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
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