Cellular and Porous Materials in Structures and Processes (Cellular and Porous )
Venue: CISMM, Udine, Italy
|Event Date/Time: Sep 28, 2009||End Date/Time: Oct 02, 2009|
|Registration Date: Sep 25, 2009|
|Early Registration Date: Sep 02, 2009|
Engineering structures made of porous materials, especially metal foams and powders, have been used in different applications in the last decades. Metal foam is a cellular structure consisting of a solid metal, for example aluminium, steel, copper etc., containing a large volume fraction of gas-filled pores. There are two types of metal foams: namely, closed-cell and open-cell foams. The defining characteristic is a very high porosity: typically well over 80%, 90% and even 98% of the volume consists of void spaces. Another example of perspective material is syntactic foam. They are composite materials synthesized by filling a metal, polymer or ceramic matrix with hollow particles.
The course is devoted to cellular and porous materials, and the modelling of the material behaviour, but also the analysis of structures made of foams, the testing, processes, and applications will be discussed. The first question is on which scale one has to model the material. In materials modelling, a minimum of three scales can be distinguished: namely, micromechanical, mesomechanical, and macromechanical scale. During the lectures the advantages and disadvantages of each approach will be demonstrated.
The basics of the analysis of structures made of foams in metal powder technology are the continuum mechanics. The foundation of the theory of elasticity are briefly presented. In addition, the introduction to the theory of plasticity and viscoelasticity is given. Special attention will be paid to the yield criteria because foams are pressure sensitive, anisotropic and have different behaviour in tension and compression.
Many structural elements made of foams can be presented by beam, plate or shell models. As an example, a special plate theory will be presented. One of the basic elements of this theory is the effective property concept. Such a theory is suitable for the global analysis of plates (deflections, frequencies, etc.). It will be shown that in the case of foams classical approaches like the Kirchhoffâ€™s plate theory may result in wrong results. How to improve theories will be demonstrated for three application cases: the bending problem, the eigenvibration problem, and the viscoelastic problem.
Specialised lectures cover in detail further advanced topics such as the finite element modelling, fracture mechanics and the impact behaviour.