Which is helpful if the material is somewhat ductile. That’s what they do with aircrafts that are checked for microcracks. In a brittle material such as carbon

Which is helpful if the material is somewhat ductile. That’s what they do with aircrafts that are checked for microcracks. In a brittle material such as carbon fibre composites, the step between “a crack appears” and “the whole piece shatters” is typically measured in milliseconds. So monitoring crack propagation is not that useful. Both stresses and strains would look completely normal up until the point of failure. It’s the same for the bond between the titanium and carbon composite bits. These things deform differently and at different rates. Stress monitoring is much more difficult than in a single piece.