Hi all, I'm a 1st year (first 2 weeks) engineering student, with a quick question in regards to fracture points of materials. We're currently going through the elastic modulus and the deflection formula, which is pretty handy and I think I've got a decent (basic) grasp on it now. Thinking though, it's all well and good seeing my material would deflect 100mm over the 400mm span, but obviously it would have snapped well before that. I'm assuming that the deflection forumla has no way of knowing this point. My question is then, how do I determine the point my material is going to fracture, to make sure I'm not trying to deflect it to far? (Full story - Balsa wood beam, spanning 400mm using minimum of materials, has to hold 2.5kg. Must deflect between 1 - 6.5mm. I've worked out it will deflect 5.5 mm but I don't know if it would have snapped beforehand). Cheers.