Transcript 5.7 New Features - Slovak University of Technology in

3.4 Dynamics Enhancements
• Mode Superposition method allows nonproportional damping
• Full harmonic analysis allows prestress effects
NEW FEATURES 5.7
• Block Lanczos solver enhancements
Training Manual 001419
15 Aug 2000
3.4-1
Dynamics Enhancements
Q-R Damp & Mode Superposition
• Non-proportional damping available with mode
superposition method at 5.7
– Allows all types of damping including element damping
– Extremely fast compared to full method
Only applicable in a full
or reduced harmonic
C    M      c K    j 1
NMAT
Element damping valid at 5.7
 j K j   Ck  C 
Alpha damping valid
Material damping valid
NEL
NEW FEATURES 5.7
– Modal analysis carried out using Q-R damped eigensolver
k 1
Frequency dependent
damping valid
Beta damping valid
Training Manual 001419
15 Aug 2000
3.4-2
Dynamics Enhancements
… Q-R Damp & Mode Superposition
Applications
• For example:
– components of an automobile suspension system
– dashpot mechanism on a door
– simplified bearings on a rotor shaft
NEW FEATURES 5.7
• Models where a “spring-damper” component needs
to be represented by a single stiffness and damping
constant.
– dampers used in a nuclear piping assembly
Training Manual 001419
15 Aug 2000
3.4-3
Dynamics Enhancements
… Q-R Damp & Mode Superposition
Procedure
• Modal analysis
– Define damping*
• ALPHAD; BETAD; MP,DAMP (as before)
• New: element damping is also allowed, via COMBIN7,
COMBIN14, COMBIN37, COMBIN40, CONT178 etc.
• Mode superposition
NEW FEATURES 5.7
– MODOPT, qrdamp
– Transient analysis: TRNOPT,msup
– Harmonic analysis: HROPT,msup
*All damping must be specified in the modal analysis step
Training Manual 001419
15 Aug 2000
3.4-4
Dynamics Enhancements
… Q-R Damp & Mode Superposition
• Limitations:
– Damping specified during mode superposition is ignored.
– Gap conditions (GP) are not supported.
NEW FEATURES 5.7
– QR damping does not support DMPRAT and MDAMP.
Training Manual 001419
15 Aug 2000
3.4-5
Dynamics Enhancements
… Q-R Damp & Mode Superposition
Benchmark Results
NEW FEATURES 5.7
FY = 200
SOLID92’s
COMBIN40
FZ = 1000
Elements: SOLID92 and COMBIN40
DOFs:
5531
Damping: Rayleigh, material, and element
COMBIN40
Training Manual 001419
15 Aug 2000
3.4-6
Dynamics Enhancements
… Q-R Damp & Mode Superposition
Performance Improvement Using QR Damped Method
in a Mode Superposition Analysis
800
CPU time (secs)
600
NEW FEATURES 5.7
700
Harmonic Analysis
Transient Analysis
Modal Analysis
500
Mode Superposition Method
is 10.72 times faster than
Full Method!
400
300
Mode Superposition Method
is 20.26 times faster than
Full Method!
200
100
0
Mode Sup Transient
(20 modes)
Full Transient
Mode Sup Harmonic
(50 modes)
Full Harmonic
Note 1: Mode superposition transient displacements are within 3.51% of full transient results.
Note 2: Mode superposition harmonic displacements are within 3.70% of full harmonic results.
Training Manual 001419
15 Aug 2000
3.4-7
Dynamics Enhancements
Block Lanczos Enhancements
• Improved memory management
– Automatic supplemental memory allocation
– Minimum memory mode
– Example:
• 1.4 million DOF problem, 10 modes, Compaq Alpha
platform (1 cpu)
– Required only 870 MB (-m 870) of memory.
(5.6 required -m 2580)
NEW FEATURES 5.7
– Intelligent choice of workspace
– 8093 cpu sec, 11723 wall-clock sec
Training Manual 001419
15 Aug 2000
3.4-8