2012 Spacecraft & Launch Vehicle Dynamic Environments Workshop
I had the opportunity to give the keynote speech at the workshop. Here is my presentation, which is rather non-technical. Enjoy… Dynamics Engineering: A Call to Serve – Tom
Cross Power Spectral Density
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
von Karman Continuous Gust PSD
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
San Francisco Runway 28R
There are many variables which affect the touchdown shock level of an aircraft. These include: Descent or sink rate Forward and side velocities Roll, pitch, and yaw angles and corresponding rates Weight and center of gravity Cross wind, wind shear, gusts, etc. Runway contact loads… Read more
Matlab: generate your own time history
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
God Commands Abraham to Sacrifice Isaac
The following was written by Rabbi Shmuley Boteach. The most confusing story of the Bible involves G-d’s commandment to Abraham to sacrifice his son Isaac. What was this G-d, who would later declare that all human, and especially child, sacrifice to be an abomination, thinking?… Read more
Bessel Lowpass Filter
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 Man of God from Judah
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
Time History Synthesis for Shaker Shock Testing
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
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