Most fasteners are essentially springs, and when these fasteners fail it is usually abrupt, "out of nowhere," and caused by fatigue. Fatigue failure is estimated to account for 80-90% of all fastener breaks. However, by its very definition, fatigue damage happens over time, due to repeated loading that stresses an already weakened location. ASTM E1823-10a, Terminology Relating to Fatigue and Fracture Testing, defines fatigue as: "The process of progressive localized permanent structural change occurring in a material subjected to conditions that produce fluctuating stresses and strains at some point or points and that may culminate in cracks or complete fracture after a sufficient number of fluctuations." Preventing fatigue failure is a critical part of engineering designs.Read More…
Latest News and Application Notes
Start to Finish at the Shows
April 8, 2022
LECO is heading back to the show floor!
Are you attending the Cast Expo in Columbus, Ohio, from April 23 to April 26? Stop by Booth #2016 to meet our instrument experts and get answers to your metallographic questions!
Heading to AIST in Pittsburgh, Pennsylvania, from May 16 to May 19, instead? LECO will be at Booth #505!Read More…
Focusing on the Field of View
May 7, 2021
When magnification was as simple as one eyepiece and one objective, finding your total magnification was as easy as multiplying the two values together. The addition of film brought a third value to the equation, but the result remained a static, concrete number.
And then along came the computer.
With a huge variety of video camera chips and monitor sizes and camera couplers and screen resolution, suddenly viewing something at 500X magnification became much more challenging. There was no way to take into account all of the permutations possible. For example, even if two systems were otherwise exactly the same, but one had a 23" monitor and the other had a 24" monitor, the magnification would be different.
It was time to replace the magnification focus with a different way of looking at things: the Field of View (F.O.V.)Read More…