I recently flew as a passenger in a CRJ-200 (aka CL-65) jet similar to the one shown in Figure 1. This aircraft has two General Electric CF34-3B1 turbofan engines, as shown in Figure 2. Here are the rotational speeds for each rotor. N1 Fan Speed… Read more
PowerPoint File: webinar_22_integration_part_2.ppt Audio/Visual File: NESC Academy Integration and Differentiation – Recommend viewing in Firefox with Sliverlight Plugin * * * ASCII Text Data Files: navmat_spec.psd two_wheeled_trailer_vertical.txt * * * Matlab script: Vibrationdata Signal Analysis Package * * * Python version: Unit_22_integration_part_2_python.ppt Python Signal Analysis Package GUI… Read more
The Pierson–Moskowitz (PM) spectra is an empirical relationship that defines the distribution of energy with frequency within the ocean. The result is given as a wave height power spectra density. Developed in 1964, the PM spectrum is one of the simplest descriptions for the energy… Read more
Here is a paper. Estimating Fatigue Damage from Stress Power Spectral Density Functions: estimate_fatigue_psd.pdf Note that the duration for the example in the paper was 600 sec. * * * This following Matlab program calculates the cumulative rainflow fatigue damage for an input stress PSD… Read more
PowerPoint File: Unit_21_integrate_differentiate.ppt Audio/Visual File: NESC Academy Integration and Differentiation, Part 1 – Recommend viewing in Firefox with Sliverlight Plugin * * * Pyrotechnic Shock File: pyro_test.txt – time(sec) & accel(G) * * * Matlab script: Vibrationdata Signal Analysis Package * * * Python Version: Unit_21_integrate_differentiate_python.ppt Python… Read more
The original Tacoma Narrows Bridge was opened to traffic on July 1, 1940. It was located in Washington State, near Puget Sound. Strong winds caused the bridge to collapse on November 7, 1940. Initially, 35 mile per hour winds excited the bridge’s transverse vibration mode,… Read more
Here is an empirical method for directing calculating a fatigue damage spectrum from a shock response spectrum: srs_fds.pdf * * * See also: Using Random Vibration Testing to Cover Shock Requirements – Tom Irvine
Aerospace and military components must be designed and tested to withstand shock and vibration environments. Some of this testing occurs as qualification, whereby a sample component is tested to levels much higher than those which it would otherwise encounter in the field. This is done… Read more
Here is a sample SRS specification. The ramp is a constant velocity line with slope = 6 dB/octave. SRS Q=10 fn(Hz) Peak Accel (G) 10 10 2000 2000 10000 2000 Here is a set of files which satisfy the SRS. ASCII text: srs2000G.zip The files… Read more
PowerPoint File: webinar_20_digital_filtering_part_2.pptx Audio Visual File NESC Academy Digital_Filtering_Part_2 – Recommend viewing in Firefox with Sliverlight plugin * * * PSD Data File: navmat_spec.psd * * * Python Version: webinar_20_digital_filtering_part_2_python.ppt Python script: Python Signal Analysis Package GUI * * * Reference Papers: An Introduction to the… Read more