| With the increasing complexity of modem war environment,the miniaturization of equipment has become one of the main development trends.The military thermal battery is known as the "heart" of the missile borne weapon system.Therefore,there is a huge demand for military thermal batteries,and the existing ways of activating thermal batteries have a long activation time and occupy a large space in the bomb,which seriously restrict the development of miniaturization of thermal batteries.In this paper,the original method of activation of thermal batteries is subverted,and a new self-powered technology is proposed.The stacked piezoelectric ceramics are used as the activation energy.The key technology of piezoelectric ceramics actuated micro-sized thermochemical batteries is studied by combining experimental research with numerical simulation.The main research results are obtained as follows:The experimental simulation platform for a thermal battery activation system consisting of piezoelectric ceramics,electric ignition heads,electrodes,and insulation systems were built.The one-stage light gas gun and Hopkinson are used as loading system.The test systems for impact pressure of polyvinylidene fluoride(PVDF)and electrical output characteristics of piezoelectric ceramics were built.The one-stage light gas gun is used to load projectiles at different velocities to impact the composite structure of PZT-5H piezoelectric ceramic stacks with different layers and sizes in order to explore the propagation of stress waves in piezoelectric ceramics under different conditions.Combining civil electric ignition head,military electric ignition head and aluminothermic energy-containing bridge as load,the experiments of different combined structures are carried out and the electrical output signals under different combinations are obtained.The results show that the impact pressure peak of piezoelectric ceramics rises with the increase of impact speed,and the output voltage peak of piezoelectric ceramics increases linearly with the peak value of impact pressure.The experiment of Hopkinson loading projectiles acting on piezoelectric ceramics at different speeds was carried out and combined with ANSYS LS-DYNA numerical simulation to visually study the distribution of stress states in piezoelectric ceramics.And the military electric ignition head as a load,the electrical output signals of piezoelectric ceramics impacted by projectiles with different velocities are obtained.The results show that the simulation results are basically consistent with the experimental results.The impact pressure duration of the piezoelectric ceramics obtained by Hopkinson loading projectiles is longer than the tens of microseconds of the piezoelectric ceramics obtained by loading the projectiles with the one-stage light gas gun.Therefore,the effect of chamber pressure on piezoelectric ceramic can be obtained by the experiment on impacting piezoelectric ceramics by Hopkinson loading projectile.It is one of the vital technology that enhance reliability of piezoelectric ceramics actuated micro-sized thermochemical batteries.To make it more reasonable,the firing mechanism of electric ignition head is studied,and the minimum calorific value of electric ignition head fire is determined.In the case of pre-crushing of piezoelectric ceramics,the piezoelectric ceramic composite target was impacted at a speed of 208 m/s by using the one-stage light gas gun to load the projectile,and to verify the reliability of the piezoelectric ceramics actuated micro-sized thermochemical batteries.The experimental results show that the ignition process of the electric ignition head belongs to the thermal excitation process,and the minimum calorific value of electric ignition head fire is 0.27 mJ.The piezoelectric properties of piezoelectric ceramics remain unchanged in the case of precrushing,that is to say,the reliability of piezoelectric effect of piezoelectric ceramics to realize early activation of thermal batteries is relatively high. |
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