The Green River Bridge is a reinforced concrete structure with an expansion joint on its West end. The joint allows the concrete to naturally expand and contract without cracking as the deck undergoes thermal changes and other loading conditions. Passenger cars have very minor dynamic… Read more
Cannondale Hybrid Bike Vibration over Gravel Road
The orange block near the seat post is a Slam Stick X accelerometer. I recorded the frame vibration as I rode the bike over a gravel road adjacent to the Green River in Kent, WA at 10 mph. The time history and power spectral density… Read more
Pedestrian Tunnel Acoustics
Pedestrian tunnel below Hayden Rd, Scottsdale, Arizona The tunnel is north of Indian School Rd & south of Camelback Rd. It is connected to the Indian Bend Wash which has a series of parks and a golf course along its length. The tunnel is about… Read more
True T-43-HC Refrigerator Sound Analysis
This is the spectral analysis of the refrigerator in my allergist’s office that stores the allergen doses, as measured with my Smartphone. Spectral peaks occur at 60, 129, 133.5, 267, 401 & 641 Hz. The 133.5 Hz peak has integer harmonics at 267 & 401… Read more
Marine Propeller Cavitation
Cavitation is the formation of vapor bubbles within a liquid at low-pressure regions that occur in places where the liquid has been accelerated to high velocities, as in the operation of centrifugal pumps, water turbines, and marine propellers. The water jet slows down after traveling… Read more
Salish Explorer Ship Sound & Vibration
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
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
MV Tacoma Ferry Vibration
The MV Tacoma is a ferry that runs between Seattle and Bainbridge Island. MV stands for “motor vehicle” and is used to designate a ferry. The ferry’s size class is “Jumbo Mark II.” The total engine power is 16,000 hp from 4 x EMD 16-710G… Read more
West Seattle Bridge
The West Seattle Bridge was built between 1981 and 1984 after the previous bridge was deemed inoperable as a result of being struck by the freighter Antonio Chavez in 1978. The bridge spans the east and west channels that form the mouth of the Duwamish… 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