TABLE OF CONTENTS
- INTRODUCTION TO LINEAR DYNAMICS (SIMCENTER NASTRAN)
- some examples of linear vibration analysis (predictive)
- eigenvalue or normal modes analysis (gotta have mass)
- FOUNDATIONS OF FREQUENCY ANALYSIS
- baby’s first beam model.
- here’s your modal analysis checklist
- setting up the model for normal modes with mass participation
- interpreting results based on orthogonality and mass participation
- symmetry and frequency analysis
- significance of strain energy for frequency analysis
- baby’s first beam model.
- STANDARD NORMAL MODES ANALYSIS
- model setup
- natural frequency results and interpretation
- mass participation
- MODAL FREQUENCY ANALYSIS
- running a modal frequency analysis in Simcenter Femap and Simcenter Nastran
- INTRODUCTION TO RANDOM VIBRATION
- the psd function
- the nx nastran method
- psd units
- EXAMPLE 1: PSD ANALYSIS OF PCB WITH TWO HEAVY ELECTRICAL COMPONENTS
- EXAMPLE 2: CANTILEVER BEAM
- problem definition
- analytical solution
- defining the system damping
- creating the psd function
- creating the modal frequency table/setting up the load set options for dynamic analysis
- loading & constraining the model
- specifying groups for nodal and elemental output
- creating an analysis set – simple psd
- interpreting the output
- positive crossings
- fatigue analysis using rms stress and positive crossings
- fatigue analysis – time to failure
- EXAMPLE 3: SOLID MESHED BEAM
- analytical solution
- psd function input
- psd stress results
- comparing miles’ approximation and psd results
- DIRECT TRANSIENT ANALYSIS.
- QUESTIONS AND ANSWERS ABOUT FREQUENCY ANALYSIS
- BEING AN EXPERT: VIBRATION IS ABOUT MASS AND CONSTRAINTS
- check fo6 for mass summation and know what you know
- ground check if you are doing aerospace quality work
- RANDOM VIBRATION CONCLUSION
- INTRODUCTION TO RESPONSE SPECTRUM ANALYSIS
- the accelerogram
- creating a response spectrum
- nx nastran method
- RESPONSE SPECTRUM ANALYSIS EXAMPLE: CANTILEVER BEAM
- problem definition
- analytical solution
- step 1: creating the fe model
- step 2: defining the response spectrum
- step 3: creating interpolation table
- step 4: creating a modal damping function
- step 5 creating the excitation node
- step 6: constraining the model
- step 7: setting up the analysis
- post processing the results
- results comparison
- EXTRA CREDIT: SOLID MESHED BEAM
- APPENDIX
- flow chart from nx nastran theoretical manual
- creating modal frequency table
- autocorrelation function
- multiple excitation spectrums
- why we do a psd analysis