Gnuplot is a portable command-line driven graphing utility for Linux, OS/2, MS Windows, OSX, VMS, and many other platforms. The source code is copyrighted but freely distributed (i.e., you don’t have to pay for it). It was originally created to allow scientists and students to… Read more
David O. Smallwood, An Improved Recursive Formula for Calculating Shock Response Spectra, Shock and Vibration Bulletin, No. 51, May 1981. DS_SRS1.pdf Time History Synthesis for Shock Testing on Shakers: th_syn.pdf The Shock Response Spectrum at Low Frequencies: low_srs.pdf A Family of Transients Suitable for Reproduction… Read more
The following animation file is useful for demonstrating the Shock Response Spectrum (SRS) concept : HS_SRS.avi & Alternate Link Each system is subjected to a common base input which is a 1 G, 1 second half-sine pulse. Each system has an amplification factor of Q=10.… Read more
Occasionally I receive questions regarding the equivalent SRS for a MIL-S-901 shock test. Alas, I have no experience with MIL-S-901 testing. But a “MIL-S-901 Medium Weight Shock Test” SRS plot is given on page 45 of the following document: Gaberson, Pseudo Velocity Shock Analysis, Shock Severity… Read more
Howard A. Gaberson (1931-2013) was a shock and vibration specialist with more than 45 years of dynamics experience. He was with the U.S. Navy Civil Engineering Laboratory and later the Facilities Engineering Service Center from 1968 to 2000, mostly conducting dynamics research. Gaberson specialized in… Read more
Shock and vibration environments produce dynamic stresses which can cause material failure in structures. The potential failure modes include fatigue, yielding, and ultimate stress limit. F.V. Hunt wrote a seminal paper on this subject, titled “Stress and Stress Limits on the Attainable Velocity in Mechanical… Read more
Here are some useful references: Laplace Transform Table Partial Fractions Bessel Functions * * * Examples of the Laplace Transform as a Solution for Mechanical Shock and Vibration Problems: Free Vibration of a Single-Degree-of-Freedom System: free.pdf Response of a Single-degree-of-freedom System Subjected to a Unit… Read more
These Matlab scripts determine an optimum envelope for an acceleration power spectral density: envelope_plateau.zip The optimum envelope is the that which yields the lowest GRMS and Velocity RMS values. The acceleration is assumed to be the base excitation for an array of independent, parallel single-degree-of-freedom… Read more
Revised software uploaded on January 9, 2013 Accelerometers signals for pyrotechnic events often have spurious offsets. Numerous potential causes include: 1. Excitation of the accelerometer’s piezoelectric crystal natural frequency 2. Signal conditioner overload 3. Base strain sensitivity 4. Instrumentation noise 5. Electromagnetic interference These causes… Read more
I am offering another Shock & Vibration course. The next course date is February 26-28, 2013 in Huntsville, Alabama. Location: Best Western Plus Madison – Huntsville Hotel 9035 Madison Blvd, Hwy 20 West, Madison, AL 35824 (Formerly The Inn at Madison) Students receive software &… Read more