Question NASA-STD-7003A states wrt joint attenuation predictions that “….up to a maximum of three joints….” be used. I realize this maximum of 3-joint attenuation has been typically utilized in the industry. Does anyone know the basis behind this guideline (i.e. what’s the history and/or data… 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
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
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
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
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
Question: MIL-STD-810G, Method 526 Rail Impact, outlines the physical test of an actual system at 4, 6, and 8 mph. Is there an equivalent laboratory shock test for equipment which is to be transported via railroad car? Answer 1: from Tom Irvine U.S. Army TB… Read more