Introduction Many engineers are proficient at measuring strain and converting strain-gage output into stress using the elastic modulus and gage factor. Fewer have worked through the next step: reconstructing the applied forces and moments that produced those strains. This is the load identification problem, and… Read more
Dynamic Versus Static Modulus: Why ASTM E1876 and ASTM E111 Don’t Always Agree Engineers frequently encounter situations where material properties reported in handbooks don’t quite match experimental data. A classic example occurs when comparing elastic modulus values obtained from different test standards. When evaluating stiffness,… Read more
San Mateo Bridge, Highrise Section, San Francisco Bay Area UC Berkeley Professor Ed Wilson raised a pointed concern about the Response Spectrum Method (RSM) that structural engineers should take seriously. In his 2015 note, he described the San Mateo Bridge retrofit as a revealing case… Read more
At John Wayne Airport (SNA) in Orange County, California, noise abatement on departures is managed through a combination of specialized Noise Abatement Departure Procedures (NADPs), strict regulatory limits, and operational constraints. Because SNA is located in a densely populated, noise-sensitive residential area, the airport enforces… Read more
NASA’s Nancy Grace Roman Space Telescope has passed its final major prelaunch environmental tests at Goddard Space Flight Center. The test sequence included electromagnetic compatibility, vibration, and acoustic testing. These are the kinds of tests that determine whether a large precision observatory can survive launch… Read more
NASA released Revision B of NASA-STD-5002, Load Analyses of Spacecraft and Payloads, on March 10, 2026. The standard supersedes NASA-STD-5002A and defines accepted NASA practices and requirements for load analyses used in the design, development, verification, and testing of spacecraft and payload structures. Although the… Read more
Tough day for Blue Origin’s New Glenn. Blue Origin was performing a static fire (hotfire) test ahead of an anticipated fourth launch — the rocket was likely fully fueled, contributing to what is described as one of the largest rocket explosions in U.S. history. Blue Origin,… Read more
Slide Link Static fire tests are among the most critical — and most dangerous — milestones in a launch vehicle’s life. The vehicle is fully fueled, the engines are lit, and everything that can go wrong is present in one place at one time. This… Read more
This September 2026 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
ModalMass_revK.pdf Effective modal mass and modal participation factors provide a quantitative basis for identifying dynamically significant vibration modes and for guiding modal truncation in structural dynamic analyses. This paper presents a unified formulation for both base-excited systems and grounded systems subjected to externally applied forces.… Read more