I’m by no means a structural engineer, but with bike parts — in steel or aluminum, if you get a tiny 1mm chip in the material, you can more-or-less just treat it as if the steel is 1mm thinner. With engineering tolerances it is irrelevant.

But in a carbon fiber, that 1mm chip could be totally unnoticed for months, while slowly causing an invisible hairline crack, until the entire component suddenly explodes with no warning.

Maybe someone can verify if that is possible at a larger scale, but I feel like it must be to some extent.. especially if there is an invisible manufacturing imperfection due to the higher precision required in carbon fiber

The BOAC Comet failures (cracks propagating from squared-off window corners) is a notorious example, with multiple total hull losses in flight.

I've experienced somewhat less significant failures of bicycle components (though they could easily have proved far worse). It's a good idea to replace components after a wreck or even hard-cornering of a crankset.

https://www.youtube.com/watch?v=-DjnG74DDno

The cracks actually started on the top of the plane, at cutouts for radio antennas. The windows always had rounded corners (although they made them even rounder later, which may have led to the confusion.)

Thanks!

I'm sure the story around composites will improve in due time.

That's not true at all: metals have a grain structure, and how those grains are oriented can change the metal's properties in different directions.

>Composites vary cure to cure.

Metal castings can vary from cast to cast.

These folks, among others, make a lot of them. You are also incorrect about forging being used to introduce uniformity into the grain, it is typically (though not always, as some forging operations may just be for establishing shape) to stretch the grains such that they are oriented along the load path, resulting in higher allowable stresses. Look up highly loaded aircraft parts like landing gear, they are typically forged to establish the grain direction and then machined to final dimension. Nothing stops you from heat treating metal after it has been cast, either. Some heat treatments are also expressly to produce nonuniform conditions in the metal, case hardening for example.