daveyrace wrote:
I agree it is designed to be part of the impact structure and is doing an important job, I was just trying to compare it to the main impact structure behind which will take much higher loads. I just worded it badly
! As you say those stiffeners will be important in the failure mode of the tip in a crash.
I meant that the top half of the nose tip appears thicker than the base so will be more of a structural part than the base, if it is thinner. Obviously together it forms a tube shape which gives it a lot of its strength, I just thought it interesting that the top half is a thicker composite than the base. If you look at the sides, the far side has broken off forward of the near side and still appears thicker than the section under.
I thought it may be a honeycomb structure when I first looked in the bottom half, not sure though, if you look at the original photo there is an indent which I have followed in green, where the lower half meets the top and appears to be thinner composite. A kevlar weave rather than honeycomb would make more sense for stiffening this part? It looks thinner to me and kevlar weave would be that colour and leave those 'fluffy' yellow bits sticking out which doesnt happen at the top.
It appears to have failed differently to the top half, tearing more, whereas the top part looks to have cracked with the laminate layers separating from the honeycomb centre. There is far more of the bottom section remaining. This would indicate to me that the bottom part is more flexible and tear resistant than the top, which is what would happen if it were thinner and had a kevlar weave rather than honeycomb. It is a pity the photo is not a better resolution. anyway...
Yeah, I grumbled at the low resolution too. Hi-res would be extremely interesting.
I looked very closely again and still I don't see kevlar. All I see is nomex honeycomb all around. Kevlar would be yellow/greenish in colour. I don't know if kevlar would make sense. Its specific stiffness is way lower than carbon , specific tensile strength is better but then again the compressive properties aren't so impressive as far as I know. Because of the low stiffness it only makes sense to use them if you can keep them loaded in-plane as long as possible which is quite difficult in a thin structure like this.
Honeycomb on the other hand does miracles for the buckling load, which is exactly what you are looking for in this application.
About the different failure modes, don't forget that we don't even know exactly what happened. Might be that the jack hit the tip from the side.