Crack propagation in brittle porous media under compression

אודיטוריום ע"ש דיוויד וואנג, קומה 3, בנין דליה מידן
Lihi Shenhav, MSc candidate

Lihi Shenhav, MSc candidate
Dept. of Materials Science and Engineering
Technion, Haifa-32000, Israel

Over the last three decades, a tremendous amount of investigations have been performed in evaluating the mechanical properties and modeling of foams, or cellular brittle and ductile materials, under tension and under compression, in the presence of stress concentration such as holes and slits . However, to the best of our knowledge, crack propagation under compression in brittle foams and similar porous materials has not been thoroughly investigated yet. It is therefore the aim of this research is to deepen the knowledge on how brittle porous materials break under compression.

A model material for anticrack-type fracture under compression was fabricated by 3D printing. These models consist of open cubic and rhombohedral cells of well-defined geometry. As such, repeatability of the effective elastic modulus and fracture properties is expected. Basic mechanical properties, crack initiation, the effective elastic modulus, strength and fracture energy under compressive stresses were evaluated both experimentally and numerically. Euler Beam buckling based model at the process zone with exact bridging law fitted to experimental local strains at the crack tip by Digital Image Correlation (DIC) method well predicts the fracture energy of the material.

Fig. Digital Image Correlation (DIC) camera images of the process zone during loading; gradual but fast collapse of the rods under buckling is shown from top left to bottom right.

The conclusions of this research applies to practical problems in several disciplines and at multiple length scales: geophysics (earthquakes in the deep crust), engineering (cutting-edge lightweight materials), natural hazards (snow avalanches) and in medicine (human bones), all of great interest to the fracture community and the associated fields.

Supervisor: Prof. Dov Sherman