Study on Optimum Design of an Intelligent Composite Plate with Heat Resistance

(1)本文针对一种由耐热结构层和两层压电陶瓷层构成的复合材料板，通过压电热弹性分析和数值模拟，建立了一种控制热弹性位移的智能系统。当一个未知的瞬态加热温度作用在底部自由表面上时，由中间压电陶瓷层上感应的电势分布来推断，然后确定施加在顶部压电陶瓷层上的控制底部自由表面弹性位移的瞬态电势分布。(2)在一个由耐热结构层和多层压电陶瓷层组成的复合板中，讨论了一个优化设计问题。当底部自由表面上的热致弹性位移通过向每个压电陶瓷层施加电势来控制时，每个压电陶瓷层的厚度被确定为受到应力约束，使得最大施加电势最小化。采用基于拟牛顿法的神经网络，得到了适当的设计结果。通过放松应力约束，对多层复合材料板进行了再优化设计。(3)提出了一种基于平面应力条件的简便解法，并以此为基础分析了压电陶瓷圆板的热弹性问题。基于平面应力解的数值结果与以前推导的精确三维解吻合良好。平面应力公式比三维公式简单得多。将平面应力解应用于多层复合材料板，可以大大减少数值计算所需的时间，从而提高智能函数的响应速度。

(1) In a composite plate constructed of a structural layer with heat resistance onto which two piezoceramic layers are bonded, an intelligent system of controlling a thermoelsatic displacement is developed by means of piezothermoelastic analyses and numerical simulations. When a transient unknown heating temperature acts on the bottom free surface, it is inferred from the electric potential distribution induced on the middle piezoceramic layer, and then a transient electric potential distribution applied to the top piezoceramic layer which controls the elastic displacement on the bottom surface is determined.(2) In a composite plate consisting of a structural layer with heat resistance onto which multiple piezoceramic layers are bonded, an optimum design problem is demonstrated. When the thermally induced elastic displacement on the bottom free surface is controlled by applying an electric potential to every piezoceramic layer, the thickness of each piezoceramic layer is determined subject to stress constraints so that the maximum applied electric potential is minimized. Employing neural networks based on the quasi-Newton method, appropriate design results are obtained. Re-optimum design of the multi-layered composite plate is also demonstrated by relaxing the stress constrains.(3) A convenient solution technique based on the plane-stress conditions is proposed and then thermoelastic problems of piezoceramic circular plates are analyzed. Numerical results based on the plane-stress solution are in good agreement with those derived from a previously derived exact three-dimensional solution. The Plane-stress formulations are much simpler than the three-dimensional formulations. Applying the plane-stress solution to the multi-layered composite plate, it is considered that the executing time required to numerical calculations will be considerably reduced and thus response of an intelligent function will be improved.