 20. Connecting column; 21. Pin hole. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Identical components are indicated by the same reference numerals.

[0025] Figure 1-3 As a first embodiment of the present invention, a constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens includes a base 1, on which a mounting seat 2 is formed, which is used for preliminary positioning of the circular wood.

[0026] It also includes an anti-instability sleeve 3, which forms an installation channel 4 along its length, and the installation channel 4 forms multiple installation stations along its length.

[0027] It also includes multiple linear bearings 5, which are respectively disposed at multiple installation stations. The axes of the multiple linear bearings 5 ​​are aligned with each other for installing cylindrical timber. In this embodiment, the linear bearings 5 ​​are interlocked with the installation stations.

[0028] It also includes two fixed sleeves 6, which are symmetrically arranged at both ends of the anti-instability sleeve 3. The upper and lower fixed sleeves 6 are used to connect the mechanical testing machine sensor and the base 1 respectively. At the same time, the axes of the two fixed sleeves 6 and multiple linear bearings 5 ​​are aligned with each other to ensure the constraint of the circular wood specimen.

[0029] The fixed sleeve 6 includes two interlocking arc-shaped plates 8, which are connected by a hose clamp 9. The hose clamp 9 is provided with a tightening bolt 10 for adjusting the tightness. The hose clamp fixing method can ensure the connection strength and stability of the two arc-shaped plates after they are interlocked, and at the same time make the tightness adjustment more convenient.

[0030] When it is necessary to test the tensile and compressive modulus of elasticity of wood along the grain, the following steps are included:

[0031] S1. Insert the wood specimen into the anti-instability sleeve 3, and make both ends of the wood specimen protrude.

[0032] S2. Apply strong adhesive within 5cm of both ends of the wood specimen, and then join the two arc-shaped plates of the fixing sleeve 6 at the adhesive application point to complete the connection with the wood specimen.

[0033] S3. Place the hose clamp at the middle height position outside the fixed sleeve 6 and tighten it with the loosening bolt.

[0034] S4. Connect the upper and lower fixed sleeves 6 to the sensor and base of the mechanical testing machine, respectively.

[0035] S5. Compressive modulus of elasticity test: The mechanical testing machine 7 is slowly lowered by 0.5-1.0 mm at a rate of 1 mm / min-5 mm / min, and the force-displacement curve of the loading process is output. After the loading process is completed, the mechanical testing machine is returned to the zero-load position. This step can be repeated multiple times.

[0036] S6. Tensile modulus of elasticity test: Operate the mechanical testing machine 7 to slowly rise 0.5-1.0 mm at a rate of 1 mm / min-5 mm / min, and output the force-displacement curve of the loading process. After the loading is completed, operate the mechanical testing machine to return to the zero load position. This step can be repeated multiple times.

[0037] Preferably, it also includes a bracket 18, and the anti-instability sleeve 3 is fixed to the base 1 through the bracket 18. The bracket 18 includes a sleeve 19 and connecting posts 20 symmetrically arranged on the sleeve 19. The sleeve 19 is used to fit the anti-instability sleeve 3, and the two ends of the connecting posts 20 are respectively connected to the sleeve 19 and the base 1.

[0038] Preferably, each of the two fixing sleeves 6 has a pin hole 21 at the end away from the anti-instability sleeve 3.

[0039] Because of the constraint method of using multiple linear bearings 5 ​​and two fixed sleeves 19, the tensile modulus of elasticity parallel to the grain and the compressive modulus of elasticity parallel to the grain can be measured on the same wood specimen. Furthermore, the overall structure of the specimen and the device is simple, which greatly reduces the difficulty and cost of testing.

[0040] Figure 4 This is the second embodiment of the present invention. The difference from the first embodiment is that the anti-instability sleeve 3 includes two plates 11 that are spliced ​​together. The edges of the two plates 11 extend outward to form a mounting surface 12. The mounting surface 12 is provided with a connecting hole 13 and is connected to each other by bolts.

[0041] The two interlocking plates 11 facilitate the installation of the linear bearing 5.

[0042] Meanwhile, in this embodiment, the sleeve 19 is fitted onto the non-mounting surface 12 area of ​​the plate 11 to complete the connection of the anti-instability sleeve 3.

[0043] Preferably, the anti-instability sleeve 3 is provided with multiple retaining seats 14 detachably along the axial direction. The installation station is the gap formed between adjacent retaining seats 14 corresponding to the installation channel 4. The retaining seats 14 can be set to select an appropriate number of linear bearings 5 ​​according to the testing needs of different lengths of wood.

[0044] Preferably, the anti-instability sleeve 3 has multiple positioning holes 15 along its length, and the card holder 14 has an installation part 16 corresponding to the positioning holes 15 and engages with the positioning holes 15, thereby realizing the quick assembly and disassembly of the card holder 14.

[0045] Preferably, positioning holes 15 are arranged along the length of both plates 11, and the card holder 14 includes two arc-shaped seats 17 that fit together, with the two arc-shaped seats 17 respectively corresponding to the two plates 11.

[0046] The arc-shaped base 17 allows for a suitable assembly method, facilitating the installation and shaping of the card holder 14.

[0047] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens, characterized in that, Includes a base (1), on which a mounting base (2) is formed; Anti-instability sleeve (3), wherein the anti-instability sleeve (3) forms an installation channel (4) along the length direction, and the installation channel (4) forms multiple installation positions along the length direction; Multiple linear bearings (5) are respectively disposed at multiple installation positions, and the axes of the multiple linear bearings (5) are aligned with each other for installing cylindrical timber; Fixed sleeves (6), two of which are symmetrically arranged at both ends of the anti-instability sleeve (3), and the upper and lower fixed sleeves (6) are used to connect the mechanical testing machine (7) and the base (1) respectively.

2. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 1, characterized in that, The fixed sleeve (6) includes two interlocking arc plates (8), which are connected by a hose clamp (9). The hose clamp (9) is provided with a tightening bolt (10) for adjusting the tightness.

3. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 1, characterized in that, The anti-instability sleeve (3) includes two plates (11) that are joined together. The edges of the two plates (11) extend outward to form a mounting surface (12). The mounting surface (12) is provided with a connecting hole (13) and is connected to each other by bolts.

4. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 3, characterized in that, The anti-instability sleeve (3) is provided with multiple detachable card holders (14) along the axial direction. The installation station is the gap formed between adjacent card holders (14) corresponding to the installation channel (4).

5. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 4, characterized in that, The anti-instability sleeve (3) has multiple positioning holes (15) along its length. The mounting base (14) has a mounting part (16) corresponding to the positioning holes (15) and is engaged with the positioning holes (15).

6. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 5, characterized in that, The two plates (11) are provided with positioning holes (15) along the length direction. The card holder (14) includes two arc-shaped seats (17) that fit together with each other. The two arc-shaped seats (17) are respectively provided for the two plates (11).

7. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 1, characterized in that, It also includes a bracket (18), the anti-instability sleeve (3) is fixed to the base (1) by the bracket (18), the bracket (18) includes a sleeve (19) and connecting columns (20) symmetrically arranged on the sleeve (19), the sleeve (19) is used to fit the anti-instability sleeve (3), and the two ends of the connecting column (20) are respectively connected to the sleeve (19) and the base (1).

8. The constraint and fixing device for measuring the elastic modulus of cylindrical wood specimens according to claim 1, characterized in that, Both of the fixed sleeves (6) have pin holes (21) at the ends away from the anti-instability sleeve (3).

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