An automatic device for measuring Young's modulus based on STM32 single-chip microcomputer

Abstract

This invention discloses an automated device for measuring Young's modulus based on an STM32 microcontroller. The device includes a base, a parallel connecting rod fixedly connected to the upper side of the base, a top plate fixedly connected to the upper end of the parallel connecting rod, a pedestal on one side of the parallel connecting rod resting on the base, a measuring cylinder containing water, and a cylinder containing a tray connected to the upper end of the cylinder. A metal wire to be measured is fixedly connected between the tray and the top plate. A single-point weighing sensor is also provided on the base. This invention features a simple structure and operation, automated reading, automatic data calculation by the microcontroller, and fast result output, significantly reducing the shortcomings of existing devices that suffer from large reading errors and calculation errors due to structural defects.

Description

Technical Field

[0001] This invention relates to the field of experimental apparatus, specifically to an automated device for measuring Young's modulus based on an STM32 microcontroller. Background Technology

[0002] Let the original length of a uniform metal wire be L, and its cross-sectional area be S. After a force F is applied along its length, its length changes by ΔL. Then, what is the perpendicular force per unit area on the metal wire? This is called normal stress, the relative elongation of a metal wire. This is called linear strain. Experimental results indicate that, within the elastic range, according to Hooke's Law, the normal stress of an object is directly proportional to the linear strain, i.e.

[0003]

[0004] The proportionality constant Y is Young's modulus, or simply Young's modulus. It characterizes the properties of a material; the larger Y is, the greater the force required per unit cross-sectional area to induce a certain relative deformation. The SI unit for Y is the Pascal, denoted as Pa (1 Pa = 1 N / m). 2 ).

[0005] ΔL is a tiny change in length (in this experiment, when L≈1m, the corresponding ΔL is approximately 0.3mm for every 1kg change in F). Therefore, this experiment utilizes the optical magnification effect of the optical lever to indirectly measure the tiny elongation ΔL of the steel wire.

[0006] However, in actual measurement, the metal wire and the groove weights beneath it are difficult to keep stable, causing the projected cursor to drift erratically, making accurate readings difficult and introducing experimental errors. Therefore, a more accurate, efficient, and stable method for measuring the elongation of the metal wire is needed. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, this invention provides an automated device for measuring Young's modulus based on an STM32 microcontroller. The microcontroller automatically calculates the data, resulting in fast output speed, which greatly reduces the disadvantages of existing devices that suffer from large reading errors and easy calculation errors due to structural defects.

[0008] Technical solution

[0009] An automated device for measuring Young's modulus based on an STM32 microcontroller includes a base, a parallel connecting rod fixedly connected to the upper side of the base, a top plate fixedly connected to the upper end of the parallel connecting rod, a base placed on the base on one side of the parallel connecting rod, a measuring cylinder containing water placed on the base, a cylinder containing a tray connected to the upper end of the cylinder, a metal wire to be measured fixedly connected between the tray and the top plate, a single-point weighing sensor also being mounted on the base, and the single-point weighing sensor being circuitically connected to an analog weight transmitter, a Bluetooth circuit module, an OLED screen, and an STM microcontroller minimum system board.

[0010] Furthermore, the upper half of the cylinder is connected and fixed to the tray.

[0011] Furthermore, a gap exists between the cylinder and the graduated cylinder after the cylinder is inserted.

[0012] Furthermore, the tray is provided with slots for adding weight to stretch the wire.

[0013] Furthermore, the cylinder is inserted into the measuring cylinder and comes into contact with the water. As the cylinder descends, the distance the cylinder descends can be calculated by measuring the changing gravity data of the measuring cylinder using the single-point weighing sensor.

[0014] Beneficial effects

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The experimental equipment is simpler to use, cheaper, and less prone to damage compared to existing devices;

[0017] 2. Simple to operate; after measurement, the results are directly displayed on the OLED screen. It is convenient to use, easy to learn, and extremely easy to disassemble and assemble.

[0018] 3. The readings are accurate and stable. The sensor has high reading accuracy, and even slight shaking of the metal wire and slotted weights will not have a significant impact on the readings.

[0019] 4. The principle is simple, easy to learn and operate, and has high accuracy;

[0020] 5. Automated reading: The microcontroller automatically calculates data and outputs results quickly, greatly reducing the shortcomings of existing devices that suffer from large reading errors and easy calculation errors due to structural defects. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an automated device for measuring Young's modulus based on an STM32 microcontroller according to the present invention.

[0022] Figure 2 This is the circuit schematic of the central control section of an STM32 microcontroller.

[0023] Figure 3 This is the circuit schematic of the STM32 microcontroller crystal oscillator circuit.

[0024] Figure 4 This is the circuit schematic of an STM32 microcontroller OLED display module.

[0025] Figure 5 Schematic diagram of the step-down module for the STM32 microcontroller LM2596S;

[0026] Figure 6 This is the circuit schematic of the STM32 microcontroller HX711 A / D converter.

[0027] Figure 7 This is the circuit schematic for the STM32 microcontroller HC-05 Bluetooth module.

[0028] Figure 8 This is a schematic diagram illustrating how the cylindrical shape of the present invention causes the water level to rise.

[0029] Reference numerals: 1. Measuring cylinder, 2. Cylinder, 3. Water, 4. Tray, 5. Slot, 6. Metal wire, 7. Parallel connecting rod, 8. Top plate, 9. Base, 10. Analog weight transmitter, 11. Bluetooth circuit module, 12. OLED screen, 13. STM32 microcontroller minimum system board, 14. Single-point weighing sensor, 15. Base, F, tension of the metal wire on the cylinder, l, water level rise. Detailed Implementation

[0030] To make the measurement method, technical solution, and advantages of this combined device clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments. In the following description, detailed features such as specific devices and components are provided merely to aid in a comprehensive understanding of the embodiments of the invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this combined device. Furthermore, for clarity and brevity, descriptions of known functions and structures have been omitted.

[0031] It should be understood that the phrase "an embodiment" or "an embodiment" mentioned throughout the specification means that a particular feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "in an embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0032] In various embodiments of the present invention, it should be understood that the sequence number of each process described below does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0033] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0034] In the embodiments provided in this application, it should be understood that "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B solely based on A; B can also be determined based on A and / or other information.

[0035] have Figures 1-8 As shown, this invention discloses an automated device for measuring Young's modulus based on an STM32 microcontroller. The device includes a base 9, a parallel connecting rod 7 fixedly connected to the upper side of the base 9, a top plate 8 fixedly connected to the upper end of the parallel connecting rod 7, a base 15 placed on the base 9 on one side of the parallel connecting rod 7, a measuring cylinder 1 placed on the base 15, water 3 placed inside the measuring cylinder 1, a cylinder 2 placed inside the measuring cylinder 1, a tray 4 connected to the upper end of the cylinder 2, a metal wire 6 to be measured fixedly connected between the tray 4 and the top plate 8, a single-point weighing sensor 14 also placed on the base 15, and the single-point weighing sensor 14 is also circuitically connected to an analog weight transmitter 10, a Bluetooth circuit module 11, an OLED screen 12, and an STM32 microcontroller minimum system board 13.

[0036] Furthermore, the upper half of the cylinder 2 is connected and fixed to the tray 4.

[0037] Furthermore, there is a gap between the cylinder 2 and the graduated cylinder 1 after the cylinder 2 is inserted.

[0038] Furthermore, the tray 4 is equipped with slots 5 for adding weight to stretch the wire 6.

[0039] Furthermore, the cylinder 2 is inserted into the measuring cylinder 1 and comes into contact with the water 3. After the cylinder 2 descends, the distance the cylinder 2 descends can be calculated by measuring the changing gravity data of the measuring cylinder 1 through the single-point weighing sensor 14.

[0040] Specifically, let the inner diameter of the measuring cylinder 1 be D1, and let the cylinder 1 be filled with water 3 with density ρ. Let the diameter of the sufficiently long cylinder 2 be D2 (D1>D2 and D1≈D2). Fix or suspend the cylinder 2 at the bottom of the tray 4 connected to the metal wire 6. Insert the cylinder 2 into the measuring cylinder 1 so that the water 3 in the measuring cylinder 1 can completely submerge the bottom surface of the cylinder 2. Fix the position of the measuring cylinder 1.

[0041] Add a slot 5 to tray 4. Under the gravity of the slot 5, the metal wire 6 is stretched downward by a distance x. The cylinder 2 moves downward by a distance x, the water level rises by a height l, and the pressure sensor value changes by F. 浮 F 浮 The buoyancy force exerted by water 3 on cylinder 2 is V, and the displacement is V.

[0042] Formula derivation:

[0043] Let the mass of cylinder 2 be m1, the mass of water 3 and graduated cylinder 1 be m2, and let S0 be the bottom area of ​​graduated cylinder 1.

[0044] For cylinder 2: F 拉 +F 浮 =m1g(1)

[0045] For cylinder 2 and water 3 as a whole: F 拉 +F 压 =(m1+m2)g(2)

[0046] (2)-(1)F 压 =m2g+F 浮

[0047] F 浮 =ρ 水 gS0l

[0048] F 压 =m2g+ρ 水 g·S0·l

[0049] Therefore F 压 It is linearly related to l

[0050] have

[0051]

[0052] That is, and

[0053]

[0054] again

[0055]

[0056] Right now

[0057]

[0058] As can be seen from the formula, the downward stretching length x of the metal wire can be indirectly measured by measuring the water level rise height l. If we let... k can be called the magnification factor.

[0059] have

[0060]

[0061]

[0062] l = kx

[0063] F 压 =m2g+ρ 水 g·S0·k·x

[0064]

[0065] Therefore F 压 It has a linear relationship with x.

[0066] x=k1F 压 +b0

[0067] Multiple experiments can yield k1 and b0.

[0068] If we take the diameter D2 of the solid cylinder 2 to be 100mm, the relationship between D1-D2 and k can be obtained as shown in the table below:

[0069] k 10 15 20 30 40 50 <![CDATA[D1 - D2 (Unit: mm)]]> 4.881 3.280 2.470 1.653 1.242 0.995

[0070] It is evident that the higher the magnification, the smaller the difference between D1 and D2, and the higher the required measurement accuracy, which is not easy to achieve. However, by increasing the cylinder diameter D2, the magnification k can be increased within the measurable accuracy range of the micrometer, thereby reducing experimental errors.

[0071] On the other hand, if the traditional method of adding groove weights to generate positive pressure F = mg is used, the F pressure exerted by the water in the beaker on the cylinder should also be considered. 浮 The effect of this formula becomes

[0072]

[0073] cross-sectional area of ​​steel wire Substituting into formula (2), we obtain Young's modulus.

[0074]

[0075] Where x = k1F 压 +b0

[0076] In the above formula, x can be replaced by taking the average value using the method of successive differences to reduce experimental error;

[0077] The above calculation process is completed by an STM32 microcontroller. After the measurement is completed, the calculation result is directly displayed on the OLED screen, so the result can be obtained directly.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing description, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A device for automatically measuring Young's modulus based on an STM32 microcontroller, characterized in that: Includes a base (9), on which a parallel connecting rod (7) is fixedly connected to the upper side, and a top plate (8) is fixedly connected to the upper end of the parallel connecting rod (7). A base is provided on one side of the parallel connecting rod (7) and placed on the base. A measuring cylinder (1) is placed on the base. Water (3) is placed inside the measuring cylinder (1). A cylinder (2) is also placed inside the measuring cylinder (1). A tray (4) is connected to the upper end of the cylinder (2). A metal wire (6) to be measured is fixedly connected between the tray (4) and the top plate (8). A single-point weighing sensor (14) is also provided on the base. The single-point weighing sensor (14) is also connected to an analog weight transmitter (10), a Bluetooth circuit module (11), an OLED screen (12), and an STM32 microcontroller minimum system board (13). The upper half of the cylinder (2) is connected and fixed to the tray (4); There is a gap after the cylinder (2) is inserted into the measuring cylinder (1); The tray (4) is provided with slots (5) for adding weight to stretch the wire (6). The cylinder (2) is inserted into the measuring cylinder (1) and comes into contact with the water (3). When the cylinder (2) descends, the distance the cylinder (2) descends can be calculated by measuring the change in gravity data of the measuring cylinder (1) through the single-point weighing sensor (14). The formula for calculating Young's modulus is given below. （1） Where L is the original length of the wire, S is the cross-sectional area of ​​the wire, and F is the force acting on the wire along its length. Let Y be the change in the length of the metal wire, and Y be the Young's modulus. Let the inner diameter of the graduated cylinder (1) be... It contains a density of The water (3), the diameter of the sufficiently long cylinder (2) is Fix or suspend the cylinder (2) at the bottom of the tray (4) connected to the metal wire (6), insert the cylinder (2) into the measuring cylinder (1) so that the water (3) in the measuring cylinder (1) can completely submerge the bottom surface of the cylinder (2), and fix the position of the measuring cylinder (1). Add slots (5) to the tray (4), and the wire (6) is stretched downwards by a distance under the gravity of the slots. The cylinder (2) moves downward a distance water level rise height Meanwhile, the pressure sensor readings change , The buoyancy increase of water (3) on cylinder (2) is the displacement of water. , Formula derivation: Let the mass of cylinder (2) be... Mass of water (3) and graduated cylinder (1) ,remember The bottom area of ​​graduated cylinder (1) is... For cylinder (2): (2) For the cylinder (2) and water (3) as a whole: (3) Formula (3) minus Formula (2) yields (4) (5) (6) Therefore and Linear relationship have (7) and (8) From formulas (7) and (8), we can derive... （9） again （10） Right now （11） As can be seen from formula (11), the rise in water level can be measured. To indirectly measure the downward stretching length of the metal wire , make (12) Can be called For magnification, we have （13） （14） （15） （16） （17） Therefore and A linear relationship exists. （18） Multiple experiments can yield the following results ; Positive pressure is generated by adding slotted weights. The method considers the effect of the water in the beaker on the cylinder. Due to the influence of this, formula (1) becomes （19） Substituting formula (4) into formula (19) yields Young's modulus. （20） in ; The above calculation process is completed by an STM32 microcontroller. After the measurement is completed, the calculation result is directly displayed on the OLED screen, so the result can be obtained directly.

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