Hi, I was hoping someone might be able to help with some questions about composite toughness. I am trying to find an FRP composite with comparable impact toughness and yield strength to 7075 T6 Aluminium. I'm having trouble finding any means of direct comparison. I've read that Kic is not a good measure of low-velocity impact toughness for composites as it varies a lot with impact velocity. Other properties that I thought might be useful are Izod or Charpy energies. Does anyone know where I can find values for these? I have found data for the Izod and Charpy of many plastics but data for Aluminium seems harder to come by. I found a paper ( http://nvl.nist.gov/pub/nistpubs/jres/104/6/j46sie.pdf ) about Izod and charpy from which its possible to calculate the charpy of 7075-T6, but this gave a value of around 60 kJ/m^2 and I'd like to check this. What is the best way to compare impact toughness for a low-velocity application? For composites it seems there is no 'accepted' way that really represents a fundamental material property. Tests so far are all specific to the test setup, impact shape/mass/velocity/hardness etc. Would it be best to just take Kic and Charpy/Izod results and use them as a rough means of gauging performance. Is there a better way that doesn't involve computation?