Evaluation method of the life of ship structure using X ray CT scaned image base analysis

研究了有限覆盖法的迭代求解方法。通常的迭代求解方法如PCG，在单元内施加位移边界条件时不收敛，从而施加多点约束。为了解决这一难题，采用了共轭投影梯度法，并与传统的预条件共轭梯度法和增广拉格朗日法的结果进行了比较。将有限覆盖法与网格叠加法统一起来。在此过程中，代表整个模型行为的全局网格由体素类元素组成，而代表模型边界周围行为的局部网格由普通有限元组成。可以提高边界周围分析的准确性。数值算例表明了该方法的有效性。

The iterative solver for finite cover method is investigated. Usual iterative solver such as PCG does not converge when the displacement boundary condition is applied within an element, hence multi point constraint are imposed. To solve this difficulty, the conjugate projected gradient method is employed, and compared with the results of traditional preconditioned conjugate gradient method and augumented Lagrangian method.Also, Finite Cover Method (FCM) and the mesh superposition method are unified. In this process, the global mesh, which represents the behavior of the whole model is composed of voxel type elements, while the local mesh, which represents the behavior around the model boundaries is composed of ordinary finite elements. The accuracy of analysis around the boundaries can be improved. Several numerical examples show the performance of the presented technique.