februari 27, 2004
Philip Ball skriver i sin Nature-artikel Shattered eggs reveal secrets of explosions om forskning kring exploderande ägg.
Exploding eggs might help investigators work out the causes of industrial explosions or airline disasters, according to researchers who have been smashing egg-shells.
The distribution of sizes of fragments left after a blast can be used to work out the pressure of the explosion, say Ferenc Kun of the University of Debrecen in Hungary and his co-workers.
Naturligtvis hittar man power laws även här:
The mathematical equations that predict the number of pieces of each size can be described by something called a power law [...].
[Hans] Herrmann speculates that their mathematical formula could also be used to figure out the size of fragments missing from broken archaeological vessels, provided that enough shards are found to map out the overall size distribution of the pieces.
The problem, Herrmann says, will be in gathering enough fragments to do any calculations. Debris in aircraft explosions can be scattered over kilometres, he says, and the smaller the fragments, the harder they are to find.
Se Falk Wittel, Ferenc Kun, Hans J. Herrman, Bernt H. Kroplin: Fragmentation of shells
We present a theoretical and experimental study of the fragmentation of closed thin shells made of a disordered brittle material. Experiments were performed on brown and white hen egg-shells under two different loading conditions: impact with a hard wall and explosion by a combustible mixture both give rise to power law fragment size distributions. A three-dimensional discrete element model of shells is worked out. Based on simulations of the model we give evidence that power law fragment mass distributions arise due to an underlying phase transition which proved to be abrupt for explosion and continuous for impact. We demonstrate that the fragmentation of closed shells defines a new universality class of fragmentation phenomena.
Posted by hakank at februari 27, 2004 09:57 FM Posted to Dynamiska system