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Aircraft Auxiliary Power Unit (APU)

June 13, 2015 by admin

GTCP85-98D APU The APU is a small gas turbine engine which is normally located in the tail cone of the aircraft but, in some cases, is located in an engine nacelle or in the wheel well. The APU can be started utilizing only the aircraft… Read more

Circuit Board Shock & Vibration Analysis

June 10, 2015 by admin

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

Pyrotechnic Shock Propagation across Material Distance & Joints

June 5, 2015 by admin

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

Rectangular Plate Bending Frequencies and Mode Shapes, Finite Element Method, GUI version

May 8, 2015 by admin

I have added a feature for rectangular plate bending modes to the Matlab GUI package. Matlab script: Vibrationdata Signal Analysis Package The script allows for the addition of point masses and point constraints. This is a work-in-progress. The next step will be to add base… Read more

Two-degree-of-freedom System Subjected to an Applied Force

April 29, 2015 by admin

I have added a feature for a two-degree-of-freedom system subjected to an applied force to the Matlab GUI package. The applied force options are steady-state sine, arbitrary time history and PSD. Matlab script: Vibrationdata Signal Analysis Package The new feature can be accessed via: Vibrationdata… Read more

Correcting Acceleration, Velocity & Displacement Time Histories

April 23, 2015 by admin

There is a need in certain analysis problems to correct an acceleration signal so that its integrated velocity and double integrated displacement each oscillates about its respective zero baseline. This may require using high pass filtering, trend removal and tapering throughout the integration process. Trial-and-error… Read more

Boeing 717-200

April 22, 2015 by admin

I recently flew as a passenger on a Boeing 717-200 aircraft similar to the one shown in the image. This aircraft has two Rolls-Royce BR700 engines, with the following specifications: Maximum Engine Rotational Speeds (Both Engines) N1 Low Pressure Turbine = 6,195 RPM (103 Hz) N2… Read more

Digitizing Plots

April 22, 2015 by admin

Here is audio/visual file: Digitizing Plots Here are slides, Matlab scripts and data samples: Unit_33_PP.zip Here is another script: digitize_plots.m This is vintage presentation. I need to add the Matlab scripts to the Vibrationdata GUI package. – Tom Irvine

Notes on Fatigue for Pure Compression Stress

April 10, 2015 by admin

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

Webinar 48 – Rainflow Cycle Counting for Multiaxial Stress

March 10, 2015 by admin

Slides: To be added before 4/4/2015 This unit gives a method for converting a time-varying stress tensor into a weighted-average equivalent uniaxial stress. The weights are chosen to maximize the fatigue damage. * * * Matlab script: Vibrationdata Signal Analysis Package * * * Reference… Read more