如何合并节点？

momochong

附件中提出了所要咨询大家的问题。

mingbai1984

TG中的merge就是通过定义距离来实现的，有不同的容差设定来满足不同的需要……

你的问题在tg手册2.1版中的第五章开篇就有一种简单的解决办法，sii命令……

好好挖掘手册吧，里面才是正真的解答

tiny0o0

stp

momochong

谢谢。看过帮助手册后，问题解决了。
我要输出的格式是lsdyna格式。
在控制阶段使用sid命令定义滑移接口的类型，在block阶段使用sii命令master和slave接触面。在merge阶段，这些定义了滑移接口的面面之间就不合并节点了。输出格式中，就有了所定义的各个master和slave接触面的节点集（*set_segment关键字)。如果输出格式中不想使用这些节点，那么在使用sid命令时，滑移接口类型使用dummy，就不输出相应的接触面的节点集了。

momochong

truegrid网站的FAQ是这样说的，转给大家。
FAQ Q3: Is TrueGrid capable of generating a mesh for a component system as well as for stand-alone parts?

Answer: Yes. There are many features and techinques in TrueGrid® that help in building assemblies.

The code enables you to easily put 2 different parts together such that they have a node-for-node correspondence. TrueGrid® has a "block boundary" technology for an exact node-for-node match between similar regions of different parts. It also has a transition block boundary interface between parts that automatically sews two parts together with all hex elements when there is no node-for-node correspondence between the two parts.

One method of handling assemblies with a group of users is to first create the interfaces between the components using the block boundary feature. Then each individual working on the project must attach his or her component to the appropriate interface, guaranteeing that the parts will meet perfectly.

In those cases where there is no need to have a one-to-one correspondence at the interface between components, then it is sufficient to have the faces of the two parts be projected to the same surface. This will assure that the interface nodes on both sides of the interface lie on the same surface. This method typically requires that the interface be identified as a contact surface. This is simulation code specific and TrueGrid® supports a wide viriety of contact surfaces (see the SID command).

Within a simgle component, it is easy to add partitions in the mesh so that interior faces of the mesh can be projected to interior surfaces of the geometry. Then one can assign different materials to different regions of the TrueGrid® part. This makes it possible to build several components within one TrueGrid® part. In fact, this becomes a challenge amoung TrueGrid® experts to pack as many components as possible into one TrueGrid® part. This is not a frivolous activity, however, since there can be a significant savings in time, effort, and adaptive flexibility when this is done.

The offset command can be used to add an offset to the node and element numbering so that one can paste together multiple components from multiple outputs from TrueGrid® without a numbering comflict. This only works if you are building a model for a simulation code that has a keyword format. One can also import a mesh in several different formats and it will be integrated with the parts that are generated within TrueGrid®.

Alternatively, if the geometry is formed initially so that everyone uses the same geometry, then it is a simply matter of concatenating the session files from each component part and then rerunning TrueGrid® in batch mode. One can also use parameters that can easily be changed globally, once the session files are concatenated to avoid conflicts in numbering. In many situations, a CAD model is braught into TrueGrid® through the iGES interface. This reduces the potential problem of a conflict in geometric identification, since everyone can use the same IGES file with the same numbering of surfaces and curves. It should be pointed out that any surface or curve can be ignored when building a component. One uses only those surfaces that are explicitly projected to and only those curves that are explicitly attached to. Therefore, it causes no problem for everyone to use the geometry for the entire assembly, even though each individual may only use a portion of that geometry.

Some expert users take this one step further and build parametric compenents. TrueGrid® has a rich collection of parametric features that make this possible. When a specific component is required, one sets the appropriate parameters and includes the file with the parametric model. This is analogous to calling a subroutine in a programming language. The savings with this method can be significant since a component can be reuseed in many settings.

There are numerous examples of assemblies in the TrueGrid® gallery.