Structural dynamics systems can be represented in terms of mass, damping and stiffness matrices. Each of these matrices may be coupled depending on the model complexity, degrees-of-freedom, etc. The mass and stiffness matrices in the assembled equation of motion may be uncoupled using the normal… Read more
Shock and vibration analysis can be performed either in the frequency or time domain The time domain method requires more computation time but is much better suited for transient and nonstationary excitation Time domain methods are also better for rainflow fatigue cycle counting Students should… Read more
The punch file method may be used to extract the mass & stiffness matrices from Nastran models. The format is awkward since zero terms are not stored. Also the matrices are assumed to be symmetric, and the upper triangular portion above the diagonal is not… Read more
A function for calculating the natural frequencies and mode shapes for an elastic beam undergoing rotation is given in: Matlab script: Vibrationdata Signal Analysis Package The function can be accessed via: >> vibrationdata > Miscellaneous > Structural Dynamics > Beam Bending FEA > Rotating Beam,… Read more
A function for calculating the natural frequencies and mode shapes for an elastic beam supported by end springs is included in: Matlab script: Vibrationdata Signal Analysis Package The function can be accessed via: >> vibrationdata > Miscellaneous > Structural Dynamics > Beam Bending > Beam… Read more
I have added a feature for rectangular plate bending modes to the Matlab GUI package. Matlab script: Vibrationdata Signal Analysis Package The script allows for the addition of point masses and point constraints. This is a work-in-progress. The next step will be to add base… Read more
The static deflection method can be used for estimating the fundamental frequency of a grounded dynamic system. A 1 G body load is applied to the system for this analysis. The method can be used as a “ballpark” check for finite element models in conjunction… Read more
I have begun work on a Matlab GUI finite element package for structural dynamics. This is a long-term work-in-progress! Here is the current package: vibrationdata_fea_preprocessor.zip vibrationdata_fea_preprocessor.m is the main script. The remaining scripts are supporting functions. * * * Here are sample input files in… Read more
Here is a Matlab script that converts a time history to a format which can be input to Femap or some other preprocesser for Nastran analysis. time_history_nastran.m with supporting function: datafix.m It can be used for force, pressure, acceleration or other amplitude types. The script… Read more
Here is a paper which gives a derivation of the mass and stiffness matrices for beam bending: beam_FEM.pdf * * * Here is a Matlab script for the modal analysis of a straight beam. beam.zip * * * Here is Matlab script for the modal… Read more