Method for measuring internal stress of composite material by using pressure-sensitive material

Abstract

The invention discloses a method for measuring the internal stress of a composite material by using a pressure-sensitive material, and provides a novel stress detection technology. According to the technology, pressure-sensitive particles are embedded into a composite material. The pressure-sensitive material is deformed after being stressed, the conductivity distribution of particles in the material is changed, signals are collected by a signal detection device and uploaded to an upper computer according to the response of the particles to external pressure under the action of an excitation magnetic field, and the internal stress of the composite material is measured through an image reconstruction algorithm. The stress measurement method provided by the invention is suitable for various occasions requiring real-time and non-destructive monitoring of the internal stress change of the material, such as building structures and mechanical parts. By monitoring the stress change in the material in real time, potential problems of the structure are found in time, and preventive measures are taken to avoid potential faults. The method not only improves the accuracy and efficiency of monitoring, but also has important significance for prolonging the service life of the material and guaranteeing the safety of the structure.

Description

Technical Field

[0001] The present invention belongs to the technical field related to nondestructive testing of composite materials, and specifically relates to a method for measuring the internal stress of a composite material by using a pressure-sensitive material. Background Art

[0002] In the field of modern engineering, accurate measurement of internal stress of materials is crucial to ensure structural safety and extend service life. Although traditional stress measurement methods, such as resistance strain gauges and fiber grating sensors, can provide stress information to a certain extent, they usually have certain limitations, such as complex installation, high cost, limited measurement range or damage to the measured material. In addition, these methods often find it difficult to achieve real-time and continuous monitoring of deep stress inside the material.

[0003] With the development of materials science and intelligent sensing technology, the use of pressure-sensitive materials to measure the internal stress of composite materials has become a hot topic of research. For example, pressure-sensitive and piezoresistive materials can convert mechanical stress into electrical signals to achieve high sensitivity and non-destructive detection of internal stress of materials. However, the existing technology has challenges in integrating pressure-sensitive materials, resisting environmental interference, and achieving high-precision real-time monitoring. The present invention aims to overcome these difficulties through innovative material integration and detection methods, and provide a stable and accurate stress measurement technology to meet the monitoring needs under complex structures and dynamic environments, and promote the progress of materials science and intelligent monitoring technology. In response to the above problems, the present invention proposes a method for measuring the internal stress of composite materials using pressure-sensitive materials. By embedding auxiliary particles with electrical or magnetic properties in the composite material, when the material is subjected to pressure, the response of these particles to external excitation is used, and the internal stress of the material is accurately measured through an image reconstruction algorithm to meet the needs of real-time stress detection.

[0004] This method can not only provide richer and more accurate stress information, but also has the advantages of easy installation, low cost, strong adaptability, etc. The invention is based on an in-depth analysis of existing stress measurement technology and full use of the characteristics of pressure-sensitive materials, aiming to break through the limitations of existing technology and provide a more effective and reliable solution for stress monitoring of composite materials. Through continuous technological innovation and optimization, this method is expected to play an important role in engineering practice and contribute to ensuring structural safety, optimizing material design, and improving engineering efficiency. Summary of the invention

[0005] In order to achieve a more effective implementation scheme for composite material internal stress detection, the present invention provides a method for measuring composite material internal stress using a pressure-sensitive material, and the method for measuring composite material internal stress using a pressure-sensitive material comprises the following steps:

[0006] Step S1: installing the detection device on the platform of the force-applying mechanism so that the n-channel data acquisition units can receive the induced voltage signal without hindering the detection process;

[0007] Step S2: The signal generating device generates an excitation signal, and the signal is transmitted to the excitation coil to generate an excitation magnetic field. At the same time, the conductivity distribution of the auxiliary particles inside the material changes after being subjected to force, and a secondary magnetic field is generated under the action of the excitation magnetic field. The generated induced voltage signal is captured by the induction coil;

[0008] Step S3: the n-channel data acquisition units sample the signals and transmit them to the signal processing device, and then use the image reconstruction algorithm to calculate the distribution position of the electric particles inside the material before and after the pressure and the change of the conductivity at the position, thereby indirectly realizing the stress measurement inside the material;

[0009] Step S4: cyclically excite the coils in sequence, and use the other coils as induction coils to obtain an induced voltage signal of each coil, and repeat the above steps to detect the internal stress of the material.

[0010] On the basis of the above technical solution, preferably, the auxiliary particles are pressure-sensitive particles, which contain particles with electrical or magnetic properties, such as carbon black or metal particles, showing better stability and lower dielectric loss.

[0011] On the basis of the above technical solution, preferably, the n (n≥2) sensor arrays include 1 excitation coil and n-1 induction coils, and the n sensors are evenly distributed around the test piece.

[0012] Based on the above technical solutions, preferably, the integrated method is: synthesizing and surface modifying the particles, ensuring that the particles are approximately uniformly dispersed in the composite material by mixing, pouring or spraying, etc. The treated particles are incorporated into the matrix of the composite material in a specific ratio.

[0013] On the basis of the above technical solution, preferably, the coils are excited cyclically in sequence to obtain an induced voltage signal of each coil of the object to be tested.

[0014] On the basis of the above technical solution, preferably, the measuring device includes: an excitation coil, an induction coil, a signal generating and processing device, and n-channel data acquisition units.

[0015] On the basis of the above technical solution, preferably, the induced voltage signal is generated by the auxiliary particles under pressure and the excitation magnetic field.

[0016] On the basis of the above technical solution, preferably, the step of obtaining the internal stress change of the material according to the received signal includes the following steps: the collected signal is subjected to preprocessing steps such as filtering, amplification and digitization. Features related to the stress state, such as peak value, energy, frequency component, etc., are extracted from the preprocessed signal. The position distribution of particles and the change in conductivity at the particle position can be determined by image reconstruction algorithms, such as algebraic methods, filtered back projection methods, iterative algorithms, etc., and the change in internal stress of the material can be indirectly obtained.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] 1. The present invention provides a method for measuring the internal stress of a composite material using a pressure-sensitive material, which can effectively measure the stress inside the composite material, which is crucial for understanding the deformation behavior of the material during the stress process.

[0019] 2. Traditional stress measurement may require the destruction of materials, while the method of the present invention is non-destructive, which can reduce damage to materials and reduce testing costs. It is applicable to a variety of composite materials, including but not limited to soil, concrete, metal-based, ceramic-based and polymer-based composite materials, and has broad application prospects.

[0020] 3. The present invention provides a method for measuring the internal stress of a composite material using a pressure-sensitive material. The method embeds pressure-sensitive auxiliary particles in the composite material to actively generate an excitation signal. Under the action of a magnetic field, an induction signal is generated. An image reconstruction algorithm is used to measure the internal structural stress of the material. This method not only meets the needs of real-time stress detection, but also has non-destructive characteristics, which is of great significance for extending the service life of the material and ensuring structural safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For all other implementations obtained by ordinary technicians in this field without creative work, other drawings can also be obtained based on these drawings. In the drawings:

[0022] Figure 1 The present invention is a flowchart of a method for measuring internal stress of a composite material by using a pressure-sensitive material.

[0023] Figure 2 It is a schematic diagram of an application scenario of a method for measuring internal stress of a composite material using a pressure-sensitive material according to an embodiment of the present invention.

[0024] Figure 3It is a schematic diagram of the distribution positions of sensors in a method for measuring internal stress of a composite material using a pressure-sensitive material when n=8 in an embodiment of the present invention.

[0025] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0026] 1. Excitation coil; 2. Induction coil; 3. Auxiliary particles with specific electromagnetic properties; 4. Outer edge of cylindrical composite material; 5. Signal generation and processing device; 6. Platform of force-applying mechanism; 7. n-channel data acquisition unit; 8. Schematic diagram of pressure application direction. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail in conjunction with the illustrations. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention will be further described in detail below with reference to the accompanying drawings.

[0029] See also Figure 2-Figure 3 The present invention implements a method for measuring the internal stress of a composite material using a pressure-sensitive material and is applied to Figure 2 In the detection system shown, pressure-sensitive particles are embedded in a composite material, and the particles contain auxiliary particles 3 with electrical properties, such as carbon black or metal particles, which are approximately uniformly distributed inside the material.

[0030] Figure 2 In the detection system shown, the detection system includes a signal generation and processing device 5, an amplifying filter, an analog switch, a PGA gain amplifier, an n-channel data acquisition unit 7, a platform 6 of a force-applying mechanism, and n coil sensors, wherein the sensors are evenly distributed around the material column. Figure 2 Schematic diagram of coil distribution when n=8 is shown.

[0031] See also Figure 1 The present invention implements a method for measuring the internal stress of a composite material using a pressure-sensitive material and is applied to Figure 1 Taking the detection system shown in FIG. 1 as an example, an embodiment of the present invention is explained, and the method for measuring the internal stress of a composite material using a pressure-sensitive material is as follows:

[0032] Step S1: Install the detection device on the platform 6 of the force-applying mechanism so that the n-channel data acquisition unit 7 can receive the induced voltage signal without hindering the detection process.

[0033] Considering that the signal is weak during the implementation of step S1, a filter amplifier is added to ensure the quality and accuracy of the signal.

[0034] Step S2: The signal generating device 5 generates an excitation signal, which is transmitted to the excitation coil 1 to generate an excitation magnetic field. At the same time, the conductivity distribution of the auxiliary particles inside the material changes after being subjected to force, and a secondary magnetic field is generated under the action of the excitation magnetic field. The generated induced voltage signal is captured by the induction coil 2.

[0035] The specific steps to obtain stress information based on the sensing signal are as follows:

[0036] The signal strength of the collected electrical signal is enhanced by a gain amplifier, and the key features related to the stress state, such as peak value and energy, are extracted from the filtered and amplified signal using a signal collection and processing device.

[0037] Step S3: the n-channel data acquisition unit 7 samples the signal and transmits it to the signal processing device 5, and then calculates the distribution position of the electric particles inside the material before and after the pressure through the image reconstruction algorithm, thereby indirectly realizing the stress measurement inside the material.

[0038] This includes using image reconstruction algorithms, such as algebraic methods, filtered back projection methods, iterative algorithms, etc. to determine the center position of the particles and the rate of change of conductivity at their location, and indirectly determine the stress inside the material.

[0039] Step S4: cyclically excite coil 1 in sequence, and use other coils as induction coils 2 to obtain an induced voltage signal of each coil, and repeat the above steps to detect the internal stress of the material.

[0040] The present invention provides a method for measuring the internal stress of a composite material by using a pressure-sensitive material, which can accurately measure the stress inside the composite material, which is crucial for understanding the deformation behavior of the material during the stress process.

[0041] The present invention provides a method for measuring the internal stress of a composite material using a pressure-sensitive material. Auxiliary particles are embedded in the composite material, and the material is deformed by force. The conductivity distribution of the internal particles changes, and a response is generated under the action of an excitation magnetic field. The center position of the particle and the change in conductivity at the location are measured by an image reconstruction algorithm, thereby measuring the internal stress of the composite material. This method not only meets the needs of real-time stress detection, but also has non-destructive characteristics, which is of great significance for extending the service life of the material and ensuring the safety of the structure.

[0042] The above description is only a partial embodiment of the present invention. The protection scope required by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for measuring internal stress of a composite material using a pressure-sensitive material, characterized in that: include: The composite material is integrated and placed on a platform of a force-applying mechanism, and m pressure-sensitive particles are embedded in the composite material. The particles contain pressure-sensitive materials with electrical or magnetic properties. When external pressure is applied to the composite material, the pressure-sensitive material is deformed by the force, and the conductivity distribution of the particles inside it changes. Under the action of the excitation magnetic field, the pressure-sensitive particles respond to the external pressure. The signal is collected by a signal detection device and uploaded to a host computer. The coil is cyclically excited, and the center position of the particle before and after the force is applied and the change in conductivity at the particle position are measured by a filtered back-projection reconstruction algorithm, thereby realizing the measurement of the internal stress of the composite material. This method is applied to stress detection of composite materials.

2. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: The composite material comprises one or more combinations of soil, concrete, metal-based, ceramic-based and polymer-based composite materials.

3. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: The m pressure-sensitive particles are millimeter-scale pressure-sensitive particles, which show significantly improved electromagnetic induction performance. The pressure-sensitive particles used contain materials with electrical or magnetic properties, such as carbon black or metal particles.

4. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: The conductivity of the auxiliary particles differs from that of the composite material by two orders of magnitude or more to ensure the accuracy and reliability of the measurement.

5. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: Methods for integrating composite materials include: synthesizing and surface modifying particles, ensuring that these particles are approximately evenly dispersed in the composite material through mixing, infusion or spraying techniques, and incorporating these treated particles into the matrix of the composite material in a specific proportion.

6. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: An array of n stress detection sensors is used, which are evenly arranged around a cylindrical sensitive field, with 1 excitation sensor coil and n-1 receiving sensor coils. The coils are excited in turn to obtain an induced voltage signal of each coil.

7. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: The signal detection device comprises: a signal generating device, n stress measurement array coils, and a signal processing device for processing signals and extracting stress information.

8. The method for measuring internal stress of a composite material using a pressure-sensitive material according to claim 1, characterized in that: Through image reconstruction algorithms, such as algebraic methods, filtered back projection methods, and iterative algorithms, the position distribution of particles and the change in conductivity at the particle positions can be determined, and the change in internal stress of the material can be indirectly obtained.

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