$-----------------------------------------------------------------------
$ Rigid Format 103 - Normal modes analysis
$ MSC/NASTRAN Version 2001 or NX Nastran Version 1.0
$
$
$ ******************************************************
$ ***** COPYRIGHT (C) 2003 *****
$ ***** BY ATA ENGINEERING INC. *****
$ ***** ALL RIGHTS RESERVED *****
$ ******************************************************
$
$ 09-03- ATA/Paul Blelloch
$
$ Description:
$
$ This alter calculates pseudo and cross-orthogonality of a set of FEM
$ mode shapes and optionally a set of test mode shapes with respect to a
$ TAM reduced mass matrix and shapes.
$
$ Two runs are required. The first should use alter write_modes to write
$ the mode shapes of the full FEM. The second reads those mode shapes in
$ in order to calculate pseudo and cross-orthgonality. If test mode shapes
$ are available that need to be included on DMIG cards.
$
$ The FEM pseudo-orthogonality is defined as follows:
$
$ T
$ PORTHO = PHI * MAA * PHI
$ FEM FEM
$
$ WHERE:
$
$ PHI - FEM mode shapes partitioned to A-set DOF
$ FEM
$
$ MAA - TAM mass matrix
$
$ By default the FEM modes are not normalized before this calculation, so the
$ diagonals are not necessarily 1.0. This provides a measure of the accuracy
$ of the reduction. Optionally they can be renormalized to 1.0 on the diagonals
$ by using PARAM,NORMFEM. This provides a calculation that is consistent with
$ most implementations of cross-orthogonality.
$
$ The cross-orthogonality is defined as follows;
$
$
$ T
$ XORTHO = PHI * MAA * PHI
$ TAM FEM
$
$ WHERE:
$
$ PHI - TAM mode shapes
$ TAM
$
$ If test mode shapes are available the pseudo-orthogonality of the test
$ shapes, and the cross-orthogonality between the test and FEM shapes are
$ also calculated.
$
$ See 'write_modes' alter for more on options for writing FEM mode shapes
$
$ Special instructions to use this alter:
$-----------------------------------------------------------------------
$ FILE MANAGEMENT SECTION (FMS)
$
$
$ If the OUTPUT2 or OUTPUT4 options are chosen these should be assigned
$
$ ASSIGN INPUTT4=fem_modes.op4 UNIT=11
$
$ or
$
$ ASSIGN INPUTT2=fem_modes.op2 UNIT=11
$
$ Note that a formatted OUTPUT4 file can be used as follows
$
$ ASSIGN INPUTT4=fem_modes.op4 UNIT=11 FORMATTED
$
$-----------------------------------------------------------------------
$ EXECUTIVE CONTROL DECK
$
$ SOL 103
$ Include this alter immediately before the CEND statement
$
$-----------------------------------------------------------------------
$ CASE CONTROL DECK
$
$ No special input is required. The Case Control deck must include
$ standard modal solution requests (SPC, METHOD, etc.). Some output
$ request such as DISP(PLOT)=ALL is required to force data recovery.
$
$-----------------------------------------------------------------------
$ BULK DATA DECK
$
$ Optional parameters:
$
$ PARAM,OMODES,I <0 : Read FEM modes from OUTPUT2 file UNIT = |OMODES|
$ 0 : Read FEM modes from DMIG cards in bulk data
$ >0 : Read FEM modes from OUTPUT4 file UNIT = OMODES
$
$ PARAM,MAC,CHAR8 'YES' : Calculate Pseudo and Cross MAC
$ 'NO' : Do not calculate Pseudo and Cross MAC (Default)
$
$ PARAM,NORMFEM,CHAR8 'YES' : Normalize FEM modes to ASET mass matrix
$ 'NO' : Do not renormalize FEM modes (Default)
$
$ PARAM,TMODORT,CHAR8 'YES' : Orthogonalize Test Modes using Barach's Method
$ 'NO' : Do not orthogonalize test modes (Default)
$
$ PARAM,RESFOR,CHAR8 'YES' : Calculate residual forces and MRPT stiffness
$ 'NO' : Do not calculate residual forces
$
$ PARAM,WRTOP4,CHAR8 'YES' : Write perturbation matrices in OP4 format
$ 'NO' : Do not write perturbation matrices in OP4 format (default)
$
$ PARAM,WRTMOD,CHAR8 'YES' : Write mode shapes and mass matrix to OUTPUT4 file
$ 'NO' : Do not write mode shapes and mass matrix OP4 format (default)
$
$ If the FEM shapes are included on DMIG cards in bulk data they must be
$ named UGFEM. A matrix FLAMA with the frequencies in the 1st row must
$ also be included on DMI cards.
$
$ If test mode shapes are included, they must be named PHITEST on DMIG cards,
$ and a matrix TLAMA with the test frequencies in the 1st row must also
$ be included on DMI cards.
$
$-----------------------------------------------------------------------
$ EXAMPLE NASTRAN DECKS
$
$
$ ASSIGN INPUTT4='gpsc_modes.op4' UNIT=11 OLD
$ ASSIGN MASTER='gpsc_aset.MASTER'
$ ASSIGN DBALL ='gpsc_aset.DBALL'
$ RESTART
$ $
$ SOL 103
$ INCLUDE ortho.v2001
$ CEND
$ $
$ TITLE = GENERAL PURPOSE SPACECRAFT
$ SUBTITLE = NORMAL MODES DATA RECOVERY RESTART
$ LABEL = CALCULATE PSEUDO AND CROSS-ORTHOGONALITY
$ $
$ SPC = 1
$ METHOD = 50 $ Modes to 50 Hz
$ $
$ DISP(PLOT) = ALL $ Recover but don't print displacements
$ $
$ BEGIN BULK
$ $
$ PARAM,OMODES,11 $ Calculate residual kinetic energy
$ $
$ ENDDATA
$
$-----------------------------------------------------------------------