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本帖最后由 tonnyw 于 2013-7-12 22:19 编辑
小弟新手,请教几个小问题哈
1. FE displacement results are most accurate at the nodes.
Strains are most accurate when determined at the Gauss Points.这句话怎么解释,具体啥意思?
》For derivatives, Gauss points are usually the superconvergence points. For displacement, it might happen that the nodal points are the superconvergence points.
2.In the inter-element terms, natural (non-essential ) boundary conditions are eliminated by imposing equilibrium at the nodes in the direct assembly process.
In the inter-element terms, the essential conditions are usually imposed only after the global stiffness matrix is assembled. 这句咋解释,还有这个自然边界条件是啥?
>Natural boundary conditions are related to derivatives and can used directly to form the load vector. Essential boundary conditions are not related to derivatives. They are something like displacement, temperature, and so on. To enforce this type of boundary conditions, penalty method is usually employed after forming the global stiffness matrix.
3. 在求刚度矩阵的时候,会用到 weak form吗,我看都是直接BDB积分直接出来了,weak form 在求刚度里面用不到,还是只在通过控制方程求解的时候才用到。
谢谢各位哈,初学者,轻拍哈。
>First we have strong form which is the partial differential equation. Then we have discrete form where everything is still continuous. Next we introduce the discrete form based on the weak form from which we get the finite element formulation.
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