A device for testing the relaxation modulus of a viscoelastic material

Abstract

The application discloses a kind of viscoelastic material relaxation modulus testing device, including bottom channel steel, bottom channel steel is equipped with fixed screw rod, L type support seat;Fixed screw rod top fixed connection is equipped with fixed end coupling, fixed end coupling is horizontally equipped with lever, and is hinged between fixed end coupling and lever by fixed end pin;L type support seat is fixedly equipped with ball screw sliding table assembly.The application has the advantages compared with prior art: simple structure, convenient to use.The high-speed rotation of stepper motor, the linear motion of sliding table, the low-speed vertical linear motion of loading rod, the spherical indenter is driven into the measured viscoelastic material, and the stress response of the material to the specific strain loading is measured by the pull pressure sensor.The movement law of the indenter is indirectly monitored by the eddy current displacement sensor whether it meets the experimental requirements.Therefore, the relaxation modulus of different viscoelastic materials can be tested and studied, and the parameterization characterization of the relaxation modulus of different viscoelastic materials is realized.

Description

Technical Field

[0001] This invention relates to the field of material relaxation modulus testing technology, specifically to a device for testing the relaxation modulus of viscoelastic materials. Background Technology

[0002] Coal resources are one of my country's most important basic energy sources, with both its production and consumption ranking first in the world. As a vital economic pillar, the transformation and upgrading of the coal industry is urgently needed. Technological advancements are key to this transformation and upgrading, with the improvement and upgrading of coal mining machinery being particularly crucial.

[0003] In coal mining machinery, belt conveyors are responsible for transporting coal both on the surface and underground, making them crucial machinery for coal production and transportation. The technological level of belt conveyors significantly impacts a company's operating costs and coal transportation efficiency. In recent years, although my country has made significant progress in some coal mining machinery such as coal mining machines and hydraulic supports, the improvement and research of belt conveyors has lagged behind, especially in reducing energy consumption. Currently, many belt conveyors feature high transport speeds, large carrying capacities, and long-distance transport capabilities, and their future development will inevitably move towards even higher speeds, larger carrying capacities, and longer distances. Therefore, energy reduction must be a key consideration when manufacturing and developing belt conveyors.

[0004] The resistance experienced by a belt conveyor during operation significantly impacts its energy consumption. Under stable operating conditions, its resistance generally includes: additional resistance, primary resistance, special resistance, and angular tilt resistance. Among these, the primary resistance has the greatest impact. Primary resistance includes the rotational resistance of the idlers, the indentation resistance generated by the contact between the idlers and the conveyor belt, the resistance generated by the repeated bending and deformation of the conveyor belt, the frictional resistance of the cleaner, and the reversing resistance of the conveyor belt.

[0005] Among the numerous operating resistances, the two that have the greatest impact on the energy consumption of belt conveyors are the rotational resistance of the idlers and the indentation resistance generated by the contact between the idlers and the conveyor belt. According to relevant data, in the operation of a high-power, high-speed belt conveyor with a length of 1 kilometer, the rotational resistance of the idlers accounts for approximately 9% of the total operating resistance, while the indentation resistance generated by the contact between the idlers and the conveyor belt accounts for approximately 61%. This shows that the indentation resistance generated by the contact between the idlers and the conveyor belt accounts for the largest proportion of the various operating resistances of the conveyor, exceeding 50%. Therefore, to achieve energy-saving and optimized design of belt conveyors, it is essential to first conduct in-depth research on the indentation resistance generated by the contact between the idlers and the conveyor belt.

[0006] Belt conveyors utilize the reciprocating rotation of a conveyor belt to transport coal. The upper cover layer, belt core, and lower cover layer are the main components of a conveyor belt. The upper and lower cover layers are generally made of natural viscoelastic materials, synthetic viscoelastic materials, and mixtures of various viscoelastic materials. Rubber, as a typical viscoelastic material, is widely used in the manufacture of the upper and lower cover layers. The upper cover layer transports and carries the material, while the lower cover layer transfers the load to the idlers. During the operation of the belt conveyor, under the action of the load and the weight of the conveyor belt itself, the contact area between the lower cover layer and the rigid idlers deforms. Because the conveyor belt, composed of rubber and other materials, has viscoelasticity, this causes stress delay at the contact area, resulting in uneven stress distribution around the contact area and causing indentation resistance at the contact point between the idlers and the lower cover layer.

[0007] Investigating the indentation resistance generated by the contact between idlers and conveyor belts is of great significance for the energy-saving optimization design of belt conveyors. However, the generation of indentation resistance is closely related to the viscoelastic properties of the conveyor belt, so it is necessary to conduct in-depth research on the viscoelastic mechanical properties of rubber materials before analyzing indentation resistance. Currently, some scholars have used numerical calculation methods based on the three-element Maxwell model of viscoelastic materials to analyze the indentation resistance under common operating conditions, but the parameters in the three-element Maxwell model used are not suitable for different viscoelastic materials.

[0008] Therefore, it is necessary to design a testing device to test and study the relaxation modulus of different viscoelastic materials, and to achieve parametric characterization of the relaxation modulus of different viscoelastic materials. Summary of the Invention

[0009] The purpose of this invention is to solve the problems mentioned in the background art and to provide a device for testing the relaxation modulus of viscoelastic materials.

[0010] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a viscoelastic material relaxation modulus testing device, including a bottom channel steel, on which a fixing screw and an L-shaped support seat are connected by bolts;

[0011] The top of the fixed screw is fixedly connected to a fixed end connector by bolts. A lever is horizontally provided on the fixed end connector. The fixed end connector and the lever are hinged by a fixed end pin.

[0012] A ball screw slide assembly is fixedly mounted on the L-shaped support base. A stepper motor is fixedly mounted on the ball screw slide assembly. A coupling is provided on the top of the stepper motor. A ball screw is connected to the top of the coupling. The ball screw slide assembly also includes a slide. The end of the lever away from the fixed screw is hinged to the slide via a slide shaft pin.

[0013] A loading rod is provided between the fixed screw and the L-shaped support base. The top of the loading rod is fixedly connected to a loading rod connector by bolts. The loading rod connector has an elliptical pin hole. The loading rod connector and the lever are hinged by a loading rod pin. The loading rod pin moves horizontally left and right in the pin hole. The bottom of the loading rod connector is provided with a spring seat, a spring, and a linear bearing in sequence. The spring and the linear bearing are both sleeved on the outside of the loading rod. A tension and compression sensor is threadedly connected to the bottom of the loading rod. The bottom of the tension and compression sensor is connected to a spherical indenter by a connecting screw. The viscoelastic material to be tested is located below the spherical indenter. The viscoelastic material to be tested is fixed to the bottom channel steel by a sample pressure plate and bolts.

[0014] A support rod is also provided on the bottom channel steel. The support rod is located between the loading rod and the L-shaped support seat. A sensor fixing plate and a support plate are horizontally provided on the support rod by bolts. The support plate is located above the sensor fixing plate. The end of the support plate away from the support rod is connected to the linear bearing. The linear bearing is vertically fixed to the support plate by bolts and nuts. An eddy current displacement sensor is fixedly provided on the end of the sensor fixing plate away from the support rod. The top of the eddy current displacement sensor is connected to the loading rod through a sensing plate. The sensing plate is fixedly connected to the loading rod by bolts.

[0015] The end of the lever furthest from the L-shaped support is provided with a weight hanging hole;

[0016] The distance between the centerline of the loading rod and the centerline of the fixing screw is one-twentieth of the distance between the centerline of the slide pin and the centerline of the fixing screw.

[0017] As a preferred embodiment, the support plate has a thickness of 5 mm.

[0018] As a preferred embodiment, the ball screw slide assembly is model CBX1204-100, and the stepper motor is model KL42BYGH405.

[0019] As a preferred embodiment, the L-shaped support plate is a 5mm thick Q235 steel sheet, processed by bending it to a 90° angle using a bending machine. The advantages of this invention compared to existing technologies are: simple structure and ease of use. The high-speed rotation of the stepper motor is converted into the linear motion of the slide table, and then the motion of the slide table is converted into the low-speed vertical linear motion of the loading rod via a lever. Simultaneously, a spherical indenter is pressed into the viscoelastic material being tested. The stress response of the material to a specific strain loading is measured by a tension / compression sensor. An eddy current displacement sensor can indirectly monitor whether the movement of the indenter meets the experimental requirements by testing the movement pattern of the sensing plate. Therefore, the relaxation modulus of different viscoelastic materials can be tested and studied, achieving parametric characterization of the relaxation modulus of different viscoelastic materials. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 This is a top view of the present invention.

[0022] Figure 3 This is a schematic diagram of the power unit of the present invention.

[0023] Figure 4 This is a schematic diagram of the loading part of the present invention.

[0024] As shown in the figure: 1. Bottom channel steel, 2. Fixing screw, 3. L-shaped support base, 4. Fixed end connector, 5. Lever, 6. Fixed end pin, 7. Stepper motor, 8. Coupling, 9. Ball screw, 10. Slide table, 11. Slide table shaft pin, 12. Loading rod, 13. Loading rod connector, 14. Pin hole, 15. Loading rod pin, 16. Spring, 17. Linear bearing, 18. Tension / compression sensor, 19. Connecting screw, 20. Spherical indenter, 21. Viscoelastic material under test, 22. Sample pressure plate, 23. Support rod, 24. Sensor fixing plate, 25. Support plate, 26. Eddy current displacement sensor, 27. Sensing plate, 28. Weight hanging hole. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "back," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the manner or components must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a point connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] Referring to the accompanying drawings, a viscoelastic material relaxation modulus testing device includes a bottom channel steel 1, on which a fixing screw 2 and an L-shaped support seat 3 are bolted together.

[0029] The top of the fixed screw 2 is fixedly connected to a fixed end connector 4 by bolts. A lever 5 is horizontally provided on the fixed end connector 4. The fixed end connector 4 and the lever 5 are hinged by a fixed end pin 6.

[0030] The L-shaped support 3 is fixedly provided with a ball screw slide assembly, the ball screw slide assembly is fixedly provided with a stepper motor 7, the top of the stepper motor 7 is provided with a coupling 8, the top of the coupling 8 is connected to a ball screw 9, the ball screw slide assembly also includes a slide 10, and the end of the lever 5 away from the fixed screw 2 is hinged to the slide 10 through a slide shaft pin 11;

[0031] A loading rod 12 is provided between the fixed screw 2 and the L-shaped support 3. The top of the loading rod 12 is fixedly connected to a loading rod connector 13 by bolts. The loading rod connector 13 is provided with an elliptical pin hole 14. The loading rod connector 13 and the lever 5 are hinged by a loading rod pin 15. The loading rod pin 15 moves left and right in the horizontal direction in the pin hole 14. The bottom of the loading rod connector 13 is provided with a spring seat, a spring 16, and a linear bearing 17 in sequence. The spring 16 and the linear bearing 17 are both sleeved on the outside of the loading rod 12. A tension and compression sensor 18 is threadedly connected to the bottom of the loading rod 12. The bottom of the tension and compression sensor 18 is connected to a spherical indenter 20 by a connecting screw 19. The viscoelastic material 21 to be tested is located below the spherical indenter 20. The viscoelastic material 21 to be tested is fixed on the bottom channel steel 1 by a sample pressure plate 22 and bolts.

[0032] A support rod 23 is also provided on the bottom channel steel 1. The support rod 23 is located between the loading rod 12 and the L-shaped support seat 3. A sensor fixing plate 24 and a support plate 25 are horizontally provided on the support rod 23 by bolts. The support plate 25 is located above the sensor fixing plate 24. The end of the support plate 25 away from the support rod 23 is connected to the linear bearing 17. The linear bearing 17 is vertically fixed on the support plate 25 by bolts and nuts. An eddy current displacement sensor 26 is fixedly provided on the end of the sensor fixing plate 24 away from the support rod 23. The top of the eddy current displacement sensor 26 is connected to the loading rod 12 through a sensing plate 27. The sensing plate 27 is fixedly connected to the loading rod 12 by bolts.

[0033] The lever 5 is provided with a weight hanging hole 28 at the end away from the L-shaped support 3;

[0034] The distance between the centerline of the loading rod 12 and the centerline of the fixing screw 2 is one-twentieth of the distance between the centerline of the slide pin 11 and the centerline of the fixing screw 2.

[0035] The support plate 25 has a thickness of 5mm.

[0036] The ball screw slide assembly is model CBX1204-100, and the stepper motor 7 is model KL42BYGH405.

[0037] The L-shaped support plate 25 is a 5mm thick Q235 steel sheet, which is processed by bending it into a 90° angle using a bending machine.

[0038] In specific implementations of this invention, such as Figure 3As shown, the power unit of this experimental setup consists of a stepper motor and a ball screw slide. They are fixed to the base plate channel steel via an L-shaped support. The stepper motor is fixed to the ball screw slide assembly, and the motor shaft is connected to the ball screw via a coupling. When the motor rotates, it drives the ball screw to rotate, causing the slide to move up and down along the guide rail, thus achieving power output. The non-fixed end of the slide and the lever are connected by a pin. When the slide moves up and down, it drives the pin to move back and forth in the slot of the lever, thereby achieving the lifting and lowering of the lever.

[0039] For the power unit of the viscoelastic material relaxation modulus testing device, a KL42BYGH405 stepper motor was selected. This model of stepper motor has advantages such as high motion accuracy, small step angle error, wide operating temperature range, large output torque, and high temperature resistance, which can meet the requirements of this experiment. The stepper motor ball screw slide assembly is a CBX1204-100 model. This assembly has advantages such as high positioning accuracy, large maximum operating load, long effective working distance, and can be used to transmit high-speed motion. The L-shaped support plate is made of 5mm thick Q235 steel sheet, bent at a 90° angle using a bending machine, which gives it both good rigidity and ease of processing. The stepper motor is fixed to the lead screw slide assembly with screws, and the lead screw slide assembly is rigidly connected to the L-shaped support base with screws. Finally, four bolts are used to fix the L-shaped support base to the channel steel at the bottom. This connection method ensures a rigid connection between the parts, prevents mutual movement between the parts when the stepper motor moves, and reduces vibration of the power unit. The specific technical parameters of the CBX1204-100 stepper motor linear ball screw slide assembly are shown in the table below.

[0040]

[0041] As mentioned above, this testing device utilizes the lever principle to decelerate the linear motion of the slide table. Based on the motion law of the spherical indenter pressing into the viscoelastic material required by Hertz's formula and the stable operating speed of the stepper motor, a lever with a reduction ratio of 20:1 is designed. This lever principle reduces the speed of the slide table by a factor of 20, ensuring that the speed of the slide table acting on the spherical indenter through the lever and loading rod just meets the requirements of Hertz's formula. The motion law of the slide table can also be obtained based on the reduction ratio of the lever and Hertz's formula, and thus the corresponding motion law of the stepper motor can be derived.

[0042] like Figure 4As shown, the fixing screw is connected to the bottom channel steel and the fixed end connector respectively by nuts. A pin connects the lever and the fixed end connector, fixing one end of the lever. A pin also connects the lever and the loading rod connector, but this pin hole is oval, allowing the loading rod pin to move left and right within it. Both ends of the fixed end pin and the loading rod pin are threaded, and threaded nuts connect them to the fixed end connector and the loading rod connector respectively, preventing them from moving relative to each other. The loading rod connector is rigidly connected to the loading rod by a threaded nut. A spring seat is located at the lower end of the loading rod connector. The spring is compressed by the spring seat and the linear bearing, providing an upward force to the loading rod connector, ensuring the loading rod pin remains in contact with the lever. The linear bearing is vertically fixed to a 5mm thick horizontal support plate by hexagonal bolts and nuts. Because the loading rod moves up and down within the linear bearing, the direction of movement of the loading rod is always vertical. The lower end of the loading rod is threadedly connected to a tension / compression sensor, which in turn is connected to a spherical indenter via a short screw. The downward movement of the loading rod determines the depth to which the spherical indenter penetrates the viscoelastic material. The pressure data measured by the tension / compression sensor represents the stress response of the viscoelastic material. The penetration depth can be determined by measuring the movement distance of the sensing plate fixed to the loading rod using an eddy current displacement sensor. The viscoelastic material under test is fixed to the bottom channel steel by a sample plate and bolts. At the leftmost end of the lever is a hole for suspending a weight. During the relaxation modulus test of the viscoelastic material, a sufficient weight is suspended at this hole. Combined with the upward reaction force of the spring, this ensures that the fixed end pin, loading rod pin, and slide pin remain in contact with the lever throughout the test, thereby reducing vibration during movement and improving motion accuracy.

[0043] like Figure 1 , Figure 2 As shown, in order to make the speed at which the spherical indenter presses into the viscoelastic material, i.e., the speed at which the loading rod moves, one-twentieth of the speed at which the slide moves, according to the lever principle, the viscoelastic material relaxation modulus testing device must satisfy the requirement that the distance between the center line of the loading rod and the center line of the fixed screw is one-twentieth of the distance from the fixed screw to the center of the slide pin.

[0044] In summary, the mechanical system of the viscoelastic material relaxation modulus testing device mainly consists of a stepper motor, a lead screw slide assembly, an L-shaped support base, a lead screw, a lever, a linear bearing, a spring, a tension / compression sensor, an eddy current sensor, a spherical indenter, a loading rod, a connector, a pin, and a base plate channel steel. The testing device converts the high-speed rotation of the stepper motor into the linear motion of the slide, and then, through the lever, converts the slide's motion into the low-speed vertical linear motion of the loading rod. Simultaneously, the spherical indenter, rigidly connected to the loading rod, vertically presses into the viscoelastic material. By controlling the stepper motor's rotation speed, the rigid spherical indenter can be made to press into the viscoelastic material according to a specific motion pattern, achieving specific strain loading on the viscoelastic material. The pressure sensor fixed on the loading rod can measure the stress response of the viscoelastic material to specific strain loading, and the eddy current displacement sensor can indirectly monitor whether the indenter's movement pattern meets the experimental requirements by testing the movement pattern of the sensing plate.

[0045] Working principle of the invention:

[0046] 1. Generally, a spherical indenter is used to press into viscoelastic materials to test the creep flexibility of viscoelastic materials. This device uses a spherical indenter to press into viscoelastic materials to test the relaxation modulus of viscoelastic materials.

[0047] 2. A pressure sensor mounting point was designed on the loading rod, which can measure the stress response of the viscoelastic material to a specific strain loading.

[0048] 3. A fixed point for the eddy current displacement sensor was designed based on the lever principle. The movement pattern of the pressure head can be indirectly monitored by testing the movement pattern of the sensing plate to see if it meets the experimental requirements.

[0049] 4. Connect the motor to the microcontroller and use Hertz's formula to burn a program into the microcontroller to control the motor speed, so that the motor can achieve non-uniform rotation. The motor drives the slide to achieve non-uniform linear motion on the ball screw.

[0050] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A device for testing the relaxation modulus of viscoelastic materials, characterized in that: It includes a bottom channel steel, on which a fixing screw and an L-shaped support seat are bolted together; The top of the fixed screw is fixedly connected to a fixed end connector by bolts. A lever is horizontally provided on the fixed end connector. The fixed end connector and the lever are hinged by a fixed end pin. A ball screw slide assembly is fixedly mounted on the L-shaped support base. A stepper motor is fixedly mounted on the ball screw slide assembly. A coupling is provided on the top of the stepper motor. A ball screw is connected to the top of the coupling. The ball screw slide assembly also includes a slide. The end of the lever away from the fixed screw is hinged to the slide via a slide shaft pin. A loading rod is provided between the fixed screw and the L-shaped support base. The top of the loading rod is fixedly connected to a loading rod connector by bolts. The loading rod connector has an elliptical pin hole. The loading rod connector and the lever are hinged by a loading rod pin. The loading rod pin moves horizontally left and right in the pin hole. The bottom of the loading rod connector is provided with a spring seat, a spring, and a linear bearing in sequence. The spring and the linear bearing are both sleeved on the outside of the loading rod. A tension and compression sensor is threadedly connected to the bottom of the loading rod. The bottom of the tension and compression sensor is connected to a spherical indenter by a connecting screw. The viscoelastic material to be tested is located below the spherical indenter. The viscoelastic material to be tested is fixed to the bottom channel steel by a sample pressure plate and bolts. A support rod is also provided on the bottom channel steel. The support rod is located between the loading rod and the L-shaped support seat. A sensor fixing plate and a support plate are horizontally provided on the support rod by bolts. The support plate is located above the sensor fixing plate. The end of the support plate away from the support rod is connected to the linear bearing. The linear bearing is vertically fixed to the support plate by bolts and nuts. An eddy current displacement sensor is fixedly provided on the end of the sensor fixing plate away from the support rod. The top of the eddy current displacement sensor is connected to the loading rod through a sensing plate. The sensing plate is fixedly connected to the loading rod by bolts. The end of the lever furthest from the L-shaped support is provided with a weight hanging hole; The distance between the centerline of the loading rod and the centerline of the fixing screw is one-twentieth of the distance between the centerline of the slide pin and the centerline of the fixing screw.

2. The viscoelastic material relaxation modulus testing device according to claim 1, characterized in that: The thickness of the support plate is 5mm.

3. The viscoelastic material relaxation modulus testing device according to claim 1, characterized in that: The ball screw slide assembly is model CBX1204-100, and the stepper motor is model KL42BYGH405.

4. The viscoelastic material relaxation modulus testing device according to claim 1, characterized in that: The L-shaped support is made of 5mm thick Q235 steel sheet, which is bent into a 90° angle by a bending machine.

Images