FEA Boundary Conditions - Revision history

Nairnj: /* XML Input Files */

2022-02-11T21:54:29Z

XML Input Files

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	</pre>		</pre>

	These commands and attributes function exactly as defined [[#args\|above]] for the scripted <tt>FixLine</tt> and ~~<tt>~~<tt>FixPoint</tt> commands.		These commands and attributes function exactly as defined [[#args\|above]] for the scripted <tt>FixLine</tt> and <tt>FixPoint</tt> commands.

	An alternative to the above boundary conditions commands, <tt>XML</tt> files can alternative [[#Explicit XML Boundary Conditions\|explicitly set boundary conditions]] on nodes and element faces, but this method is rarely used.		An alternative to the above boundary conditions commands, <tt>XML</tt> files can alternative [[#Explicit XML Boundary Conditions\|explicitly set boundary conditions]] on nodes and element faces, but this method is rarely used.

Nairnj at 21:57, 2 June 2015

2015-06-02T21:57:47Z

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	<dt><span id="exEBCs"></span><EdgeBCs>		<dt><span id="exEBCs"></span><EdgeBCs>
	<dd>This command is used to apply stress to edges of elements. Subordinate to the command can be <tt><stress></tt> commands. Each <tt><stress></tt> command specifies an element (using <tt>elem</tt>), a <tt>face</tt> of the element, and a direction (using <tt>dir</tt> with setting 1 or n for normal stress or 2 or t for tangential or shear stress). The value of the <tt><stress></tt> tag should be 1 to 3 stresses (in ~~MPa~~), separated by commas, to allow applying constant or variable stress. If three stresses are given, the entered values correspond to the applied stress at the endpoints and in the ~~middle~~ of the face and stresses vary quadratically through these three points. If only two stresses are given, the stress will vary linearly between the endpoints of the face. If only one stress is given, the stress will be constant. The [[FEA Elements\|element]] faces are numbered around the element in the counter-clockwise direction starting with 1.		<dd>This command is used to apply stress to edges of elements. Subordinate to the command can be <tt><stress></tt> commands. Each <tt><stress></tt> command specifies an element (using <tt>elem</tt>), a <tt>face</tt> of the element, and a direction (using <tt>dir</tt> with setting 1 or n for normal stress or 2 or t for tangential or shear stress). The value of the <tt><stress></tt> tag should be 1 to 3 stresses (in [[ConsistentUnits Command#Legacy and Consistent Units\|pressure units]]), separated by commas, to allow applying constant or variable stress. If three stresses are given, the entered values correspond to the applied stress at the endpoints and in the [[ConsistentUnits Command#Legacy and Consistent Units\|pressure units]] of the face and stresses vary quadratically through these three points. If only two stresses are given, the stress will vary linearly between the endpoints of the face. If only one stress is given, the stress will be constant. The [[FEA Elements\|element]] faces are numbered around the element in the counter-clockwise direction starting with 1.

	</dl>		</dl>

Nairnj at 21:25, 2 June 2015

2015-06-02T21:25:29Z

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	* <tt>(dir)</tt> is <tt>x</tt> or <tt>y</tt> (or 1 or 2) to specify the direction of the applied displacement. In axisymmetric calculations use <tt>x</tt> (or 1) for <tt>R</tt> and <tt>y</tt> (or 2) for <tt>Z</tt>.		* <tt>(dir)</tt> is <tt>x</tt> or <tt>y</tt> (or 1 or 2) to specify the direction of the applied displacement. In axisymmetric calculations use <tt>x</tt> (or 1) for <tt>R</tt> and <tt>y</tt> (or 2) for <tt>Z</tt>.
	* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.		* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.
	* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disp</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).		* <tt>(disp)</tt> specifies magnitude of the displacement in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disp</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).

	Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero displacement in the r directions. You therefore need not set those conditions.		Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero displacement in the r directions. You therefore need not set those conditions.
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	<dt><span id="exDBCs"></span><DisplacementBCs>		<dt><span id="exDBCs"></span><DisplacementBCs>
	<dd>This command can set fixed displacement boundary conditions on nodes. Subordinate to the command can be any number of <tt><fix></tt> and <tt><rotate></tt> commands. The <tt><fix></tt> commands specify a <tt>node</tt> (by number) and the direction that is fixed with <tt>dof</tt> of x (or 1) for x direction or y (or 2) for y direction (or R and Z directions if axisymmetric). The value of the <tt><fix></tt> tag is the fixed displacement in mm.<br>		<dd>This command can set fixed displacement boundary conditions on nodes. Subordinate to the command can be any number of <tt><fix></tt> and <tt><rotate></tt> commands. The <tt><fix></tt> commands specify a <tt>node</tt> (by number) and the direction that is fixed with <tt>dof</tt> of x (or 1) for x direction or y (or 2) for y direction (or R and Z directions if axisymmetric). The value of the <tt><fix></tt> tag is the fixed displacement in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]].<br>
	The <tt><rotate></tt> tag can be used to apply skewed displacement boundary conditions that are in some direction that is not along the x or y axis. The method is to rotate the node first using a <tt><rotate></tt> command where the <tt>node</tt> attribute gives the node to rotate and the <tt>axis</tt> attribute is the axis of rotation, which must be 3 or z for 2D calculations or for rotation about the z axis. The value of the <tt><rotate></tt> tag is the angle to rotate in the clockwise direction in degress. Alternatively, the angle can be set using an <tt>angle</tt> attribute. Any rotated node can only be rotated once. After rotating a node, you can apply displacement (or load) boundary conditions in the rotated coordinate system.<br>		The <tt><rotate></tt> tag can be used to apply skewed displacement boundary conditions that are in some direction that is not along the x or y axis. The method is to rotate the node first using a <tt><rotate></tt> command where the <tt>node</tt> attribute gives the node to rotate and the <tt>axis</tt> attribute is the axis of rotation, which must be 3 or z for 2D calculations or for rotation about the z axis. The value of the <tt><rotate></tt> tag is the angle to rotate in the clockwise direction in degress. Alternatively, the angle can be set using an <tt>angle</tt> attribute. Any rotated node can only be rotated once. After rotating a node, you can apply displacement (or load) boundary conditions in the rotated coordinate system.<br>

Nairnj: /* Scripted Input Files */

2015-06-02T21:10:00Z

Scripted Input Files

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	* <tt>(pathid)</tt> to select a previously defined [[Path Command\|path]] by <tt>id</tt>, which must have be used in an [[Area Command\|area]].		* <tt>(pathid)</tt> to select a previously defined [[Path Command\|path]] by <tt>id</tt>, which must have be used in an [[Area Command\|area]].
	* (<tt>x1,y1</tt>) to (<tt>x2,y2</tt>) define (<tt>x,y</tt>) coordinates (in mm) for the points at the beginning and end of the line (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). All nodes close to that line are selected.		* (<tt>x1,y1</tt>) to (<tt>x2,y2</tt>) define (<tt>x,y</tt>) coordinates (in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]) for the points at the beginning and end of the line (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). All nodes close to that line are selected.
	* <tt>(tolerance)</tt> is an optional tolerance (in mm). When used it accepts nodes within that distance of the define line; when omitted, tolerance is set to small number bases on mesh dimensions.		* <tt>(tolerance)</tt> is an optional tolerance (in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]). When used it accepts nodes within that distance of the define line; when omitted, tolerance is set to small number bases on mesh dimensions.
	* <tt>(keyid)</tt> to select a previously defined [[Keypoint Command\|keypoint]] by <tt>id</tt>, which must be part of a [[Path Command\|path]] that is in an [[Area Command\|area]].		* <tt>(keyid)</tt> to select a previously defined [[Keypoint Command\|keypoint]] by <tt>id</tt>, which must be part of a [[Path Command\|path]] that is in an [[Area Command\|area]].
	* (<tt>x3,y3</tt>) define (<tt>x,y</tt>) coordinates (in mm) for a single point (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). The node closest to that point is selected.		* (<tt>x3,y3</tt>) define (<tt>x,y</tt>) coordinates (in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]) for a single point (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). The node closest to that point is selected.

	All nodes along the selected path or along the selected line (for <tt>FixLine</tt> commands) or the single selected node (for <tt>FixPoint</tt> commands) can be assigned nodal [[#Displacement Conditions\|displacement]] or [[#Load Conditions\|load]] conditions, rotated for [[#Skewed Conditions\|skewed boundary conditions]], or [[#Selecting Nodes\|designated]] for conditional output.		All nodes along the selected path or along the selected line (for <tt>FixLine</tt> commands) or the single selected node (for <tt>FixPoint</tt> commands) can be assigned nodal [[#Displacement Conditions\|displacement]] or [[#Load Conditions\|load]] conditions, rotated for [[#Skewed Conditions\|skewed boundary conditions]], or [[#Selecting Nodes\|designated]] for conditional output.

Nairnj: /* Load Conditions */

2014-01-03T19:11:05Z

Load Conditions

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	* <tt>(dir)</tt> is <tt>x</tt> or <tt>y</tt> (or 1 or 2) to specify the direction of the applied displacement. In axisymmetric calculations use <tt>x</tt> (or 1) for <tt>R</tt> and <tt>y</tt> (or 2) for <tt>Z</tt>.		* <tt>(dir)</tt> is <tt>x</tt> or <tt>y</tt> (or 1 or 2) to specify the direction of the applied displacement. In axisymmetric calculations use <tt>x</tt> (or 1) for <tt>R</tt> and <tt>y</tt> (or 2) for <tt>Z</tt>.
	* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.		* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.
	* <tt>(load)</tt> specifies magnitude of the ~~displacement~~ in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric loads use a <tt>load</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute.		* <tt>(load)</tt> specifies magnitude of the load in N. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric loads use a <tt>load</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute.

	To apply a load along any other direction, find the (x,y) coordinates of the load vector and then use two <tt>Load</tt> command in the x and y directions.		To apply a load along any other direction, find the (x,y) coordinates of the load vector and then use two <tt>Load</tt> command in the x and y directions.

Nairnj: /* Displacement Conditions */

2014-01-03T19:05:46Z

Displacement Conditions

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	* <tt>(dir)</tt> is <tt>x</tt> or <tt>y</tt> (or 1 or 2) to specify the direction of the applied displacement. In axisymmetric calculations use <tt>x</tt> (or 1) for <tt>R</tt> and <tt>y</tt> (or 2) for <tt>Z</tt>.		* <tt>(dir)</tt> is <tt>x</tt> or <tt>y</tt> (or 1 or 2) to specify the direction of the applied displacement. In axisymmetric calculations use <tt>x</tt> (or 1) for <tt>R</tt> and <tt>y</tt> (or 2) for <tt>Z</tt>.
	* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.		* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.
	* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>~~disk~~</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).		* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disp</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).

	Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero displacement in the r directions. You therefore need not set those conditions.		Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero displacement in the r directions. You therefore need not set those conditions.

Nairnj: /* Displacement Conditions */

2013-09-13T18:45:39Z

Displacement Conditions

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	* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disk</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).		* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disk</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).

	Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero ~~velocity~~ in the r directions. You therefore need not set those conditions.		Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero displacement in the r directions. You therefore need not set those conditions.

	See [[#Skewed Conditions\|below]] for how to fix displacement that are not along the <tt>x</tt> or <tt>y</tt> axes.		See [[#Skewed Conditions\|below]] for how to fix displacement that are not along the <tt>x</tt> or <tt>y</tt> axes.

Nairnj: /* Displacement Conditions */

2013-09-13T18:45:17Z

Displacement Conditions

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	* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.		* <tt>(dirnum)</tt> - in <tt>XML</tt> files, the displacement direction must be specified by number (1 or 2) only.
	* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disk</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).		* <tt>(disp)</tt> specifies magnitude of the displacement in mm. It can be specified by a number or by a [[User Defined Functions\|user-defined function]] of nodal point position. In scripted files, a [[User Defined Functions\|function]] is specified by enclosing an expression in quotes. In <tt>XML</tt> files, numeric displacements use a <tt>disk</tt> attribute while [[User Defined Functions\|functions]] are specified using a <tt>function</tt> attribute. If <tt>(disp)</tt> is omitted, the default displacement is 0 (<i>i.e.</i>, a fixed node).

			Note than when you are running axisymmetric FEA, nodes at r=0 will automatically be set to zero velocity in the r directions. You therefore need not set those conditions.

	See [[#Skewed Conditions\|below]] for how to fix displacement that are not along the <tt>x</tt> or <tt>y</tt> axes.		See [[#Skewed Conditions\|below]] for how to fix displacement that are not along the <tt>x</tt> or <tt>y</tt> axes.

Nairnj: /* Notes */

2013-09-13T18:44:36Z

Notes

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	</dl>		</dl>

	~~== Notes ==~~

	~~# When doing axisymmetric FEA, nodes at r=0 will automatically be set to zero velocity in the r directions. You therefore need not set those conditions.~~

Nairnj: /* Skewed Conditions */

2013-09-13T18:42:21Z

Skewed Conditions

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	where		where

	* (axis) is the rotation axis which must be <tt>z</tt> (or 3) for 2D analyses (which means rotation about θ axis if axisymmetric).		* <tt>(axis)</tt> is the rotation axis which must be <tt>z</tt> (or 3) for 2D analyses (which means rotation about θ axis if axisymmetric).
	* (ange) specifies angle of rotation (in degrees). The rotation is in the clockwise direction.		* <tt>(ange)</tt> specifies angle of rotation (in degrees). The rotation is in the clockwise direction.

	<tt>Rotate</tt> commands should be combined with [[#Displacement Conditions\|<tt>Displacement</tt> commands]]. Rotations do not affect [[#Stress Conditions\|stress]] or [[#Load Conditions\|load]] boundary conditions. To apply a load in a skewed direction, find the (x,y) coodinates of the skewed load vector and then apply the full vector in two [[#Load Conditions\|<tt>Load</tt> commands]] in the x and y directions.		<tt>Rotate</tt> commands should be combined with [[#Displacement Conditions\|<tt>Displacement</tt> commands]]. Rotations do not affect [[#Stress Conditions\|stress]] or [[#Load Conditions\|load]] boundary conditions. To apply a load in a skewed direction, find the (x,y) coodinates of the skewed load vector and then apply the full vector in two [[#Load Conditions\|<tt>Load</tt> commands]] in the x and y directions.

← Older revision		Revision as of 21:10, 2 June 2015
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	* <tt>(pathid)</tt> to select a previously defined [[Path Command\|path]] by <tt>id</tt>, which must have be used in an [[Area Command\|area]].		* <tt>(pathid)</tt> to select a previously defined [[Path Command\|path]] by <tt>id</tt>, which must have be used in an [[Area Command\|area]].
	* (<tt>x1,y1</tt>) to (<tt>x2,y2</tt>) define (<tt>x,y</tt>) coordinates (in mm) for the points at the beginning and end of the line (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). All nodes close to that line are selected.		* (<tt>x1,y1</tt>) to (<tt>x2,y2</tt>) define (<tt>x,y</tt>) coordinates (in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]) for the points at the beginning and end of the line (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). All nodes close to that line are selected.
	* <tt>(tolerance)</tt> is an optional tolerance (in mm). When used it accepts nodes within that distance of the define line; when omitted, tolerance is set to small number bases on mesh dimensions.		* <tt>(tolerance)</tt> is an optional tolerance (in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]). When used it accepts nodes within that distance of the define line; when omitted, tolerance is set to small number bases on mesh dimensions.
	* <tt>(keyid)</tt> to select a previously defined [[Keypoint Command\|keypoint]] by <tt>id</tt>, which must be part of a [[Path Command\|path]] that is in an [[Area Command\|area]].		* <tt>(keyid)</tt> to select a previously defined [[Keypoint Command\|keypoint]] by <tt>id</tt>, which must be part of a [[Path Command\|path]] that is in an [[Area Command\|area]].
	* (<tt>x3,y3</tt>) define (<tt>x,y</tt>) coordinates (in mm) for a single point (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). The node closest to that point is selected.		* (<tt>x3,y3</tt>) define (<tt>x,y</tt>) coordinates (in [[ConsistentUnits Command#Legacy and Consistent Units\|length units]]) for a single point (or (<tt>R,Z</tt>) coordinates in axisymmetric calculations). The node closest to that point is selected.

	All nodes along the selected path or along the selected line (for <tt>FixLine</tt> commands) or the single selected node (for <tt>FixPoint</tt> commands) can be assigned nodal [[#Displacement Conditions\|displacement]] or [[#Load Conditions\|load]] conditions, rotated for [[#Skewed Conditions\|skewed boundary conditions]], or [[#Selecting Nodes\|designated]] for conditional output.		All nodes along the selected path or along the selected line (for <tt>FixLine</tt> commands) or the single selected node (for <tt>FixPoint</tt> commands) can be assigned nodal [[#Displacement Conditions\|displacement]] or [[#Load Conditions\|load]] conditions, rotated for [[#Skewed Conditions\|skewed boundary conditions]], or [[#Selecting Nodes\|designated]] for conditional output.