Microstructure and interfacial adhesion of high velocity oxy‐fuel‐sprayed MoB–CoCr alloy coating on 316L stainless steel

In this article, a newly developed MoB–CoCr alloy coating was deposited on 316L stainless steel substrate by high velocity oxy‐fuel thermal spraying process. The microstructures and interfacial adhesion of the alloy coating were determined by scanning electron microscopy, X‐ray diffraction and three‐point bending. The results show that the coating consisted of ternary transition metal boride matrix phases (CoMo₂B₂, CoMoB) and a little amount of binary borides (MoB and CrB), the former composed of partially amorphous phase. The formation of the amorphous phase was attributed to the high cooling rates of molten droplets and the proper powder compositions. In the interfacial adhesion measurement, the delamination of the coating is induced during the three‐point bending test, and the interfacial fracture toughness is analyzed using a finite element analysis model. The critical load is determined by comparing the load versus deflection curves obtained by finite element analysis under assumed no crack conditions with the experimental data, and other inputs are determined by test. Copyright © 2009 John Wiley & Sons, Ltd.     

压电陶瓷非线性断裂的再生核点法分析

采用一个简单的包含有极化反转及电饱和影响的压电材料的本构模型,以局部J积分作为断裂准则,应用再生核点法这一无网格数值方法导出了作用电场与断裂载荷的关系曲线,该曲线的趋势与Park的实验观察现象一致。本文还介绍了再生方程、再生核点法形函数及本质边界条件处理的边界转换法,计算程序采用面向对象方法实现。     

垂直界面裂纹断裂力学问题的实验研究

用实验方法研究了具有垂直界面方向裂纹的界面断裂力学问题．根据实验结果对裂尖区域的奇异性性质、角位移分布、应力强度因子等进行了分析，并将实验结果与理论结果进行了比较和讨论     

弹塑性体脆断相场模型的一致性无单元伽辽金法

采用无单元伽辽金法（EFG）对弹塑性体脆性断裂的相场模型进行了数值实现。利用无单元法便于构建高阶近似函数的优势，位移和相场均采用二阶移动最小二乘（MLS）近似。刚度阵的数值积分采用更为高效的二阶一致三点积分格式QC3（Quadratically Consistent 3-point integration scheme）。本构算法采用Newton-Raphson迭代和弹塑性一致性切线模量。数值结果表明了本文方法模拟弹塑性体脆性断裂的有效性。