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发表于 2010-9-11 03:45:01
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来自 美国
你在二楼中提到的F在线性问题里可以理解为F_ext,
在非线性问题里可以理解为F_ext - F_int。
我在楼上提到的F,就是所谓的等效节点内力,
F_{int} = \int B^t \sigma dV,
不论在线性还是非线性问题都成立。
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bbssbb 发表于 2010-9-11 00:50
Let us focus on the linear problem at the moment. When we form the element stiffness matrix and load vector, we have for an element
K^e*U^e = F^e
The load vector F^e could be the summation of concentrated loads, body force such as weight, thermal expansion, and so on. It is the stuff we know before we get the finite element solution. But this equality does not hold and we miss the load vector from the internal force. So it should be
K^e*U^e = F^e + f^e
The internal node force f^e can be calculated only after we have the finite element solution. This load vector f^e converges faster than the finite element solution. That's why for a big model we can use coarse mesh to get the load and take some important part, use finer mesh, higher order element and apply the load from the coarse mesh. |
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