A method and system for testing one-dimensional force-electricity characteristics of a concrete test piece
By combining a one-dimensional Hopkinson bar test apparatus with a piezoelectric sensor, the mechanical and electrical signals of the concrete specimens are acquired simultaneously, solving the problem of sensor calibration under dynamic stress and realizing high-precision monitoring and accurate signal acquisition of the internal damage evolution process of concrete.
Patent Information
- Application Number
- CN202511476284.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-16
- Publication Date
- 2026-06-05
Smart Images
Figure CN122150024A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the interdisciplinary field of dynamic mechanical property testing of civil engineering materials and intelligent sensing technology, and in particular to a testing method and system for the one-dimensional electromechanical properties of concrete specimens. Background Technology
[0002] With the development of intelligent civil structures, self-sensing concrete has become a research hotspot. By embedding piezoelectric sensors in concrete, it is possible to monitor its own stress and damage state. However, the mechanical-electrical coupling response characteristics of concrete materials and their internal sensors under dynamic impact loads are very complex. Traditional static or quasi-static testing methods cannot reflect its behavior under high-speed loads.
[0003] Existing technologies for testing the dynamic mechanical properties of concrete using the Split Hopkinson Bar (SHPB) system typically only obtain the overall stress-strain response of the specimen, making it difficult to effectively monitor the evolution of micro-damage within the material. Furthermore, there is a lack of precise calibration methods for the force-electric response characteristics of embedded sensors under impact loads. In addition, problems such as acoustic impedance mismatch, inaccurate positioning, and poor interface adhesion often exist between the sensor and the concrete matrix, leading to signal distortion or measurement errors. Summary of the Invention
[0004] To address the aforementioned issues, this application provides a method and system for testing the one-dimensional mechanical and electrical properties of concrete specimens, which solves the problem that existing technologies cannot simultaneously and accurately test the mechanical response of concrete under dynamic stress and the electrical output of internal sensors.
[0005] The first technical solution adopted in this application is: a method for testing the one-dimensional electromechanical properties of concrete specimens, comprising the following steps:
[0006] S1: A axial impact load is applied to a concrete specimen with a pre-embedded piezoelectric sensor using a one-dimensional Hopkinson bar test apparatus. In response to the axial impact of the impact bar with the incident bar, incident wave signals, reflected wave signals, and transmitted wave signals are acquired. The changes of incident wave signals, reflected wave signals, and transmitted wave signals over time are recorded. The current and voltage corresponding to the resistance connected in parallel across the piezoelectric sensor are acquired.
[0007] S2: Based on the incident wave signal, the reflected wave signal, and the transmitted wave signal, obtain the axial stress time history, axial strain time history, and axial strain rate of the concrete specimen; and then obtain the one-dimensional stress-strain curve of the concrete specimen;
[0008] S3: Obtain the amount of charge generated by the piezoelectric sensor based on the current and the voltage;
[0009] S4: Change the axial impact velocity of the impact rod and repeat steps S1 to S3 to obtain the one-dimensional stress-strain curves of the concrete specimen under different axial strain rates and the charge generated by the piezoelectric sensor under different impact loads. Fit the axial stress and charge to obtain the stress-charge variation curve.
[0010] In an optional embodiment, in step S1, the incident wave signal, reflected wave signal, and transmitted wave signal are acquired by strain gauges attached to the incident rod and the transmitted rod, and recorded by a hyperdynamic strain gauge.
[0011] In an optional embodiment, in step S1, the resistance value of the resistor connected in parallel across the piezoelectric sensor is known, and the current flowing through the piezoelectric sensor is obtained by measuring the voltage across its terminals and calculating it.
[0012] In an optional embodiment, in step S2, the stress time history, strain time history, and strain rate of the concrete specimen are calculated based on the incident wave, reflected wave, and transmitted wave signals according to the one-dimensional stress wave theory.
[0013] In an optional embodiment, the piezoelectric sensor is positioned at the center of the concrete specimen via a plastic bracket.
[0014] In an optional embodiment, the incident rod, the transmission rod, the concrete specimen, and the impact rod have the same diameter.
[0015] In an optional embodiment, in step S3, the amount of charge generated by the piezoelectric sensor is obtained by integrating the current signal over time.
[0016] In an optional embodiment, the stress and charge data obtained under different impact loads are fitted, and the slope of the resulting fitted curve is the dynamic sensitivity of the piezoelectric sensor.
[0017] The second technical solution adopted in this application is: a one-dimensional electromechanical property testing system for concrete specimens used to implement any of the methods described above is provided, the testing system including a one-dimensional Hopkinson bar test device and a pre-embedded sensor specimen;
[0018] The one-dimensional Hopkinson pressure bar experimental apparatus includes an impact bar, an incident bar, a transmission bar, and an absorption bar arranged coaxially.
[0019] The embedded sensing specimen is a concrete specimen with a piezoelectric sensor embedded in it, and the specimen is placed between the incident rod and the transmission rod.
[0020] In an optional embodiment, the test system further includes a data acquisition unit and a signal recording and analysis unit;
[0021] The data acquisition unit includes:
[0022] Strain gauges are attached to the incident rod and the transmission rod to collect one-dimensional stress wave signals;
[0023] A resistor of known resistance is connected in parallel across the piezoelectric sensor;
[0024] The signal recording and analysis unit includes:
[0025] An ultra-dynamic strain gauge connected to the strain gauge on the rod is used to record one-dimensional strain time history signals;
[0026] A high-performance oscilloscope connected to the parallel resistor is used to record the voltage and current signals across the resistor.
[0027] The processing module is configured to perform the calculation and analysis functions described in steps S2 to S4 above.
[0028] Due to the adoption of the above technical solution, this application has at least one of the following beneficial effects compared with the prior art:
[0029] 1. By synchronously acquiring the axial stress of concrete specimens under different impact loads and the charge output by the piezoelectric sensor, a stress-charge relationship curve was constructed, realizing the quantitative calibration of the dynamic sensitivity of the piezoelectric sensor embedded in the concrete under dynamic compression conditions.
[0030] 2. By pre-embedding piezoelectric sensors inside concrete specimens, the propagation of stress waves and the evolution of damage within the material are directly sensed using the piezoelectric effect, thus achieving high-precision in-situ monitoring of the force-electric coupling behavior of concrete.
[0031] 3. The testing system integrates an ultra-dynamic strain gauge and a high-performance oscilloscope, which are used to acquire strain wave signals on the incident / transmitted rod and voltage / current signals of the piezoelectric sensor circuit, respectively, ensuring synchronous, complete and low-noise acquisition of multi-physics field signals under high strain rate conditions.
[0032] 4. The incident rod, transmission rod, concrete specimen, and impact rod have the same diameter to ensure the effective transmission and measurement of stress waves in the experimental setup. Attached Figure Description
[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0034] in:
[0035] Figure 1A schematic flowchart illustrating a method for testing the one-dimensional electromechanical properties of concrete specimens according to an embodiment of this application;
[0036] Figure 2 A waveform diagram of the incident rod provided in an embodiment of this application;
[0037] Figure 3 A waveform diagram of a transmission rod provided in an embodiment of this application;
[0038] Figure 4 This is a charge-time history diagram of a concrete specimen provided in an embodiment of this application;
[0039] Figure 5 This is a schematic diagram of a stress-strain curve provided in an embodiment of this application;
[0040] Figure 6 This is a schematic diagram of a stress-charge curve provided in an embodiment of this application;
[0041] Figure 7 This is a schematic diagram of the structure of a one-dimensional electromechanical property testing system for concrete specimens provided in an embodiment of this application. Detailed Implementation
[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0043] The terms "first," "second," etc., used in this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.
[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0045] In existing technologies, when using the Split Hopkinson Bar (SHPB) system to test the dynamic mechanical properties of concrete, only the stress-strain response of the specimen as a whole can usually be obtained. It is difficult to effectively monitor the evolution of micro-damage inside the material, and there is a lack of accurate calibration methods for the force-electric response characteristics of embedded sensors under impact loads. At the same time, there are often problems such as acoustic impedance mismatch, inaccurate positioning and poor interface adhesion between the sensor and the concrete matrix, which lead to signal distortion or measurement errors.
[0046] This application, by embedding a piezoelectric sensor in the center of a concrete specimen and combining it with a one-dimensional Hopkinson pressure bar device, simultaneously acquires current and voltage signals from the sensor under different impact loads while obtaining traditional mechanical signals. This allows for the calculation of charge quantity and the fitting of stress-charge change curves and their dynamic sensitivity. This not only achieves real-time, in-situ monitoring of the internal mechanical state of concrete but also solves the problem of difficult sensor response calibration. Furthermore, a well-designed system enhances the integration and data reliability of the testing system. Figure 1 As shown, Figure 1 A flowchart illustrating a method for testing the one-dimensional electromechanical properties of a concrete specimen according to an embodiment of this application includes the following steps:
[0047] S1: A axial impact load is applied to a concrete specimen with a pre-embedded piezoelectric sensor using a one-dimensional Hopkinson bar test apparatus. In response to the axial impact of the impact bar on the incident bar, incident wave signals, reflected wave signals, and transmitted wave signals are acquired. The changes of incident wave signals, reflected wave signals, and transmitted wave signals over time are recorded. The current and voltage corresponding to the resistance connected in parallel across the piezoelectric sensor are acquired.
[0048] A piezoelectric sensor with a diameter less than one-quarter the diameter of the concrete specimen was selected. This size design effectively meets the requirement of ignoring the non-homogeneity caused by coarse aggregate, ensuring the reliability of experimental data. The concrete strength range was selected as C15-C80, and for high-strength concrete, the strength range was set as C80-C200 to cover the study of concrete material properties in different engineering application scenarios. A specially made plastic bracket was used to support the piezoelectric sensor. The upper and lower surfaces of the bracket are parallel and the structure is stable, which can accurately ensure the parallelism of the upper and lower surfaces of the piezoelectric sensor, laying the foundation for the accuracy of the experiment. The cast concrete specimen was a disposable cylindrical plastic mold with a small hole slightly larger than the piezoelectric sensor in the middle of the side wall to allow the lead wire to be pulled out. The incident rod, transmission rod, concrete specimen and impact rod have the same diameter to ensure the effective transmission and measurement of stress waves in the experimental device.
[0049] In this embodiment, a high-strength alloy steel incident rod with a diameter of 74 mm and a length of 2800 mm and a transmission rod with the same diameter and a length of 1800 mm are used, along with an impact rod of 400 mm and an absorption rod of 1000 mm to form a complete split Hopkinson pressure bar (SHPB) experimental system; the concrete specimen is a cylinder with dimensions of Φ74 mm × 50 mm, with a 10 mm diameter PZT type piezoelectric ceramic sensor pre-embedded in the center of the interior, and led out through a high-temperature resistant wire.
[0050] The piezoelectric sensor is positioned at the center of the concrete specimen using a plastic bracket. After ensuring that the upper and lower surfaces of the sensor are parallel to the lower surface of the mold, concrete slurry is poured and simultaneously subjected to vibration treatment to eliminate air bubbles and improve the density and uniformity of the specimen.
[0051] The poured concrete specimens were then cured until the piezoelectric sensor and concrete were fully hardened. Care was taken to remove the disposable plastic mold to avoid damaging the sensor leads. Using the lower surface of the specimen as a reference, the upper surface was ground smooth to ensure parallelism between the upper and lower surfaces, ultimately producing a pre-embedded sensor concrete specimen that met the experimental requirements.
[0052] The end faces of the impact rod, incident rod, and transmission rod are tightly fitted together, and the axes of the three rods are strictly aligned to provide the prerequisite for the accurate propagation and measurement of stress waves. The prepared pre-embedded sensor concrete specimen is placed between the incident rod and the transmission rod, ensuring that the end faces are tightly fitted and the axes of the incident rod and the transmission rod are aligned, thus completing the core assembly of the experimental device.
[0053] Incident wave signals, reflected wave signals, and transmitted wave signals are acquired by strain gauges attached to the incident rod and the transmission rod, and recorded by a super-dynamic strain gauge. Resistance strain gauges are symmetrically attached to the incident rod and the transmission rod at appropriate distances from the end face of the specimen and connected to the super-dynamic strain gauge for real-time acquisition of stress wave signals.
[0054] The resistance value of the resistor connected in parallel across the piezoelectric sensor is known. The current flowing through the piezoelectric sensor is obtained by measuring the voltage across its two ends and calculating it. In this embodiment, a 10Ω resistor is connected in parallel between the two electrodes of the piezoelectric sensor, and the two ends of the resistor are connected to a high-performance digital oscilloscope. The oscilloscope is set to differential voltage measurement mode. The current flowing through the sensor is calculated in real time using Ohm's law, and the voltage signal is recorded directly at the same time.
[0055] It should be noted that in other embodiments, the resistance value can be selected differently, and no limitation is made in this regard.
[0056] like Figure 2 — Figure 3 As shown, Figure 2 A waveform diagram of the incident rod provided in an embodiment of this application; Figure 3 This is a waveform diagram of a transmission rod provided in one embodiment of this application. During the experiment, the impact rod is controlled by adjusting the air pressure to strike the incident rod at different speeds (e.g., 10 m / s, 20 m / s, 30 m / s), generating stress waves. When the stress waves propagate to the concrete specimen, part of the energy is reflected back to the incident rod to form a reflected wave, and part is transmitted through the specimen into the transmission rod to form a transmitted wave. The ultra-dynamic strain gauge simultaneously records the superimposed signal of the incident wave + reflected wave on the incident rod and the transmitted wave signal on the transmission rod to obtain the strain waveform that changes over time. At the same time, a high-performance oscilloscope simultaneously acquires the voltage across the parallel resistor and the current converted from it.
[0057] By using an ultra-dynamic strain gauge to acquire the strain signal of the rod and a high-performance oscilloscope to acquire the resistance voltage / current signal, the two systems operate independently, are powered independently, and have separate circuits. This effectively avoids electromagnetic interference caused by the thousands of volts high-voltage discharge signal generated by the piezoelectric sensor under impact on the weak strain signal, thus ensuring the integrity and accuracy of the multi-physics data.
[0058] S2: The axial stress time history, axial strain time history, and axial strain rate of the concrete specimen are obtained based on the incident wave signal, reflected wave signal, and transmitted wave signal. The stress time history, strain time history, and strain rate of the concrete specimen are calculated based on the one-dimensional stress wave theory, according to the incident wave, reflected wave, and transmitted wave signals. The calculation formulas are as follows:
[0059]
[0060] Where σ(t) is the stress time history, ε(t) is the strain time history, and ε(t) is the strain rate; E0, C0, and A0 represent the elastic modulus, elastic wave velocity, and cross-sectional area of the incident or transmitted rod, respectively; A s L s These represent the initial cross-sectional area and initial length of the concrete specimen, respectively.
[0061] By pairing the calculated stress-time history and strain-time history data points synchronously over time and plotting them on a Cartesian coordinate system with strain as the horizontal axis and stress as the vertical axis, a complete dynamic stress-strain curve of the concrete specimen under the impact load can be obtained. By changing the impact velocity, multiple stress-strain curves at different strain rates can be obtained, thus acquiring the stress-strain curve of the concrete specimen, which can be used to analyze the influence of strain rate on the mechanical properties of concrete.
[0062] It can not only obtain the peak stress and peak strain of concrete specimens during the impact process, but also obtain the time history curves of stress, strain, and strain rate changing continuously over time. The stress and strain are not measured directly on the concrete specimen, but are indirectly calculated based on the stress wave propagation theory by measuring the strain wave signal on the metal rod. This avoids the problems of interface debonding and signal distortion caused by directly placing sensors on brittle concrete, and ensures the stability of the measurement and the mechanical integrity of the specimen.
[0063] like Figure 4 , Figure 4 This is a charge-time history diagram of a concrete specimen provided in an embodiment of this application.
[0064] S3: The amount of charge generated by the piezoelectric sensor is obtained based on current and voltage; the amount of charge generated by the piezoelectric sensor is obtained by integrating the current signal over time, and the calculation formula is as follows:
[0065]
[0066] Where Q(t) represents the discharge charge at both ends of the sensor under impact load, and R is the resistance value of the resistor connected in parallel across the piezoelectric sensor.
[0067] S4: Change the impact speed of the impact rod and repeat steps S1 to S3 to obtain the stress-strain curves of the concrete specimen under different strain rates and the charge generated by the piezoelectric sensor under different impact loads. Fit the axial stress and charge to obtain the stress-charge variation curve.
[0068] By repeatedly varying the impact velocity of the impact rod, stress-strain curves of the concrete specimens at different strain rates were obtained, as shown below. Figure 5 As shown, Figure 5 This is a schematic diagram of a stress-strain curve provided in an embodiment of this application; the amount of charge generated by the piezoelectric sensor embedded in the concrete specimen under different impact loads is obtained by fitting the stress and charge generated by the piezoelectric sensor specimen under multiple different impact loads to obtain the stress-charge variation curve.
[0069] like Figure 6 As shown, Figure 6 This is a schematic diagram of a stress-charge curve provided in an embodiment of this application;
[0070] In another embodiment, the testing method further includes fitting the stress and charge data obtained under different impact loads, and the slope of the obtained fitting curve is the dynamic sensitivity of the piezoelectric sensor; by simultaneously acquiring the dynamic stress of the concrete specimen and the charge output of the embedded piezoelectric sensor under different impact loads, and performing linear fitting, the dynamic sensitivity is determined by the slope of the fitting curve, thus successfully realizing the quantitative calibration of the key performance parameters of the core sensing element of intelligent concrete.
[0071] In summary, the method for testing the electromechanical properties of concrete specimens in this embodiment includes the following steps: S1: Using a one-dimensional Hopkinson bar test apparatus, an axial impact load is applied to the concrete specimen with a pre-embedded piezoelectric sensor. In response to the axial impact of the impact bar against the incident bar, incident wave signals, reflected wave signals, and transmitted wave signals are acquired; the current and voltage corresponding to the resistance connected in parallel across the piezoelectric sensor are acquired; S2: A one-dimensional stress-strain curve of the concrete specimen is acquired; S3: The amount of charge generated by the piezoelectric sensor is acquired based on the current and voltage; S4: The impact velocity of the impact bar is changed, and steps S1 to S3 are repeated to acquire the stress-charge change curve. By simultaneously acquiring the axial stress of the concrete specimen and the charge output by the piezoelectric sensor, a stress-charge relationship curve is constructed, achieving quantitative calibration of the dynamic sensitivity.
[0072] This application also provides a one-dimensional electromechanical property testing system for concrete specimens used to implement the testing methods of any of the above embodiments, such as... Figure 7 As shown, Figure 7 A schematic diagram of the structure of a one-dimensional electromechanical property testing system for concrete specimens provided in an embodiment of this application, including a one-dimensional Hopkinson bar test device and a pre-embedded sensor specimen;
[0073] The one-dimensional Hopkinson pressure bar experimental apparatus includes an impact bar 1, an incident bar 2, a transmission bar 3, and an absorption bar 4 arranged coaxially;
[0074] The embedded sensing specimen is a concrete specimen 7 with a piezoelectric sensor embedded in it, and the specimen is placed between the incident rod 2 and the transmission rod 3.
[0075] In an optional embodiment, the test system further includes a data acquisition unit and a signal recording and analysis unit;
[0076] The data acquisition unit includes:
[0077] Strain gauges are attached to the incident rod and the transmission rod, with strain gauge 5 used to collect the one-dimensional stress wave signal of the incident rod 2 and strain gauge 6 used to collect the one-dimensional stress wave signal of the transmission rod 3.
[0078] A resistor R of known resistance is connected in parallel across the piezoelectric sensor;
[0079] The signal recording and analysis unit includes:
[0080] An ultra-dynamic strain gauge connected to a strain gauge on a rod is used to record one-dimensional strain time history signals;
[0081] A high-performance oscilloscope 8 connected in parallel with a resistor is used to record the voltage and current signals across the resistor.
[0082] The processing module is configured to perform the calculation and analysis functions of the aforementioned steps S2 to S4.
[0083] The working principle of the one-dimensional electromechanical property testing system for concrete specimens in this embodiment is described in detail below:
[0084] Impact rod 1 impacts incident rod 2. When the incident wave load is transferred to the concrete specimen 7, reflected waves propagate into incident rod 2 and transmitted waves propagate into transmission rod 3. The transmitted waves are transferred to absorbing rod 4, where the energy is gradually reduced. Strain gauge 5 on incident rod 2 measures the incident wave signal and reflected wave signal. Strain gauge 6 on transmission rod 3 measures the transmitted wave signal. Then, the stress-strain curve of concrete specimen 7 is obtained through the relationship.
[0085] When the concrete specimen 7 is subjected to impact, during the impact compression process, the high-performance oscilloscope 8 measures the current and voltage on the resistor R, and obtains the amount of charge generated by the concrete specimen 7 pre-embedded in the piezoelectric sensor under the impact load through the relationship.
[0086] By repeatedly changing the impact velocity of the impact rod 1, stress-strain curves of the concrete specimen 7 under different strain rates were obtained. The amount of charge generated by the piezoelectric sensor embedded in the concrete specimen under different impact loads was obtained. The stress and charge generated by the piezoelectric sensor specimen 7 under multiple different impact loads were fitted to obtain the stress-charge variation curve.
[0087] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.
[0088] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.
[0089] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.
[0090] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
Claims
1. A method for testing the one-dimensional electromechanical properties of concrete specimens, characterized in that, Includes the following steps: S1: A axial impact load is applied to a concrete specimen with a pre-embedded piezoelectric sensor using a one-dimensional Hopkinson bar test apparatus. In response to the axial impact of the impact bar with the incident bar, incident wave signals, reflected wave signals, and transmitted wave signals are acquired. The changes of incident wave signals, reflected wave signals, and transmitted wave signals over time are recorded. The current and voltage corresponding to the resistance connected in parallel across the piezoelectric sensor are acquired. S2: Based on the incident wave signal, the reflected wave signal, and the transmitted wave signal, obtain the axial stress time history, axial strain time history, and axial strain rate of the concrete specimen; and then obtain the one-dimensional stress-strain curve of the concrete specimen; S3: Obtain the amount of charge generated by the piezoelectric sensor based on the current and the voltage; S4: Change the axial impact velocity of the impact rod and repeat steps S1 to S3 to obtain the one-dimensional stress-strain curves of the concrete specimen under different axial strain rates and the charge generated by the piezoelectric sensor under different impact loads. Fit the axial stress and charge to obtain the stress-charge variation curve.
2. The method for testing the one-dimensional electromechanical properties of concrete specimens according to claim 1, characterized in that, In step S1, the incident wave signal, reflected wave signal, and transmitted wave signal are acquired by strain gauges attached to the incident rod and the transmitted rod, and recorded by a super-dynamic strain gauge.
3. The method for testing the one-dimensional electromechanical properties of concrete specimens according to claim 2, characterized in that, In step S1, the resistance value of the resistor connected in parallel across the piezoelectric sensor is known, and the current flowing through the piezoelectric sensor is obtained by measuring the voltage across its terminals and calculating the current.
4. The method for testing the one-dimensional electromechanical properties of concrete specimens according to claim 1, characterized in that, In step S2, the stress time history, strain time history, and strain rate of the concrete specimen are calculated based on the one-dimensional stress wave theory and the incident wave, reflected wave, and transmitted wave signals.
5. The method for testing the one-dimensional electromechanical properties of concrete specimens according to claim 1, characterized in that, The piezoelectric sensor is positioned at the center of the concrete specimen via a plastic bracket.
6. The method for testing the one-dimensional electromechanical properties of concrete specimens according to claim 1, characterized in that, The incident rod, the transmission rod, the concrete specimen, and the impact rod have the same diameter.
7. The method for testing the one-dimensional electromechanical properties of concrete specimens according to claim 1, characterized in that, In step S3, the amount of charge generated by the piezoelectric sensor is obtained by integrating the current signal over time.
8. The method for testing the one-dimensional electromechanical properties of concrete specimens according to any one of claims 1-7, characterized in that, The stress and charge data obtained under different impact loads are fitted together, and the slope of the resulting fitted curve is the dynamic sensitivity of the piezoelectric sensor.
9. A system for testing the one-dimensional electromechanical properties of concrete specimens for implementing the method according to any one of claims 1-8, characterized in that, The testing system includes a one-dimensional Hopkinson bar test apparatus and a pre-embedded sensor specimen; The one-dimensional Hopkinson pressure bar experimental apparatus includes an impact bar, an incident bar, a transmission bar, and an absorption bar arranged coaxially. The embedded sensing specimen is a concrete specimen with a piezoelectric sensor embedded in it, and the specimen is placed between the incident rod and the transmission rod.
10. The testing system according to claim 9, characterized in that, The testing system also includes a data acquisition unit and a signal recording and analysis unit; The data acquisition unit includes: Strain gauges are attached to the incident rod and the transmission rod to collect one-dimensional stress wave signals; A resistor of known resistance is connected in parallel across the piezoelectric sensor; The signal recording and analysis unit includes: An ultra-dynamic strain gauge connected to the strain gauge on the rod is used to record one-dimensional strain time history signals; A high-performance oscilloscope connected to the parallel resistor is used to record the voltage and current signals across the resistor. A processing module configured to perform the calculation and analysis functions described in steps S2 to S4 of claim 1.