The Challenge of the Ringing Moon: Structural Dynamics and Fatigue Design for Lunar Habitats

As NASA’s Artemis program and international space agencies transition from short-duration sorties to a sustained human presence on the Moon, mission planners and structural engineers must confront a mechanical hazard that received little attention during the Apollo era: lunar seismicity. The Moon is not a… Read more

Dynamic vs. Static Moduli — Practical Considerations for Structural Dynamics

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

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

Stress Concentration Factor & Crack Initiation

This photo was taken outside of my former office in Huntsville, Alabama. As newly poured concrete hardens and dries, it shrinks. This is due to the evaporation of excess mixing water.  The cracks in the photo may have formed during this phase. In addition, the concrete experiences… Read more