The Matlab scripts in waterfall_FFT.zip calculate the Waterfall FFT of a time history. The main script is: waterfall_FFT.m The remaining scripts are supporting functions. The scripts also have options for spectrogram and contour plots. Here is another script useful for tracking sine sweeps: sine_sweep_spectral.m *… Read more
The Matlab scripts in PSD.zip calculate the power spectral density function for a time history. The main script is: PSD.m The remaining scripts are supporting functions. * * * A Fortran power spectral density program is given at: PSD.F * * * See also: Matlab Random Vibration… Read more
The overall RMS level of a power spectral density function is equal to the square root of the area under the curve. Power spectral density specifications are typically given in log-log format. Thus special integration rules apply. The Matlab scripts in psd_integ.zip calculate the overall… Read more
This set of Matlab scripts calculates the response of a single-degree-of-freedom system to an acceleration power spectral density base input: sdof_ran.zip The power spectral density may vary arbitrarily with frequency. The main script is: sdof_ran.m The user must specify the natural frequency and damping ratio. The… Read more
The software in the zip file was updated on December 21, 2012. A time history consisting of a series of damped sinusoids can be synthesized to satsify a shock response spectrum (SRS). A Matlab script for this is given in: damped_sine_syn.zip. The main script is: … Read more
The following Matlab files are given at: psd_syn_revD.zip psd_syn.m is the main Matlab script. The remaining scripts in the zip file are supporting functions. It synthesizes an acceleration time history to satisfy a power spectral density function. It also calculates the corresponding velocity and displacement… Read more
Here are some edited notes given to me by a colleague who is writing software programs to import Nastran data into Matlab. DMAP DMAP (Direct Matrix Abstraction Programming) is the language running under the hood in the various nastran solution sequences. All the math that happens… Read more
I will be presenting a 3-hour tutorial session at the 83rd Shock and Vibration Symposium in New Orleans, on November 4, 2012. My session is called “Shock Response Spectra & Time History Synthesis.” Students will receive basic instruction in calculating shock response spectra for time… Read more
Pyrotechnic devices such as linear shaped charge and frangible joints are used for stage and fairing separation in launch vehicles. These devices generate high-frequency mechanical shock energy. Avionics components mounted in the vehicle must be designed and tested to withstand this shock energy. Thus, ground… Read more
Listening to music releases certain neurochemicals according to psychologist Dr. Daniel Levitin. Enjoyable music stimulates the brain to release dopamine, a so-called “feel-good hormone.” Dopamine is a neurotransmitter, a chemical released by nerve cells to send signals to other nerve cells. It helps regulate emotional responses.… Read more