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W. G. Pritchard Lab Seminar: 11:15 AM - 12:15 PM, 216 McAllister Bldg

	            **Monday September 26, 2005**
	
How spaghetti breaks: stress waves and buckling in brittle rods

Andrew Belmonte

Dept of Mathematics
Penn State University

Abstract:

Thin rods are ubiquitous in natural and engineered structures. Under large 
axial loading such structures may buckle, and for brittle materials 
breaking may result. I will present experimental results on the dynamic 
buckling and fragmentation of slender rods - including uncooked spaghetti, 
teflon, glass, and steel - due to impact by a rapidly moving object. By 
combining the results of Saint-Venant with elastic beam theory, we obtain 
a preferred buckling wavelength from the coupled partial differential 
equations for stress and deformation. Experimentally, we find that the 
measured distribution of fragment lengths has peaks near 1/2 and 1/4 of 
the buckling wavelength. This non-monotonic distribution represents the 
influence of the deterministic buckling process on the apparently random 
fragmentation processes.

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