Study On Mechanical Response And Electrical Output Characteristics Of Piezoelectric Ceramic Under High Velocity Impact

With the rapid development of electronic information and electromechanical technology,wireless electronic products have been widely used in traffic management,instrumentation,medical,communications,aerospace and military equipment.At present,the piezoelectric self powered technology is the development direction of the portable electronic devices and wireless sensor power supply.In order to better simulate the real conditions of the self powered technology which is used for fuze bridge ignition activation,high overload micro thermal battery activation,rocket ignition and aircraft escape lifesaving system ignition.The effect of high overload standing wave on the piezoelectric ceramics is simulated by using the projectile impacting on the piezoelectric ceramics composite target,which is generated by the ammunition launching or the ammunition collision with the target.This paper is based on this background,the dynamic response and electrical output characteristics of high speed impact piezoelectric ceramic composite target are studied with the research methods of combining experimental research,theoretical analysis and numerical simulation.The main research results are as follows:The overall scheme design of high speed impact piezoelectric ceramic composite target was carried out.The one-stage light gas gun is used as the loading system,and the shock pressure testing system and power output test system were designed.Based on the one dimensional stress wave communication theory,we have calculated the peak value of the shock pressure at different interfaces in composite target that is made up of different front substrates under typical collision conditions.Based on the numerical simulation of typical impact parameters,we have extracted the stress history and stress nephogram of piezoelectric ceramics in composite structure and the stress time history of multi points is averaged.Experiments of high speed impact piezoelectric ceramic composite target under typical impact parameters are carried out while a PVDF pressure sensor is clamped between the front substrate and the piezoelectric ceramic.The output voltage time history of PVDF was collected by impact pressure test system and the time history of impact stress is obtained by MATLAB software programming.The experimental results verify the accuracy of the theoretical calculation and the reliability of numerical simulation.Ideally,when the projectile impacts the front plate of different materials at the same speed,the pressure peak of piezoelectric ceramic is greater,when the wave impedance of the front plate material is smaller than the piezoelectric ceramic.In fact,due to the different collision energy and destruction effects,the plastic deformation consumes a lot of energy that result the reduction of the impact stress on the piezoelectric ceramics.The experiment of high speed impact piezoelectric ceramic composite target was carried out under different resistance load resistors,different capacitance energy storage capacitors and similar impact speed.The influence of different load on the output voltage,output current and output energy of piezoelectric ceramics is obtained by analyzing the time history of shock stress and the output curve of piezoelectric ceramics which is obtained by the impact pressure test system and the piezoelectric ceramic output test system.The peak value of the output voltege is proportional to the resistance value under stress pulse of PZT-5H is about 230 MPa,and the peak value of the output current is inversely proportional to the resistance value.The energy output is highest when the load resistance is 50 ohms.The peak value of the output voltege and the output energy are proportional to the capacity of the energy storage capacitor under stress pulse of PZT-5H is about 230 MPa.Experiments were carried out on the projectile with different length diameter ratio(diameter of projectile)to collide the piezoelectric ceramic composite target at different velocities.We got the relationship between peak stress and peak value of the output voltage and reveals the relationship between time and output voltage with different length to diameter ratio of projectile impact stress duration by analyzed the peak value of the stress,the peak value of the output voltage and their respective durations which is obtained by the impact pressure test system and the piezoelectric ceramic output test system.When the pressure peak is in the range of 200~700MPa,the output voltage of PZT-5H is proportional to the impact pressure peak.With the increase of the length of the projectile,should increase the time effect of stress wave in the piezoelectric ceramics,The PZT-5H can continue external power supply after the stress wave unloading.