Hello everyone,
Due to a partial foot amputation i’m trying to build a full carbon running blade, but i’m encountering some problems.
The blade is " tapered", so it starts as 3mm thickness in the head, and 6mm thickness in the tail.
I’ve tried 2 different method of lamination, but the results were very similar : the blade breaks where the maximum strenght is concentrated, and I’ve noticed ( as you can see in those photoes), it breaks in the top side, where it works in compressive strenght ( so probably microbulking).
The first blade has been built in autoclave with 2*plain 200g/m^2 topside and downside( 45 degrees), and full t700 (0 degrees) inside, starting from the base and growing in thickness while reaching the top.
The second blade has been built with a simply vacuum at room temperature, 2x200, 45 degrees plain top and down, and a HR ud carbon inside , with the growing of the thickness obtained simmetrically ( so in the middle of the blade there are full lenght sheets, and reaching the top side( and simmetrically the bot side), there are shorter sheets, to incraese the thickness.
In both cases, you can see a fracture in the topside, reaching the middle of the blade, so i’m assuming the problem is in compressive strenght.
Do you have any idea how to prevent this break? The blade breaks only if a huge impulsive force is applied ( like simulating running ), but if i just try to walk, it doesn’t brak! I’ve already tried to incraese the thickness in tail, but i got the same break result.
Thank you for any tips!
Andrea