structure node initialize command

Syntax

structure node initialize keyword ... <range>

Primary keywords:

displacement    displacement-x    displacement-y    displacement-z    displacement-rotational    displacement-rotational-x    displacement-rotational-y    displacement-rotational-z    position    position-x    position-y    position-z    ratio-target    velocity    velocity-x    velocity-y    velocity-z    velocity-rotational    velocity-rotational-x    velocity-rotational-y    velocity-rotational-z

Initialize quantities on all structure nodes in the range. Note that positions can only be specified in the global system.

Be aware that in the structural element logic, node velocities and displacements are stored in the local system. This means that changes to the local system can change the values in the global system. This is particularly important because the node local system is not calculated for a given structural element system until the first cycle or step, until then the node system is the default, which corresponds to the global system. When the first cycle command occurs, the node local system is adjusted and any values of velocity that have been assigned will likely change their direction in the global system.

The best way to handle this is to emit a model cycle 0 command before assigning velocities to nodes—this will cause the local node system to be updated.

displacement v <[nodeinitializeblock]>

translational displacement

displacement-x f <[nodeinitializeblock]>

translational displacement (\(x\)-component)

displacement-y f <[nodeinitializeblock]>

translational displacement (\(y\)-component)

displacement-z f <[nodeinitializeblock]>

translational displacement (\(z\)-component)

displacement-rotational v <[nodeinitializeblock]>

rotational displacement

displacement-rotational-x f <[nodeinitializeblock]>

rotational displacement (\(x\)-component)

displacement-rotational-y f <[nodeinitializeblock]>

translational displacement (\(y\)-component)

displacement-rotational-z f <[nodeinitializeblock]>

translational displacement (\(z\)-component)

position v <[nodeinitializeblock]>

position of node (global system). This is used for positioning of a structural element grid; must be used after creating the node, but before executing any cycles. Any node that is moved into a zone (see the structure link list command) will have its link deleted (if one is present) and will have a new link created with attachment conditions corresponding to the type of structural element using the node (see this table). If more than one element type is using the node, then the attachment condition will correspond with the first element type in the following list: liner, geogrid, pile, cable, shell, and beam. Thus, if a node is being used by both a geogrid and a cable, then the attachment condition after moving this node will correspond with that of a geogrid.

position-x f <[nodeinitializeblock]>

\(x\)-coordinate of node (global system). See position above.

position-y f <[nodeinitializeblock]>

\(y\)-coordinate of node (global system). See position above.

position-z f <[nodeinitializeblock]>

\(z\)-coordinate of node (global system). See position above.

ratio-target f <[nodeinitializeblock]>

Sets the target local force ratio that is considered to be converged for mechanical calculations. The default value is 1e-4. A local force ratio of this value will result in a convergence value of 1.0 for the node. See the convergence keyword in the model solve command.

velocity v <[nodeinitializeblock]>

translational velocity

velocity-x f <[nodeinitializeblock]>

translational velocity (\(x\)-component)

velocity-y f <[nodeinitializeblock]>

translational velocity (\(y\)-component)

velocity-z f <[nodeinitializeblock]>

translational velocity (\(z\)-component)

velocity-rotational v <[nodeinitializeblock]>

rotational velocity

velocity-rotational-x f <[nodeinitializeblock]>

rotational velocity (\(x\)-component)

velocity-rotational-y f <[nodeinitializeblock]>

rotational velocity (\(y\)-component)

velocity-rotational-z f <[nodeinitializeblock]>

rotational velocity (\(z\)-component)

structure node initialize Keyword Block

The initialization values specified with the structure node initialize command may be optionally modified with the keywords below.

They apply (except where noted with regard to the local keyword), to all of the major keywords of the command: displacement, displacement-rotational, displacement-rotational-x, displacement-rotational-y, displacement-rotational-z, displacement-x, displacement-y, displacement-z, position, position-x, position-y, position-z, ratio-target, velocity, velocity-rotational, velocity-rotational-x, velocity-rotational-y, velocity-rotational-z, velocity-x, velocity-y and velocity-z.

add

the existing value of the parameter (of all nodes in the range) is set to its current value plus the given value. For example, one can add 0.1 to all node \(x\)-displacements with the command structure node initialize displacement-x 0.1 add.

multiply

the existing value of the parameter (of all nodes in the range) is multiplied by the given value rather than being set to the given value. For example, one can multiply all node \(x\)-displacements by a factor of 1.5 with the command structure node initialize displacement-x 1.5 multiply.

local

specifying the supplied value will initialize the node in local coordinates. This keyword may not be used with position (position, position-x, etc.).

gradient v

the value installed in each node in the range is \(val_f\) = \(v\) + \(xg_x\) + \(yg_y\) + \(zg_z\), where the gradient keyword is given immediately after the the supplied value (\(val\) here), and (\(x\), \(y\), \(z\)) are the components supplied by v, which specifies the reference position of the node. If the multiply keyword is also present, then the given gradient is applied to the multiplier.