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Here are some papers… Notes on Mechanical Shock & Bending Waves Waves in Structures * * * Functions for calculating wave speeds are given in: Matlab script: Vibrationdata Signal Analysis Package The functions can be accessed via >> vibrationdata > Miscellaneous > Acoustics & Vibroacoustics… Read more

Maximum predicted environment (MPE) levels can be derived for acoustic, shock, and vibration levels where flight data is available.  The enveloping for multiple sets of data can be performed using tolerance factors as described in the following papers. Normal Tolerance Factors for Upper Tolerance Limits:… Read more

Here are some papers: Electronic Circuit Board Design Reliability Lessons Learned: electronics_design_reliability.pdf Effect of Conformal Coating on Circuit Board Vibration Response:  conformal_coat.pdf * * * Steinberg’s Vibration Analysis for Electronic Equipment describes the methods for designing electronic equipment that must work with a high degree of… Read more

The following is mostly an academic problem. The Response of an Undamped Two-degree-of-freedom System Subjected to Base Displacement via Modal Analysis:  twodof_base_disp_modal.pdf The Response of an Undamped Two-degree-of-freedom System Subjected to Base Displacement via Laplace Transforms: twodof_base_disp_Laplace.pdf * * * See also:  Two-degree-of-freedom Systems – Tom… Read more

Sloshing can occur in swimming pools, trucks carrying liquids, rocket vehicle propellant tanks and in other situations. Sloshing of propellants may adversely affect the stability of a space vehicle and the integrity of the tank structure. Sloshing describes the free-surface oscillations of fluid in a… Read more

In some cases, the sampling rate of measured data needs to be increased, particularly for time domain analysis.  One method is do a cubic spline curve-fit.  This is an “engineering judgment” process with some limitations. The “Input Data” in the figure above is a 12… Read more

Here is series of course units that I have developed for circuit board analysis: Circuit_Board_Slides (The zip file can be downloaded using the icon with the downward pointing arrow.) The corresponding Matlab software allows for the creation of finite element models for rectangular boards. The… Read more

Here is letter that I recently send to some of my colleagues… We have been discussing establishing a database of shock data both for characterizing source shock levels and attenuation through material distance and joints.   We have also discussed sharing attenuation curves if the… Read more

Fatigue is usually associated with tensile stresses. Engineering knowledge of compressive fatigue is very limited. Compression stresses do not cause cracks, but plastic compressive strain can cause tension stresses when the load is returned to zero and the resulting tension stress causes cracks. * *… Read more