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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Selfdriven tunneling crack arrays  a 3Dfracture mechanics bifurcation analysis
 International Journal of Fracture 141 (2006), Nr.34, S.345356 ISSN: 03769429 ISSN: 15732673 ISSN: 00207268 

 Englisch 
 Zeitschriftenaufsatz 
 Fraunhofer IWS () 
Abstract
Tunneling cracks driven by drying in a ceramic precursor confined between two glass plates represent a simple type of threedimensional (3D) crack pattern. They arrange themselves via mutual unloading which causes some cracks to stop whereby the remaining ones get the right spacing for further propagation. By extending a 2Dmodel of selfdriven propagation of crack arrays, a fracture mechanical bifurcation analysis for 3Dcrack patterns based on calculating the postcritical contour of the alternating bifurcation mode has been developed. Shrinkage due to drying is replaced here by a simplified thermomechanical model based on an effective heat flow whose related temperature field and thermal stresses drive crack propagation. By means of the finite element method, the propagation velocity and the minimum spacing between the steadystate parallel tunnelling cracks are determined. Comparison of theory and experiment suggests that propagation may be nonstationary in these experiments. The observed relation between crack spacing and layer thickness, p similar to e(2/3), follows from a scaling analysis.