EKE

I/O Options and Subcase Information Entry The EKE command can be used in the I/O Options or Subcase Information sections to request kinetic energy and kinetic energy density output for all subcases or individual subcases, respectively.

Format

EKE (format_list, type, dmig, peakoutput, group, SUBSYS=SUBSYS_ID) = option

Definitions

Argument	Options	Description
`format`	<HM, H3D, PUNCH, OP2, PLOT, blank>	HM Results are output in HyperMesh results format (.res file). H3D Results are output in Hyper3D format (.h3d file). PUNCH Results are output in Nastran punch results format (.pch file). OP2 Results are output in Nastran output2 format (.op2 file). PLOT Results are output in Nastran output2 format (.op2 file) when PARAM,`POST` is defined in the Bulk Data section. blank (Default) Results are output in all active formats for which the result is available.
`type`	<AVERAGE, AMPLITUDE, PEAK>	AVERAGE (Default) 7 In Frequency Response Analysis average energy is output. AMPLITUDE In Frequency Response Analysis the amplitude of energy is output. PEAK In Frequency Response Analysis the peak energy is output. This is the sum of AVERAGE and AMPLITUDE.
`dmig`	<DMIG, NODMIG>	DMIG Results are provided for external superelements in the .out file. If the punch format is specified, DMIG energy is also output to the .pch file, for Linear Static and Normal Modes Analysis only. NODMIG (Default) Results are not provided for external superelements in the .out file.
`peakoutput`	<PEAKOUT> Default = blank	If PEAKOUT is present, only the filtered frequencies from the PEAKOUT card will be considered for this output.
`group`	<PROP, COMP, SET, OPROP, OCOMP, OSET> Default = blank	PROP Group kinetic energy based on property ID is output. This output is available in addition to the elemental kinetic energy output. 8 COMP Group kinetic energy based on HM component is output. This output is available in addition to the elemental kinetic energy output. 8 SET Group kinetic energy based on SET with Boolean operator OR is output. This output is available in addition to the elemental strain energy output. 8 OPROP Only group kinetic energy based on property ID is output. Elemental kinetic energy is not output. 8 OCOMP Only group kinetic energy based on HM component is output. Elemental kinetic energy is not output. 8 OSET Only group strain energy based on SET with Boolean operator OR is output. Elemental strain energy is not output. 8
`SUBSYS`	<`SUBSYS_ID`> No default	ID of the subsystem. When used along a subsystem definition, this option generates an individual result file for each subsystem with results for that subsystem only. For more information, refer to the SET Bulk Data Entry.
`option`	<YES, ALL, NO, NONE, SID> Default = ALL	YES, ALL, blank Element kinetic energy and kinetic energy density are output for all elements. NO, NONE Element kinetic energy and kinetic energy density are not output. SID If a set ID is given, element kinetic energy and kinetic energy density are output only for elements listed in that set.

Comments

When an EKE command is not present, element kinetic energy and kinetic energy density is not output.
Initial thermal strain is included in the calculation of kinetic energy and kinetic energy density.
Multiple formats are allowed on the same entry; these should be comma separated. If a format is not specified, this output control applies to all formats defined by the OUTPUT command, for which the result is available.
Multiple instances of this card are allowed. If instances are conflicting, the last instance dominates.
For optimization, the frequency of output to a given format is controlled by the I/O option OUTPUT.
type only applies to Frequency Response Analysis.
The three ways to calculate the element kinetic energy in Frequency Response Analysis are:

Output Type

Formula

Average

$E_{0} = \frac{1}{4} (v_{r}^{T} M_{E} v_{r} + v_{i}^{T} M_{E} v_{i})$

Amplitude

$E_{a} = \frac{1}{4} \sqrt{{(v_{r}^{T} M_{E} v_{r} - v_{i}^{T} M_{E} v_{i})}^{2} + {(2 v_{r}^{T} M_{E} v_{i})}^{2}}$

Peak

$E_{p e a k} = E_{0} + E_{a}$

Where,

$E$

Corresponding Element Energy

$v_{r}$

Real part of Displacement

$v_{i}$

Imaginary part of Displacement

$M_{E}$

Element Mass Matrix
The group argument is supported only for Static, Eigenvalue, Frequency Response, Transient Analysis and Aeroelastic Divergence Analysis with H3D and PUNCH formats.
- In the H3D file, group kinetic energy and group kinetic energy density are available under the element kinetic energy results type.
- In the PUNCH file, the Property/Component ID’s and the corresponding kinetic energy and kinetic energy density are available.
If SET/OSET is requested, a SID of Boolean set with operator OR is expected in the field option. Element SETs referenced when using this option should have the OPERATOR field set to OR. Regular element sets without Boolean OR are not allowed. SET/OSET is currently only supported for H3D and PUNCH formats.
Rotor energy output for Direct/Modal Complex Eigenvalue Analysis (with ASYNC, SYNC, and multiple rotors) is available in the <filename>.rengy file when ESE or EKE output requests are present in the model. The output printed to the .rengy file is calculated as a percentage of the ratio of rotor energy to the requested energy output of elements. It is recommended that you request energy output for ALL elements so that the rotor energy percentage printed in the .rengy file is meaningful.