PVDF Pressure Transducers for Shock Wave and Explosives Research

Gustavson, P. K.; Tasker, D.G.; Forbes, J. W.

doi:10.21236/ada277319

Cited by 6 publications

(6 citation statements)

References 5 publications

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“…To determine the influence of the equivalent capacitance C S on the output characteristics of the PVDF electrical signal, this paper calculates the ratio of the maximum value of Q 1 to the maximum of Q 2 , as shown in equation (13), where t a , t b represent the times when Q 1 and Q 2 reach the maximum value. To simplify the analysis, this paper assumes that the signal frequency f remains unchanged during the impact process.…”

Section: Discussionmentioning

confidence: 99%

“…In fact, as one of the most commonly used piezoelectric sensors, PVDF has been widely used in various types of impact load measurement. For the measurement of blast waves under complex conditions, Gustavson et al [13] measured the blast load underwater, and compared the results of PVDF connected to a 3 Ω resistor and a 100 nF capacitor, respectively. It was believed that the charge mode was suitable for a load with long pulse rise time, while the current mode was suitable for a short rise time (tens of µs).…”

Section: Introductionmentioning

confidence: 99%

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Equivalent capacitor of polyvinylidene fluoride sensor and its influence on impact load measurement

Huang¹,

Li²,

Liao³

et al. 2021

Smart Mater. Struct.

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As one of the main components of the polyvinylidene fluoride (PVDF) piezoelectric sensor, the equivalent capacitor of PVDF will influence the electrical signal output when subjected to the impact load, thus influencing the accuracy of its measurement. However, in previous research, the equivalent capacitor of PVDF and its possible influence on measurement results have usually been ignored. In this paper, by changing the external resistance, the influence of the equivalent capacitor of PVDF on its electrical signal output characteristics when subjected to impact load is studied. The results show that at this time, the charge generated by the PVDF will be partially concentrated on the equivalent capacitor, and the amount of concentration is determined by the impact load characteristics, external resistance and equivalent capacitance. Therefore, in some cases, it is unreasonable to ignore the equivalent capacitor in previous research, and this may lead to some errors and even get completely wrong results. Considering the charge concentrated on the equivalent capacitor can effectively avoid the problems of conventional methods, and reflect the applied impact load more accurately. In addition, to improve the accuracy of the measurement, on the basis of quantitative evaluation of the influence of the equivalent capacitor on electrical signal output, this paper puts forward a design method of the test circuit; that is, for different types of impact load and measurement accuracy requirements, PVDF with appropriate capacitance and reasonable external resistance should be selected. The research in this paper is helpful for the impact load measurement of PVDF and will improve the accuracy of the measurement to a certain extent.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Equivalent capacitor of polyvinylidene fluoride sensor and its influence on impact load measurement

Huang¹,

Li²,

Liao³

et al. 2021

Smart Mater. Struct.

View full text Add to dashboard Cite

show abstract

“…The pressure-time curves in the far field were studied in previous works; however, the characteristics of the underwater explosion pressure decay of this new composite explosive at closer distances still need further research. At present, pressure sensors used in underwater explosion measurements are mainly based on tourmaline crystals, which have a limited measurement range because of impedance mismatch with water [4]. Therefore, it is difficult to measure the pressure within a relatively close range in an underwater explosion.…”

Section: Introductionmentioning

confidence: 99%

“…The actual charge density was ρ ≈ 1.62 g/cm 3 . According to the recommendation in [4], the pressure sensor was used in the current mode circuit, and a resistor with a resistance of 1 kΩ was connected in parallel with the pressure element at the bottom of the sensor. The pressure-time curves were obtained by integrating the signals recorded by the pressure sensor.…”

Section: Introductionmentioning

confidence: 99%

Application of polyvinylidene fluoride for pressure measurements in an underwater explosion of aluminized explosives

Fan

Shen

et al. 2015

Combust Explos Shock Waves

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To study underwater explosions, a new type of an underwater pressure sensor using polyvinylidene fluoride as a sensing element is developed and well calibrated. The sensor is then applied in underwater explosion tests of RDX explosives with addition of aluminum in the fiber or powder form. The results show that the peak pressure of shock waves slightly decreases when aluminum is added to RDX, and the peak pressure of the fiber aluminum composite explosive is slightly inferior to that of the explosive containing the aluminum powder at the same measuring positions.

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“…For the high loading rate of CO 2 phase change shock wave pressure, the method can represent more transient information during the loading process, and is very sensitive to the structure of shock wave. However, the charge mode is suitable for measuring pressure signals with a long pulse rise time [20].…”

mentioning

confidence: 99%

Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors

Huang

Wei

et al. 2020

Sensors

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Liquid carbon dioxide phase change fracturing technology (LCPCFT) has been widely used in engineering blasting due to the advantage of no flames, and no toxic and harmful gas. However, few studies have been conducted on the acquisition of shock wave pressure and its loading characteristics, which are key parameters in fracturing. Referring to the CO 2 in-situ fracturing technology, an indoor test system for shock wave pressure generated during LCPCFT has been built, with a protected polyvinylidene fluoride (PVDF) piezoelectric sensor. Then three verification experiments with different radial distances between the fracturing tube and test points were carried out on the test system, and in each experiment, four PVDF sensors as four test points were arranged with different axial distance from the detonating point to test the pressure distribution. The experimental results show that when the radial distance between the fracturing tube and test points is not too large (≤345 mm), the pressure generated during LCPCFT is approximately uniformly distributed within the axial length of the fracturing tube, but when it is relatively large (≈895 mm), the results between different test points are in a certain degree of dispersion. And finally, this paper uses the intraclass correlation coefficient (ICC) and coefficient of variation (C V ) of peak pressure and impulse to process the test results to evaluate the reliability and stability of the test system. Evaluation results show that the test results are in good consistency. The test system in this paper has good stability and high reliability. The test system provides a useful tool for accurately obtaining the shock wave pressure, which is helpful for further research on LCPCFT.Hu [6] conducted permeability enhancement experiments of a coal seam by using LCPCFT; the test results show that cracks generated inside the coal seam will greatly increase the gas permeability of the coal seam. In addition, the process of LCPCFT is endothermic, which belongs to cold blasting, so the process of permeability enhancement is safer and more environmentally friendly. Because the small surface tension of supercritical CO 2 , it can penetrate into the interior of rock mass along the cracks, therefore the rock failure is accompanied by the generation of tensile cracks [7], and its rock breaking ability is usually better than that of a water jet [8]. Under the effect of competitive adsorption, the gaseous CO 2 produced during the fracturing process will convert the gas absorbed in the coal seam to a free state, which will increase the amount of gas released and reduce the possibility of a gas outburst during excavation [9]. Through experiments and numerical simulations, Sun [10] believed that the rock breaking under LCPCFT is the result of a stress wave and gasified CO 2 ,and the influence of initial confining pressure and blasting pressure on the effect of LCPCFT are also analyzed [11]. Zhu [12] analyzed the damage evolution process of concrete specimens under the action of high-pressure gas e...

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PVDF Pressure Transducers for Shock Wave and Explosives Research

Cited by 6 publications

References 5 publications

Equivalent capacitor of polyvinylidene fluoride sensor and its influence on impact load measurement

Equivalent capacitor of polyvinylidene fluoride sensor and its influence on impact load measurement

Application of polyvinylidene fluoride for pressure measurements in an underwater explosion of aluminized explosives

Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors

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