admin 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 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
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
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