教程5.13g加密所屬nas102appendix-a

1、Appendix AGeneralized Dynamic ReductionAppendix AGeneralized Dynamic ReductionGENERALIZED DYNAMIC REDUCTION.OPTIONS IN GDR.B-, C-, AND R-SET USE IN GDR.EXAMPLE OF CASE CONTROL AND BULK DATA SETUPS FOR GDR.GDR TRADEOFFSGUYAN REDUCTION VERSUS GDR.SOLUTION CONTROL FOR GENERALIZED DYNAMIC REDUCTION (GDR

2、).SOLUTION TO PROBLEM A-1.Generalized Dynamic ReductionCombines two methodsGuyan reductionModal analysisAnalysis set is divided into the following:whereuq=generalized coordinates ut=set of retained physical DOFsThe uq set contains scalar points with a single degree of freedom per point or grid point

3、s with six degrees of freedom per point.Generalized Dynamic Reduction (Cont.)Transformation from A-set to F-setwhere Got=static shape vector from Guyan reduction Goq=foq - Gotftq foq and ftq are partitions of fvqThe equation of motion for the F-set is written in terms of reduced coordinates (A-set).

4、Generalized Dynamic Reduction (Cont.)fvq is obtained by an inverse iteration beginning with a set of random starting vectors.The user specifies:The number of random starting vectors, NIRV (Default = 6)The number of iterations, NIT (Default = 10)The maximum frequency of interest, FMAXThe scalar or gr

5、id points to serve as generalized coordinates, UqThe program performs the following:Calculates the shift point ls (from FMAX and NIT)Computes fvq position of K + lsMNIT steps of inverse iterationMass orthogonalization of un , un-1, etc.Generalized Dynamic Reduction (Cont.)Computes Got (static conden

6、sation matrix) if presentReduces stiffness, damping, and mass matricesOptions in GDRUse only Fmax on the DYNRED entry; the program uses default values and computes NQDES.If clusters of nearly identical mode frequencies with more than 6 modes per cluster are suspected, then increase the default value

7、 for NIRV.Do not select excessive Fmax becauseThe cost increases rapidly with number of modes.If more than 2/3 of all modes are below Fmax, inaccurate results may occur. The number of shape vectors will exceed the number of physical degrees of freedom in the problem.B-, C-, and R-Set Use in GDRThe B

8、-, C-, and R-sets are mutually exclusive subsets of the T-set.Static shape vectors are calculated by Guyan reduction for the B-, C-, and R-set points.B-set points are held fixed during the GDR vector calculation.C- and R-set points are free to move during GDR vector calculation.R-set points have oth

9、er special uses depending on the type of dynamic analysis.If degrees of freedom are defined as belonging to the A-set, they belong to the B-set by default.Example of Case Control and Bulk Data Setups For GDRCase ControlDYNRED = SIDBulk DataQSET requiredHow to pick the number of QSET pointsID2 - ID1

10、1.5 x (number of expected modes below FMAX)GDR TradeoffsGuyan Reduction Versus GDRSolution Control For Generalized Dynamic ReductionExecutive Control SectionAny dynamic analysis SOLCase Control SectionDYNRED (required - selects Bulk Data DYNRED entry)Bulk Data SectionDYNRED (required - selects param

11、eters for GDR)ASET (optional - analysis set for GUYAN RED)QSET (required for GDR)SPOINT (required for GDR)BSET (optional - specifies B-set)CSET (optional - specifies C-set)SUPORT (optional - specifies R-set)Solution Control For Generalized Dynamic Reduction (GDR) (Cont.)Problem A-1Determine the norm

12、al modes between 0 and 1500 Hz for the example structure used in problem 1, using generalized dynamic reduction (GDR).Solution To Problem A-1ID DYNI,WORKSHOPSOL 103TIME 30CENDTITLE= REDUCTION PROCEDURES, NORMAL MODES EXAMPLESUBTITLE= USING GENERALIZED DYNAMIC REDUCTION (GDR)LABEL= DYNAMICS I WORKSHO

13、PECHO= UNSORTEDSPC= 100$DISPLACEMENT= ALLSUBCASE 1DYNRED= 100 $ POINTS TO DYNRED CARD IN BULK DATAMETHOD= 100BEGIN BULK$ PLATE DESCRIBED IN NORMAL MODES EXAMPLE PROBLEM$INCLUDE PLATE.BULK$ EIGENVALUE EXTRACTION PARAMETERS$EIGR,100,AGIV,5$ DEFINE SCALAR POINTS FOR GDR VECTORS$SPOINT,6000,THRU,6020$ A

14、SSIGN SCALAR POINTS TO Q-SET$QSET1,0,6000,THRU,6020$ NOTE: ANALYSIS SET (A-SET) WILL CONSIST OF Q-SET$ POINTS ONLY. NO PHYSICAL DEGREES-OF-FREEDOM WILL BE$ CONTAINED IN A-SET.$ SET DYNAMIC REDUCTION PARAMETERS$DYNRED,100,1500.$ENDDATASolution To Problem A-1 (Cont.) REDUCTION PROCEDURES, NORMAL MODES

15、 EXAMPLE USING GENERALIZED DYNAMIC REDUCTION (GDR)* USER INFORMATION MESSAGE 4158STATISTICS FOR SYMMETRIC POSITION OF DATA BLOCK SCRATCH FOLLOW NUMBER OF NEGATIVE TERMS ON FACTOR DIAGONAL = 6* USER INFORMATION MESSAGE 4181NUMBER OF ROOTS BELOW 0.1500E+04 CYCLES IS 6 NUMBER OF GENERALIZED COORDINATES

16、 SET TO 12* USER INFORMATION MESSAGE 4415, THE FOLLOWING A-SET DEGREES OF FREEDOM HAVE EITHER NULL MASSES OR NULL MASSES AND STIFFNESS. REDUCTION PROCEDURES, NORMAL MODES EXAMPLE JANUARY 17, 1990 MSC.Nastran 1/ 4/89 PAGE 7 USING GENERALIZED DYNAMIC REDUCTION (GDR) DYNAMICS I WORKSHOP VAXW POINT VALU

17、E POINT VALUE P0INT VALUE POINT VALUE OINT VALUE COLUMN 1 6012 S 1.00000E S 1.00000E S 1.00000E S 1.00000E S 1.00000E S 1.00000E S 1.00000E S 1.00000E S 1.00000E+00 * USER INFORMATION MESSAGE 5010, STURM SEQUENCE DATA FOR EIGENVALUE EXTRACTION. TRIAL EIGENVALUE = 2.965874D+04, CYCLES = 2.740921D+01

18、NUMBER OF EIGENVALUES BELOW THIS VALUE = 0* USER INFORMATION MESSAGE 4158STATISTICS FOR SYMMETRIC POSITION OF DATA BLOCK SCRATCH FOLLOW NUMBER OF NEGATIVE TERMS ON FACTOR DIAGONAL = 8* USER INFORMATION MESSAGE 5010, STURM SEQUENCE DATA FOR EIGENVALUE EXTRACTION. TRIAL EIGENVALUE = 1.575445D+08, CYCLES = 1.997661D+03 NUMBER OF EIGENVALUES BELOW THIS VALUE = 8 E I G E N V A L U E A N A L Y S I S S U M M A R Y (LANCZOS ITERATION) BLOCK SIZE USED 6 NUMBER OF POS