*CONSTRAINED_EXTRA_NODES_OPTION

Available options include: 

NODE 

SET 

Purpose: Define extra nodes for rigid body. 为刚体定义额外的节点（节点集）

PID：Part ID of rigid body to which the nodes will be added

     将添加节点的刚体的part ID

NID / NSID：Node (keyword option: NODE) or node set ID (keyword option: SET), see *SET_NODE, of added nodes.

     新增节点的node ID或者 Node Set ID

IFLAG：This flag is meaningful if and only if the inertia properties of the Part ID are defined in PART_INERTIA. If set to unity, the centerof-gravity, the translational mass, and the inertia matrix of the PID will be updated to reflect the merged nodal masses of the node or node set. If IFLAG is defaulted to zero, the merged nodes will not affect the properties defined in PART_INERTIA since it is assumed the properties already account for merged nodes.

     当且仅当PART_ INERTIA中定义了part ID的惯性属性时，该标志是有意义的。如果设置为1，PID的重心、平动质量和惯性矩阵将被更新，以反映节点或节点集的合并节点质量。如果IFLAG默认为0，则合并节点不会影响PART_INERTIA中定义的属性，因为它假定属性已经包含在合并节点中。

Remarks: 

Extra nodes for rigid bodies may be placed anywhere, even outside the body, and they are assumed to be part of the rigid body. They have many uses including:

刚体的额外节点可以放置在任何地方，甚至可以放置在体外部，并假设它们是刚体的一部分。它们有许多用途，包括：

1. The definition of draw beads in metal forming applications by listing nodes along the draw bead.
2. Placing nodes where joints will be attached between rigid bodies.
3. Defining a node where point loads are to be applied or where springs may be attached.
4. Defining a lumped mass at a particular location.

1. 拉延筋在金属成形应用中的定义，通过列出沿拉延筋的节点。
2. 在刚体之间放置连接节点。
3. 定义一个节点，在该节点上要施加点荷载或者在该节点上可以附加弹簧。
4. 在特定位置定义一个集中质量。

The coordinates of the extra nodes are updated according to the rigid body motion.

根据刚体运动更新额外节点的坐标。

Examples:

01：Rigidly attach nodes 285 and 4576 to part 14. (Part 14 MUST be a rigid body.)

    将节点285和4576刚性连接到 Part 14上。( Part14 必须是一个刚体（rigid body）。)

*CONSTRAINED_EXTRA_NODES_NODE

$ pid nid

  14     285

  14    4576

02：Rigidly attach all nodes in set 4 to part 17. (Part 17 MUST be a rigid body.)

    将节点集 4 中的所有节点刚性连接到 Part 17上。(part17 必须是一个刚体（rigid body）。)

In this example, four nodes from a deformable body are attached to rigid body 17 as a means of joining the two parts.

在这个例子中，来自一个可变形体（非刚体或者成为柔性体）的四个节点被附加到 Part 17上，作为连接这两个part的手段。

*CONSTRAINED_EXTRA_NODES_SET

$ pid nsid

  17     4

*SET_NODE_LIST

$ sid

   4 

$ nid1 nid2 nid3 nid4 nid5 nid6 nid7 nid8

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