Seminar - Itai Einav - Micro-Thermo-Mechanics For Randomly Distributed Elasto-Plastic Materials

Friday, April 1, 2005, 1.10 - 1.50 pm
Civil Engineering Lecture Room 3

Abstract

Many engineering materials such as granular assemblies, cellular metallic foams and different type of ceramics are playing an increasing role in providing solutions to our everyday needs. Metallic powders are applied as surface coatings and in component manufacturing for automotive industry; cellular metallic foams are used as implants replacing the superior mechanical characteristics of trabecular bones due to their unique architecture, high stiffness and strength and damping properties; ceramics are used in dentistry to sustain the complex environment of high cyclic stresses, with a US market of $200-$250 millions for the crowns ceramics industry alone. Although those materials may intuitively seem rather different, they are physically and phenomenologically related. Physically, their micro-mechanical structure can be represented using the concept of Voronoi tessellation, they usually tend to posses fractal geometry and self-similarity, and many of them are heavily density (or pressure) dependent. Phenomenologically, upon loading their stress-strain curves are non-linear, and upon unloading and reloading they indicate the presence of plastic strains and often damage.

The state of the art in modelling these materials usually involves the physical characterization of their micro-scale geometric-mechanical properties followed by the use of traditional homogenization techniques mapping these properties into their macro-scale constitutive behaviour. But there is something fundamental missing. So far homogenization techniques have been capable to represent quite consistently the mapping of elasticity properties, but the few attempts in mapping their plasticity properties usually failed or ended up with either non-applicable or non-approachable equations that are questionably satisfying the laws of nature in the form of thermodynamics.

In this seminar an alternative is suggested for modelling randomly distributed elastoplastic materials. When combined with modern thermomechanical approach, many of the phenomenological constitutive features could be explained directly from the microscopic quantities of the materials. As an example, a model will be presented, rationalizing the aspect of soil particle crushing under the action of compression loading.

Short Biography
Itai completed his undergraduate and graduate education at the Technion, Israel Institute of Technology, with a PhD in Civil Engineering in September 2002. In December 2002 Itai has joined the Centre for Offshore Foundation Systems (COFS) at the University of Western Australia (UWA). Recently, Itai has been awarded four years of Australian Postdoctoral Fellowship to work on developing and applying “continuum damage mechanics in geotechnical engineering.” Further interest in the material modelling field includes the characterization of advanced engineering materials and biomechanical materials. Other topics of research range from the development of energy methods and variational techniques for soil-structure interaction problems to applications of limit analysis in penetration problems.