Photograph taken at a seaside retaining wall in Madeira, Portugal, July 2026. The bolt and nut shown are carbon steel — heavily corroded after prolonged exposure to the Atlantic marine environment.Figure 1. Severely corroded carbon steel bolt and nut at a seaside retaining wall, Madeira,… Read more
Image Courtesy of http://www.mbrosia.co.kr/en/product/product0101.php Ultrasonic fatigue testing at 20 kHz has become the standard method for characterizing material fatigue in the Very High Cycle Fatigue (VHCF) regime — beyond 107 cycles, extending to 109 (gigacycle) and beyond. At 20 kHz, a test that would require… Read more
ZW12 (Mg–1Zn–2Y wt.%) is a research-stage magnesium alloy developed at Helmholtz-Zentrum Hereon (Geesthacht, Germany) targeting lightweight structural applications under cyclic loading. Recent work presented at IFC14 (14th International Fatigue Congress, 2026) by Trujillo-Tadeo et al. reveals that ZW12’s fatigue and corrosion-fatigue performance is strongly microstructure-dependent… Read more
intergranular SCC of an Inconel heat exchanger tube with the crack following the grain boundaries. photo courtesy Stress corrosion cracking (SCC) is a time-dependent fracture mechanism driven by the simultaneous presence of sustained tensile stress and a corrosive environment. Neither factor alone is sufficient. Their combination… 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
Internal friction and heat generation cause a deviation from perfect elasticity, resulting in the hysteresis loop in the stress-strain curve. The damping capacity ψ is: ψ = ΔW/W where W is the initial strain energy and ΔW is the energy lost during one cycle of oscillation. Some damping capacities… Read more
Introduction Vibration test fixtures are the mechanical interface between the shaker system and the unit under test (UUT). Their purpose appears simple: hold the test item securely and transmit the specified vibration input. In practice, fixture design is one of the most important and often… Read more
The plot shows the applied strain on the horizontal axis and the resisting stress on the vertical axis. The area inside the triangle represents the maximum energy that can be absorbed elastically, if the member is strained up to its proportional limit stress. The member… Read more
Introduction Neither shock nor vibration response should be used to cover rigid-body acceleration because material limits depend on the strain rate and on the duration of the load. Furthermore, static deflection shapes differ from dynamic mode shapes. Material Stress Limits The following is an excerpt… Read more