View larger image Figure 1. Olive View Hospital, 1994 Northridge earthquake: 0.9 g on the ground, 2.3 g on the roof. Source: USGS Fact Sheet 068-03. A component bolted to a roof or an upper floor does not feel the earthquake. It feels the floor.… Read more
A large welded machine base comes out of the fabrication shop looking straight and square. It goes to the machine shop, where the mounting pads are milled flat to a few hundredths of a millimetre. The next morning the pads are out of flat again.… Read more
This February 2027 course series provides practical training in shock, vibration, fatigue, structural dynamics, FEA, machinery vibration, acoustics, and rotor dynamics for engineers working with test data, qualification requirements, failure analysis, and mechanical system reliability. Each one-hour class is organized in a semester-style format, 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
A question that comes up whenever a laboratory is planning its first large electrodynamic shaker installation: the specification and the quotations keep referring to a seismic mass, or a reaction mass, or an inertia block. Is that a real, physically heavy object that has to… Read more
ETH Zurich researchers have built a quantum chip whose working memory is not electromagnetic — it is mechanical. For those of us who work in structural dynamics, this is modal analysis pushed to its ultimate limit. In July 2026, the Hybrid Quantum Systems Group at… Read more
A departure from the usual structural dynamics and forensic engineering material — a personal aside on speech as an acoustic information channel, prompted by a conversation about why some languages sound faster than others. Speech as a Communication Channel: Why Fast Languages Aren’t Actually Faster… Read more
The London Eye: A Sound & Vibration Field Study from Inside a Capsule Revised 5 July 2026 to correct the interpretation of the low-frequency harmonic series. Riding the London Eye on 5 July 2026, I ran an impromptu two-sensor experiment from my seat: a smartphone… Read more
Introduction Liquid hydrogen (LH₂) and liquid oxygen (LOX) are the highest-performing chemical propellant combination available to launch vehicle designers, delivering specific impulse values in the 450–460 second range in vacuum. The BE-3U engine powering Blue Origin’s New Glenn GS-2 upper stage, the RL-10 family powering… Read more
Rolling-element bearings are a masterpiece of mechanical engineering. They are also a notorious headache for Finite Element Analysis (FEA) engineers. Because they rely on Hertzian contact, bearings are inherently non-linear systems. The rolling elements, raceways, contact angles, internal clearances, and thermal conditions all shift dynamically… Read more