Argosy Cruises’ Salish Explorer Passenger Ship (Image courtesy of Vessel Finder) This ship is used for tours around the Puget Sound waterways in the Seattle area. My family and I had the opportunity to take a ride on this ship recently. The Salish Explorer is… Read more
Uncategorized
Blue Bird Bloodmobile Vibration
I had the opportunity to donate blood recently inside this diesel bloodmobile. The vehicle had an onboard generator to provide electrical power for the lights, refrigerator, and other equipment. The generator produced vibration spectra mainly at ~ 60 and 120 Hz which could be both… Read more
Relative Fatigue Damage Statistics for an SDOF System Subjected to Base Excitation
This is a work-in-progress. More to come later… SDOF Response to White Noise Base Input Rainflow Statistical Study: white_noise_sdof_rainflow_study.pptx See also: Rainflow Cycle Counting Tom Irvine
k factor for one-sided normal tolerance limit
Matlab script: %% k_factor.m ver 1.0 by Tom Irvine%% k factor for one-sided normal tolerance limit%% p = probability percent% c = confidence percent% nsamples = number of samples%% k = tolerance factor% Zp = Z limit corresponding to probability area in the normal% distribution… Read more
Transforming Complex Mode Shapes into Real, Undamped Shapes
Modal test data processing methods perform curve-fitting on measured frequency response functions. These are indirect methods for extracting natural frequencies and damping ratios. The FRF methods also yield mode shapes which may be complex if the system has non-proportional damping. Each complex mode shape can… Read more
Architectural Helmholtz Resonators
Tapiola Lutheran Church in Espoo, Finland, Opened in 1965 Helmholtz-type resonators are built into the walls of the church. The slots between brick pairs and cavities behind them act as both absorbers and diffusors of sound. The absorption reduces the reverberation time as desired for… Read more
PSD Fatigue Damage Severity Criteria
PV = pseudo velocity The following method is intended for components which are to be tested to power spectral density (PSD) specifications on shaker tables. The method can be applied to sine-on-random specifications as well. The purpose of this document is to recommend velocity severity… Read more
Hot Fire Test of an Upper Stage Rocket Engine
Liquid fuel rocket engines undergo hot fire testing before flight in order to verify their performance, design integrity, etc. The engines are mounted to heavy-duty, immovable stands for this purpose. These tests are also referred to as static fire tests. Furthermore, the tests are almost… Read more
Consecrating our Suffering unto the Lord
Catholic Prayer Lord Jesus Christ, I consecrate myself today anew and without reserve to your divine Heart. I consecrate to you my body with all its senses, my soul with all its faculties, my entire being. I consecrate to you all my thoughts, words and… Read more
Alpha & Omega
Revelations 1 [8] I am Alpha and Omega, the beginning and the ending, saith the Lord, which is, and which was, and which is to come, the Almighty. [11] Saying, I am Alpha and Omega, the first and the last: and, What thou seest, write… Read more