Titanium - Vibrationdata Engineering Blog

Hardness and Fatigue: How Metal Hardness Governs Fatigue Strength and Damage Tolerance

July 20, 2026July 1, 2026 by Tom Irvine

Hardness is cheap and fast to measure — but how far can it really predict fatigue behavior? Introduction Hardness is one of the cheapest and fastest mechanical properties to measure — a Rockwell or Brinell indenter, a few seconds, and a single number. Because hardness… Read more

S/N Fatigue Curves: Constant vs Variable Amplitude Loading

July 19, 2026July 1, 2026 by Tom Irvine

Nearly every published S/N curve was measured under steady, repeatable loading. Real structures never see that. Introduction The S/N curve — stress amplitude versus cycles to failure — is the foundation of classical fatigue analysis. It is intuitive, experimentally well-established, and embedded in virtually every… Read more

Dwell and Time-Dependent Damage in Pressurized Aluminum Fuselages

July 20, 2026July 1, 2026 by Tom Irvine

Introduction A previous VibrationData post examined cold dwell fatigue in titanium — the phenomenon in which simply holding a moderate stress for one to two minutes causes far more damage per cycle than the same stress applied and immediately removed. The mechanism is driven by… Read more

Titanium Dwell Fatigue

July 22, 2026July 1, 2026 by Tom Irvine

Introduction Most engineers have an intuitive feel for fatigue: apply a stress repeatedly, and eventually the material cracks — even if each individual load is well below the static yield strength. Dwell fatigue adds a further, less intuitive twist. Dwell fatigue occurs when a sustained… Read more

Frequency and Strain Rate in Fatigue Testing: Does Test Speed Matter?

July 20, 2026June 30, 2026 by Tom Irvine

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

July 22, 2026June 30, 2026 by Tom Irvine

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

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

July 20, 2026June 9, 2026 by Tom Irvine

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

Fatigue Cracks in Anodized Coatings

July 20, 2026January 16, 2026 by Tom Irvine

Image reference: https://onlinelibrary.wiley.com/doi/full/10.1002/adem.202300394 What Is Anodizing? Anodizing is widely used to improve corrosion resistance and surface durability in aluminum and other light metals. However, under cyclic loading, anodized coatings can play a surprising, and sometimes detrimental, role in fatigue performance. This post walks through why… Read more

United Airlines Flight 328

July 22, 2026March 1, 2021 by admin

United Airlines Flight 328 was a scheduled domestic passenger flight from Denver to Honolulu, Hawaii on February 20, 2021. The Boeing 777-200 aircraft operating the route suffered engine failure shortly after takeoff The failure was “contained” but resulted in a debris field at least one… Read more

Material Shock Loading

July 19, 2026July 20, 2020 by admin

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