【作者】 张攀；

【导师】 王省哲；

【作者基本信息】 兰州大学 ， 固体力学， 2013， 硕士

【摘要】 经过电极化后的PZT95/5铁电陶瓷能够在冲击波加载作用下快速去极化释放出束缚电荷,以形成高功率的瞬态电能输出,在国防工业中有着重要的应用。但是在冲击波的作用下,PZT95/5陶瓷可能会发生力学损伤或破坏以及电击穿等,使得PZT95/5铁电陶瓷脉冲电源失效,不能输出稳定的电能。因此,研究冲击波作用下PZT95/5陶瓷的动力学性能及电学特性对于认识PZT95/5陶瓷的性能及提高其利用率有重要意义。基于此,本文通过数值模拟方法研究了冲击波加载下PZT95/5陶瓷的动力学及电学特性。本文的主要工作与结果如下：1、开展了PZT95/5铁电陶瓷在冲击波作用下的动力学特性的数值模拟与仿真。采用显式分析有限元软件ANSYS/LS-DYNA,选用JH-2陶瓷类脆性材料动力学本构模型,参考美国Sandia实验室及中国工程物理研究院等实验观测结果,计算获得了PZT95/5铁电陶瓷的JH-2模型相关参数。数值模拟了氧化铝(A1203)陶瓷飞片以不同速度撞击PZT95/5铁电陶瓷的动力学响应过程,给出了PZT95/5铁电陶瓷自由面的粒子速度历程曲线,并与实验结果进行了对比分析。2、分析了电极化后的PZT95/5铁电陶瓷在冲击波加载下的瞬态放电过程与特征。对于垂直于极化方向的冲击波加载情形,我们通过将去极化过程中的PZT95/5铁电陶瓷等效为—电流源、电容和电导的并联,同时考虑电路负载、冲击波前后的铁电陶瓷材料介电常数、电导率的影响效应等,建立了一描述冲击波垂向加载下PZT95/5铁电陶瓷去极化和放电过程的模型。该模型较系统地考虑了冲击波压力对其波速、去极化相变过程等的影响,并解析获得了冲击波作用下铁电陶瓷的放电电流表述。3、在上述去极化放电模型基础上,开展了短路和电阻负载条件下铁电陶瓷冲击放电过程中的输出电流特征分析,冲击波前后材料介电常数和电导率的变化对输出电流的影响,并与相关实验观测结果进行了对比。相关结果表明：本文模型能够较好地模拟实验观测的PZT95/5铁电陶瓷的冲击放电过程,以及冲击波压力、负载电阻等对冲击放电输出电流的影响规律等。更多还原

【Abstract】 Bound charges of PZT95/5ferroelectric ceramics with polarization will be released by shock wave loading, to form a high-power electrical energy output, which is very important and applied in the defense industry. However, PZT95/5ceramic may be damaged and destroyed on mechanics or broke out on electricity, then PZT95/5ceramic pulse power failed and the stable power cannot be output. So, studying on the mechanical and electrical properties of PZT95/5ceramic under shock loading important, which is very important for recognizing PZT95/5ceramic performance and improve their utilization. For this reason, kinetic and electrical properties of PZT95/5ceramics under shock wave load were study by the numerical simulation in this paper. The main work of this paper as follows:1The kinetic properties of PZT95/5ferroelectric ceramic were analyzed by using numerical simulation method. The explicit finite element analysis software ANSYS/LS-DYNA was used and the JH-2ceramic material dynamics model was chose as the kinetic model. The JH-2model parameters of PZT95/5ceramic were calculated by means of the experimental results of the U.S. Sandia Laboratory and the Chinese Academy of Engineering Physics. The process of alumina (Al2O3) ceramic impact PZT95/5ceramic at different speeds was simulated, and the particle velocity history curves of free surface of PZT95/5ceramic was given. The simulation results were comparing with the experiment results, and the reason for the difference was analyzed.2The transient discharge process and characteristics of PZT95/5ferroelectric ceramic with polarization was analyzed. For a shock loading perpendicular to the polarization direction, a model describing the depolarization and discharge process of PZT95/5ferroelectric ceramic by normal shockwave is proposed. The effects of Shockwave pressure on the wave velocity and the depolarization phase transition process are considered systematically in our study. The PZT95/5ferroelectric ceramics depoling process is analyzed by a parallel circuit with a current source, a capacitance and a conductance, and the circuit load. The effects of changes in the dielectric constant and conductivity during shock loading are taken into consideration.3The output current characteristics of ferroelectric ceramics discharge process in the short-circuit and resistive load conditions, the effects of changes in the dielectric constant and conductivity are analyzed by using the model and compared with the experimental results. The results show that, the present theoretical model can predict well the discharge process of PZT95/5ferroelectric ceramics under shock compression.更多还原