nastran热模态分析normal modes with preload
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The first subcase is a static subcase calling out the preload. The second subcase calculated the modes with a method = x callout. The second subcase must also contain a statsub = y command, where y = subcase ID of the first subcase.
Use SOL 106. Include linear or nonlinear material properties as required by modeling. If material is linear, then only linear material properties are referenced. Include PARAM,LGDISP,1 in the Bulk Data Section. Only the residual structure (SEID=0) may contain nonlinear elements. All upstream superelements must be linear. A Method = X Case Control Command above the first subcase calls out the appropriate EIGRL entry. Include PARAM,NMLOOP,X where X<>0. The nonlinear normal modes will be computed at the last iteration loop of each subcase in which a Method command appears
y Fx x
Reaction y x
Differential Stiffness
Preloaded Structure
NAS102
March 2004, Page 18-3
Normal Modes With Differential Stiffness (Cont.)
Large Geometry Changes
SOL 103 TIME 600 CEND TITLE = Normal Modes Example SUBCASE 1 METHOD = 1 SPC = 1 VECTOR=ALL BEGIN BULK PARAM WTMASS .00259 PARAM COUPMASS 1 EIGRL 1 3 0 PBARL 1 1 I + A 2. 1. 1. .1 .1 .1 CBAR 1 1 1 2 0. 1. 0. CBAR 2 1 2 3 0. 1. 0. CBAR 3 1 3 4 0. 1. 0. CBAR 4 1 4 5 0. 1. 0. CBAR 5 1 5 6 0. 1. 0. CBAR 6 1 6 7 0. 1. 0. CBAR 7 1 7 8 0. 1. 0. CBAR 8 1 8 9 0. 1. 0. CBAR 9 1 9 10 0. 1. 0. CBAR 10 1 10 11 0. 1. 0. MAT1 1 1.+7 .3 .101 GRID 1 0. 0. 0. 345 GRID 2 10. 0. 0. 345 GRID 3 20. 0. 0. 345 GRID 4 30. 0. 0. 345 GRID 5 39.9999 0. 0. 345 GRID 6 49.9999 0. 0. 345 GRID 7 60. 0. 0. 345 GRID 8 70. 0. 0. 345 GRID 9 80. 0. 0. 345 GRID 10 90. 0. 0. 345 GRID 11 100. 0. 0. 345 SPC1 1 1234 1 SPC1 1 234 11 ENDDATA
Section 18
Normal Modes of Preloaded Structures
NAS102
March 2004, Page 18-1
Section 18 Normal Modes of Preloaded Structures
NORMAL MODES WITH DIFFERENTIAL STIFFNESS…………………………… 18 - 3 PROBLEM #14 - NORMAL MODES WITH PRELOAD………………………..….. 18 - 7 PROBLEM #14 - MODES OF PRELOADED STRUCTURE………………………. 18 - 9 INPUT FILE FOR PROBLEM #14A - MODES WITHOUT PRELOAD…………… 18 - 10 PARTIAL OUTPUT FILE FOR PROBLEM #14A - MODES WITHOUT PRELOAD……………………………………………………………………… 18 - 11 INPUT FILE FOR PROBLEM #14B - MODES WITH PRELOAD USING SOL 106………………………………………………… 18 - 12 PARTIAL OUTPUT FILE FOR PROBLEM 14B - MODES WITH PRELOAD USING SOL 106………………………………………………… 18 - 13 INPUT FILE FOR PROBLEM #14C - MODES WITH PRELOAD USING SOL 103…………………………………………...…… 18 - 14 PARTIAL OUTPUT FILE FOR PROBLEM #14C MODES WITH PRELOAD USING SOL 103………………………………………………… 18 - 15
NUMBER OF ROOTS FOUND ................
NUMBER OF SOLVES REQUIRED ............ 1 0 NORMAL MODES EXAMPLE
3
4 5
APRIL 8, 1998 MSC.Nastran 4/ 6/98 PAGE SUBCASE 1
NAS102
March 2004, Page 18-2
Normal Modes With Differential Stiffness
Calculate the modes of structures with preloads, large changes in geometry, and/or nonlinear materials.
NAS102
March 2004, Page 18-11
Solution File For Problem #14B - Modes With Preload Using SOL 106
SOL 106
TIME 600 CEND $ TITLE = Normal Modes with Differential Stiffness METHOD = 10 SUBCASE 1 NLPARM = 1 SPC = 1 LOAD = 1 DISPLACEMENT=ALL $ BEGIN BULK PARAM COUPMASS 1 PARAM WTMASS .00259 PARAM LGDISP 1 NLPARM 1 5 AUTO 5 25 PW + A .001 1.-7 PARAM,NMLOOP,5 $ EIGRL,10,,,3 PBARL 1 1 I + + B 2. 1. 1. .1 .1 .1 CBAR 1 1 1 2 0. 1. 0. CBAR 2 1 2 3 0. 1. 0. CBAR 3 1 3 4 0. 1. 0. CBAR 4 1 4 5 0. 1. 0. CBAR 5 1 5 6 0. 1. 0. CBAR 6 1 6 7 0. 1. 0. CBAR 7 1 7 8 0. 1. 0. CBAR 8 1 8 9 0. 1. 0. CBAR 9 1 9 10 0. 1. 0. CBAR 10 1 10 11 0. 1. 0. $
1.0 in 0.1 in
2.0 in
0.1 in
0.1 in 1.0 in
Length: Height: Width: Thickness: Area: I 1: I 2:
100 in 2 in 1 in 0.100 in 0.38 in2 0.229 in4 0.017 in4
NAS102
March 2004, Page 18-9
k1
F
k0 u1 K0 = k1 Nonlinear Material
NAS102
March 2004, Page 18-4
Normal Modes With Differential Stiffness (Cont.)
Procedures for obtaining frequencies of a preloaded structure. Method 1
NAS102
March 2004, Page 18-5
Normal Modes With Differential Stiffness (Cont.)
Procedures for obtaining frequencies of a preloaded structure. Method 2 Use SOL 103. Material must be linear. Two subcases are required.
Solution File For Problem #14A Modes Without Preload
+
A
Biblioteka Baidu
NAS102
March 2004, Page 18-10
Partial Output File For Problem #14A Modes Without Preload
0 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 (READ MODULE) BLOCK SIZE USED ...................... 7 2 NUMBER OF DECOMPOSITIONS .............
NAS102
March 2004, Page 18-6
Problem #14
Normal Modes With Preload
NAS102
March 2004, Page 18-7
Problem #14 - Modes of Preloaded Structure
Consider the simply supported beam as shown below. Calculate the first bending frequency:
Without preload With preload using SOL106 With preload using SOL 103
P
NAS102
March 2004, Page 18-8
Problem #14 - Modes of Preloaded Structure (Cont.)
MODE NO. 1 2 3
REAL EIGENVALUES EXTRACTION EIGENVALUE RADIANS CYCLES GENERALIZED GENERALIZED ORDER MASS STIFFNESS 1 2.239398E+04 1.496462E+02 2.381693E+01 1.000000E+00 2.239398E+04 2 3.549898E+05 5.958102E+02 9.482614E+01 1.000000E+00 3.549898E+05 3 1.771818E+06 1.331096E+03 2.118506E+02 1.000000E+00 1.771818E+06
Use SOL 106. Include linear or nonlinear material properties as required by modeling. If material is linear, then only linear material properties are referenced. Include PARAM,LGDISP,1 in the Bulk Data Section. Only the residual structure (SEID=0) may contain nonlinear elements. All upstream superelements must be linear. A Method = X Case Control Command above the first subcase calls out the appropriate EIGRL entry. Include PARAM,NMLOOP,X where X<>0. The nonlinear normal modes will be computed at the last iteration loop of each subcase in which a Method command appears
y Fx x
Reaction y x
Differential Stiffness
Preloaded Structure
NAS102
March 2004, Page 18-3
Normal Modes With Differential Stiffness (Cont.)
Large Geometry Changes
SOL 103 TIME 600 CEND TITLE = Normal Modes Example SUBCASE 1 METHOD = 1 SPC = 1 VECTOR=ALL BEGIN BULK PARAM WTMASS .00259 PARAM COUPMASS 1 EIGRL 1 3 0 PBARL 1 1 I + A 2. 1. 1. .1 .1 .1 CBAR 1 1 1 2 0. 1. 0. CBAR 2 1 2 3 0. 1. 0. CBAR 3 1 3 4 0. 1. 0. CBAR 4 1 4 5 0. 1. 0. CBAR 5 1 5 6 0. 1. 0. CBAR 6 1 6 7 0. 1. 0. CBAR 7 1 7 8 0. 1. 0. CBAR 8 1 8 9 0. 1. 0. CBAR 9 1 9 10 0. 1. 0. CBAR 10 1 10 11 0. 1. 0. MAT1 1 1.+7 .3 .101 GRID 1 0. 0. 0. 345 GRID 2 10. 0. 0. 345 GRID 3 20. 0. 0. 345 GRID 4 30. 0. 0. 345 GRID 5 39.9999 0. 0. 345 GRID 6 49.9999 0. 0. 345 GRID 7 60. 0. 0. 345 GRID 8 70. 0. 0. 345 GRID 9 80. 0. 0. 345 GRID 10 90. 0. 0. 345 GRID 11 100. 0. 0. 345 SPC1 1 1234 1 SPC1 1 234 11 ENDDATA
Section 18
Normal Modes of Preloaded Structures
NAS102
March 2004, Page 18-1
Section 18 Normal Modes of Preloaded Structures
NORMAL MODES WITH DIFFERENTIAL STIFFNESS…………………………… 18 - 3 PROBLEM #14 - NORMAL MODES WITH PRELOAD………………………..….. 18 - 7 PROBLEM #14 - MODES OF PRELOADED STRUCTURE………………………. 18 - 9 INPUT FILE FOR PROBLEM #14A - MODES WITHOUT PRELOAD…………… 18 - 10 PARTIAL OUTPUT FILE FOR PROBLEM #14A - MODES WITHOUT PRELOAD……………………………………………………………………… 18 - 11 INPUT FILE FOR PROBLEM #14B - MODES WITH PRELOAD USING SOL 106………………………………………………… 18 - 12 PARTIAL OUTPUT FILE FOR PROBLEM 14B - MODES WITH PRELOAD USING SOL 106………………………………………………… 18 - 13 INPUT FILE FOR PROBLEM #14C - MODES WITH PRELOAD USING SOL 103…………………………………………...…… 18 - 14 PARTIAL OUTPUT FILE FOR PROBLEM #14C MODES WITH PRELOAD USING SOL 103………………………………………………… 18 - 15
NUMBER OF ROOTS FOUND ................
NUMBER OF SOLVES REQUIRED ............ 1 0 NORMAL MODES EXAMPLE
3
4 5
APRIL 8, 1998 MSC.Nastran 4/ 6/98 PAGE SUBCASE 1
NAS102
March 2004, Page 18-2
Normal Modes With Differential Stiffness
Calculate the modes of structures with preloads, large changes in geometry, and/or nonlinear materials.
NAS102
March 2004, Page 18-11
Solution File For Problem #14B - Modes With Preload Using SOL 106
SOL 106
TIME 600 CEND $ TITLE = Normal Modes with Differential Stiffness METHOD = 10 SUBCASE 1 NLPARM = 1 SPC = 1 LOAD = 1 DISPLACEMENT=ALL $ BEGIN BULK PARAM COUPMASS 1 PARAM WTMASS .00259 PARAM LGDISP 1 NLPARM 1 5 AUTO 5 25 PW + A .001 1.-7 PARAM,NMLOOP,5 $ EIGRL,10,,,3 PBARL 1 1 I + + B 2. 1. 1. .1 .1 .1 CBAR 1 1 1 2 0. 1. 0. CBAR 2 1 2 3 0. 1. 0. CBAR 3 1 3 4 0. 1. 0. CBAR 4 1 4 5 0. 1. 0. CBAR 5 1 5 6 0. 1. 0. CBAR 6 1 6 7 0. 1. 0. CBAR 7 1 7 8 0. 1. 0. CBAR 8 1 8 9 0. 1. 0. CBAR 9 1 9 10 0. 1. 0. CBAR 10 1 10 11 0. 1. 0. $
1.0 in 0.1 in
2.0 in
0.1 in
0.1 in 1.0 in
Length: Height: Width: Thickness: Area: I 1: I 2:
100 in 2 in 1 in 0.100 in 0.38 in2 0.229 in4 0.017 in4
NAS102
March 2004, Page 18-9
k1
F
k0 u1 K0 = k1 Nonlinear Material
NAS102
March 2004, Page 18-4
Normal Modes With Differential Stiffness (Cont.)
Procedures for obtaining frequencies of a preloaded structure. Method 1
NAS102
March 2004, Page 18-5
Normal Modes With Differential Stiffness (Cont.)
Procedures for obtaining frequencies of a preloaded structure. Method 2 Use SOL 103. Material must be linear. Two subcases are required.
Solution File For Problem #14A Modes Without Preload
+
A
Biblioteka Baidu
NAS102
March 2004, Page 18-10
Partial Output File For Problem #14A Modes Without Preload
0 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 (READ MODULE) BLOCK SIZE USED ...................... 7 2 NUMBER OF DECOMPOSITIONS .............
NAS102
March 2004, Page 18-6
Problem #14
Normal Modes With Preload
NAS102
March 2004, Page 18-7
Problem #14 - Modes of Preloaded Structure
Consider the simply supported beam as shown below. Calculate the first bending frequency:
Without preload With preload using SOL106 With preload using SOL 103
P
NAS102
March 2004, Page 18-8
Problem #14 - Modes of Preloaded Structure (Cont.)
MODE NO. 1 2 3
REAL EIGENVALUES EXTRACTION EIGENVALUE RADIANS CYCLES GENERALIZED GENERALIZED ORDER MASS STIFFNESS 1 2.239398E+04 1.496462E+02 2.381693E+01 1.000000E+00 2.239398E+04 2 3.549898E+05 5.958102E+02 9.482614E+01 1.000000E+00 3.549898E+05 3 1.771818E+06 1.331096E+03 2.118506E+02 1.000000E+00 1.771818E+06