Tom Irvine A reader has a measured time history, he wants a low-frequency sine test level from it, and the FFT does not seem to give him the real amplitude at each frequency. His governing handbook sends him to something called ESI, which produces a swept sine… Read more
Tom Irvine A phone that slips out of your hand is a shock problem, and a surprisingly rich one. The drop height fixes only one thing, the velocity at impact. Everything that matters after that, the pulse duration, the peak acceleration, and where the stress… Read more
A colleague who has started building a simulator wrote in with a short question. He has welded rods in S355 or S420 steel, the welding process is not yet fixed, and he expects that a fatigue assessment will be needed. He has not worked with… Read more
Two days ago a wind storm came through our neighborhood in Madison, Alabama. Limbs came down, the power flickered, and by evening everything seemed to be over. This morning, in calm air, one of the wooden distribution poles on our street broke through at about… Read more
View larger image Figure 1. A circular laminated elastomeric bearing on a pier cap, instrumented with displacement transducers straddling the bearing and additional sensors on the pier face. The rubber cover bulges between the internal steel shim planes. Whether a lead core is buried inside… Read more
The Constraint Factor You Inherited — Vibrationdata Vibrationdata Fracture & Fatigue Crack closure modeling The Constraint Factor You Inherited Newman’s crack opening equation contains a single user input, α, that most analysts take from a material file default without ever deciding on it. At the… Read more
A slender store hanging under a fighter wing sits in an acoustic field near 164 dB overall. A wind chime tube hanging from a porch beam sits in an acoustic field near 40 dB. The store is asked to survive; the chime is asked to… Read more
A reader sent in a question that every test engineer runs into sooner or later: For mission synthesis we get three-axis data from the real machine. What is the best way to simulate the same thing on a single-axis shaker table to create the same… Read more
This post is a reply to a recent LinkedIn questionon whether a low-energy impact really costs a bonded joint any fatigue life. It is a good question, and the answer has a number attached to it. The question was posed about aluminum-to-composite adhesively bonded joints:… Read more
The pair below sits on South Bayshore Drive in Coconut Grove, Miami, on the site of the old Grand Bay Hotel. Bjarke Ingels Group designed them, DeSimone Consulting Engineers made them stand up, and they were completed in 2016. Each tower rotates a total of… Read more