The scripts in: cross_psd.zip calculate the cross power spectral density of two signals. These scripts have an option to sub-divide the data into segments and then take an ensemble average. This tends to smooth the resulting magnitude and phase curves, but the spectral frequency resolution… Read more
FAA Federal Aviation Regulations FAR-25 Appendix G, Continuous Gust Design Criteria, requires a continuous turbulent gust analysis for transport aircraft. The gust PSD function is given in: The von Karman Vertical Gust Spectrum A Matlab script for generating a continuous gust velocity PSD is given… Read more
There is a occasional need in shock & vibration analysis for a user to generate his or her own time history. The resulting time history could be used to test a modal transient script, for example. The scripts in generate.zip can be used to output the… Read more
These Matlab scripts apply a two-pole Bessel lowpass filter to a time history signal: Bessel_lowpass_filter.zip The main script is: Bessel_lowpass_filter.m The remaining scripts are supporting functions. The filter coefficients were derived using a bilinear transformation, as shown in Bessel_filter_two_pole.pdf * * * The U.S. Navy… Read more
Consider a component which is to be subjected to a shock test using a shaker table. The test specification for this example is a Shock Response Spectrum (SRS). The control computer must synthesize a time history for the test. The typical method is via a… Read more
Matlab scripts for a Butterworth Sixth order filter are given in: Butterworth.zip The main script is: Butterworth_filter.m The scripts have options for lowpass, highpass and bandpass filtering. There is also an option for refiltering for phase correction. The scripts also demonstrate the calculation of the… Read more
“Shock Diamonds” in the afterburner of a NASA SR-71B Jet * * * Sound pressure levels are limited by the physical characteristics of the surrounding medium. The ambient air pressure at sea level is “one atmosphere,” or approximately 14.7 psi on the absolute scale. The… Read more
A number of my colleagues have told me that they will be unable to participate in the Symposium due to travel cost, schedule conflicts, etc. So here are the slides for my presentation: SAVE_conference_2012_Irvine The presentation includes Matlab exercises. The scripts are given in: … Read more
Endo & Matsuishi (1968) developed the Rainflow Counting method by relating stress reversal cycles to streams of rainwater flowing down a Pagoda. This method is very useful for fatigue analysis. The rainflow method allows the application of Miner’s rule in order to assess the fatigue… Read more
Shock Response Spectrum, Q=10 1940 El Centro Earthquake North-South Component * * * The Matlab scripts srs_tripartite.zip calculate the shock response spectrum of a base input acceleration time history. The results are plotted in tripartite format. Acceleration, velocity, and relative displacement are each represented as… Read more