Composite material damage location and assessment method based on amorphous wire distributed sensing

Abstract

The present invention discloses a composite material damage location and assessment method based on distributed induction of amorphous wires, which belongs to the intersection of magnetic material technology and structural health monitoring. Based on the mapping relationship between the local magnetic induction signal of amorphous wires and the local stress field, the present invention can accurately identify the stress state changes in different sections of amorphous wires through distributed analysis of the amorphous wire induction signal, thereby realizing the location and assessment of composite material damage. This method overcomes the limitation of existing testing methods that can only perform overall signal analysis on amorphous wires, further expands the application of amorphous wires in the field of composite material structural health monitoring, and significantly enhances the engineering application value of amorphous wires in aerospace, rail transportation and other fields.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic material technology and structural health monitoring engineering, and relates to the engineering application of the magneto-mechanical coupling effect of amorphous wires and a method for locating and quantitatively evaluating internal damage in composite materials, and in particular to a method for locating and evaluating damage in composite materials based on distributed induction of amorphous wires. Background Art

[0002] Fiber-reinforced resin-based composite materials are widely used in aerospace, automotive, new energy and other fields, which have extremely high requirements for safety and reliability. If the damage in the composite material is not detected in time and continues to expand during service, it may cause structural failure and trigger a major safety accident. In addition, the manufacturing cost of aviation composite components accounts for 35% of the entire aircraft. Accurate damage assessment can reduce maintenance costs by 57% and avoid material waste caused by excessive maintenance. The US NTSB report pointed out that 21% of composite structure accidents in the past decade were caused by damage assessment errors, highlighting the strategic value of accurate damage detection in ensuring the safe operation of major equipment.

[0003] The current technology system for locating and assessing damage in composite materials still has some shortcomings. In the field of physical field detection, although ultrasonic technology can detect damage through the propagation characteristics of sound waves, it is limited by its poor adaptability to complex surfaces and the need for interface coupling agents. X-ray tomography can image internal defects, but there are radiation hazards and high equipment costs. In terms of intelligent sensing technology, fiber Bragg grating technology monitors strain changes through information such as grating wavelength and phase, but is susceptible to temperature interference and can reduce material strength. Piezoelectric sensors use the time difference of stress wave propagation to locate damage, but there are problems with severe high-frequency signal attenuation and layout dependence. These technologies all face problems such as limited spatial resolution, lack of quantitative assessment, and complex implementation.

[0004] Amorphous wires are a type of micron-sized metal fiber with an amorphous structure. Their atomic arrangement is long-range disordered but short-range ordered, exhibiting unique magnetic, mechanical, and electrical properties. This type of material is typically prepared through ultrafast cooling technology, which avoids the formation of crystals, resulting in properties such as isotropy, low defect density, and high strength. Based on the giant magneto-impedance effect and stress-impedance effect of amorphous wires, the technology of embedding amorphous wires into composite materials to monitor composite materials for structural health monitoring has become a research hotspot in the field of amorphous wire intelligent sensing. However, existing detection methods usually use amorphous wires as homogeneous sensing units for overall signal acquisition and analysis. This macro-scale signal acquisition method lacks the ability to spatially resolve stress gradients within the material, making it difficult for existing technology systems to accurately locate and quantitatively analyze internal damage in composite materials. Summary of the Invention

[0005] Based on the pain points of the above-mentioned composite material damage detection technology and the shortcomings of amorphous wire in the application of composite material internal damage location and assessment, the present invention proposes a composite material damage location and assessment method based on amorphous wire distributed sensing, the method comprising the following steps:

[0006] S1: thermal stability treatment of amorphous wire to release residual stress of amorphous wire;

[0007] S2: During the fiber-reinforced resin matrix composite material molding stage, amorphous filaments are embedded into the composite material to form a detectable self-sensing composite material after integrated molding;

[0008] S3: A mobile magnetic excitation-detection integrated probe is used to perform scanning detection along the axial direction of the amorphous wire at a constant rate;

[0009] S4: Damage location and assessment inside the composite material is performed by analyzing the amplitude changes of characteristic signals in the collected signals.

[0010] According to a preferred embodiment of the present invention, the S3 integrated magnetic excitation-detection probe consists of a U-shaped electromagnet and a solenoid coil, which is placed in the magnetic pole gap of the U-shaped electromagnet and flush with it; an external signal generator generates an excitation signal and excites the U-shaped electromagnet after amplification by a gain amplifier, and the U-shaped electromagnet continuously generates an alternating magnetic field with a frequency of 100-500 Hz and an amplitude of 1~2Oe, while the solenoid coil obtains the induction signal in real time.

[0011] According to a preferred embodiment of the present invention, in S4, analyzing the amplitude change of the characteristic signal in the collected signal includes the following steps:

[0012] S41: filtering and amplifying the source signal collected by S3;

[0013] S42: performing differential processing on the signal processed in S41 and the signal collected in the state without amorphous wire sensing to obtain a characteristic signal;

[0014] S43: Analyze the changes in characteristic signals of different sections of amorphous wire to complete composite material damage location and assessment;

[0015] The filtering and amplification of the S41 source signal are completed by the filter, and the processed signal is extracted and analyzed by the oscilloscope;

[0016] The characteristic signal of S42 originates from the magnetization jump behavior of the internal magnetic domains after the amorphous wire is embedded in the composite material. When the local magnetic field generated by the probe's U-shaped electromagnet exceeds the coercive force of the amorphous wire (less than 1 Oe), the local magnetic domains in the corresponding amorphous wire below the probe will flip 180 degrees. The resulting change in local magnetic flux will generate an additional induction signal in the solenoid coil inside the probe. This signal is extracted to form the characteristic signal.

[0017] The characteristic signal of S43 is modulated by the stress field. The stronger the local stress field, the larger the characteristic signal amplitude. The characteristic signal amplitude collected in the initial undamaged state is the highest. After the composite material is damaged, the stress around the amorphous wire is released, and the characteristic signal extracted from the amorphous wire will decrease. The higher the difference with the initial characteristic signal, the more serious the damage.

[0018] Compared with the prior art, the innovative advantages of the present invention are:

[0019] 1) The local magnetic induction signal of the amorphous wire is collected, which makes up for the deficiency of the existing detection technology that can only analyze the overall signal of the amorphous wire;

[0020] 2) A new method for composite material damage localization and assessment is proposed, which further expands the capabilities of amorphous wires in composite material internal damage localization and assessment based on real-time structural health monitoring.

[0021] 3) Compared with existing composite material damage detection technologies, this method has the advantages of low cost, simple operation, and strong engineering applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : Initial hysteresis loop characteristic curve of amorphous wire;

[0023] Figure 2 : Magnetic hysteresis loop characteristic curve after amorphous wire is embedded in the composite material;

[0024] Figure 3 : Schematic diagram of the structure of the amorphous wire distributed magnetic induction signal acquisition device;

[0025] Figure 4 : The waveform of the collected signal when there is no amorphous wire;

[0026] Figure 5 : The waveform of the collected signal when there is amorphous wire response;

[0027] Figure 6 : Characteristic signal waveform after differential processing;

[0028] Figure 7 : Waveform of the signal collected at the damaged part of the composite material;

[0029] Figure 8 : Comparison of signal waveforms collected after composite materials are treated with different degrees of damage. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments. The present invention includes but is not limited to the described embodiments.

[0031] In view of the fact that the existing composite material damage location and assessment technology system still has problems such as lack of quantitative assessment, complex implementation and only overall signal analysis of amorphous wires, the present invention proposes a composite material damage location and assessment method based on distributed sensing of amorphous wires.

[0032] The core of the technical solution of the present invention is to locate and evaluate the internal damage of the composite material by analyzing and collecting the magnetic induction signals of the amorphous wire embedded in the composite material.

[0033] This method, based on the magneto-mechanical coupling effect of amorphous wires, uses distributed sampling of the wire's local magnetic induction signals to analyze the differences in stress fields within different sections of the wire. By embedding the amorphous wire within a composite material, the strength of the magnetic induction signals from different sections of the amorphous wire can be analyzed to reveal differences in stress fields within the composite material, allowing the location of damage and assessment of the extent of the damage.

[0034] The invention provides a wireless detection method with the advantages of simple operation, low cost and wide engineering applicability.

[0035] The present invention proposes a composite material damage location and assessment method based on amorphous wire distributed sensing, the method comprising the following steps:

[0036] S1: Pretreatment of amorphous wire 1: thermal stability treatment of amorphous wire;

[0037] S2: Composite material function integration: During the composite material forming stage, amorphous filaments are embedded into the composite material to form a detectable self-sensing composite material 2 after integrated molding;

[0038] S3: Distributed induction signal acquisition: A mobile magnetic excitation-detection integrated probe is used to scan and detect along the axis of the amorphous wire at a constant rate;

[0039] S4: Damage signal decoupling analysis: By analyzing the amplitude changes of characteristic signals in the collected signals, internal damage of composite materials can be located and evaluated.

[0040] As a preferred embodiment of the present invention, the amorphous wire in S1 is a cobalt-based amorphous wire with negative magnetostrictive properties and a linear hysteresis loop. Its diameter parameter can be preferably selected to be larger, while ensuring the mechanical properties of the composite material. Cobalt-based amorphous wire has important applications in fields such as sensors, electronic devices, and smart materials. Magnetostriction refers to the effect of a material's length changing in response to a magnetic field. Cobalt-based amorphous wire has negative magnetostrictive properties, meaning it contracts in an applied magnetic field. This property stems from the alloying of cobalt (Co) with non-magnetic elements (such as B, Si, and P), resulting in a unique response in its electronic structure and magnetic moment arrangement in the amorphous state.

[0041] As a preferred embodiment of the present invention, the thermal stabilization treatment S1 involves subjecting the amorphous filaments to the curing temperature used in subsequent composite material processing for 0.5-2 hours and then air-cooling them to room temperature. The thermal stabilization treatment is intended to release residual stress in the amorphous filaments, ensuring that their magnetic induction signals before and after curing are affected only by the composite material curing stress.

[0042] As a preferred embodiment of the present invention, the S2 can embed a single amorphous wire or a bundle of multiple amorphous wires into the fiber reinforced resin matrix composite material along a preset detection path, and can adopt a variety of paths such as straight lines, curves or loops for embedding.

[0043] As a preferred embodiment of the present invention, the hysteresis loop of the S1 amorphous wire changes from linear to rectangular after being embedded in the composite material, and its magnetization jump behavior is significantly enhanced. The more obvious its magnetization jump behavior is, the stronger the characteristic signal collected subsequently.

[0044] As a preferred solution of the present invention, the upper limit of the number of amorphous filaments embedded in S2 should ensure that the overall mechanical properties of the composite material are not damaged.

[0045] As a preferred embodiment of the present invention, the magnetic excitation-detection integrated probe of S3 is composed of a U-shaped electromagnet 3 and a solenoid 4. The solenoid is placed in the magnetic pole gap of the U-shaped electromagnet and is flush with it. Figure 3 As shown, the external signal generator 5 generates an excitation signal and excites the U-shaped electromagnet after amplification by the gain amplifier 6. The U-shaped electromagnet continuously generates an alternating magnetic field with a frequency of 100-500 Hz and an amplitude of 1-2 Oe. At the same time, the solenoid coil obtains the induction signal in real time.

[0046] As a preferred embodiment of the present invention, the closer the distance between the acquisition probe of S3 and the amorphous wire is, the stronger the signal collected is. To ensure signal quality, the distance between the probe and the surface of the composite material is less than 5 mm. The smaller the distance, the better. The distance from the surface of the composite material should be kept constant during the damage detection process.

[0047] As a preferred solution of the present invention, the S3 signal acquisition is performed in a distributed manner along the length direction of the amorphous wire until the entire amorphous wire is traversed.

[0048] As a preferred embodiment of the present invention, the S4 damage signal decoupling analysis includes the following steps:

[0049] S41: including filtering and amplifying the source signal collected by S3;

[0050] S42: performing differential processing on the signal processed in S41 and the response signal collected in the initial undamaged state to obtain a characteristic signal;

[0051] S43: Analyze the changes in characteristic signals of different sections of amorphous wire to complete composite material damage location and assessment;

[0052] The filtering and amplification of the S41 source signal are completed by the filter 7 , and the processed signal is extracted and analyzed by the oscilloscope 8 .

[0053] The characteristic signal of S42 comes from the magnetization jump behavior of the internal magnetic domains after the amorphous wire is embedded in the composite material. When the local magnetic field generated by the U-shaped electromagnet of the probe exceeds the coercive force of the amorphous wire, the local magnetic domains in the corresponding amorphous wire under the probe will flip 180°. The local magnetic flux change caused by this will generate an additional induction signal in the spiral coil inside the probe. After this signal is extracted, it becomes the characteristic signal.

[0054] The characteristic signal of S43 is modulated by the stress field. The stronger the local stress field, the larger the characteristic signal amplitude. The highest characteristic signal amplitude is obtained in the initial undamaged state. After the composite material is damaged, the stress around the amorphous filaments is released, and the characteristic signal extracted from the amorphous filaments decreases. A higher difference from the initial characteristic signal indicates more severe damage.

[0055] The present embodiment is described and illustrated below through preferred embodiments:

[0056] Amorphous wires are embedded in fiber-reinforced resin-based composite materials and are wrapped by the resin matrix. After the composite material is damaged, the stress field change is transferred from the resin matrix to the amorphous wires. Here, the amorphous wires embedded in the resin matrix for testing can represent the application of amorphous wires in actual fiber-reinforced resin-based composite material damage location and assessment. The selected amorphous wire composition is: Co 68.7 Fe4Si 11 B 13 Ni1Mo 2.3 , prepared by the Taylor-Ulitoviskiy method, with a diameter of 60 μm. The resin matrix is ​​polylactic acid, and the curing temperature of polylactic acid is 200 ℃. The initial hysteresis loop of the amorphous wire is shown in Figure 1As shown, the whole is linear and has excellent soft magnetic properties. The amorphous wire is placed at 200 ° C for one hour for heat treatment to release its residual internal stress and ensure the stability of its amorphous structure during the subsequent composite material processing. Then, four annealed amorphous wires are tightly embedded in parallel at the bottom of the polylactic acid matrix to prepare a composite material three-point bending specimen with a length of 10 cm, a width of 1 cm, and a thickness of 2 mm. The hysteresis loop of the amorphous wire after embedding in the composite material is shown as follows Figure 2 As shown, the hysteresis loop has changed from linear to rectangular, with an obvious large Barkhausen effect.

[0057] Signal acquisition devices such as Figure 3 As shown in the figure, the signal generator generates a 5V, 200 Hz sine wave signal, which is amplified by a power amplifier (gain factor of 4) and then input into the U-shaped electromagnet, generating an alternating magnetic field with an intensity of 1 Oe and a frequency of 200 Hz between the two ends of the electromagnet's magnetic poles. The two ends of the U-shaped electromagnet's magnetic poles are separated by 1 cm, and a 1 cm long, 600-turn spiral coil is placed as a magnetic signal acquisition coil. The collected signal is filtered and amplified by a filter and then read using an oscilloscope. When there is no amorphous wire near the probe, the induced signal collected is caused by the alternating magnetic field generated by the U-shaped electromagnet, as shown in the figure. Figure 4 When the probe is placed on the upper surface of the three-point bending sample with embedded amorphous wire composite material prepared above, when the magnetic field intensity generated by the U-shaped electromagnet is greater than the local coercive force of the amorphous wire, the local magnetic domain of the amorphous wire will instantly flip 180°, causing the magnetic flux near the amorphous wire to change, and the acquisition coil will also generate additional induced voltage, as shown in Figure 2. Figure 5 As shown, compared Figure 4 In terms of the two extra peaks in each signal cycle, it is due to the large Barkhausen effect of the amorphous wire itself. After differential processing of the signal and the background signal, the characteristic signal caused by the large Barkhausen effect of the amorphous wire itself can be intuitively seen as follows: Figure 6 As shown, its amplitude is 0.12 V.

[0058] The three-point bending test was conducted on the above specimen to damage it. The span used in the three-point bending test was 5 cm and the indenter diameter was 0.5 mm. After the specimen was damaged by obvious cracks, the signal intensity collected in the undamaged area did not change significantly, but the signal intensity at the damaged area was as Figure 7 As shown in the figure, the amplitude is 0.05 V, which is 0.07 V lower. This is because the damage destroys the stress field around the amorphous wire and weakens the large Barkhausen effect, which leads to a decrease in signal intensity. By comparing the signal intensity collected from different areas of the amorphous wire, the location of the damage can be accurately determined. Further, by controlling the downward pressure distance of the indenter, different degrees of damage can be generated, such as Figure 8As shown in the figure, when the indenter pressed down 2.4 mm, the sample showed no obvious damage, and the signal intensity at the damaged site did not change significantly, with the amplitude remaining at 0.12 V. When the indenter pressed down 3.4 mm, the sample suffered slight damage, and the signal intensity at the damaged site decreased, with the amplitude decreasing by 0.01 V to 0.11 V. When the indenter pressed down 3.6 mm, the damage further expanded, and the signal intensity at the damaged site also decreased further, with the amplitude decreasing by 0.06 V to 0.06 V. This shows that by analyzing the amplitude intensity of the characteristic signal, the degree of damage to the composite material can be further assessed: the greater the amplitude reduction, the more severe the damage.

[0059] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A composite material damage location and assessment method based on amorphous wire distributed sensing, characterized in that: The method comprises the following steps: S1: performing thermal stability treatment on the amorphous wire (1) to release the residual stress of the amorphous wire; S2: During the composite material forming stage, the amorphous filaments are embedded into the composite material to form a detectable self-sensing composite material after integrated forming (2); S3: A mobile magnetic excitation-detection integrated probe is used to perform scanning detection along the axial direction of the amorphous wire at a constant rate; S4: Damage location and assessment inside the composite material by analyzing the amplitude changes of characteristic signals in the collected signals; In S4, analyzing the amplitude change of the characteristic signal in the collected signal includes the following steps: S41: filtering and amplifying the source signal collected by S3; S42: performing differential processing on the signal processed in S41 and the signal collected in the state without amorphous wire sensing to obtain a characteristic signal; S43: Analyze the changes in characteristic signals of different sections of amorphous wire to complete composite material damage location and assessment; The filtering and amplification of the S41 source signal are completed by the filter (7), and the processed signal is extracted and analyzed by the oscilloscope (8); The characteristic signal of S42 originates from the magnetization jump behavior of the internal magnetic domains after the amorphous wire is embedded in the composite material. When the local magnetic field generated by the U-shaped electromagnet of the probe exceeds the coercive force of the amorphous wire, the local magnetic domains in the corresponding amorphous wire below the probe will flip 180 degrees. The resulting local magnetic flux change will generate an additional induction signal in the solenoid coil inside the probe. This signal is extracted to form the characteristic signal. The characteristic signal of S43 is modulated by the stress field. The stronger the local stress field, the larger the characteristic signal amplitude. The characteristic signal amplitude collected in the initial undamaged state is the highest. After the composite material is damaged, the stress around the amorphous wire is released, and the characteristic signal extracted from the amorphous wire will decrease. The higher the difference with the initial characteristic signal, the more serious the damage.

2. The composite material damage location and assessment method based on amorphous wire distributed sensing according to claim 1, characterized in that: The amorphous wire in S1 is a cobalt-based amorphous wire with negative magnetostrictive properties.

3. The composite material damage location and assessment method based on amorphous wire distributed sensing according to claim 1, characterized in that: The thermal stability treatment of S1 is to place the amorphous wire at the curing temperature used in the composite material forming stage, keep it at this temperature for 0.5-2 hours, and then air-cool it to room temperature.

4. The composite material damage location and assessment method based on amorphous wire distributed sensing according to claim 1, characterized in that: In S2, the composite material is a fiber-reinforced resin-based composite material.

5. The composite material damage location and assessment method based on amorphous wire distributed sensing according to claim 1, characterized in that: In S2, a single amorphous wire or a bundle of multiple amorphous wires can be embedded into the composite material along a preset path to be detected, and the embedding can be performed using a straight line, a curved line, or a loop path.

6. The composite material damage location and assessment method based on amorphous wire distributed sensing according to claim 1, wherein: The magnetic excitation-detection integrated probe of S3 consists of a U-shaped electromagnet (3) and a solenoid (4), wherein the solenoid is placed in the magnetic pole interval of the U-shaped electromagnet and is flush with it; an external signal generator (5) generates an excitation signal and excites the U-shaped electromagnet after amplification by a gain amplifier (6), and the U-shaped electromagnet continuously generates an alternating magnetic field with a frequency of 100-500 Hz and an amplitude of 1-2 Oe, while the solenoid acquires an induction signal in real time.

7. The composite material damage location and assessment method based on amorphous wire distributed sensing according to claim 1, characterized in that: During the S3 scanning test, the distance between the probe and the composite material surface is less than 5 mm, and the distance between the probe and the composite material surface remains constant during the scanning test process.

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