High-strength bolt fatigue damage monitoring system and method based on piezoelectric active sensing

Abstract

The invention belongs to the technical field of bolt fatigue damage monitoring, and discloses a high-strength bolt fatigue damage monitoring system and method based on piezoelectric active sensing, and the method comprises the steps: achieving the rapid monitoring of the fatigue damage of a high-strength bolt through the cooperative work of piezoelectric ceramic pieces PZT-A and PZT-B in combination with the driving of a high-voltage amplifier and the signal conversion of a charge adapter, meanwhile, the complex stress state of the high-strength bolt in actual service is simulated, and the damage state is fed back in real time through stress wave propagation characteristic changes. The test period is shortened, a large number of test pieces do not need to be consumed for statistical test, and the research cost is remarkably reduced. A standardized monitoring scheme is provided for high-strength bolt fatigue performance evaluation, and integrated deployment of a structural health monitoring system is supported. And through real-time monitoring data feedback, the research efficiency and precision are improved, and an intelligent solution is provided for safe operation and maintenance of an engineering structure.

Description

Technical Field

[0001] This invention belongs to the field of bolt fatigue damage monitoring technology, and relates to a high-strength bolt fatigue damage monitoring system and method based on piezoelectric active sensing. Background Technology

[0002] In space frame structure engineering, high-strength bolts, as key load-bearing components, play a crucial role in transmitting axial tensile forces. They are tightly connected to bolt ball joints or flanges via threads, forming a stable spatial frame structure. However, the threaded portion of high-strength bolts exhibits significant stress concentration, primarily due to the complex geometry of the thread root and surface defects that may be introduced during manufacturing. This stress concentration makes the bolts highly susceptible to fatigue cracking under cyclic loading, significantly reducing their fatigue strength and service life.

[0003] Currently, fatigue performance evaluation of high-strength bolts in space frame structures mainly relies on traditional fatigue testing methods. This method applies cyclic loading until the bolt completely fractures due to fatigue, using the number of cycles at fracture as an indicator of fatigue strength. However, this method has significant limitations. For example, it cannot monitor crack initiation and propagation in real time; traditional methods only focus on the final fracture result of the bolt, failing to capture crucial information such as the initial moment of crack initiation, propagation path, and rate. This makes it difficult for researchers to deeply analyze the evolution mechanism of fatigue damage, hindering the establishment of fatigue life prediction models. The testing cycle is long and costly. Because it requires waiting for the bolt to completely fracture, a single test can take several days or even weeks, consuming a large number of specimens to obtain statistical patterns. This not only increases research costs but also delays the engineering application of research results. Furthermore, it is difficult to reproduce actual working conditions. High-strength bolts in space frame structures are often under complex stress states, and traditional tests cannot accurately simulate these conditions, leading to biases in fatigue performance evaluation. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of traditional fatigue testing methods in the prior art, such as the inability to monitor crack initiation and propagation in real time, long test cycles, high costs, and difficulty in reproducing actual working conditions. This invention provides a fatigue damage monitoring system and method for high-strength bolts based on piezoelectric active sensing.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing is characterized by comprising: a data acquisition instrument, a computer, a signal function generator, a high-strength bolt, a piezoelectric ceramic sheet PZT-B, and a piezoelectric ceramic sheet PZT-A; the piezoelectric ceramic sheet PZT-A is disposed on the nut surface of the high-strength bolt; the piezoelectric ceramic sheet PZT-B is disposed on the bottom of the bolt shank of the high-strength bolt; the piezoelectric ceramic sheet PZT-A is connected to the signal function generator; the piezoelectric ceramic sheet PZT-B is connected to the data acquisition instrument; and the data acquisition instrument is connected to the computer.

[0006] A further improvement of the present invention is that: Furthermore, there are several high-strength bolts connected by a bolt ball specimen; the bottom of the high-strength bolt is located inside the bolt ball specimen, that is, the piezoelectric ceramic sheet PZT-B is located inside the bolt ball specimen.

[0007] Furthermore, both the piezoelectric ceramic sheet PZT-B and the piezoelectric ceramic sheet PZT-A are coated with a waterproof layer, and an insulating layer is provided between the piezoelectric ceramic sheet PZT-B and the piezoelectric ceramic sheet PZT-A and the high-strength bolt; the material of the insulating layer is epoxy resin.

[0008] Furthermore, a charge adapter is connected between the piezoelectric ceramic sheet PZT-B and the data acquisition instrument; the charge adapter converts the high-impedance charge signal generated by the piezoelectric ceramic sheet PZT-B into a low-impedance voltage signal; the charge adapter captures weak charges through high input impedance and then converts them into a low-impedance voltage signal, which is then transmitted to the computer for processing by the data acquisition instrument.

[0009] Furthermore, a high-voltage amplifier is provided between the piezoelectric ceramic sheet PZT-A and the signal function generator. The high-voltage amplifier amplifies the low-amplitude excitation signal from the signal function generator, driving the piezoelectric ceramic sheet PZT-A to generate a stress wave. The stress wave is transmitted along the high-strength bolt to the piezoelectric ceramic sheet PZT-B. Since the cracks generated during the fatigue damage process of the high-strength bolt reduce the energy of the stress wave propagation, the piezoelectric ceramic sheet PZT-B detects the reduction in energy, thereby monitoring the fatigue damage of the high-strength bolt and transmitting the data to the computer through a data acquisition instrument.

[0010] Furthermore, the process of placing piezoelectric ceramic sheet PZT-A on the nut surface of the high-strength bolt and piezoelectric ceramic sheet PZT-B on the bottom of the bolt is as follows: The surfaces of piezoelectric ceramic sheets PZT-A and PZT-B are cleaned with anhydrous alcohol, left to stand, and allowed to dry naturally. Then, wires are soldered onto the piezoelectric ceramic sheets PZT-A and PZT-B. The pre-attached area on the high-strength bolt surface is smoothed by grinding, and an epoxy resin insulating layer is evenly applied to the smoothed pre-attached area. The treated piezoelectric ceramic sheets PZT-A and PZT-B are then attached to the high-strength bolt, and the wires are led out. Finally, a waterproof layer is used to encapsulate the stable-attached piezoelectric ceramic sheets PZT-A and PZT-B, and the encapsulation is cured at room temperature for one day.

[0011] Furthermore, the conductor is a shielded cable; the waterproof layer material is epoxy resin.

[0012] The monitoring method of a high-strength bolt fatigue damage monitoring device based on piezoelectric active sensing includes: placing piezoelectric ceramic plates PZT-A and PZT-B on the nut surface and the bottom of the bolt respectively; a high-voltage amplifier amplifies the low-amplitude excitation signal from the signal function generator to drive piezoelectric ceramic plate PZT-A to generate a stress wave; the stress wave is transmitted along the high-strength bolt to piezoelectric ceramic plate PZT-B; since the cracks generated during the fatigue damage process of the high-strength bolt reduce the energy of the stress wave propagation, piezoelectric ceramic plate PZT-B detects the energy reduction; a charge adapter converts the high-impedance charge signal generated by piezoelectric ceramic plate PZT-B into a low-impedance voltage signal; the charge adapter captures weak charges through high input impedance and then converts them into a low-impedance voltage signal, which is transmitted to a computer for processing via a data acquisition instrument.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes the synergistic operation of piezoelectric ceramic sheets PZT-A and PZT-B, combined with high-voltage amplifier driving and charge adapter signal conversion, to achieve rapid monitoring of fatigue damage in high-strength bolts. Simultaneously, it simulates the complex stress states of high-strength bolts in actual service, providing real-time feedback of damage status through changes in stress wave propagation characteristics. This shortens the experimental cycle and eliminates the need for large-scale statistical testing, significantly reducing research costs. This invention provides a standardized monitoring scheme for the fatigue performance evaluation of high-strength bolts and supports the integrated deployment of structural health monitoring systems. Real-time monitoring data feedback not only improves research efficiency and accuracy but also provides an intelligent solution for the safe operation and maintenance of engineering structures. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to the present invention. Figure 2 This is a schematic diagram of the polarization direction of piezoelectric ceramics; Figure 3 This is a schematic diagram showing the bonding location of piezoelectric ceramics on the surface of a high-strength bolt. Figure 4 A schematic diagram of a piezoelectric ceramic sensor.

[0016] Among them, 1-data acquisition instrument, 2-high voltage amplifier, 3-signal function generator. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing 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, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0021] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0022] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 This invention discloses a fatigue damage monitoring system for high-strength bolts based on piezoelectric active sensing, comprising: a data acquisition instrument 1, a computer, a signal function generator 3, a high-strength bolt, a piezoelectric ceramic sheet PZT-B, and a piezoelectric ceramic sheet PZT-A; The piezoelectric ceramic sheet PZT-A is disposed on the nut surface of the high-strength bolt; the piezoelectric ceramic sheet PZT-B is disposed on the bottom of the bolt of the high-strength bolt; the piezoelectric ceramic sheet PZT-A is connected to the signal function generator 3; the piezoelectric ceramic sheet PZT-B is connected to the data acquisition instrument 1; the data acquisition instrument 1 is connected to the computer.

[0024] See Figure 2 The polarization direction of piezoelectric ceramics is closely related to their operating mode. When a material is subjected to mechanical stress along its polarization axis, it generates an electric charge. The polarization direction of piezoelectric ceramics is typically along the thickness direction, and their operating mode is a longitudinal vibration mode. In this mode, the stress direction is consistent with the polarization direction, and both the generated charge and deformation are along the thickness direction.

[0025] See Figure 3The high-strength bolts are a plurality of bolts connected by a bolt ball specimen; the bottom of the high-strength bolt is located inside the bolt ball specimen, that is, the piezoelectric ceramic sheet PZT-B is located inside the bolt ball specimen.

[0026] Both the piezoelectric ceramic sheet PZT-B and the piezoelectric ceramic sheet PZT-A are coated with a waterproof layer, and an insulating layer is provided between the piezoelectric ceramic sheet PZT-B and the high-strength bolt; the insulating layer is made of epoxy resin.

[0027] A charge adapter is connected between the piezoelectric ceramic sheet PZT-B and the data acquisition instrument 1. The charge adapter converts the high-impedance charge signal generated by the piezoelectric ceramic sheet PZT-B into a low-impedance voltage signal. The charge adapter captures weak charges through high input impedance and then converts them into a low-impedance voltage signal, which is then transmitted to the computer for processing via the data acquisition instrument 1. The charge adapter can convert the charge source of the high internal resistance sensor into a low internal resistance output voltage source, making the voltage output proportional to the input charge.

[0028] A high-voltage amplifier 2 is installed between the piezoelectric ceramic sheet PZT-A and the signal function generator 3. The high-voltage amplifier 2 amplifies the low-amplitude excitation signal from the signal function generator 3, driving the piezoelectric ceramic sheet PZT-A to generate a stress wave. The stress wave is transmitted along the high-strength bolt to the piezoelectric ceramic sheet PZT-B. Because the cracks generated during the fatigue damage process of the high-strength bolt reduce the energy of the stress wave propagation, the piezoelectric ceramic sheet PZT-B detects the energy reduction, thereby monitoring the fatigue damage of the high-strength bolt and transmitting the data to the computer via the data acquisition instrument 1. The insulation layer thickness is 0.08~0.12mm; the frequency of the signal generated by the signal function generator 3 is 500Hz~10KHz.

[0029] See Figure 4The process of placing piezoelectric ceramic sheet PZT-A on the nut surface of the high-strength bolt and piezoelectric ceramic sheet PZT-B on the bottom of the bolt is as follows: Clean the surfaces of piezoelectric ceramic sheets PZT-A and PZT-B with anhydrous alcohol, let them stand, and allow them to dry naturally. Then, solder wires onto the piezoelectric ceramic sheets PZT-A and PZT-B. To ensure that the solder joints are as small and flat as possible, a small amount of solder paste is used to improve the soldering quality, and shielded cables are selected as the conductors. The surface of the high-strength bolt with pre-attached areas is smoothed by grinding, and an epoxy resin insulation layer is evenly applied to the smoothed pre-attachment area. The treated piezoelectric ceramic sheets PZT-A and PZT-B are then attached to the high-strength bolt, and wires are led out. A waterproof layer is used to encapsulate the stable-attached piezoelectric ceramic sheets PZT-A and PZT-B, and the encapsulation is cured at room temperature for one day. The wires are shielded cables; the waterproof layer material is epoxy resin.

[0030] A method for monitoring fatigue damage of high-strength bolts based on piezoelectric active sensing, characterized in that it includes: After piezoelectric ceramic plates PZT-A and PZT-B are respectively placed on the nut surface of the high-strength bolt and the bottom of the bolt, the high-voltage amplifier 2 amplifies the low-amplitude excitation signal of the signal function generator 3, driving the piezoelectric ceramic plate PZT-A to generate a stress wave. The stress wave is transmitted along the high-strength bolt to the piezoelectric ceramic plate PZT-B. Since the cracks generated during the fatigue damage process of the high-strength bolt will reduce the energy of the stress wave propagation, the piezoelectric ceramic plate PZT-B detects the reduction in energy. The charge adapter converts the high-impedance charge signal generated by the piezoelectric ceramic plate PZT-B into a low-impedance voltage signal. The charge adapter captures weak charges through high input impedance and then converts them into low-impedance voltage signals, which are then transmitted to the computer for processing through the data acquisition instrument 1.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing, characterized in that, include: Data acquisition instrument (1), computer, signal function generator (3), high-strength bolts, piezoelectric ceramic sheet PZT-B and piezoelectric ceramic sheet PZT-A; The piezoelectric ceramic sheet PZT-A is disposed on the nut surface of the high-strength bolt; the piezoelectric ceramic sheet PZT-B is disposed on the bottom of the bolt of the high-strength bolt; the piezoelectric ceramic sheet PZT-A is connected to the signal function generator (3); the piezoelectric ceramic sheet PZT-B is connected to the data acquisition instrument (1); the data acquisition instrument (1) is connected to the computer.

2. The high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to claim 1, characterized in that, The high-strength bolts are a plurality of bolts connected by bolt ball specimens; the bottom of the high-strength bolts is located inside the bolt ball specimens, that is, the piezoelectric ceramic sheet PZT-B is located inside the bolt ball specimens.

3. The high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to claim 2, characterized in that, Both the piezoelectric ceramic sheet PZT-B and the piezoelectric ceramic sheet PZT-A are coated with a waterproof layer, and an insulating layer is provided between the piezoelectric ceramic sheet PZT-B and the high-strength bolt; the insulating layer is made of epoxy resin.

4. The high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to claim 3, characterized in that, A charge adapter is connected between the piezoelectric ceramic sheet PZT-B and the data acquisition instrument (1). The charge adapter converts the high-impedance charge signal generated by the piezoelectric ceramic sheet PZT-B into a low-impedance voltage signal. The charge adapter captures weak charges through high input impedance and then converts them into a low-impedance voltage signal, which is then transmitted to the computer for processing through the data acquisition instrument (1).

5. The high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to claim 4, characterized in that, A high-voltage amplifier (2) is provided between the piezoelectric ceramic sheet PZT-A and the signal function generator (3); the high-voltage amplifier (2) amplifies the low-amplitude excitation signal of the signal function generator (3) and drives the piezoelectric ceramic sheet PZT-A to generate stress waves. The stress waves are transmitted along the high-strength bolt to the piezoelectric ceramic sheet PZT-B. Since the cracks generated by the high-strength bolt during fatigue damage will reduce the energy of stress wave propagation, the piezoelectric ceramic sheet PZT-B detects the reduction in energy, thereby monitoring the fatigue damage of the high-strength bolt and transmitting it to the computer through the data acquisition instrument (1).

6. The high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to claim 5, characterized in that, The process of placing piezoelectric ceramic sheet PZT-A on the nut surface of a high-strength bolt and piezoelectric ceramic sheet PZT-B on the bottom of the bolt shaft of a high-strength bolt is as follows: Clean the surfaces of piezoelectric ceramic sheets PZT-A and PZT-B with anhydrous alcohol, let them stand, and allow them to dry naturally. Then, solder wires onto the piezoelectric ceramic sheets PZT-A and PZT-B. Grind the pre-attached areas on the high-strength bolt surface until smooth, and then evenly apply an epoxy resin insulation layer to the smoothed pre-attached areas. Attach the treated piezoelectric ceramic sheets PZT-A and PZT-B to the high-strength bolt and lead out the wires. Encapsulate the stabilized piezoelectric ceramic sheets PZT-A and PZT-B with a waterproof layer and allow them to cure at room temperature for one day.

7. The high-strength bolt fatigue damage monitoring system based on piezoelectric active sensing according to claim 6, characterized in that, The conductor is a shielded cable; the waterproof layer material is epoxy resin.

8. A monitoring method using the high-strength bolt fatigue damage monitoring device based on piezoelectric active sensing as described in claim 7, characterized in that, include: After the piezoelectric ceramic sheet PZT-A and piezoelectric ceramic sheet PZT-B are respectively placed on the nut surface of the high-strength bolt and the bottom of the bolt, the high-voltage amplifier (2) amplifies the low-amplitude excitation signal of the signal function generator (3) to drive the piezoelectric ceramic sheet PZT-A to generate stress waves. The stress waves are transmitted along the high-strength bolt to the piezoelectric ceramic sheet PZT-B. Since the cracks generated by the high-strength bolt during fatigue damage will reduce the energy of stress wave propagation, the piezoelectric ceramic sheet PZT-B detects the reduction in energy. The charge adapter converts the high-impedance charge signal generated by the piezoelectric ceramic sheet PZT-B into a low-impedance voltage signal. The charge adapter captures weak charges through high input impedance and then converts them into low-impedance voltage signals, which are then transmitted to the computer for processing through the data acquisition instrument (1).

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