Corsi 2022-2023

Teachers: Prof. Ondrej Jirousek, Prof. Anne Jung

Hours / Credits: 3h / 1cf

Dates: 

Tue 25 October - 14:30 -> 17:30

Topics:

Mechanical properties of metamaterials (organized by Prof. L. Biasetto)

Metamaterials are defined as materials possessing non naturally occurring properties (such as negative Poisson’s ratio or refractive index) that depend on the materials’ geometry made of three-dimensional repeating units. 3D printing represents a suitable technology to produce these complex structures.

The two seminars proposed in this short course will offer an introduction to preparation modes, characterization and simulation of metamaterials.

 

1)     Preparation, multiscale mechanical characterization and simulation of hybrid foams and metamaterials

Prof. Anne Jung

Universität des Saarlandes, Germany

 

2)     Strain rate dependency of 3D printed metamaterials

Prof. Ondrej Jirousek

Czech Technical University in Prague, Czech Republic

 

3D printing has enabled to design and manufacture highly optimized structures which can have very unique properties. These properties can be tailored to a specific use or to have very special properties. Thanks to 3D printing, it is possible to design structures and materials that are very lightweight yet rigid, even optimized in their internal structure for a given stress state. One way to design such a material or component is to use topological optimization. Often complex internal structure is used to achieve the maximum ratio between weight and stiffness of the material, but in general 3D printing can be used to achieve almost any desired property, for instance, negative Poisson's ratio.
Some materials possess strain rate dependent material properties, i.e. they behave differently when subjected to loading at different loading velocities (strain rates). This behaviour can be essential for e.g. crash and impact applications and the exact knowledge of the behaviour is essential for numerical modelling, i.e. proper constitutive modelling must be used in a numerical crash and impact analyses.
To investigate the strain rate dependent properties it is necessary to perform a series of experiments at different strain rates. This is important namely in plasticity, when the flow stress of the material exhibits a dependence on the strain rate, mostly in the form of a dynamic amplification of the static flow stress.
The most used experimental technique to establish this dependency of the flow stress on the strain rate is the Split Hopkinson Pressure bar (SHPB).
In the talk experimental techniques to assess this strain rate dependent mechanical properties will be described with a special attention on 3D printed materials and structures. Overview of digital image correlation techniques used for evaluation of the strain fields on the sample surface will be given together with an overview of instrumentation of the SHPB experiment designed for dynamic testing of materials with low mechanical impedance, particularly for cellular 3D printed structures.

Location

Viale Margherita: Room "Sala 8" -> VM18

Vicenza, Dipartimento di Tecnica e Gestione

Evaluation:

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