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
Aircraft and launch vehicles behave as unconstrained systems in flight, with six rigid-body modes. These vehicles may be “trimmed” using aerodynamic control surfaces and thrust vector control to prevent rotation about the vehicle center-of-gravity (CG). There is a need to calculate the vehicle’s displacement response… Read more
Ideally, a modal test on a structure would be performed with completely free boundary conditions. This configuration can be approximated by mounting the structure on compliant air cushions, or by suspending it with elastic cords, so that the mounted natural frequency is much smaller that… 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 function for calculating the free vibration response of an SDOF system to initial conditions to the Vibrationdata GUI package. Matlab script: Vibrationdata Signal Analysis Package >> vibrationdata > Miscellaneous > Structural Dynamics > Spring-Mass Systems > SDOF Free Vibration Response to… Read more
A function for calculating cylindrical shell natural frequencies via the wave method is now included in the Vibrationdata GUI package. Matlab script: Vibrationdata Signal Analysis Package This function may be accessed via: vibrationdata > Structural Dynamics > Rings & Cylinders > Cylinder, Wave Model Reference… 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
I have added a feature for a two-degree-of-freedom system subjected to an applied force to the Matlab GUI package. The applied force options are steady-state sine, arbitrary time history and PSD. Matlab script: Vibrationdata Signal Analysis Package The new feature can be accessed via: Vibrationdata… Read more
PowerPoint Slides: Webinar_30_rectangular_plates.pptx Audio Visual File: NESC Academy Rectangular Plate Shock & Vibration – Recommend viewing in Firefox with Sliverlight Plugin * * * References: Leissa, Vibration of Plates Plate Base Excitation: plate_base_excitation.pdf The Natural Frequency of a Rectangular Plate Point-Supported at Each Corner: plate_point_corner.pdf * *… Read more