(4 ) because calculation of stress intensity factors using the finite element method of the linear elastic fracture mechanics cannot satisfy the need for the real-time monitoring and the real-time analysis of cracks in concrete dams, a four-layer neural network optimized by genetic algorithm and chaos optimization algorithm is proposed . the example shows that the optimized neural network can yield good results (4)用断裂力学有限元计算应力强度因子不能满足对混凝土坝裂缝实时监测、实时分析中的要求,提出了利用遗传算法和混沌优化算法改进的四层神经网络的解决方法,实例分析表明,本文提出的四层优化神经网络计算的应力强度因子接近于用断裂力学有限元计算的应力强度因子。
A general consensus exists related to the influence of slow crack propagation ahead of the crack tip upon the nonlinearity observed in the typical load-deflection response of the concrete specimen, namely, concrete exhibits somewhat quasibrittle behavior, which has been verified by the inapplicability of the conventional linear elastic fracture mechanics ( lefm ) and fracture models suitable for metal-like materials 现在已经意识到,混凝土在其典型的位移曲线中呈现出的非线性特征是由于裂缝在端部的缓慢扩展引起的,可以认为是混凝土的一种半脆性性能。这是在发现传统的线弹性断裂力学(lefm)和适合金属类材料的断裂模型不适用于混凝土研究时得出的结论。