Introduction Flow stress is one of those quantities that shows up everywhere in structural metals engineering, yet it rarely gets the dedicated treatment that stress intensity factor, S-N curves, or fatigue strength coefficients receive. It appears quietly in cyclic plasticity models, in fracture toughness test… Read more
Introduction A question that comes up regularly in fatigue testing and vibration qualification programs is whether the frequency of cyclic loading — or the associated strain rate — influences the fatigue life of a component. The honest answer is: it depends very much on the… Read more
Strain Rate Effects: Why Metals Get Stronger but Less Ductile Under Dynamic Loading Introduction A common observation in shock, impact, and ballistic engineering is that metals behave differently under dynamic loading than they do under slow, quasi-static loading. A structural steel or aluminum alloy that… Read more
Image reference: https://www.sciencedirect.com/science/article/abs/pii/S0020740323003296 Introduction Classical fatigue analysis is built on stress. The stress-life (S-N) approach correlates nominal stress amplitude to cycles to failure; the strain-life ($\varepsilon$-N) approach handles the plasticity at notch roots through the Coffin-Manson equation; linear elastic fracture mechanics (LEFM) characterizes crack growth… 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
A good question came up recently regarding the practical design of a satellite bus panel for low random vibration response. The concern was not simply whether the panel is strong enough, but whether the panel can be designed so that mounted components see a lower… 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
The B-52 Involved In Tragic Crash Was Heading out on Radar Test Sortie The mission objective was to test a new Active Electronically Scanned Array (AESA) radar system (the Raytheon APQ-188), which is a core component of the upcoming B-52J upgrade package. B-52 Crash at… Read more
Image courtesy of: https://www.rhfs.com Introduction Water hammer is one of those phenomena that every piping engineer encounters eventually—and usually remembers. It is the sudden, jarring metallic bang that makes everyone in the control room sit up straight, the distinct shudder transmitted through a facility’s pipe… Read more
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