Originally Posted by
SansAnhedral
1. Largely isotropic materials like classic metallics (even forged parts) are inherently less weight efficient for a given design than composites that take advantage of the orthotropic structural aspect of fibers within a matrix on a blade.
2. Metal blades, for an equivalent fatigue life, will always outweigh a properly designed composite part (see #1)
3. Metal fatigue failure is usually sudden and typically less predictable than a properly designed composite equivalent.
I have a question about composites, specifically I wonder about the state of the art in NDT? I remember the middle east 139 that lost the empennage ( on the ground ) due to a failed repair in the carbon fiber... Given the large amount of composites being used in modern airliners, I'm guessing testing composites must have advanced in recent years. What kind of testing exists today to detect internal manufacturing defects / operational damage in modern composite structures? How does state of the art compare to eddy current testing, x-ray, etc used in metallic structures?
I must admit to trusting older composites like fiberglass, but still regard carbon fiber composites with some distrust as a "new" material, despite the fact that they're not that new anymore, and are widely used.