CN110082209A - A kind of controllable timber micro mechanics measuring device of moisture content and its measurement method - Google Patents

Abstract

The invention relates to a wood micromechanical measuring device with controllable moisture content, comprising a lifting device; a connecting device is used for connecting the lifting device and the first end of the wood fiber to be tested, and the lifting device pulls the wood fiber to be tested through the connecting device; The weighing device is provided with a first base, the first base is fixedly connected to the second end of the wood fiber to be measured, and the first base is placed on the weighing pan of the weighing device; the temperature and humidity container is adjustable, A heating sheet and a humidifier are arranged in the container, the weighing device and the wood fiber to be measured are placed in an adjustable temperature and humidity container, and a temperature and humidity probe for detecting the ambient temperature and humidity of the wood fiber to be measured is also arranged in the container; The wood fibers to be tested are arranged vertically. The device can detect the elastic modulus and tensile length of wood fibers under different moisture contents; the measurement problem in the field of wood is solved, and the device is simple, the cost is low, and the measurement accuracy is high.

Description

A kind of wood micromechanics measuring device with controllable moisture content and its measuring method

technical field

The invention relates to a measuring device, in particular to a wood micromechanical measuring device and a measuring method thereof with controllable moisture content.

Background technique

A single fiber of wood is the main bearing unit of wood, and the mechanical properties of fiber cell walls have a crucial impact on the entire wood. The elastic modulus and tensile strength of the wood fibers to be tested under different moisture contents will be larger. In practical applications such as wood processing, pulp and paper, medium density fiberboard, etc., the elastic modulus and tensile strength need to be considered to ensure that they can fully play their role.

Elastic modulus is an important performance parameter of materials. From a macroscopic point of view, elastic modulus is a measure of the ability of an object to resist elastic deformation, and an important index to measure the stiffness characteristics of wood. The currently recognized measurement technology is the static bending method, but the measurement process of this method is too cumbersome, the test time is long, and it is destructive, which can no longer meet the requirements of modern continuous production. In recent decades, the measurement technology of elastic modulus has been continuously updated and upgraded. The widely used measurement technologies include stress wave method, vibration detection method, and the testing principle of stress wave velocity detector: one end of the wood is affected by the shock wave, The stress wave propagates back and forth in the wood. By measuring the propagation velocity of the stress wave in the wood, the elastic modulus value of the wood is determined, and the mechanical strength of the wood is finally estimated. The vibration detection method is based on the mathematical relationship between the wood resonance frequency and the elastic modulus. The principle is to use vibration measurement to obtain the resonance frequency of the wood and then obtain the dynamic elastic modulus of the wood.

Tensile strength refers to the maximum force that the specimen bears during the tensile process, when the material passes through the yield stage and then enters the strengthening stage as the transverse cross-sectional size is significantly reduced, divided by the stress obtained by dividing the original cross-sectional area of the specimen. , known as tensile strength or strength limit, which represents the maximum ability of a material to resist failure under tension. A common method is to test materials for tensile strength using a tensile testing machine.

Although there are many studies on the testing of mechanical properties of solid materials such as wood, and many results have been summarized, there are relatively few micromechanical measurement methods for single wood fibers with different moisture contents. Conventional wood fibers to be tested are Most of the test methods are difficult because the test fibers are very small and easily deformed under small loads. Since a single fiber is the main load-bearing structural unit of wood, the mechanical properties of fiber cell walls have a crucial impact on the macroscopic mechanical properties of wood. The study of the mechanical properties of a single fiber of wood is actually the study of wood mechanics. The transition from macro to micro research.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device that can control the moisture content of wood fibers and can measure the micromechanical properties of wood fibers under the moisture content, the device can detect the elastic modulus and tensile length of wood fibers; The measurement is difficult, the equipment is simple, the cost is low, and the measurement accuracy is high.

The technical scheme adopted by the present invention is as follows: a moisture content controllable wood micromechanics measuring device, including a lifting device;

a connecting device for connecting the lifting device and the first end of the wood fiber to be tested, and the lifting device pulls the wood fiber to be tested through the connecting device;

A weighing device, a first base is arranged on the weighing device, the first base is fixedly connected to the second end of the wood fiber to be tested, and the first base is placed on the scale of the weighing device redistribute;

An adjustable temperature and humidity container, a heating plate and a humidifier are arranged in the container, the weighing device and the wood fiber to be measured are placed in the temperature and humidity container, and a a temperature and humidity probe for detecting the ambient temperature and humidity of the wood fiber to be measured;

The wood fibers to be tested are arranged vertically.

Further, the lifting device is a slide-away microtome, the connecting device is fixedly connected to the slide-away microtome through a specimen holder, and the step of the slide-away microtome is micron level.

Further, the specimen holder includes a second base, a slide plate and an adjusting rod, the second base is provided with a vertical plate, the vertical plate is arranged opposite to the slide plate, and a chute is also provided on the second base , the sliding plate approaches or moves away from the vertical plate in a one-dimensional direction along the chute, and the sliding plate clamps the connecting device between the sliding plate and the vertical plate through the adjusting rod.

Further, a column is fixed on the second base, and a screw hole is arranged on the column, and the axial direction of the screw hole is consistent with the moving direction of the slide plate. After passing through the stud, the sliding plate is connected, and the clamping force of the sliding plate and the vertical plate on the connecting device is adjusted by rotating the adjusting rod.

Further, the connecting device is an L-shaped bracket, one end of the L-shaped bracket is fixedly connected to the lifting device, and the other end is connected to the first end of the wood fiber to be tested.

Further, the wood fiber to be tested and the connecting device are bonded by a UV-curable adhesive.

Further, the first base is a copper block, and the mass of the copper block is 30-100 g; the first base and the wood fiber to be tested are firmly bonded with an ultraviolet light curing adhesive.

Further, the weighing device is an electronic balance.

Further, the humidifier is a small humidifier that humidifies when power is turned on, and stops humidifying when power is turned off, and the spray is uniform and the size of the spray volume can be adjusted; the humidifier is inserted on the humidity controller panel, and the temperature and humidity It is switched on and off.

Further, the heating sheet is a heating sheet that heats when power is turned on, and stops heating when power is turned off, and its heating temperature ranges from 0 to 55°C.

Further, there are two independent sockets on the temperature and humidity controller, which are respectively connected to the power supply of the heating plate and the humidifier. The temperature and humidity controller can detect a temperature range of 0 to 55°C, and the humidity range is such that the humidity in the glass box can be controlled at ambient humidity -100%; the temperature and humidity controller is provided with a temperature probe and a humidity probe.

The invention also provides a measurement method of a wood micromechanics measurement device with controllable moisture content, comprising the following steps

S01 reads the initial reading of the weighing device; adjusts the temperature and humidity in the container to a set value;

S02 pulls the wood fiber to be tested by the lifting device and the connecting device, records the displacement of the lifting device and the reading of the weighing device, and obtains the tensile load according to the reading and the initial reading of the weighing device, Obtain the absolute elongation under the load according to the displacement of the lifting device;

S03 obtains the elastic modulus and tensile strength of the wood fiber to be tested according to the tensile load, breaking load and absolute elongation.

Further, the present invention uses the temperature and humidity probe to detect the temperature and humidity in the glass box and reflects it on the temperature and humidity controller in real time, and sets the upper and lower limit values of the temperature and humidity controller. Once the temperature and humidity are lower than or higher than the set value, the temperature and humidity control The device will turn on or off the power of the heating plate and humidifier accordingly, adjust the temperature and humidity in the box, and thus control the moisture content of the wood. Under certain temperature and humidity conditions, use a precision electronic balance to measure the force, which includes the following steps

(1) measure the cross-sectional size of the wood fiber to be tested with a high-power microscope to obtain the cross-sectional area S of the wood fiber to be tested;

(2) placing the weighing device under the connecting device passing through the container, the connecting device is an L-shaped bracket, and one end of the L-shaped bracket is facing the weighing device;

(3) The wood fiber to be tested is placed on the weighing device through the first base, the L-shaped bracket is lowered to contact with the first base through the lifting device, and the center point of the first base is adjusted so that the center point of the first base is connected to one end of the L-shaped bracket The center points of the two are completely coincident, and the L-shaped bracket is vertically lifted to separate from the first base;

(4) Adhere one end of the wood fiber to be tested to the first base by using an ultraviolet curing adhesive, and fix the wood fiber to be tested on the center point of the first base;

(5) Adjust the lifting device so that the L-shaped bracket is moved down until it just touches the other end of the wood fiber to be tested, and the two are adhered with ultraviolet curing adhesive, and the reading of the weighing device is reset to zero;

(6) Adjust the temperature and humidity in the container to the set value;

(7) Within the linear elasticity range of the wood fiber to be tested, the wood fiber to be tested is stretched by controlling the lifting device to generate a tensile load F, and the lifting displacement of the recording lifting device is the single wood fiber to be tested under the load. The absolute elongation dL is recorded, and the electronic balance reading m under the elongation is recorded at the same time, and the tensile load F=-mg is calculated; according to the formula (1), the elastic modulus E of a single wood fiber to be tested is calculated,

Wherein: F is the tensile load, S is the cross-sectional area of the fiber, L is the initial length of the fiber, see step (11) for the measurement method, and dL is the elongation of the fiber;

(8) Continue to move the L-shaped bracket to stretch the wood fiber to be tested to the set distance, record the absolute elongation dL of the wood fiber to be tested and the reading m of the electronic balance, and calculate the wood fiber to be tested according to formula (1). Elastic modulus E; do at least 5 sets of data and take the average value as the elastic modulus test data;

(9) Control the lifting device to further stretch the wood fiber to be tested until the wood fiber to be tested breaks in the length direction, record the reading m _c of the electronic balance when the break occurs, and calculate the critical load F _c =-m _c g;

(10) Calculate the tensile strength σ of the wood fiber to be tested according to formula (2),

Among them, F _c is the critical load when the fiber breaks, and S is the cross-sectional area of the fiber.

Further, the lifting device is a slide-away slicer, and the initial length measurement method of the wood fiber to be measured is:

When the end of the wood fiber to be tested is bonded to the L-shaped bracket and the tensile load of the wood fiber to be tested is zero, the step of the slide-away slicer is zero;

After the wood fiber to be tested is broken, the balance indication will automatically return to zero. Operate the slide-away slicer to move the L-shaped bracket down until the UV-curable glue on the L-shaped bracket just touches the UV-curable glue on the base. At this time, the balance indicates the number. If it is just positive, record the step length at this time, which is the initial length L of a single wood fiber.

Description of drawings

Fig. 1 is the schematic diagram of the wood micromechanics measuring device with controllable moisture content of the present invention;

Figure 2 is a front view of the specimen holder in the present invention;

Figure 3 is a left side view of the specimen holder in the present invention;

Figure 4 is a plan view of the specimen holder in the present invention;

Fig. 5 is a schematic diagram of the fixation of wood fibers in the micromechanical measurement method of wood with different moisture contents in the present invention;

Fig. 6 is a fitting diagram of the stress increment-strain increment data measured on Chinese fir using the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

The invention provides a micromechanical measurement method and device for testing micron-level moisture content controllable wood by using a temperature and humidity controller to control the moisture content of wood, and directly applying a tensile load in the vertical direction to wood fibers with different moisture contents to be tested. .

In the present invention, within the set temperature and humidity range, the temperature and humidity controller controls the connection or disconnection of the heating plate and the humidifier, the precision electronic balance measures the load size, and designs a vertical The L-shaped bracket that measures the tensile load of the wood fiber is used to drive the L-shaped bracket to move up in the vertical direction, so that the fiber is stretched and deformed within the linear elastic range, and the distance displayed by the control panel of the slicing machine is directly used as The amount of fiber deformation and elongation, the elastic modulus of a single wood fiber to be tested is calculated according to the relationship of stress increment and strain increment, and the wood fiber to be tested is further stretched until the wood fiber to be tested breaks. The load value and fiber size can calculate the tensile strength of the fiber.

The elastic modulus is measured by the relationship between the stress increment and the strain increment. In order to solve the problem of precise measurement of the load, an L-shaped bracket is designed that directly acts on the tensile load of the wood fiber to be measured. Uniaxial tensile stress, the fiber length is L under the microscope, and the L-shaped bracket is moved by operating the slide-away slicer, so that the wood fiber to be tested is displaced in the length direction, and then its elastic modulus is calculated according to the definition of elastic modulus. . When the tensile load is further increased until the wood fiber to be tested breaks, the tensile strength can be calculated from the critical load value of breaking and the cross-sectional area of the wood fiber to be tested.

Therefore, the present invention specially designs a wood micromechanics measuring device with controllable moisture content. Referring to FIG. 1, the measuring device mainly includes a slide-away slicer 1, an L-shaped bracket 2, an electronic balance 3, a first base 4 of the wood fiber to be measured, a container, a heating sheet 15, a humidifier 12, a temperature and humidity controller 13, etc. part. In this embodiment, the container is a glass box, an L-shaped bracket 2 is fixed on the specimen holder 6 of the slide-away microtome 1, and the center of the other end of the L-shaped bracket 2 is connected to the wood fiber 5 to be tested; the electronic balance 3, the heating plate 15 is attached to the inner wall of the glass box 14, the humidifier 12, the probe 11 and a part of the L-shaped bracket 2 are placed in the acrylic glass box 14, the heating sheet 15, the humidifier 12, the humidity probe 11 and the temperature probe 16 pass through The humidity controller 13 placed outside the glass box controls the opening and closing, the humidity probe 11 and the temperature probe 16 are placed near the wood fiber 5 to be tested and away from the humidifier 12; the electronic balance 3 is placed on the L-shaped bracket 2 In the lower part, the first base 4 of the wood fiber to be tested is placed on the electronic balance 3, the wood fiber 5 to be tested is installed on the center point of the first base 4, and the electronic balance 3 placed on the first base is connected without a connector. ; The slide-away microtome 1 is also provided with an adjustment knob 10, a control panel 8 and a step button 9 for moving the specimen holder 6 up or down.

Among them, the step range of the slide-away microtome 1 is 0-120 μm, and the minimum step is 0.25 μm, which is set by the step button 9 on the control panel 8 . To ensure accuracy, the minimum step of 0.25 μm is selected as the standard scale. The vertical moving distance of the specimen holder 6 is 40 mm, and the specimen holder 6 is used to fix one end of the L-shaped bracket 2 in the present invention, as shown in FIG. 1 . The adjustment knob 10 on the left side of the slicer, each time it is lifted up, the L-shaped bracket 2 rises correspondingly, and the wood fiber 5 to be tested produces a corresponding elongation. From the control panel 8, it can be obtained that the wood fiber to be tested moves to any vertical position resulting displacement.

Among them, the specimen holder 6 is made of light aluminum alloy, and its structure is shown in Fig. 2, Fig. 3 and Fig. 4, including an adjusting rod 7, a chute 17, a column 18, a second base 19, a sliding plate 20, and sliding feet 21 and other components. One end of the second base 19 is provided with a vertical plate, the vertical plate is opposite to the slide plate, and the other end is provided with a column 18. The column 18 is a part of the second base 19. The column 18 is integrally formed with the second base 19 and is opposite to the slide plate. The upright column 18 is provided with a threaded hole, which is used to provide support for the adjustment rod 7 to control the front and rear movement of the sliding plate 20 ; The sliding foot 21 is a part of the sliding plate 20, and the adjusting rod 7 is an elongated screw, which is fixedly connected to the sliding plate 20 through the threaded hole of the upright column 18. The three sliding feet 21 move synchronously. Put the L-shaped bracket 2 between the second base 19 and the sliding plate 20 , turn the adjusting rod 7 clockwise to push the sliding plate 20 until it cannot rotate, and clamp the L-shaped bracket 2 .

Among them, by operating the adjustment knob 10 , the computer built in the slide-away microtome 1 controls the specimen holder 6 to move up and down.

Among them, the L-shaped bracket 2 is made of lightweight aluminum alloy, one end is fixed in the specimen holder 6 of the slide-away microtome 1, and the other end is connected with the wood fiber 5 to be tested. The diagonal intersection of the port is the bracket 2 and the The connection points of the wood fibers 5 to be tested are firmly bonded with UV-curable adhesive. The vertical displacement of the L-shaped bracket 2 is used to stretch the wood fiber 5 to be tested in the vertical direction.

Among them, the electronic balance 3 and the slide-away slicer 1 are placed on the same horizontal workbench; the composition of the wood fiber fixing system to be tested is shown in Figure 5, including the wood fiber to be tested 5, the L-shaped bracket 2 and the wood fiber to be tested. The first base 4 . A copper block is used as the first base 4 of the wood fiber to be tested and placed on the electronic balance 3. The center point of the first base 4 of the wood fiber to be tested is the connection point of the wood fiber 5 to be tested and the first base 4. The first base 4 and the wood fiber 5 to be tested are firmly bonded with UV-curable adhesive.

The basic detection steps of the present invention include measuring the length and cross-sectional size of the wood fiber to be tested, fixing the wood fiber to be tested, adjusting the humidity in the glass box, and then pulling the wood fiber in the length direction within the linear elasticity range of the wood fiber to be tested. Elongation, record the corresponding elongation of the wood fiber to be tested, and read the reading of the electronic balance under the corresponding elongation to calculate the tensile load of the wood fiber to be tested under the corresponding moisture content. According to the obtained load increment and corresponding elongation and the cross-sectional area of the wood fiber to be tested, the elastic modulus of the wood fiber to be tested under the corresponding moisture content is calculated. The wood fiber to be tested continues to stretch until the fiber breaks, and the critical load is calculated, and its strength is calculated from the critical load and the cross-sectional area of the wood fiber to be tested. The test method is as follows:

(1) measure the cross-sectional size of the wood fiber to be tested with a high-power microscope to obtain the cross-sectional area S of the wood fiber to be tested;

(2) Place the electronic balance at the lower part of the L-shaped bracket passing through the glass box, and one end of the L-shaped bracket is fixed on the specimen controller of the slide-away microtome;

(3) Place the first base of the wood fiber to be tested on the electronic balance, adjust the position of the first base of the wood fiber to be tested and move the L-shaped bracket up and down through the specimen controller to make the center point of the first base of the wood fiber to be tested It is completely coincident with the diagonal intersection of one end of the L-shaped bracket, and then the L-shaped bracket is only displaced in the vertical direction by moving the specimen controller. The center point of the first base of the wood fiber to be tested and the diagonal intersection of the bracket section are in the same line vertical line;

(4) Adhere one end of the wood fiber to be tested to the first base of the wood fiber to be tested by using an ultraviolet curing adhesive, and the wood fiber to be tested is fixed on the center point of the first base;

(5) Adjust the adjustment knob of the slide-away slicer so that the L-shaped bracket moves down until it just touches the other end of the wood fiber to be tested, and the electronic balance reading does not change at this time; the two are adhered with ultraviolet curing adhesive, and then Then reset the reading of the electronic balance to zero;

(6) Set the temperature and humidity upper and lower limits of the temperature and humidity controller respectively, connect the power supply of the heating sheet and the humidifier to the temperature and humidity controller, and the temperature and humidity controller will automatically turn on or off within the set value range Power supply for heating sheet and humidifier; place the temperature and humidity probe near the wood fiber to be tested;

(7) Within the linear elasticity range of the wood fiber to be tested, the wood fiber to be tested is stretched by controlling the lifting and lowering of the slide-away slicer to generate a tensile load F. At this time, the displacement change displayed on the control panel of the slide-away slicer is a single The absolute elongation dL of the wood fiber to be tested under the load, and the electronic balance reading m under the elongation is recorded at the same time, and the tensile load F=-mg is calculated; according to the formula (1), calculate the single wood fiber to be tested. The elastic modulus E,

Wherein: F is the tensile load, S is the cross-sectional area of the fiber, L is the initial length of the fiber, see step (11) for the measurement method, and dL is the elongation of the fiber;

(8) Continue to move the L-shaped bracket to stretch the wood fiber to be tested to a certain distance, record the absolute elongation dL of the wood fiber to be tested and the reading m of the electronic balance, and calculate the elasticity of the wood fiber to be tested according to formula (1). Modulus E; do at least 5 sets of data and take the average value as the test data of elastic modulus;

(9) Control the slide-away slicer to further stretch the wood fiber to be tested until the wood fiber to be tested breaks in the length direction, record the reading m _c of the electronic balance when the break occurs, and calculate the critical load F _c =-m _c g;

(10) Calculate the tensile strength σ of the wood fiber to be tested according to formula (2),

Among them, Fc is the critical load when the fiber breaks, and S is the cross-sectional area of the fiber;

(11) After the wood fiber to be tested is broken, the balance indication is automatically reset to zero, and the slide-away slicer is operated to move the L-shaped bracket down until the UV-curable glue on the L-shaped bracket just touches the UV-curable glue on the first base. At this time, the balance indication is just positive, record the step length at this time, which is the initial length L of a single wood fiber to be tested.

The present invention will be described in detail below with reference to specific embodiments. The examples are only to specifically disclose the process of the present invention for testing the elastic modulus and strength of a single wood fiber to be tested with a controllable moisture content, and are not intended to limit other embodiments of the present invention.

Example: Measurement of micromechanical properties of poplar single fibers with a moisture content of 12%

The specific operation process is as follows:

(1) Single poplar fiber was selected as the experimental sample, and the cross-sectional area S=176 μm ² of the wood fiber was measured with a Japanese Olympus BX51 precision microscope.

(2) Turn on the humidifier and heating plate, and use the temperature and humidity controller to keep the acrylic glass box at a humidity of 65% and a temperature of 20°C. According to the corresponding map of wood moisture content and temperature and humidity, the moisture content of wood is 12% at this time.

(3) Adhere one end of the poplar fiber to the first base by using ultraviolet curing adhesive, and fix the poplar fiber at the center point of the first base; adjust the adjustment knob of the slide-away slicer to make the L-shaped bracket drop to the same level as the poplar fiber. The other end of the wood fiber just touches, at this time, the two are adhered with ultraviolet curing adhesive, and the poplar fiber is only under the action of its own gravity at this time, and naturally stretches between the first base and the L-shaped bracket; zero reading;

(4) Within the linear elasticity range of poplar fiber, operate the slide-away slicer to move the L-shaped bracket upward, so that the poplar fiber is stretched in the vertical direction, and the wood fiber is stretched to the absolute stretch through the control panel display. Length dL=3.50μm, the balance reading at this elongation is -0.414g, that is, the resulting tensile load F=-mg=-(-0.414)/1000×9.8N, after that, continue to move the L-shaped Bracket, stretch the wood fiber to the absolute elongation dL of 5.50μm, 7.50μm, 9.50μm, 11.5μm, the readings corresponding to the electronic balance m are -0.786g, -1.095g, -1.351g, -1.759g;

(5) Use the adjusting knob to further apply the load until the poplar fiber breaks, record the fiber elongation at break of 117 μm, the reading of the electronic balance m _c = -8.314g, and calculate the critical load F _c = -m _c g = -8.314/ 1000×9.8=0.0815N;

(6) After the wood fiber is broken, operate the slide-away slicer to move the L-shaped bracket down until the UV-curing glue on the L-shaped bracket just touches the UV-curing glue on the first base, and record the displayed step length at this time as -1054.3 μm, that is, the initial length of a single wood fiber L=1054.3 μm.

(7) According to formula (1), when the absolute elongation dL of poplar fibers with a moisture content of 12% is calculated to be 3.50 μm, 5.50 μm, 7.50 μm, 9.50 μm, and 11.5 μm, respectively, the elastic moduli of poplar fibers are respectively It is 6.96GPa, 8.46GPa, 8.59GPa, 8.11GPa, 8.99GPa, and the standard deviation is 0.77GPa. In order to further understand the reliability of its data, the stress increment-strain increment data fitting graphs under 5 different load increments were sorted out (see Figure 6). From Figure 6, it can be seen that the data points are very close to the fitting. Straight line, the correlation coefficient R=0.999, very close to 1, indicating that the linear correlation is good and the data is reliable.

(8) According to the formula (2), the tensile strength of the poplar single fiber with a moisture content of 12% can be calculated to be 463 MPa.

To sum up, the method and device for measuring the micromechanics of wood single fiber according to the present invention can be widely used in the field of wood, and can test wood fibers of several microns to dozens of microns without adding new equipment. The slide-away slicer in the wood laboratory can be modified. The cost is low and the operation is simple. It is of great significance for the evaluation of the mechanical properties of wood fibers and the modification and utilization of experimental equipment.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the technical principle of the present invention, several improvements and modifications can also be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (10)

1. a moisture content controllable wood micromechanics measuring device, is characterized in that: comprising: lifting device; a connecting device for connecting the lifting device and the first end of the wood fiber to be tested, and the lifting device pulls the wood fiber to be tested through the connecting device; A weighing device, a first base is arranged on the weighing device, the first base is fixedly connected to the second end of the wood fiber to be tested, and the first base is placed on the scale of the weighing device redistribute; An adjustable temperature and humidity container, a heating plate and a humidifier are arranged in the container, the weighing device and the wood fiber to be measured are placed in the temperature and humidity container, and a a temperature and humidity probe for detecting the ambient temperature and humidity of the wood fiber to be measured; The wood fibers to be tested are arranged vertically. 2. The micromechanical measuring device for wood with controllable moisture content according to claim 1, wherein the lifting device is a slide-away microtome, and the connecting device is fixedly connected to the slide-away microtome through a specimen holder, The steps of the slide-away microtome are in the micrometer scale. 3 . The wood micromechanics measuring device with controllable moisture content according to claim 2 , wherein the specimen holder comprises a second base, a sliding plate and an adjusting rod, the second base is provided with a vertical plate, and the The vertical plate is arranged opposite to the sliding plate, the second base is also provided with a chute, the sliding plate approaches or moves away from the vertical plate in a one-dimensional direction along the sliding groove, and the sliding plate passes through the adjusting rod The connecting device is clamped between the sliding plate and the vertical plate. 4. The micromechanical measuring device for wood with controllable moisture content according to claim 3, characterized in that: a screw hole is provided on the second base, and the axial direction of the screw hole is consistent with the moving direction of the slide plate, so The adjusting rod is a screw rod, one end of the adjusting rod is connected to the sliding plate after passing through the stud, and the clamping force of the sliding plate and the vertical plate on the connecting device is adjusted by rotating the adjusting rod. 5 . The micromechanics measuring device for wood with controllable moisture content according to claim 1 , wherein the connecting device is an L-shaped bracket, one end of the L-shaped bracket is fixedly connected to the lifting device, and the other end is connected to the test device. 6 . the first end of the wood fiber. 6. The wood micromechanics measuring device with controllable moisture content according to claim 1, characterized in that: the wood fiber to be measured and the connecting device are bonded by a UV-curable adhesive; the first base is made of copper block, the first base and the wood fiber to be tested are firmly bonded with UV-curable adhesive. 7 . The micromechanical measuring device for wood with controllable moisture content according to claim 1 , wherein the weighing device is an electronic balance. 8 . 8. a measuring method of the moisture content controllable wood micromechanics measuring device according to claim 1, is characterized in that: comprises the following steps S01 Reset the reading of the weighing device to zero; adjust the temperature and humidity in the container to the set value; S02 Pull the wood fiber to be tested by the lifting device and the connecting device, record the displacement of the lifting device and the reading of the weighing device, and obtain the tensile load according to the reading and the initial reading of the weighing device, Obtain the absolute elongation under the load according to the displacement of the lifting device; continue to stretch until the wood fiber breaks in the length direction to obtain the breaking load of the wood fiber; S03 According to the tensile load, breaking load and absolute elongation, the elastic modulus and tensile strength of the wood fiber to be tested are obtained. 9. The measuring method of the moisture content controllable wood micromechanics measuring device according to claim 8, characterized in that: it specifically comprises the following steps (1) measure the cross-sectional size of the wood fiber to be tested with a high-power microscope to obtain the cross-sectional area S of the wood fiber to be tested; (2) placing the weighing device under the connecting device passing through the container, the connecting device is an L-shaped bracket, and one end of the L-shaped bracket is facing the weighing device; (3) The wood fiber to be tested is placed on the weighing device through the first base, the L-shaped bracket is lowered to contact with the first base through the lifting device, and the center point of the first base is adjusted so that the center point of the first base is connected to one end of the L-shaped bracket The center points of the two are completely coincident, and the L-shaped bracket is vertically lifted to separate from the first base; (4) Adhere one end of the wood fiber to be tested to the first base by using an ultraviolet curing adhesive, and fix the wood fiber to be tested on the center point of the first base; (5) Adjust the lifting device so that the L-shaped bracket is moved down until it just touches the other end of the wood fiber to be tested, and the two are adhered with ultraviolet curing adhesive, and the reading of the weighing device is reset to zero; (6) Adjust the temperature and humidity in the container to the set value; (7) Within the linear elasticity range of the wood fiber to be tested, the wood fiber to be tested is stretched by controlling the lifting device to generate a tensile load F, and the lifting displacement of the recording lifting device is the single wood fiber to be tested under the load. The absolute elongation dL is recorded, and the electronic balance reading m under the elongation is recorded at the same time, and the tensile load F=-mg is calculated; according to the formula (1), the elastic modulus E of a single wood fiber to be tested is calculated, Where: F is the tensile load, S is the cross-sectional area of the fiber, L is the initial length of the fiber, and dL is the elongation of the fiber; (8) Continue to move the L-shaped bracket to stretch the wood fiber to be tested to the set distance, record the absolute elongation dL of the wood fiber to be tested and the reading m of the electronic balance, and calculate the wood fiber to be tested according to formula (1). Elastic modulus E; do at least 5 sets of data and take the average value as the elastic modulus test data; (9) Control the lifting device to further stretch the wood fiber to be tested until the wood fiber to be tested breaks in the length direction, record the reading m _c of the electronic balance when the break occurs, and calculate the critical load F _c =-m _c g; (10) Calculate the tensile strength σ of the wood fiber to be tested according to formula (2), Among them, F _c is the critical load when the fiber breaks, and S is the cross-sectional area of the fiber. 10. The measuring method of the moisture content controllable wood micromechanics measuring device according to claim 9, wherein the lifting device is a slide-away slicer, and the initial length measuring method of the wood fiber to be measured is: When the end of the wood fiber to be tested is bonded to the L-shaped bracket and the tensile load of the wood fiber to be tested is zero, the step of the slide-away slicer is zero; After the wood fiber to be tested is broken, the balance indication will automatically return to zero, and the slide-away slicer is operated to move the L-shaped bracket down until the UV-curable glue on the L-shaped bracket just touches the UV-curable glue on the first base. At this time, the balance The indication is just positive, record the step length at this time, which is the initial length L of a single wood fiber.