PVDF Piezoelectric Sensor Research Articles

Establishment of a Mass Concrete Strength-Monitoring Method Using Barium Titanate-Bismuth Ferrite/Polyvinylidene Fluoride Nanocomposite Piezoelectric Sensors with Temperature Stability.

Mass concrete is widely used in large-scale projects, including metro upper cover structures, water conservancy dams, and heavy equipment foundations, among others, necessitating the process of health monitoring in mass concrete construction. The development of reliable and simple strength-monitoring methods for mass concrete is challenging because the inner temperature of mass concrete is high and changes a lot. This study proposes a strength-monitoring approach for mass concrete using barium titanate-bismuth ferrite/polyvinylidene fluoride (BT-BFO/PVDF) nanocomposite piezoelectric sensors, wherein the new sensors are embedded as actuators and sensors in mass concrete. The stress wave generated by the BT-BFO/PVDF piezoelectric sensors is used to monitor the specimen's strength for 28 days. The piezoelectric voltage received by the sensors in mass concrete is analyzed. The experimental results indicate that the signal received by the BT-BFO/PVDF sensors is not easily affected by the internal temperature of mass concrete compared with that of the traditional PVDF piezoelectric sensors. The signal parameters sensitive to concrete strength variation and the change trend of concrete strength are closely related to the piezoelectric voltage. Therefore, the proposed approach using BT-BFO/PVDF nanocomposite piezoelectric sensors is efficient (error < 10%) in mass concrete monitoring. Moreover, the monitoring results do not need temperature compensation. The physical meaning of the obtained strength prediction formula is proposed. An experimental system based on PVDF dynamic strain-sensing characteristics is established.

PVDF piezoelectric sensor based on solution blow spinning fibers for structural stress/strain health monitoring

Strain monitoring is of great significance to the maintenance and safe operation of engineering structures. To address the shortcomings of piezoelectric ceramics such as high inflexibility and brittleness, in this study, polyvinylidene fluoride (PVDF) fibrous films were prepared by a safe and efficient solution blow spinning technique. In the case of similar β-phase content, the preparing efficiency of PVDF fibers by the solution blow spinning method increased by about 8–10 times compared to that of electrospinning method in our previous work. The fibers with average diameter of 0.79 μm had the highest β-phase content, around 83%. A flexible piezoelectric fiber sensor with simple design for structural strain monitoring was prepared based on the PVDF fibers. The sensor responded well to strains as low as 23 μϵ, better than commercial strain gauges, with a high response accuracy of 1.11 mV/μϵ. And the piezoelectric properties of the sensors could charge a 4.7 μF capacitor to 3 V in 40 s, offering the potential for low-cost, self-powered structural health monitoring.

Real-time online monitoring technology for sweeping frequency ultrasound (SFU) assisted extraction of amur grape (Vitis amurensis) seed oil

Sweeping frequency ultrasound (SFU) was used to assist extraction of amur grape (Vitis amurensis) seed (AGS) oil. Extraction conditions and physicochemical properties were optimized and analyzed under different extraction methods. Meanwhile, frequency and time domains were online monitored during SFU assisted extraction of AGS oil. PVDF piezoelectric sensor was used in time domain, and the hydrophone in frequency domain, so as to obtain the time–voltage waveform, signal power, spectrum distribution and other visual models. Physical models of the spatial peak acoustic intensity, charge quantity and work done by electric field force under different ultrasonic conditions were derived. The mathematical model between the work done by electric field force and the spatial peak acoustic intensity under the working state of PVDF piezoelectric sensor was constructed. Results show that the content of AGS oil by SFU assisted extraction was higher than that by organic extraction. Furthermore, the optimal single-frequency was 40 kHz and dual-frequency was 28/33 kHz, and SFU extraction time of 30 min was suitable with higher oil yield of 16.70 % and 16.94 %, respectively. In addition, the selection and combination of SFU also affected the oil oxidation degree. The peak voltage, spatial peak acoustic intensity, signal power and work of electric field force at 28/33 kHz were all higher than those at 40 kHz.

Development and Evaluation of a Flexible PVDF-Based Balloon Sensor for Detecting Mechanical Forces at Key Esophageal Nodes in Esophageal Motility Disorders.

Prevailing methods for esophageal motility assessments, such as perfusion manometry and probe-based function imaging, frequently overlook the intricate stress fields acting on the liquid-filled balloons at the forefront of the probing device within the esophageal lumen. To bridge this knowledge gap, we innovatively devised an infusible flexible balloon catheter, equipped with a quartet of PVDF piezoelectric sensors. This design, working in concert with a bespoke local key-node analytical algorithm and a sensor array state analysis model, seeks to shed new light on the dynamic mechanical characteristics at pivotal esophageal locales. To further this endeavor, we pioneered a singular closed balloon system and a complementary signal acquisition and processing system that employs a homogeneously distributed PVDF piezoelectric sensor array for the real-time monitoring of dynamic mechanical nuances in the esophageal segment. An advanced analytical model was established to scrutinize the coupled physical fields under varying degrees of balloon inflation, thereby facilitating a thorough dynamic stress examination of local esophageal nodes. Our rigorous execution of static, dynamic, and simulated swallowing experiments robustly substantiated the viability of our design, the logical coherence of our esophageal key-point stress analytical algorithm, and the potential clinical utility of a flexible esophageal key-node stress detection balloon probe outfitted with a PVDF array. This study offers a fresh lens through which esophageal motility testing can be viewed and improved upon.

Study on microcharge design and output performance test

Taking copper azide microcharge as research object, PVDF piezoelectric sensor was used to test the detonation pressure of copper azide microcharge and the detonation pressure of titanium flyer driven by copper azide microcharge explosion respectively. The effect of titanium flyers on the output performance of copper azide microcharge was investigated. The research results shown that: different microcharge structure parameters affected charge weight, and the charge weight directly affected the output pressure. The output pressure of copper azide microcharge to drive titanium flyer is much greater than the output pressure of copper azide microcharge. Titanium flyer driven by copper azide microcharge explosion, which could play the role of energy gathering and amplification.

Study on Structure health monitoring method of space vehicle based on PVDF piezoelectric film

At present, health monitoring technology of large structures has been paid more and more attention, among which structure measurement system based on PVDF piezoelectric film sensor has been widely used in various fields. To solve the problem that large structural parts of aerospace are easy to be damaged, a load measurement system based on PVDF piezoelectric film sensor is built in this paper given the complex design structure of aerospace. A large cylinder of aerospace is taken as the test part, the stress state of structural parts is measured online, and the corresponding load value is obtained. With the load value, damage to the health state of the structural parts when they are overloaded by external force can be avoided.

Tire-road friction coefficient estimation method design for intelligent tires equipped with PVDF piezoelectric film sensors

Intelligent tires, as an emerging technology, have great potential in real-time monitoring of tire-road contact information and new automotive active safety design. In this paper, a tire-road friction coefficient estimation method is proposed based on intelligent tire technology. First, an intelligent tire finite element model with the use of five PVDF piezoelectric film sensors attached to the inner liner of the tire is built using ABAQUS software, and the validity of the finite element model is verified by a piezoelectric intelligent tire test platform. Then, through the finite element analysis method and control variable method, the influence of sideslip angle on the voltage signal of each piezoelectric film under the rolling state of tire is analyzed, and when the sideslip angle is 4°, the influence of load, tire pressure, vehicle speed and slip ratio on the voltage signal of each piezoelectric film under the rolling state of tire is analyzed. Finally, based on the signal response analysis of the piezoelectric film sensors, the response mechanism of the predicted object and the linear correlation analysis, the input eigenvalues of each prediction model are extracted. The longitudinal contact patch length estimation model based on the numerical method and the sideslip angle, vertical force, lateral force and aligning moment estimation model based on the neural network algorithm are built, and the predicted parameters are input into the brush tire model to solve the tire-road friction coefficient. The result shows that the estimation error percentage of the friction coefficient estimation method without genetic algorithm optimization is 16.98%, and the estimation error percentage of the friction coefficient estimation method with genetic algorithm optimization is 5.14%, indicating that the genetic algorithm optimization effect is ideal, and the friction coefficient estimation method is practical. ● Developing an intelligent tire finite element model equipped with PVDF sensors ● Real vehicle test verifies the validity of the intelligent tire finite element model ● Analyzing the signal response of PVDF sensors under different working conditions ● Estimating the tire-road friction coefficient using intelligent tire system and brush tire model

Plantar Pressure Distribution Measurement System Based on PVDF Piezoelectric Senors

During people’s normal movement, the sole of foot is the only part of human body that contacts with the ground. The pressure information of sole directly reflects the physiological health and movement posture of human. A plantar pressure measurement system was designed with an insole type for measuring plantar pressure during normal movement. The insole embedded five PVDF piezoelectric film sensors, and then places the insole in the measured sports shoes. In order to obtain better pressure response effect, two small raised blocks were pasted under each piezoelectric film sensor to increase the sensitivity of the sensor. The plantar pressure data was sent to PC by wireless serial port. An intuitive and easy-to-use GUI interface was designed by the MATLAB software. The interface can display the pressure distribution at each point of the sole of both feet.

Pulse Taking by a Piezoelectric Film Sensor via Mode Energy Ratio Analysis Helps Identify Pregnancy Status.

In order to solve the problem of non-invasive diagnosis and monitoring of women during pregnancy, a piezoelectric film pulse sensing system combined with the mode energy ratio (MER) analysis is utilized to detect human pulses to reveal pregnant conditions. Inspired by traditional Chinese medicine (TCM), pulse diagnosis has a history of more than 2,500 years. The life energy of the human body helps the diagnosis of the disease through the circulation of blood vessels connected to the organs. A PVDF piezoelectric film sensor is used to emulate the pulse taking process in TCM to record the pulse signals. And the algorithm of MER is proposed based on empirical mode decomposition (EMD). Through the MER analysis of 83 female volunteers with different pregnancy statuses, the identification and warning of pregnancy status and physical health indicators are realized.

谷子、荞麦籽粒离心式碰撞试验装置设计及试验

This critical collision damage force of millet and sweet buckwheat grain and the shelling force of shelled granular materials are important basic data for research of threshing and shelling technology and equipment. In order to master the linear velocity and collision force of grain with different moisture content when collision damage occurs, a centrifugal collision test device is designed. Based on the dynamic and kinematic analysis of grain in the centrifugal rotary table, the collision force between grain and steel plate was measured by PVDF piezoelectric pressure sensor and data acquisition system. The results showed that: under the same moisture content, the higher the rotational speed, the higher the grain crushing rate; at the same rotational speed, with the increase of moisture content, the crushing rate first decreased and then increased. When the moisture content of Jingu-21 and Yuqiao-4 is 19.7% and 17.8%, respectively, the grain crushing rate was the lowest. In terms of the anti-collision ability of grain, the optimum moisture content of threshing is between 19.7% and 21% for millet. For sweet buckwheat, the optimum moisture content of threshing is 17.8% ~19%, while the optimum moisture content of shelling by centrifugal sheller is about 11%. The faster the rotational speed of centrifugal rotary table is, the greater the linear speed of grain is, and the greater the collision force is. When the linear velocity of grain was 8.32 m/s and 11.30 m/s respectively, the millet grain moisture content was 11.1% and 20.9% respectively, damage began to appear, and the corresponding collision force was about 5.51 N and 10.6 N, respectively. When the linear velocity of grain was 8.32 m/s and 11.30m/s respectively, and the moisture content was 11.1% and 22.8% of the sweet buckwheat grain respectively, damage began to appear, the corresponding collision force was about 8.92 N and 12.79 N, respectively. When the rotating speed of rotary table was 910 r/min, the linear speed of grain was 27.05 m/s, the crushing rate of millet and sweet buckwheat grain in harvest period were 56.30% and 63.76%, respectively, and the crushing rate of millet and buckwheat grain with 11.1% moisture content were 86.27% and 89.4%, respectively. The research results can provide theoretical basis for design and optimization of millet and sweet buckwheat combine harvester, threshing device and shelling device.

Impinging Performance of High-Pressure Water Jets Emitting from Different Nozzle Orifice Shapes

The impinging pressure of a water jet is a key factor in engineering applications, and the jet shape has a great influence on this pressure. In this paper, five different nozzle shapes were designed, and impacting tests were conducted based on a self-designed experimental platform using a PVDF piezoelectric film sensor and a high-speed camera to record the impacting data. Additionally, the computational fluid dynamics (CFD) method was also applied to study the velocity distribution. The results show that the pressure profiles of different water jet shapes impacting onto a solid surface present a consistent pattern, namely, an initial transient and enormous peak pressure and then a longer and smaller stagnation pressure. Although the stagnation pressure in this paper is not sufficiently obvious, the peak pressures of the five water jet shapes are much different from one another. Under the same inlet pressure, the peak pressure of the circular water jet is the largest, and those of the square, triangular, cross-shaped, and elliptical water jets decrease in turn. The flowing regimes captured by the high-speed camera together with the CFD simulation results indicate that the discrepancy in the peak pressure may be a combined action of the liquid velocities and jet head shapes.

PVDF Piezoelectric Sensors for Seeds Counting and Coulter Clogging Detection in Sowing Process Monitoring

The paper presents the results of a test on the use of piezoelectric sensors made of PVDF foil for counting grain and checking clogging in the sowing drill. The tests were carried out in a simulator of the sowing drill with the use of a measuring system with high input impedance. Two kinds of barley and triticale grains were investigated. Measurements were carried out for different feeding frequencies. On the basis of the signals recorded, an algorithm of counting the sown grain was developed and tested. The algorithm is based on signal statistic comparison in adjacent windows. The developed algorithm allows counting more than 90% of the sown grains.

Recognition of Wheel Polygon Based on W/R Force Measurement by Piezoelectric Sensors in GSM-R Network

The influence of polygonal wheels on vehicle dynamic responses and condition monitoring measurement, are a focal point of research to ensure operation safety and improve service quality of high speed railway transportation. Wheel defects are commonly identified by the detection of wheel–rail (W/R) contact forces based on installing strain gauge on wheelsets or rails. Compared with strain gauge, PVDF piezoelectric sensor has the advantages of high sensitivity, wide frequency response, vast dynamic range, and perfect electromagnetic-immune property. Hence, a measure system to recognize wheel polygon based on W/R force measurement by PVDF strain sensors in Railroad network is built, which has long distance and high stability. On the basis of W/R contact forces derived from wheel polygon impacts, the measured PVDF strain sensor response is processed to generate an index that reflects the condition of wheel polygon. An automatic remote condition monitoring system is designed under GSM-R transmission lines. The preliminary experimental results showed that this system is suitable for complex electromagnetic environment and stable demands of high speed railways.

Monitoring Mechanical Vibration Amplitude System Design Based on the PVDF Piezoelectric Film Sensor&lt;sup&gt;&lt;/sup&gt;

Vibration monitoring of machinery and equipment plays a very important role in judging the equipment maintenance and operational status. This paper discussed the mechanical vibration amplitude measurement system scheme based on PVDF piezoelectric sensors. The entire test system is mainly composed of PVDF piezoelectric film sensors, charge amplifiers, data acquisition and processing and display of valid values. It can display the amplitude of vibration signals in real time and alarm. The measurement system has the advantages of a simple structure and convenient operation.

Flexible Fibrous Piezo-Electric Sensor on Printed Silver Electrode

ABSTRACTHere we introduce a facile method to fabricate a flexible piezoelectric sensor using one-dimensional (1-D) piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers directly produced onto flexible printed electrodes by electro-spinning without an additional poling process. The flexible silver electrodes are fabricated on polyethylene terephthalate (PET) using silver nanowires by easy and cost-effective spraying deposition. The electrospun PVDF nanofibers have uniaxially aligned arrays on the electrodes by using a rotating collector. The fabricated PVDF piezoelectric sensors demonstrate the piezoelectric responses with repeated mechanical stimuli with good flexibility and high sensitivity. We expect that the facile fabrication of PVDF piezoelectric sensors on flexible printed electrodes can be usefully exploited to integrate the piezoelectric sensors into flexible and stretchable functional electronic devices.

Design and Analysis of Force Sensor for Condition Monitoring System of Ball Cold Heading Forming

In order to solve the forming defects in the steel ball cold heading process, a novel force sensor which chooses the PVDF piezoelectric films as force-sensing elements is designed. The advantages and disadvantages of piezoelectric force sensor on measurement of the cold heading force are compared with existing force sensors. By using FEM, sensor’s linearity and the structure size are analyzed. Compared with the traditional sensor, this structure is more reasonable. The presented PVDF piezoelectric force sensor has wide frequency range, good dynamic performance, and can realize dynamic measurement.

Research on on-line monitoring technology for steel ball's forming process based on load signal analysis method

This paper presents a novel on-line monitoring technology to obtain forming quality in steel ball's forming process based on load signal analysis method, in order to reveal the bottom die's load characteristic in initial cold heading forging process of steel balls. A mechanical model of the cold header producing process is established and analyzed by using finite element method. The maximum cold heading force is calculated. The results prove that the monitoring on the cold heading process with upsetting force is reasonable and feasible. The forming defects are inflected on the three feature points of the bottom die signals, which are the initial point, infection point, and peak point. A novel PVDF piezoelectric force sensor which is simple on construction and convenient on installation is designed. The sensitivity of the PVDF force sensor is calculated. The characteristics of PVDF force sensor are analyzed by FEM. The PVDF piezoelectric force sensor is fabricated to acquire the actual load signals in the cold heading process, and calibrated by a special device. The measuring system of on-line monitoring is built. The characteristics of the actual signals recognized by learning and identification algorithm are in consistence with simulation results. Identification of actual signals shows that the timing difference values of all feature points for qualified products are not exceed ±6ms, and amplitude difference values are less than ±3%. The calibration and application experiments show that PVDF force sensor has good static and dynamic performances, and is competent at dynamic measuring on upsetting force. It greatly improves automatic level and machining precision. Equipment capacity factor with damages identification method depends on grade of steel has been improved to 90%.

The Research of Travelling Crane Non-Destructive Health Monitoring Based on Artificial Incentive and PVDF Sensor

Many factors may lead to internal structure of travelling crane injured when it is working. Therefore, it is an important problem of industry safety to detect the main girder. In this paper, a non-destructive testing method is presented. The white noise on the main girder was generated with artificial incentive. Special PVDF piezoelectric film sensor was used to detect the change of resonant frequency of main girder of traveling crane and the frequency was analyzed to judge the non-destructive health status of the main girder. The experiment results show that traveling crane survey method based on PVDF piezoelectric film sensor has a good accuracy and feasibility.

激光驱动飞片加速特征分析

The acceleration characteristics of flyers are critical parameters for laser-driven flyer study. In this paper, a laser-driven flyer experiment was designed. The PVDF piezoelectric film sensor was employed to measure the flight time of flyers traveling different distances, also flyer velocity and acceleration were calculated. The effects of laser energy on flyer acceleration performances were analyzed. Based on the Gurney energy theory, a calculation model of laser-driven flyer velocity was established. According to experimental results, laser energy loss and effective absorption coefficient were determined, and the effects of laser energy and metal film thickness on flyer velocity were obtained. The results show that the acceleration characteristics of flyers driven by different laser energies are similar. Moreover, laser energy has little influence on acceleration time. At high laser energy, the influences of metal film thickness on flyer maximum velocity and coupling coefficient are obvious. When the metal film is thicker than a certain value, the coupling coefficient could not increase again.

The Research of Shock Wave Attenuation Test of UHMWPE-PUF Composite by PVDF Piezoelectric Sensor

In the paper, The PVDF piezoelectric sensor was customized and the structure and test circuit of PVDF piezoelectric sensor is introduced. The polyurethane(PUF) reinforced by ultra high molecular weigh polyethylene (UHMWPE) material(UHMWPE-PUF composites) was synthesized. The pressure in UHMWPE-PUF composites under explosion load was measured and shock wave attenuation waveform is gained and the data is analyzed. The studies showed that PVDF piezoelectric firm sensor is suitable to shock wave measurement in material and UHMWPE- PUF composites can improve maximally shock wave attenuation properties of the material and have good applied outlook in the realm of anti-explosion.