轴对称结构极限上限分析的完全边光滑有限元法

A FULLY EDGE-BASED SMOOTHED FINITE ELEMENT METHOD FOR UPPER-BOUND LIMIT ANALYSIS OF AXISYMMETRIC STRUCTURES

  • 摘要: 根据极限分析的机动定理,该文建立了轴对称结构极限上限分析的完全边光滑有限元法。为了避免复杂的坐标映射和雅可比矩阵的计算,对形函数的偏导项和非偏导项分别采用光滑应变技术与光滑积分伪弱形式进行处理,从而将所有的域积分都转化为更为简单的边界积分。考虑了材料的不可压缩条件,并采用罚函数法将其引入。为了克服目标函数非光滑导致的计算困难,采用逐步识别刚性区和塑性区的方案,不断修正目标函数。数值算例结果表明:该文所提方法具有格式简单、计算效率高和收敛快等优点,并且对极度不规则单元同样可获得较高的计算精度。

     

    Abstract: Based on the kinematic theorem of limit analysis, a fully smoothed edge-based finite element method is developed for upper bound limit analysis of axisymmetric structures. In order to completely avoid the complex coordinate mapping and calculation of Jacobian matrix, the partial derivative and non-partial derivative of shape functions are treated respectively by the smoothing strain technique and the quasi-weak form of smoothed integral. As a result, all the smoothed domain integrals can be converted into boundary integrals in the smoothing domains, which are relatively simpler. The plastic incompressibility can be introduced conveniently by the penalty function. By distinguishing the rigid zones from the plastic zones generally and by modifying the objective function accordingly at each iteration, the difficulties caused by a non-smoothness objective function can be easily overcome. Numerical examples show that the method proposed has some advantages such as simple formulation, high efficiency and fast convergence. In addition, high computational accuracy can also be obtained even though the extremely irregular elements are employed.

     

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