WO2021114731A1

WO2021114731A1 - Bending strain generating device, and use thereof

Info

Publication number: WO2021114731A1
Application number: PCT/CN2020/111665
Authority: WO
Inventors: 徐颖; 冯唐垚; 段璞; 岳毅
Original assignee: 华中科技大学
Priority date: 2019-12-13
Filing date: 2020-08-27
Publication date: 2021-06-17
Also published as: CN110987680A

Abstract

A bending strain generating device, and the use thereof, belonging to the field of stress intensity checking. The device comprises: a base (1), a force application member (2) with two arc-shaped force application points (21), and a pushing assembly (3), wherein the two ends of the base (1) protrude relative to the upper surface of the base (1) and are provided with screw holes (11), and are used for acting as support points for fixing the two ends of an area to be detected of a sample (4) by means of the screw holes (11); and the two force application members (2) are respectively vertically arranged above the upper surface of the base (1), the two force application points (21) and the two screw holes (11) are collinear and form four-point symmetry, and when moving perpendicular to the upper surface of the base (1) under the control of the pushing assembly (3), the two force application members are used for synchronously applying, by means of the two force application points (21), the same force to said area. The device realizes four-point bending measurement in combination with a controller and a driver for the pushing assembly (3). According to the present invention, the defect of an uneven bending distribution of a traditional three-point bending method is overcome, a middle area of the device bends evenly, the device facilitates the generation of an accurate, stable, adjustable and repeated bending strain, and the use of a four-point bending method is greatly improved.

Description

Bending strain generating device and its application

【Technical Field】

The invention belongs to the field of stress intensity checking, and more specifically, relates to a bending strain generating device and its application.

【Background technique】

In the actual work process, any material will face various forms of stress, such as compression, stretching, bending and torsion. In order for the material to work safely and stably under actual working conditions, various types of stress intensity must be checked, and the allowable stress must be tested when the material is deformed by the corresponding type of stress. At present, stretching and compression experiments are easy to implement. One end of the material is fixed, and the other end is stretched or compressed with a tensile machine or a press. But for the bending test, there are currently two methods, namely the three-point bending method and the four-point bending method. The difference is that the number of force points is different. Both have two horizontal support points. The three-point method is directly There is a force point in the middle of the two supporting points, and the four-point rule has two symmetrical force points.

There are shear forces on the three-point bending specimens and the bending moment is unevenly distributed, which leads to uneven bending distribution and affects the accuracy of the experimental results; but for four-point bending, there is no shear on the specimens in the middle area of the two force points. Force, only uniform bending moment, produces uniform bending, making the experimental results more accurate. However, in actual engineering, three-point bending is widely used because of its simple loading method, and four-point bending is less used due to the more complex structure of the device compared to the three-point bending device. Therefore, there are fewer four-point bending devices available, and mechanical devices that can achieve more in-depth functions (such as a bending experiment with adjustable parameters that are repeated multiple times in succession) are in urgent need of research and development.

[Summary of the invention]

The present invention provides a bending strain generating device and an application thereof, which are used to solve the technical problem that the existing four-point bending device is complicated in structure and cannot be used for multiple repeated measurements and has limited application.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a bending strain generating device, comprising: a base, a force applying member whose two force applying points are both arc-shaped, and a pushing component;

The two ends of the base protrude relative to the upper surface of the base and are provided with screw holes, which are used as supporting points to fix the two ends of the sample to be tested area through the screw holes; the two force applying members are respectively arranged vertically above the upper surface of the base And the two force application points are collinear with the two screw holes, and at the same time, the two force points are symmetrical with respect to the center point of the connecting line of the two screw holes, and are used to synchronize and be perpendicular to the two screw holes under the control of the pushing assembly. When the upper surface of the base moves, the same force is applied to the area to be detected through the two force application points.

The beneficial effects of the present invention are: the present invention adopts the four-point bending method, the two ends of the base are fixed to the sample, the two ends are used as two supporting points, and the two force applying members are used as two symmetrical force applying points, the force point and the support point Collinear and point-symmetrical, such four-point bending forms a pure bend in the area between the two application points and the bends are evenly distributed, which can improve the accuracy of the test. In addition, the movement state of the force applying member is controlled by pushing the component, and the magnitude of the bending stress and strain, the impact frequency, and the number of impacts are indirectly controlled. Therefore, the present invention can continuously repeat the bending experiment with adjustable parameters for multiple times on the sample, thus can generate stable and adjustable repeated bending strains on the sample material, greatly improving the application of the four-point bending method.

Based on the above technical solutions, the present invention can also be improved as follows.

Further, the pushing device includes a motor, a screw rod, and a connecting structure that are connected in sequence;

Wherein, the connecting structure member is used to fix the two force applying members, and the motor is used to control the screw rod to drive the connecting structure member to move, so that the connecting structure member drives the two force applying members movement.

Further, the connecting structure is in the shape of a flat plate, is parallel to the upper surface of the base, and is fixed by a fixing rod perpendicular to the upper surface of the base.

The further beneficial effect of the present invention is that by arranging the connecting structural member in a flat plate shape, it is easy to accurately control the force applied by the force applying member. In addition, a fixed rod is used to fix the connecting structural member to ensure the stability of the device.

Further, the force applying member is two pressure rods with the same structure.

The further beneficial effect of the present invention is that the two force applying members have the same structure, which is easy to manufacture, and at the same time, it is easy to control the force of the two force applying members to be equal.

Further, the two pressure rods are rod-shaped and are vertically arranged above the central point of the collinear line between the two force application points and the two screw holes.

Further, the two pressure rods are respectively stainless steel pressure rods, and the base is a stainless steel base.

The further beneficial effect of the present invention is that the use of stainless steel materials can ensure a large bearing force range at the time of conducting a bending strain experiment and strong practicability.

The present invention also provides a bending strain generating system, including: a controller, a driver, and any bending strain generating device as described above;

Wherein, the controller is used for controlling the pushing component in the bending strain generating device through the driver.

The beneficial effects of the present invention are: the present invention adopts the above-mentioned bending strain generating device, adopts the four-point bending method, the two ends of the base are fixed to the sample, the two ends are used as two supporting points, and the two force applying members are used as two symmetrical applying members. The force point, the force point and the support point are collinear and point symmetrical. Such four-point bending forms a pure bend in the area between the two force points and the bending is evenly distributed, which can improve the test accuracy. In addition, the controller controls the working state of the pushing component to control the motion state of the force application member, and indirectly control the magnitude of the bending stress and strain, the impact frequency, and the number of impacts. Therefore, the present invention can continuously repeat the bending experiment with adjustable parameters for multiple times on the sample, and thus can generate stable and adjustable repeated bending strains on the sample material, which greatly improves the application of the four-point bending method.

Further, the controller and the driver are both embedded in the base.

Further, a control panel is embedded on the surface of the shell of the base for inputting and displaying control signals to the controller.

The further beneficial effects of the present invention are: the controller and the driver are both embedded in the base to save volume. In addition, a control panel is embedded on the surface of the shell of the base, which is convenient for the experimenter to control the bending stress and strain, the impact frequency and the number of impact The control and practicality are strong.

The present invention also provides a bending strain generation method, which adopts the above-mentioned bending strain generation system to generate bending strain in the to-be-detected area of the sample to be tested.

The beneficial effects of the present invention are: the present invention adopts the above-mentioned bending strain generation system, and can change the magnitude of force and the number of force to achieve the required bending stress and strain control according to actual experimental needs, and accurately and simply apply four-point bending The method greatly improves the accuracy and efficiency of the material's stress intensity check.

【Explanation of the drawings】

Figure 1 is a front view of a bending strain generating device provided by an embodiment of the present invention;

2 is a schematic diagram of a bending strain generating device provided by an embodiment of the present invention;

Figure 3 is a four-point bending principle diagram of the bending strain generating device provided by an embodiment of the present invention;

Fig. 4 is a schematic diagram of a bending strain generating system provided by an embodiment of the present invention.

In all the drawings, the same reference numerals are used to denote the same elements or structures, in which:

1. Base, 11. Screw hole, 2. Force part, 21, Force point, 3. Push component, 31, Motor, 4. Material sample.

【Detailed ways】

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Example one

A bending strain generating device, as shown in FIG. 1, includes: a base 1, a force applying member 2 whose two force application points are both arc-shaped, and a pushing component 3. Wherein, the two ends of the base protrude from the upper surface of the base and are provided with screw holes 11, which are used as supporting points to fix the two ends of the sample to be tested area through the screw holes; the two force applying members are respectively arranged vertically above the upper surface of the base and The two force application points 21 are collinear with the two screw holes 11, and at the same time, the two force points are symmetrical with respect to the center point of the line connecting the two screw holes. They are used to synchronize the movement through the two The force application point applies the same amount of force to the area to be detected.

Preferably, the pushing device 3 includes a motor 31, a screw rod 32, and a connecting structural member 33 that are connected in sequence; wherein the connecting structural member is used to fix two force applying members, and the motor is used to control the screw rod to drive the two shafts through the connecting structural member. The movement of the force applying member.

Preferably, the connecting structure is in the shape of a flat plate, is parallel to the upper surface of the base, and is fixed by a fixing rod perpendicular to the upper surface of the base.

Preferably, the force applying member is two pressure rods with the same structure.

Preferably, the two pressure rods are respectively stainless steel pressure rods, and the base is a stainless steel base.

This embodiment is based on the four-point bending method, that is, two supporting points and two symmetrical force points: fix the two ends of the test material lying flat on the two ends of the aluminum alloy bottom plate as two supporting points; Two identical and symmetrical stainless steel arc-shaped compression rods connected by the rods are used as two symmetrical force application points, and the two force application points and the two support points are all about the vertical motor screw rod as the symmetry axis. Then, rationally construct various supporting structures to form an experimental platform together with motors, screw rods, struts, and aluminum alloy base plates.

First, control the linear stepping motor to drive the screw rod to move up and down, thereby driving the two same stainless steel arc-shaped pressure rods connected with the screw rod to move up and down. The two force application points and the two support points are both vertical motor screw rods. It is the axis of symmetry. When two pressure rods hit a horizontal specimen in the same state, two equal forces in the vertical direction will be applied to the specimen, resulting in only uniform bending moments in the area between the two pressure rods. Pure bending without shear force produces uniform bending stress and strain in this part of the area. Because the linear motor can control the distance, speed, and times of the up and down movement of the motor through the controller, the magnitude of the bending stress and strain, the impact frequency and the number of impacts can be correspondingly controlled.

In order to better illustrate the present invention, the following examples are now given:

As shown in Figure 2, the principle part of the mechanical impact platform provided by this example to realize the four-point bending method includes a linear stepping motor 31, a matching screw 32 for the motor, and a stainless steel arc-shaped pressing rod 2 (as shown in Figure 2, the bottom A circular arc) and aluminum alloy base 1. In addition, on the connecting structure of the screw rod and the pressure rod, the middle is the screw rod, the two corners are the pressure rod, and the other corner is a vertical stainless steel cylindrical guide rail, which is used to increase the stability of the device and ensure that the screw rod and the pressure rod The up and down movement of the rod is strictly kept vertical without deviation.

As shown in Figure 3, the two stainless steel arc-shaped compression rods and the screw holes at the left and right ends of the aluminum alloy bottom plate are symmetrical with the vertical motor screw rod in the middle. The stainless steel arc-shaped pressure rod is placed vertically, and the distance from the screw rod of the middle motor is L1. The aluminum alloy base plate is placed horizontally. There are two screw holes on the left and right ends. After placing the sample in the middle of the two screw holes at the left or right end, set the metal pressing piece with two holes and use the screws. Fixed, as a support point, the distance between the screw holes at the left and right ends and the screw rod of the middle motor is L ₂ . The vertical dashed line in the figure represents the plane perpendicular to the base.

Example two

A bending strain generating system, as shown in FIG. 4, includes: a controller, a driver, and a bending strain generating device as described in the first embodiment; wherein the controller is used to control the pushing in the bending strain generating device through the driver Components.

Using the above-mentioned bending strain generating device, the four-point bending method is adopted, the two ends of the base are fixed to the specimen, the two ends are used as two supporting points, and the two force applying parts are used as two symmetrical force points. The force point and the support point are collinear The points are symmetrical. Such four-point bending forms a pure bend in the area between the two force application points and the bends are evenly distributed, which can improve the accuracy of the test. In addition, the controller controls the working state of the pushing component to control the motion state of the force application member, and indirectly control the magnitude of the bending stress and strain, the impact frequency, and the number of impacts. Therefore, the system can carry out continuous and repeated bending experiments with adjustable parameters on the sample, so it can produce stable and adjustable repeated bending strains on the sample material, which greatly improves the application of the four-point bending method.

Preferably, the controller and the driver are both embedded in the base.

Preferably, the surface of the shell of the base is embedded with a control panel for inputting and displaying control signals to the controller.

As shown in Figure 3, under the principle part of the structure, there is a rectangular box, which contains the controller, driver and power supply of the linear stepping motor. The front slot is slotted and the part is the programming control operation panel of the motor controller. It is convenient for operators to carry out experimental operations.

The related technical solutions are the same as in the first embodiment, and will not be repeated here.

Example three

A bending strain generation method adopts the bending strain generation system as described in the second embodiment to generate the bending strain in the to-be-detected area of the sample to be tested.

The above-mentioned bending strain generation system can be used to control the required bending stress and strain by changing the amount of force and the number of force applications according to actual experimental needs. The four-point bending method is applied accurately and simply, which greatly improves the stress of the material. Strength check accuracy and efficiency.

The related technical solutions are the same as in the second embodiment, and will not be repeated here.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present invention, All should be included in the protection scope of the present invention.

Claims

A bending strain generating device, which is characterized by comprising: a base, a force applying member whose two force applying points are both arc-shaped, and a pushing component;

The two ends of the base protrude relative to the upper surface of the base and are provided with screw holes, which are used as supporting points to fix the two ends of the sample to be tested area through the screw holes; the two force applying members are respectively arranged vertically above the upper surface of the base And the two force application points are collinear with the two screw holes, and at the same time, the two force points are symmetrical with respect to the center point of the connecting line of the two screw holes, and are used to synchronize and be perpendicular to the two screw holes under the control of the pushing assembly. When the upper surface of the base moves, the same force is applied to the area to be detected through the two force application points.
The bending strain generating device according to claim 1, wherein the pushing device comprises a motor, a screw rod and a connecting structure connected in sequence;

Wherein, the connecting structure member is used to fix the two force applying members, and the motor is used to control the screw rod to drive the connecting structure member to move, so that the connecting structure member drives the two force applying members movement.
The bending strain generating device according to claim 2, wherein the connecting structure is in the shape of a flat plate, is parallel to the upper surface of the base, and is fixed by a fixing rod perpendicular to the upper surface of the base.
The bending strain generating device according to any one of claims 1 to 3, wherein the two force applying members are two pressure rods with the same structure.
The bending strain generating device according to claim 4, wherein the two pressure rods are rod-shaped and are arranged perpendicularly on the collinear line between the two force application points and the two screw holes. Above the center point.
The bending strain generating device according to claim 5, wherein the two pressure rods are stainless steel pressure rods, and the base is a stainless steel base.
A bending strain generating system, comprising: a controller, a driver, and a bending strain generating device according to any one of claims 1 to 6;

Wherein, the controller is used for controlling the pushing component in the bending strain generating device through the driver.
The bending strain generating system according to claim 7, wherein the controller and the driver are both embedded in the base.
The bending strain generating system according to claim 7 or 8, wherein a control panel is embedded on the surface of the shell of the base for inputting and displaying control signals to the controller.
A method for generating bending strain, which is characterized in that the bending strain generating system according to any one of claims 7 to 9 is used to generate bending strain in the area to be tested of the sample to be tested.