MSC.Software Corporation 2 MacArthur Place Santa Ana, CA 92707, USA Tel: (714) 540-8900 Fax: (714) 784-4056 Web: United States. - презентация

1 MSC.Software Corporation 2 MacArthur Place Santa Ana, CA 92707, USA Tel: (714) Fax: (714) Web: United States MSC.Patran Support Tel: Fax: (714) Tokyo, Japan Tel: Fax: Munich, Germany Tel: (+49) Fax: (+49) Dynamic Analysis Using MSC.Patran and MSC.Nastran August 2005 NAS122 Course Notes Part Number: NA*V2005*Z*Z*Z*SM-NAS122-NT1

2 DISCLAIMER MSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice. The concepts, methods, and examples presented in this text are for illustrative and educational purposes only, and are not intended to be exhaustive or to apply to any particular engineering problem or design. MSC.Software Corporation assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained herein. User Documentation: Copyright 2005 MSC.Software Corporation. Printed in U.S.A. All Rights Reserved. This notice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or distribution of this document, in whole or in part, without the prior written consent of MSC.Software Corporation is prohibited. MSC and MSC. are registered trademarks and service marks of MSC.Software Corporation. NASTRAN is a registered trademark of the National Aeronautics and Space Administration. MSC.Nastran is an enhanced proprietary version developed and maintained by MSC.Software Corporation. MSC.Actran, MSC.ADAMS, MSC.Dytran, MSC.EASY5, MSC.FlightLoads, MSC.Fatigue, MSC.Marc, MSC.Marc Mentat, MSC.Nastran, MSC.Patran, MSC.Laminate Modeler, MSC.Mvision, MSC.Robust Design, SimDesigner, MSC.SimManager, MSC.SOFY, MSC.visualNastran Desktop, and MSC.visualNastran for Windows are all trademarks of MSC.Software Corporation. All other trademarks are the property of their respective owners. Copyright 2005 MSC.Software Corporation

3 TABLE OF CONTENTS SectionPage 1.0Review of Fundamentals Single DOF System1-3 Single DOF System Undamped Free Vibrations 1-5 Single DOF System Damped Free Vibrations1-8 Single DOF System Undamped Forced Vibrations1-12 Single DOF System Damped Forced Vibrations1-14 MSC.Nastran Documentation1-24 Text References on Dynamic Analysis Normal Modes Analysis Overview2-3 2 DOF Equation of Motion using Engineering Approach2-4 Summarizing Some Important Ideas About Normal Modes That Emerge 2-10 Setting the Same Problem using a Matrix Approach 2-11 Case Study 1 – Normal Modes of a 2 DOF Structure 2-17 Workshop 2 – Normal Modes Analysis of a 2 DOF Structure2-44 Extending to Multi DOF Problems2-45 Eigenvalue Extraction Method2-56 Theoretical Approach for MDOF 2-46 Facts Regarding Normal Modes 2-51 Extending to Multi DOF Problems (Cont.) 2-53 Eigenvalue Extraction Method 2-61 Sturm Sequence Theory2-63 Lanczos Method2-64 Case Study 2 – Normal Modes Analysis of a Satellite2-67 Reasons to Calculate Normal Modes2-81 Workshop 13 – Modal Analysis of a Car Chassis2-83 How Accurate is the Normal Modes Analysis2-84 Mesh Density2-85 Workshop 1a to 1c – Normal Modes Analysis with Various Mesh Size2-86

4 TABLE OF CONTENTS SectionPage 2.0Normal Modes Analysis (cont.) Element Type2-89 Workshop 15a to 15e – Modal Analysis of a Tuning Fork2-90 Mass Distribution2-93 Workshop 14a – Modal Analysis of a Tower2-94 Detail of Joints2-95 Detail of Constraints2-96 Workshop 14b – Modal Analysis of a Tower with Soft Ground Connection2-97 Hand Calculations2-98 Check List for Normal Modes Prior to Doing Further Analysis Mass Modeling Mass Modeling 3-3 Coupled Versus Lumped Mass 3-4 Rod Finite Element Example 3-6 Justification for MSC.Nastran Coupled Mass Convention 3-8 Mass Units3-10 Mass Input Effective Mass Participation Factor Theory4-3 Nastran Case Control Entry4-6 Case Study4-8 Applications in Industry4-18 Workshop 19 – Effective Mass Guyan Reduction Introduction to Dynamic Reduction5-3 Reduction Methods for Dynamics Available with MSC.Nastran 5-4 Static Condensation for Statics5-5 Static Condensation for Dynamics5-8

5 TABLE OF CONTENTS SectionPage 5.0 Guyan Reduction (continued) Solution Control for Guyan Reduction5-13 Difficulties with Guyan Reduction5-15 Modal Reduction Rigid Body Modes Rigid Body Modes 6-3 Calculation of Rigid Body Modes6-8 Specification of SUPORT Degrees of Freedom6-11 Checking SUPORT Degrees of Freedom6-13 Modal Analysis with Rigid Body Modes Normal Modes Analysis for Pre-Stiffened Structures Normal Modes Analysis for Pre-Stiffened Structures7-3 Case Study: Normal Modes for Pre-Stiff. Str. Using Sol Case Study: Normal Modes for Pre-Stiff. Str. Using Sol Workshop 12a, 12b, 12c Response Method Response Types8-3 Spring Mass System8-4 Transient Analysis8-5 Frequency Response Analysis8-9 Response Types 8-10 Modal and Direct Methods8-11 Patran Menu Choice8-13 Modal and Direct Methods8-14

6 TABLE OF CONTENTS SectionPage 9.0Damping Overview Damping in Dynamic Analysis 9-3 Viscous Damping Input 9-7 Frequency Dependent Impedance Sample 9-24 Sample using CBUSH Element9-25 Displacement Output for CBUSH Element9-26 Force Output for CBUSH Element9-27 Structural Damping Input 9-28 Modal Damping Input 9-33 Rayleigh Damping Input Transient Response Analysis Introduction to Transient Response Analysis10-3 Direct Transient Response10-4 Case Study – Direct Transient Analysis of a Simple Plate10-11 Workshop 3 – Direct Transient Analysis10-39 Transient Excitation10-41 Transient Excitation Issues TLOAD1 Entry10-50 Load Set Combination – DLOAD10-55 TLOAD2 Entry10-57 Initial Conditions10-60 Damping for Direct Transient Response Analysis10-65 Viscous Damping Versus Structural Damping, SDOF System10-68 Damping for Direct Transient Response Analysis (Cont.)10-73 Damping in Dynamic Analysis10-76 Workshop 17 – Direct Transient Analysis of a Car Model10-86 Modal Transient Response Modal Transient Response without Damping Modal Transient Response with Damping 10-90

7 TABLE OF CONTENTS SectionPage 10.0Transient Response Analysis (continued) Data Recovery for Modal Transient Response10-94 Modal Transient Response10-95 Mode Truncation Modal Transient Versus Direct Transient Workshop 4 – Modal Transient Analysis Workshop 18 – Modal Transient Analysis of the Tower Model With Seismic Input Frequency Response Analysis Introduction to Frequency Response Analysis11-3 Direct Frequency Response 11-6 Case Study – Direct Frequency Response of a Plate11-9 Workshop 5 – Direct Frequency Response of a Plate11-30 Excitation Definition The RLOAD1 Entry11-34 The RLOAD2 Entry Frequency Response Considerations11-43 Solution Frequencies11-45 Recommendations11-85 Damping for Direct Frequency Response Analysis Modal Frequency Response11-92 Modal Frequency Response without Damping Modal Frequency Response with Damping11-95 Modal Frequency Response (Cont.) Damping in Modal Frequency Response Mode Truncation in Modal Frequency Response Analysis Modal vs. Direct Frequency Response Workshop 16 – Modal Frequency Response of a Car Model Interpreting Frequency Response Results in MSC.Patran11-114

8 TABLE OF CONTENTS SectionPage 12.0Enforced Motion Enforced Motion12-3 Enforced Motion Equations 12-4 Enforced Motion in Transient Analysis Workshop 8 – Direct Transient Response with Enforced Acceleration (Matrix Partitioning) Enforced Motion for Frequency Response Analysis Random Analysis Classification of Dynamic Environments13-3 Examples of Random Dynamic Environment13-4 Ergodic Random Data13-5 Random Response Analysis 13-6 What is a PSD? 13-8 Summarizing the Input How are Random Results Used ? MSC.Random Overview MSC.Random – Flowchart Case Study Input Format Random Analysis Recommendations Workshop 9 – Random Analysis using MSC.Random13-60 Workshop 11 – Random Vibration Analysis of a Satellite using MSC.Random Response/Shock Spectrum Analysis Response Spectrum Method14-3 Maximum and Relative Response 14-6 Create Response Spectra from Transient Analysis of Large Structure 14-9 Case Study – Create Response Spectra Response Spectrum Analysis Method 14-25

9 TABLE OF CONTENTS SectionPage 14.0 Response/Shock Spectrum Analysis (continued) Case Study – Response Spectrum Analysis14-31 Workshop 20 – Create Response Spectra for Tower Model with Seismic Input Workshop 21 – Response Spectrum Analysis for Equipment Mounted on Tower Model Enforced Motion, Large Mass Method Enforced Motion 15-3 Using Large Mass Method in Transient Response 15-4 Workshop 7 – Direct Transient Response with Enforced Acceleration 15-7 Enforced Motion in Frequency Response 15-8 Using Large Mass Method in Frequency Response 15-9 Recommendations in Enforced Motion 15-11

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