title: Why Hexagonal Basalt Columns?
abstract: Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons. To promote understanding of the path on which the ideal configuration can be reached, two periodically repeatable models are presented here involving linear elastic fracture mechanics and applying the principle of maximum energy release rate. They describe the evolution of the crack pattern as a transition from rectangular start configuration to the hexagonal pattern. This is done analytically and by means of three-dimensional finite element simulation. The latter technique reproduces the curved crack path involved in this transition.
authors.affiliation: Technische Universität Dresden, Institut für Festkörpermechanik, D-01062 Dresden, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hofmann
authors.affiliation: Technische Universität Dresden, Institut für Festkörpermechanik, D-01062 Dresden, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Anderssohn
authors.affiliation: Technische Universität Dresden, Institut für Festkörpermechanik, D-01062 Dresden, Germany.
authors.forename: Hans-Achim
authors.initials: HA
authors.lastname: Bahr
authors.affiliation: Technische Universität Dresden, Institut für Festkörpermechanik, D-01062 Dresden, Germany.|RIF e.V.-Institut für Forschung und Transfer, Joseph-von-Fraunhofer-Straße 20, D-44227 Dortmund, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Weiß
authors.affiliation: RIF e.V.-Institut für Forschung und Transfer, Joseph-von-Fraunhofer-Straße 20, D-44227 Dortmund, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Nellesen