A solid material internal friction measuring device and measuring method

Abstract

The application provides a solid material internal friction measuring device and a measuring method. The device comprises a vacuum cavity, a vacuum unit, a sample fixing tool, a vibration excitation assembly, a vibration detection assembly and a vibration signal processing and analysis assembly. The device is used to propose a solid material internal friction measuring method. The method can measure the internal friction of metal and non-metal solid materials at a specific vibration frequency, and has the advantages of high sensitivity and high measuring precision.

Description

Technical Field

[0001] This invention relates to the technical field of internal friction measurement equipment, and more particularly to a device and method for measuring internal friction of solid materials. Background Technology

[0002] Material internal friction refers to the phenomenon where a material vibrates in complete isolation from the external environment, and the vibration decays due to internal microstructure factors, converting mechanical energy into internal energy. Based on this phenomenon, materials with different internal friction levels are selected for different applications and functions. For example, the bed frame of a precision machine tool requires high-internal-friction cast iron to reduce the impact of vibration on machining accuracy; solid-state wave gyroscopes require resonators made of ultra-low-internal-friction materials to improve measurement accuracy and reduce power consumption. Therefore, accurately measuring the material's internal friction level is crucial for material selection in practical applications.

[0003] Currently, the main types of materials internal friction measurement devices and methods are as follows: 1. The torsion pendulum internal friction meter, also known as Ge's torsion pendulum, is a component invented by Academician Ge Tingsui of my country for measuring the internal friction of metallic materials under low-frequency torsion conditions. It applies a small force to induce torsion in the sample, measures the stress and strain, and then calculates the internal friction value. Its advantages are simple structure and easy operation; its disadvantage is low measurement sensitivity, and it is mainly suitable for internal friction values ​​greater than 10. -3 Materials of that magnitude.

[0004] 2. CN 107356522 A, "Tension-Compression Cyclic Stress Method," discloses a method for measuring and calculating the internal friction of materials. This method applies cyclic stress with a set vibration frequency and amplitude to a sample, causing the material to undergo a tensile-compressive cyclic strain. The phase difference between the stress and strain cyclic curves is obtained, and the internal friction value of the material is then calculated. The testing principle of this method is similar to that of the Graham torsion pendulum. Its advantages include reduced measurement errors in stress and strain, and improved measurement accuracy. It is mainly applicable to internal friction values ​​greater than 10. -5 Materials of that magnitude.

[0005] 3. CN 105510445 B, "A Material Internal Friction Value Measuring Instrument," discloses a device for measuring the internal friction of high-internal-friction alloy materials. It induces resonance in the sample through electromagnetic excitation, collects the frequency and amplitude of the sample vibration, and then calculates the material's internal friction value. This component is mainly used for measuring the internal friction of alloy materials.

[0006] 4. CN 103245727 B, "A Component for Measuring Internal Friction and Modulus of Micrometer-Scale Materials," discloses a device for measuring internal friction of micrometer-scale materials. It employs electrostatic excitation to vibrate the sample, records the vibration images using a high-speed video acquisition system, processes and analyzes the images to obtain vibration information such as amplitude and frequency, and then calculates the material's internal friction value. This component is mainly used for measuring the internal friction of conductive micrometer-scale materials.

[0007] Existing material internal friction measurement devices and methods have the following main shortcomings: 1. They are mainly designed for metallic and conductive materials, and are not suitable for non-metallic solid materials such as glass and ceramics; 2. They have low measurement sensitivity and are mainly used for internal friction values ​​greater than 10. -5 1. Materials of this magnitude cannot be applied to other materials with lower internal friction; 2. The effects of air damping, sample surface condition, and support method on the accuracy of material internal friction measurement are not considered. Summary of the Invention

[0008] This invention provides a device and method for measuring the internal friction of solid materials, addressing the shortcomings of existing measuring devices with excessively small measurement ranges. It enables the evaluation and measurement of internal friction in metallic and non-metallic solid materials such as alloys, glass, ceramics, and crystals, achieving a resolution of 10⁻⁶. -8 Magnitude.

[0009] This invention provides a solid material internal friction measurement device, comprising: a vacuum chamber, a vacuum unit, a sample fixing fixture, a vibration excitation component, a vibration detection component, and a vibration signal processing and analysis component; The vacuum chamber is a sealed metal cabin with a transparent observation window and is connected to the vacuum unit via a pipe; The sample fixing fixture and the vibration excitation assembly are installed inside the vacuum chamber; The vibration detection component is installed on the outside of the vacuum cavity near the observation window; The vibration signal processing and analysis component is electrically connected to the vibration detection component.

[0010] According to the solid material internal friction measuring device provided by the present invention, the vibration detection component is a laser vibrometer with a displacement resolution of less than 20 pm and a maximum vibration measurement frequency of 1 MHz.

[0011] According to the solid material internal friction measurement device provided by the present invention, the vibration signal processing and analysis component consists of a spectrum analyzer, a computer, and vibration signal analysis software.

[0012] According to the solid material internal friction measuring device provided by the present invention, the sample fixing fixture is a "C"-shaped clamp with a metal base, and a hemispherical ruby ​​contact is respectively installed at the upper and lower ends of the opening of the clamp; wherein, the lower contact is fixed and the upper contact is configured to move up and down.

[0013] According to the solid material internal friction measuring device provided by the present invention, the vibration excitation component is an excitation mechanism capable of performing a single striking action, and a polytetrafluoroethylene ball with a diameter of 1~5mm is fixed at the top of the striking part.

[0014] Another aspect of the present invention provides a method for measuring the internal friction of solid materials, specifically involving the following steps: (1) Sample preparation: The sample is in the shape of a circular sheet with a diameter of 20~100mm and a diameter-to-thickness ratio of 10~30. The overall surface is polished and the root mean square roughness value is less than 5nm. Then it is immersed in a strong acidic corrosion solution containing one or more of hydrofluoric acid, sulfuric acid, and nitric acid, or a strong alkaline corrosion solution containing one or more of sodium hydroxide and potassium hydroxide. The corrosion removal amount of the sample thickness is 5~30μm. (2) Sample mounting: Use a "C" type clamp, and use the two hemispherical contacts at the opening of the clamp to clamp the center of the upper and lower surfaces of the circular sample, keeping the circular sample horizontal; (3) Excite the sample: An excitation mechanism capable of performing a single tapping action is adopted. A small ball fixed at the top of the tapping part is close to the edge of the lower surface of the sample. The small ball taps the sample to make it vibrate. (4) Acquiring vibration signals: Turn on the laser vibrometer. The laser emitted by the vibrometer passes through the transparent observation window of the vacuum cavity and is focused on the upper surface of the sample. The laser vibrometer is in the vibration signal detection state. At this time, the sample is excited and the laser vibrometer acquires vibration signals. (5) Signal processing and analysis: The vibration signal processing and analysis component acquires the vibration signal collected by the laser vibration meter in real time, filters out interference signals, and analyzes to obtain the vibration frequency and decay time of the effective vibration wave.

[0015] According to the above embodiments, the present invention has at least the following beneficial effects: The present invention provides a solid material internal friction measuring device and measuring method. By applying an excitation component to the sample to be tested, the sample to be tested vibrates. (1) This eliminates the need to apply torque to the sample to be tested during measurement. This allows the present invention to measure not only metallic materials, but also non-metallic hard and brittle materials such as glass, ceramics, and crystals. There are no requirements for the conductivity of the material, thus expanding the scope of application of the present invention.

[0016] (2) High measurement sensitivity. This invention ensures the measurement sensitivity of material internal friction in three aspects: First, the free oscillation decay phenomenon is a direct reflection of material internal friction. Under the premise that the oscillation frequency remains unchanged, the longer the oscillation decay time, the smaller the material internal friction. Second, the laser vibrometer is used to collect sample vibration information. The displacement resolution is less than 20 pm, and the recognition accuracy is much greater than that of the image acquisition method. Third, through reasonable design and processing, the influence of factors such as air damping, sample fixing method, and sample surface quality on the measurement results is avoided, the measurement error is reduced, and the measurement sensitivity is improved.

[0017] (3) Multifunctionality: This invention can not only measure the internal friction of materials, but also calculate the elastic modulus of materials based on the sample's external dimensions and natural frequency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the internal friction measuring device provided by the present invention; Figure 2 This is a flowchart illustrating the internal friction measurement method provided by the present invention.

[0020] Figure label: 1: Computer; 2: Vibration signal processing and analysis component; 3: Vibration detection component; 4: Vacuum chamber; 5: Observation window; 6: Sample fixing component; 7: Sample to be tested; 8: Sphere; 9: Vibration excitation component; 10: Vacuum gauge; 11: Connecting tube; 12: Vacuum unit. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "upper", "lower", "vertical", "inner", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0024] In the description of this specification, the references to terms such as "specific embodiment," "some embodiments," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0025] Before describing specific embodiments, the design principles and ideas of the present invention will be explained below: First, based on the principle of measuring material internal friction using the free oscillation decay method, let Φ represent internal friction, then: In the formula: f is the vibration frequency of the sample, and τ is the decay time of the sample's free oscillation, that is, the time taken for the sample to decay from the start of oscillation to 1 / e of the initial value. Therefore, the internal friction value can be calculated by accurately measuring f and τ.

[0026] Then, based on this principle, an internal friction measurement device was designed. The design process focused on the influence of external factors on the measurement results, such as air-induced fluid damping, friction between the sample and the fixture, and residual subsurface damage on the sample surface. These factors all shorten the sample's free oscillation decay time, thus requiring a rational design to avoid their interference with the measurement results. This invention places the sample in a vacuum environment for vibration, eliminating air-induced fluid damping; employs a point contact method to avoid vibration energy loss caused by sample clamping; and polishes and chemically treats the sample surface to eliminate surface damage.

[0027] Secondly, the vibration excitation of the sample is achieved using either the impact method or the piezoelectric ceramic excitation method. The impact method allows the sample to vibrate at its natural frequency; the piezoelectric ceramic excitation method allows the sample to vibrate at any frequency within a certain frequency range, thus measuring the internal friction level of the material at different vibration frequencies. A laser vibrometer is used to collect the vibration information of the sample, and the precise vibration frequency and amplitude are obtained through signal processing. Finally, the time-domain and frequency-domain spectra of the entire vibration process of the sample are displayed on computer software, and the values ​​of f and τ are obtained to calculate the magnitude of the internal friction.

[0028] Based on the above design concept, the following is combined with Figure 1 This invention describes a solid material internal friction measurement device, comprising a vacuum chamber 4, a vacuum unit 12, a sample fixing assembly 6, a vibration excitation assembly 9, a vibration detection assembly 3, and a vibration signal processing and analysis assembly 2. The vacuum chamber 4 is a metal sealed chamber with a transparent observation window 5 and is connected to the vacuum unit 12 via a vacuum connecting pipe 11. The sample fixing assembly 6 and the vibration excitation assembly 9 are disposed inside the vacuum chamber 4. The vibration detection assembly 3 is disposed on the outside of the vacuum chamber 4 near the observation window 5. The vibration signal processing and analysis assembly 2 is connected to the vibration detection assembly 3 via a data cable.

[0029] The vacuum chamber 4 is enclosed by a shell, forming a cavity inside the shell. The environment inside the cavity is evacuated to form a vacuum chamber, ensuring a vacuum environment during the measurement process. This allows the sample 7 to be tested to be in a vacuum atmosphere, eliminating fluid damping caused by air and avoiding result deviations caused by environmental interference.

[0030] The vacuum unit 12 is connected to the vacuum chamber 4 through the connecting pipe 11. The vacuum unit 12 extracts the gas in the vacuum chamber 4, so that the vacuum chamber 4 is a vacuum environment.

[0031] Furthermore, a vacuum gauge 10 is connected to the vacuum chamber 4. The vacuum gauge 10 can measure the gas pressure in the vacuum chamber 4 to ensure that the vacuum level inside the vacuum chamber 4 meets the usage requirements. Specifically, the vacuum gauge 10 is connected to one side of the vacuum chamber 4, and the reading of the vacuum gauge 10 is set outside the vacuum chamber 4, so that the value of the vacuum gauge 10 can be read from the outside.

[0032] A transparent observation window 5 is located at the top of the vacuum chamber 4 and is used to transmit the optical signal emitted by the vibration detection component 3. Specifically, the transparent observation window 5 allows the optical signal emitted by the vibration detection component 3 to pass through the transparent observation window 5 and act on the sample 7 to be tested. The material of the transparent observation window 5 is not particularly limited. Preferably, the transparent observation window 5 is made of quartz glass, which has excellent light transmittance and high mechanical strength, and can improve the measurement accuracy of the vibration detection component 3.

[0033] The vibration excitation component 9 is located on one side of the sample 7 to be tested. It acts on the sample 7 to be tested by physical impact, causing the sample 7 to vibrate. The vibration excitation component 9 includes a drive unit, a support rod connected to the drive unit, and a ball 8 at the end of the support rod. The ball 8 can strike the sample 7 to be tested under the drive of the drive unit. The drive unit can drive the support rod to move so that the ball 8 strikes the sample 7 to be tested in a single motion.

[0034] Specifically, the ball 8 is located below the edge of the lower surface of the sample 7 to be tested. Under the action of the driving unit, the ball 8 can strike the edge of the sample 7 to cause the sample 7 to vibrate. The driving unit is not particularly limited. For example, it can be a structure in which a hydraulic cylinder or a pneumatic cylinder drives a connecting rod, so that the ball 8 moves upward and briefly impacts the sample 7 to cause the sample 7 to vibrate. Alternatively, it can be a piezoelectric ceramic or a linear motor that drives the support rod to move so that the ball 8 strikes the sample 7.

[0035] The sphere 8 needs to cause the test sample 7 to vibrate when struck. Therefore, the specific material of the sphere 8 is not particularly limited. For example, the sphere 8 can be made of hard plastic or a small metal ball. Preferably, polytetrafluoroethylene (PTFE) is used as the material of the sphere 8. PTFE balls have sufficient rigidity to cause the test sample 7 to vibrate when struck, and the PTFE balls have moderate hardness to prevent the sample from breaking or deforming due to impact.

[0036] It is understood that this application uses a physical striking method to vibrate the sample under test, rather than electrostatic or electromagnetic excitation that can only vibrate metals or conductors. Therefore, the measurement objects of this application are not only applicable to metallic materials, but also to non-metallic solid materials such as glass, ceramics, and crystals, thus expanding the application range of the measurement components.

[0037] The sample fixing component 6 can clamp the sample 7 to be tested, thus fixing the sample 7 in a vacuum environment. The sample fixing component 6 only needs to be able to clamp the sample 7 to be tested within the vacuum chamber; the specific clamping structure is not particularly limited. Preferably, the sample fixing component 6 can clamp the sample 7 to be tested in a point-contact manner, resulting in a smaller contact area and less friction between the sample 7 and the sample fixing component 6. This ensures less vibration energy loss of the sample and improves the accuracy of material internal friction measurement.

[0038] The sample fixing assembly 6 includes a base with a fixed end and a movable end to form a "C"-shaped clamp. A hemispherical contact is installed at each end of the opening of the "C"-shaped clamp, with the lower contact fixed and the upper contact movable vertically. A gap suitable for clamping the sample 7 to be tested is provided between the fixed end and the movable end, and the movable end is designed to adjust the gap distance.

[0039] The adjustable gap between the movable ends allows for clamping to accommodate the thickness of the sample 7 being tested. Specifically, the movable end is mounted on the upper part of the base, and the fixed end is mounted on the lower part of the base, positioning the movable end above the fixed end. The movable end is adjusted up and down to clamp the sample 7, meaning that lowering the movable end applies pressure to the sample 7, thus fixing it to the base. The mechanism for the movable end's up-and-down movement is not particularly limited; for example, it can be adjusted using a lead screw, a hydraulic cylinder, or a pneumatic cylinder.

[0040] Specifically, rigid hemispherical contacts are connected to the movable end and the fixed end respectively, so that the spherical surface of the hemispherical contact contacts the sample 7 to be tested for clamping.

[0041] The spherical surface contacts the sample 7 to achieve point contact clamping. The rigid spherical surface reduces the contact area with the sample 7 during clamping, avoiding friction between the sample and the clamping end from affecting the measurement of internal friction. The hemispherical contacts at both the fixed and movable ends are made of rigid materials. There are no special limitations on the rigid material; it only needs to ensure that it does not deform under pressure during clamping. For example, the hemispherical contact could be a smooth steel ball, a smooth glass ball, etc.

[0042] Furthermore, the upper movable end and the lower fixed end form a "C"-shaped clamping mechanism. The upper movable end can move up and down vertically, adjusting the gap between the upper movable end and the lower fixed end. Preferably, hemispherical rubies are connected to the upper movable end and the lower fixed end, respectively. The rubies have low surface roughness and high hardness. The hemispherical ruby ​​contacts reduce the contact area between the sample 7 and the clamping mechanism, which improves the measurement sensitivity of internal friction. This is because a larger clamping area results in greater energy loss from the vibration of the material being tested, which is detrimental to reflecting the true free oscillation decay time of the sample 7 and thus reduces the accuracy of the measured data.

[0043] For the clamping of the sample 7 to be tested, the upper movable end and the lower fixed end are clamped at the geometric center of the sample 7 to be tested. For example, if the sample 7 to be tested has a disk-shaped structure, the hemispherical contacts at the upper and lower ends are clamped to the center of the disk-shaped structure during clamping, so that the sample 7 to be tested remains in a horizontal state.

[0044] The vibration detection component 3 is a laser vibrometer, which is positioned directly above the transparent observation window 5. It emits a laser beam onto the sample 7 to be tested and simultaneously collects the laser beam reflected from the target. After interference, a Doppler frequency shift signal proportional to the target velocity is generated. The signal is then processed by the decoder of the controller and outputs an analog voltage representing the target velocity and displacement, thereby measuring the vibration signal.

[0045] A laser vibrometer with a displacement resolution of less than 20 μm and a maximum vibration measurement frequency of 1 MHz is preferred. Using a laser vibrometer with high displacement resolution improves measurement accuracy, and the limited maximum vibration measurement frequency results in a wider vibration spectrum.

[0046] The vibration signal processing and analysis component 2 is electrically connected to the vibration detection component 3 via wires. Of course, the vibration signal processing and analysis component 2 and the vibration detection component 3 can also be connected wirelessly, so that the vibration signal collected by the vibration detection component 3 can be wirelessly transmitted to the vibration signal processing and analysis component 2.

[0047] The vibration signal processing and analysis component 2 is capable of processing vibration signals and analyzing them to obtain information such as vibration frequency, amplitude, and vibration attenuation curves; however, no particular limitations are imposed on this aspect. Preferably, the vibration signal processing and analysis component 2 includes a spectrum analyzer computer 1 and vibration signal analysis software. The spectrum analyzer analyzes the vibration signal and transmits the analyzed vibration signal to the computer 1, where the computer 1 performs data processing to obtain the internal friction value. The computer 1 has a processor and a memory. The memory stores the analysis software capable of analyzing vibration signals and calculating internal friction values. By executing the analysis software, the internal friction value can be calculated.

[0048] The measurement method provided by the present invention is described below. The measurement method described below can be referred to in correspondence with the internal friction measurement device described above.

[0049] like Figure 2 As shown, a method for measuring the internal friction of solid materials is described. This method utilizes any of the aforementioned internal friction measuring devices and includes the following steps during the measurement: Step 100: Process the sample 7 to be tested so that the surface roughness of the sample 7 meets the measurement requirements, and then remove a certain thickness by means of an etching solution. Step 200: The processed sample 7 to be tested is clamped and fixed using the sample fixing assembly 6; Step 300: Use the vibration excitation component 9 to tap the sample 7 to be tested once, so that the sample 7 to be tested vibrates. Step 400: Vibration detection component 3 collects vibration signals and transmits the vibration signals to vibration signal processing and analysis component 2; Step 500: Vibration signal processing and analysis component 2 receives vibration signals and analyzes them to obtain the vibration frequency and decay time of the effective vibration wave.

[0050] The steps described above are explained in detail below.

[0051] In step 100, the sample to be tested 7 is obtained and processed into a circular sheet with a diameter of 20~100mm and a diameter-to-thickness ratio of 3~10. The overall surface is polished and the root mean square roughness value is less than 5nm. Then, it is immersed in a corrosion solution containing strong acids such as hydrofluoric acid, sulfuric acid, and nitric acid or strong bases such as sodium hydroxide and potassium hydroxide. The thickness is etched and removed by 5~30μm to complete the sample preparation.

[0052] In step 200, the disc-shaped sample is clamped by the sample fixing component 6. During clamping, the movable end of the sample fixing component 6 is adjusted so that the contact point of the upper movable end is close to the contact point of the lower movable end and the upper and lower contact points are located at the center of the disc-shaped sample, so that the disc-shaped sample is in a horizontal state after clamping.

[0053] In step 300, by connecting the vacuum unit 12 or other vacuum pumping equipment, the interior of the vacuum chamber 4 is made to be in a vacuum state, and the vacuum gauge 10 ensures that the sample 7 to be tested is always in a vacuum environment during the measurement process. The vibration excitation component 9 is activated, so that the vibration excitation component 9 strikes the sample 7 to be tested once, causing the sample 7 to vibrate under the strike.

[0054] In step 400, the laser vibrometer is turned on. The laser emitted by the vibrometer passes through the transparent observation window 5 of the vacuum cavity 4 and is focused on the upper surface of the sample 7 to be tested. The laser vibrometer is in the vibration signal detection state. At this time, the sample is excited and the laser vibrometer collects the vibration signal.

[0055] In step 500, the vibration signal processing and analysis component 2 is used by the signal processing and analysis system to acquire the vibration signal collected by the laser vibrometer in real time, filter out interference signals, analyze the vibration frequency and decay time of the effective vibration wave, and calculate the magnitude of the material internal friction Φ according to the internal friction formula.

[0056] Furthermore, the present invention can also be used to calculate the elastic modulus of a material based on the sample's external dimensions and natural vibration frequency.

[0057] The following two embodiments illustrate in detail the solid material internal friction measuring device and method provided by the present invention: Example 1: The following explanation uses the measurement of internal loss of a type of quartz glass as an example, involving the following internal loss measuring device: like Figure 1 As shown, a solid material internal friction measuring device mainly consists of a vacuum chamber 4, a vacuum unit 12, a sample fixing assembly 6, a sample vibration excitation 9, a vibration detection assembly 3, and a vibration signal processing and analysis assembly 2.

[0058] The vacuum chamber 4 is a metal sealed chamber with a transparent quartz glass observation window 5, and is connected to the vacuum unit 12 through a vacuum pipe 11.

[0059] The sample fixing component 6 and the vibration excitation component 9 are housed inside the vacuum chamber 4.

[0060] The vibration detection component 9 is located on the outside of the vacuum chamber 4 near the observation window 5.

[0061] The vibration signal processing and analysis component 2 and the vibration detection component 3 are connected by a data cable.

[0062] The vibration detection component 3 is a laser vibrometer with a displacement resolution of 18 pm and a maximum vibration measurement frequency of 1 MHz.

[0063] The vibration signal processing and analysis component 2 consists of components such as a spectrum analyzer and filters.

[0064] The sample fixing component 6 is a "C"-shaped clamp with a metal base. A hemispherical ruby ​​contact is installed at each of the upper and lower ends of the opening. The lower contact is fixed, while the upper contact can move up and down.

[0065] The vibration excitation component 9 is an excitation mechanism capable of performing a single striking action, and a polytetrafluoroethylene ball 8 with a diameter of 5mm is fixed at the top of the striking part.

[0066] A method for measuring the internal friction of solid materials, specifically involving the following steps: (1) Sample preparation: The quartz glass sample is processed into a circular sheet with a diameter of 60 mm and a thickness of 3. The overall surface is polished and the root mean square roughness value is less than 5 nm. Then it is immersed in an etching solution containing hydrofluoric acid, and the thickness is etched away by 20 μm. (2) Sample mounting: Use a "C" type clamp, and use the two hemispherical contacts at the opening of the clamp to clamp the center of the upper and lower surfaces of the circular sample, keeping the circular sample horizontal; (3) Excite the sample: An excitation mechanism capable of performing a single tapping action is adopted. A small ball fixed at the top of the tapping part is close to the edge of the lower surface of the sample. The small ball taps the sample to make it vibrate. (4) Acquiring vibration signals: Turn on the laser vibrometer. The laser emitted by the vibrometer passes through the transparent observation window 5 of the vacuum chamber 4 and is focused on the upper surface of the sample. The laser vibrometer is in the vibration signal detection state. At this time, the sample is excited and the laser vibrometer acquires vibration signals. (5) Signal processing and analysis: The signal processing and analysis system acquires the vibration signal collected by the laser vibrometer in real time, filters out interference signals, and analyzes to obtain the effective vibration wave with a vibration frequency f=5200Hz and a decay time τ=900 seconds. The material internal friction is calculated according to the following formula: ≈6.8×10 -8 .

[0067] Example 2: The following explanation uses the measurement of internal friction of a metal alloy as an example, involving the following internal friction measuring device: like Figure 1 As shown, a solid material internal friction measuring device mainly consists of a vacuum chamber 4, a vacuum unit 12, a sample fixing assembly 6, a vibration excitation assembly 9, a vibration detection assembly 3, and a vibration signal processing and analysis assembly 2.

[0068] The vacuum chamber 4 is a metal sealed chamber with a transparent quartz glass observation window 5, and is connected to the vacuum unit 12 through a vacuum pipe 11.

[0069] The sample fixing component 12 and the vibration excitation component 9 are housed inside the vacuum chamber 4.

[0070] The vibration detection component 3 is placed on the outside of the vacuum cavity 4 near the observation window 5.

[0071] The vibration signal processing and analysis component 2 and the vibration detection component 3 are connected by a data cable.

[0072] The vibration detection component 3 is a laser vibrometer with a displacement resolution of 16 pm and a maximum vibration measurement frequency of 1 MHz.

[0073] The vibration signal processing and analysis component 2 consists of components such as a spectrum analyzer and filters.

[0074] The sample fixing component 6 is a "C"-shaped clamp with a metal base. A hemispherical ruby ​​contact is installed at each of the upper and lower ends of the opening. The lower contact is fixed, while the upper contact can move up and down.

[0075] The vibration excitation component 9 is an excitation mechanism capable of performing a single striking action, and a polytetrafluoroethylene ball 8 with a diameter of 5mm is fixed at the top of the striking part.

[0076] A method for measuring the internal friction of solid materials, specifically involving the following steps: (1) Sample preparation: The quartz glass sample was processed into a circular sheet with a diameter of 100 mm and a thickness of 5 mm. The entire surface was polished and the root mean square roughness value was 1 nm. Then it was immersed in an etching solution containing sulfuric acid and nitric acid, and the thickness was etched away by 30 μm. (2) Sample mounting: Use a "C" type clamp, and use the two hemispherical contacts at the opening of the clamp to clamp the center of the upper and lower surfaces of the circular sample, keeping the circular sample horizontal; (3) Excite the sample: An excitation mechanism capable of performing a single tapping action is adopted. A small ball fixed at the top of the tapping part is close to the edge of the lower surface of the sample. The small ball taps the sample to make it vibrate. (4) Acquiring vibration signals: Turn on the laser vibrometer. The laser emitted by the vibrometer passes through the transparent observation window 5 of the vacuum chamber 4 and is focused on the upper surface of the sample. The laser vibrometer is in the vibration signal detection state. At this time, the sample is excited and the laser vibrometer acquires vibration signals. (5) Signal processing and analysis: The signal processing and analysis system acquires the vibration signal collected by the laser vibrometer in real time, filters out interference signals, and analyzes to obtain the effective vibration wave with a vibration frequency f=2865Hz and a decay time τ=36 seconds. The material internal friction is calculated according to the following formula: ≈3.1×10 -6 .

[0077] As can be seen from the above embodiments, the present invention can measure the internal friction value of various materials, has wider applicability, and can measure an internal friction value of 10. -8 The internal friction value is on the order of magnitude.

[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 embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to 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 embodiments of the present invention.

Claims

1. A method for measuring the internal friction of solid materials, characterized in that, The implementation is based on a solid material internal friction measurement device, which includes: a vacuum chamber, a vacuum unit, a sample fixing fixture, a vibration excitation component, a vibration detection component, and a vibration signal processing and analysis component. The vacuum chamber is a sealed metal cabin with a transparent observation window and is connected to the vacuum unit via a pipe; The sample fixing fixture and the vibration excitation assembly are installed inside the vacuum chamber; The vibration detection component is installed on the outside of the vacuum cavity near the observation window; The vibration signal processing and analysis component is electrically connected to the vibration detection component; The vibration detection component is a laser vibrometer with a displacement resolution of less than 20 μm and a maximum vibration measurement frequency of 1 MHz. The sample fixing fixture is a "C"-shaped clamp with a metal base. A hemispherical ruby ​​contact is installed at the upper and lower ends of the clamp opening. The lower contact is fixed, while the upper contact is movable up and down. The vibration excitation component is an excitation mechanism capable of performing a single striking action, with a polytetrafluoroethylene ball with a diameter of 1~5mm fixed at the top of the striking part; The method specifically involves the following steps: (1) Sample preparation: The sample is in the shape of a circular sheet with a diameter of 20~100mm and a diameter-to-thickness ratio of 10~30. The overall surface is polished and the root mean square roughness value is less than 5nm. Then it is immersed in a strong acidic corrosion solution containing one or more of hydrofluoric acid, sulfuric acid, and nitric acid, or a strong alkaline corrosion solution containing one or more of sodium hydroxide and potassium hydroxide. The corrosion removal amount of the sample thickness is 5~30μm. (2) Sample mounting: Use a "C" type clamp, and use the two hemispherical contacts at the opening of the clamp to clamp the center of the upper and lower surfaces of the circular sample, keeping the circular sample horizontal; (3) Excite the sample: An excitation mechanism capable of performing a single tapping action is adopted. A small ball fixed at the top of the tapping part is close to the edge of the lower surface of the sample. The small ball taps the sample to make it vibrate. (4) Acquiring vibration signals: Turn on the laser vibrometer. The laser emitted by the vibrometer passes through the transparent observation window of the vacuum cavity and is focused on the upper surface of the sample. The laser vibrometer is in the vibration signal detection state. At this time, the sample is excited and the laser vibrometer acquires vibration signals. (5) Signal processing and analysis: The vibration signal processing and analysis component acquires the vibration signal collected by the laser vibration meter in real time, filters out interference signals, and analyzes to obtain the vibration frequency and decay time of the effective vibration wave.

2. The method for measuring internal friction of solid materials according to claim 1, characterized in that, The vibration signal processing and analysis component consists of a spectrum analyzer, a computer, and vibration signal analysis software.

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