Breaking noodles under impact: stress and buckling in brittle rods

What happens to uncooked spaghetti if you hit it at 80 km/hr? The answer to this question combines fundamental aspects of elasticity and material science, from nonequilibrium Euler buckling to the failure of brittle solids. I will present an experimental study of the dynamic buckling and fragmentation of slender rods - including pasta, teflon, glass, and steel - due to rapid impact. By combining the mathematical results of Saint-Venant with elastic beam theory, we obtain a preferred buckling wavelength from the coupled partial differential equations for stress and deformation. Full time-resolved numerical simulations support these results. Experimentally, we find that the distribution of fragment lengths has peaks near 1/2 and 1/4 of the buckling wavelength. Such preferred fragment sizes represent the influence of the deterministic buckling process on the more random fragmentation processes.