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
The united tribes of Israel had grown steadily in wealth, power and glory or 120 years, under the reigns of Saul, David and Solomon. Solomon’s son Rehoboam became the next king. Rehoboam raised the taxes, which caused the northern tribes to rebel against him. Jeroboam… 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
Time Waveform Replication (TWR) for shock testing on shaker systems has been receiving some attention in MIL-STD-810G and elsewhere. The goal is to test components to measured field time histories for realism. I did some related work with NASA’s Robin Ferebee a few years ago,… Read more
Single-degree-of-freedom System ______________________________________________________________________ Please see the following post for an important revision: Peak Response to Random Vibration with Probability of Exceedance ______________________________________________________________________ Consider a single-degree-of-freedom system subjected to a broadband random vibration base input, where the input is stationary and has a normal distribution. (The… 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