CP自由度耦合

CP自由度耦合
CP,NSET,Lab,NODE1,NODE2,NODE3,NODE4,NODE5,NODE6,NODE7,NODE8,NODE9 ,NODE10,NODE11,NODE12,NODE13,NODE14,NODE15,NODE16,NODE17
Defines(or modifies)a set of coupled degrees of freedom.
定义(或者修改)一个耦合自由度集
PREP7：Coupled DOF
MP ME ST PR PRN FL EM PP
NSET
Set reference number：设置参考号
n-Arbitrary set number.任意的集合号
HIGH-The highest defined coupled set number will be
used(default,unless Lab=ALL).This option is useful when adding nodes to an existing set.
已定义的最大的耦合集号将被使用(缺省，除非Lab=ALL)。

当向一个存在的耦合集增加节点时这个选项是有用的。

NEXT-The highest defined coupled set number plus one will be used(default if Lab=ALL).This option automatically numbers coupled sets so that existing sets are not modified.
已定义的最大的耦合集号加上1之后将被使用(缺省，除非Lab=ALL)。

这个选项是自动赋耦合集号所以存在的耦合集号不被修改。

Lab
Degree of freedom label for coupled nodes(in the nodal
coordinate system).Defaults to label previously defined with NSET if set NSET already exists.A different label redefines the previous
label associated with NSET.Valid labels are：Structural labels：
UX,UY,or UZ(displacements)；ROTX,ROTY,or ROTZ(rotations)(in radians).Thermal labels：
TEMP,TBOT,TE2,TE3,...,TTOP(temperature).Fluid labels：PRES(pressure)；VX,VY,or VZ(velocities).Electric labels：VOLT(voltage)；
EMF(electromotive force drop)；CURR(current).Magnetic labels：
MAG(scalar magnetic potential)；AX,AY,or AZ(vector magnetic potentials)；CURR(current).Explicit analysis labels：UX,UY,or
UZ(displacements).If Lab=ALL,sets will be generated for each active degree of freedom(i.e.,one set for the UX degree of freedom,another
set for UY etc.),and NSET will be automatically incremented to
prevent overwriting existing sets.The ALL option cannot be used to modify existing sets--NSET must be anew set number nor NEXT.The
degree of freedom set is determined from all element types defined
and the DOF command,if used.ALL is the only label applicable to FLOTRAN.
耦合自由度的标识(在笛卡尔坐标系统中)。

如果NSET选中的集合已经存
在则缺省值为前面NSET已定义的值。

不同的标识会重新定义前面与NSET相对
应的标识。

合法的标识为：
结构标识：UX,UY,or UZ；ROTX,ROTY,or ROTZ；
其他略。

如果Lab=ALL，每个活动的自由度都会产生一个耦合集，(也就是,一个自
由度集用于约束UX,另一个用于约束UY等。

)，并且NSET会被自动增加以防止
覆盖现有的集。

ALL选项不能用于修改现有的耦合集---NSET必须是个新的n
or NEXT集号，自由度集由所有定义的单元类型和自由度命令决定，如果要用
的话，ALL是适用于FLOTRAN唯一标识。

NODE1,NODE2,NODE3,...,NODE17
List of nodes to be included in set.Duplicate nodes are ignored.If anode number is input as negative,the node is deleted from the coupled set.The first node in the list is the
primary(retained)node.If NODE1=ALL,NODE2 through NODE17 are ignored and all selected nodes[NSEL]are included in the set.If
NODE1=P,graphical picking is enabled and all remaining command fields are ignored(valid only in the GUI).A component name may also be substituted for NODE1.
列出耦合集中包含的节点。

那些复制的节点会被忽略掉。

如果一个节点号被输入为负，则该节点会从耦合集中被删除。

在节点列表中第一个节点是主要的节点。

如果NODE1=ALL，NODE2到NODE17会被忽略，且所有选中的节点都会包含在这个集合中，如果NODE1=P，图像拾取功能可用且所有保留的命令域会
被忽略(仅在GUI中合法)。

组件名可能也会代替NODE1。

Notes
Do not include the same degree of freedom in more than one coupled set.Repeat CP command for additional nodes.
Coupling degrees of freedom into aset causes the results calculated for one member of the set to be the same for all members of the set.Coupling can be used to model various joint and hinge effects.A more general form of coupling can be done with constraint equations[CE].For structural analyses,a list of nodes is defined along with the nodal directions in which these nodes are to be coupled.As aresult of this coupling,these nodes are forced to take
the same displacement in the specified nodal coordinate direction.The amount of the displacement is unknown until the analysis is completed.A set of coupled nodes which are not coincident,or which are not along the line of the coupled displacement direction,may produce an applied moment which will not appear in the reaction forces.The actual degrees of freedom available for aparticular node depends upon the degrees of freedom associated with element
types[ET]at that node.For example,degrees of freedom available with BEAM3 elements are UX,UY,and ROTZ only.For scalar field analysis,this command is used to couple nodal temperatures,pressures,voltages,etc.
在多个耦合集中不要包含相同的自由度，对于额外的节点(需要耦合的话)重复CP command即可。

耦合自由度成为一个集将导致对于一个成员的计算结果和所有的成员的相同。

耦合模型可用于模拟各种铰接和铰链的效果。

用约束方程可以做更为一般形式的耦合[CE]。

对于结构分析，列表里的节点是按照节点坐标系的方向定义的，这个方向也是将要耦合的方向，这种耦合的结果是，这些节点都被迫在指定的节点坐标方向上有相同的位移。

在分析未完成之前，位移的量是未知的。

一个耦合节点是不同步，或设置在沿着耦合位移方向不一致时，可能会产生一个在反力中不存在的力矩。

对于一个特定的节点实际上可用的自由度取决于和该自由度相关联的单元类型。

For an explicit dynamic analysis,the only valid DOF labels for coupling are UX,UY,and UZ.Since the rotational DOF(ROTX,ROTY,ROTZ)are not allowed,The CP family of commands should not be used in an
explicit analysis to model rigid body behavior that involves rotations.If CP is used in this manner,it could lead to nonphysical responses.
A set of coupled nodes which are not coincident,or which are not along the line of the coupled displacement direction,produce an artificial moment constraint.If the structure rotates,a moment may be
produced in the coupled set in the form of aforce couple.This moment is in addition to the real reaction forces and may make it appear
that moment equilibrium is not satisfied by just the applied forces and the reaction forces.Note,however,that in an explicit dynamic analysis,this artificial moment will not be produced.Rather,just the applied forces and the reaction forces will satisfy the moment equilibrium in the model.Thus,in an explicit analysis,the magnitude of nodal displacements for this set of nodes will depend on the distance from each node to the center of the coupled set,and the direction of displacement will depend on the resulting moment.This may lead to anonphysical response in some cases.
Additional sets of coupled nodes may be generated from aspecified set.Degrees of freedom are coupled within aset but are not coupled between sets.No degree of freedom should appear in more than one coupled set.Such an appearance would indicate that at least two sets were in fact part of asingle larger set.The first degree of freedom of the coupled set is the"prime"degree of freedom.All other degrees of freedom in the coupled sets are eliminated from the solution matrices by their relationship to the prime degree of freedom.Forces applied to coupled nodes(in the coupled degree of freedom direction)will be summed and applied to the prime degree of freedom.Output forces are also summed at the prime degree of freedom.Degrees of freedom with specified constraints[D]should not be included in acoupled set(unless the degree of freedom is prime).
If master degrees of freedom are defined for coupled nodes,only the prime degree of freedom should be so defined.The use of coupled nodes reduces the set of coupled degrees of freedom to only one degree of freedom.The wavefront is correspondingly decreased；however,the overall stiffness(or conductivity)matrix formulation time is increased.
In FLOTRAN,you can apply periodic boundary conditions using the CP command along with the PERI macro.Attempts to use the CP command outside the context of the PERI macro may lead to unexpected results.
Menu Paths
Main Menu Preprocessor Coupling/Ceqn Couple DOFs
Main Menu Preprocessor Coupling/Ceqn Cupl DOFs w/Mstr。