Our group investigates brittle fracture in various materials ranging from ceramics, semiconductors, human bones, porous materials and fracture phenomena in earth crust. We combine fundamental problems with practical ones. Our research is mainly experimental supported by computer calculations of various scales, finite element analysis to atomistic. We integrate with industries and international research groups to widen our knowledge and solve up to date problems in fracture mechanics.
After world war II there were significant break throughs in the study of fracture mechanics following several unexpected disastrous events of failure occuring in the Liberty ships and Comet aircrafts.
|Two known failure events are presented which occured during world war II. Brittle fractue in the Liberty ship due to thermal shock (Left) and, a specific model of the Comet aircrfat which failed due to critical stress concentration build up around the squared passenger windows (Right).|
The catastrophc failures have led to new governmental regulations and funding researches in fracture mechanics aiming at supervising and controling the safety of new developed engineered constructions.
Fracture is a phenomenon found in our every day life, whether in nature or in engineering, may occur in every material and shape – in human bones to earth quakes, from the micronscale to hundreds of kilometers lengh scales. The necessity to build stable and reliable constructions was already acknowledged in ancient egypt and greece by developing experimental mechanical rules for safe building of temples and pyramids.
Examples for fracture found in nature. Fracture in bones (Left) and, cleavage following an earth quake (right).
Cracks propagation and fracture by itself can teach a lot about interesting phenomena occuring in all life aspects. For example, cracks which appear in paint and, mud cracks in dried layers:
|Common fracture-like phenomena found in: a. mud, b. asphalt, c. paint (Mona Liza), d. crater in mars (500 m) e-f. meter length of lava in Ireland Giant’s Causway and, g. Hexagon pool in Israel, Ramat Hagolan, showing fissures.|
Today, researches show that fracture is a multiscale phenomenon which occurs macroscopically but originates at the atomic level. The ability to visualize, treat, control and prevent cracks propagation is a huge challenge for engineers. Practically, even though the technology today is very advanced, a solution for predicting catastrophic failure has yet to be found. It is only possible to analyze these fractures in post-mortem. The analyzing methods available today combine accurate laboratory fracture experiments, high resolution fracture surface analysis and, mathematical tools simulating dynamic fracture including the stress and displacement fields at the crack tip, continuum and atomistic.