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3.4 Dynamics Enhancements

3.4 Dynamics Enhancements. Mode Superposition method allows non-proportional damping Block Lanczos solver enhancements Full harmonic analysis allows prestress effects. Non-proportional damping available with mode superposition method at 5.7

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3.4 Dynamics Enhancements

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  1. 3.4 Dynamics Enhancements • Mode Superposition method allows non-proportional damping • Block Lanczos solver enhancements • Full harmonic analysis allows prestress effects Training Manual 001419 15 Aug 2000 3.4-1

  2. Non-proportional damping available with mode superposition method at 5.7 Modal analysis carried out using Q-R damped eigensolver Allows all types of damping including element damping Extremely fast compared to full method Dynamics Enhancements Q-R Damp & Mode Superposition Only applicable in a full or reduced harmonic Element damping valid at 5.7 Frequency dependent damping valid Alpha damping valid Material damping valid Beta damping valid Training Manual 001419 15 Aug 2000 3.4-2

  3. Dynamics Enhancements … Q-R Damp & Mode Superposition Applications • Models where a “spring-damper” component needs to be represented by a single stiffness and damping constant. • For example: • components of an automobile suspension system • dashpot mechanism on a door • simplified bearings on a rotor shaft • dampers used in a nuclear piping assembly Training Manual 001419 15 Aug 2000 3.4-3

  4. Dynamics Enhancements … Q-R Damp & Mode Superposition Procedure • Modal analysis • MODOPT, qrdamp • Define damping* • ALPHAD; BETAD; MP,DAMP (as before) • New: element damping is also allowed, via COMBIN7, COMBIN14, COMBIN37, COMBIN40, CONT178 etc. • Mode superposition • 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

  5. Dynamics Enhancements … Q-R Damp & Mode Superposition • Limitations: • Damping specified during mode superposition is ignored. • QR damping does not support DMPRAT and MDAMP. • Gap conditions (GP) are not supported. Training Manual 001419 15 Aug 2000 3.4-5

  6. Dynamics Enhancements … Q-R Damp & Mode Superposition Elements: SOLID92 and COMBIN40 DOFs: 5531 Damping: Rayleigh, material, and element Benchmark Results FY = 200 SOLID92’s COMBIN40 FZ = 1000 COMBIN40 Training Manual 001419 15 Aug 2000 3.4-6

  7. Dynamics Enhancements … Q-R Damp & Mode Superposition Training Manual 001419 15 Aug 2000 3.4-7

  8. Dynamics EnhancementsBlock Lanczos Enhancements • Improved memory management • Automatic supplemental memory allocation • Intelligent choice of workspace • 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) • 8093 cpu sec, 11723 wall-clock sec Training Manual 001419 15 Aug 2000 3.4-8

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