Project C1: Macro- and meso-scale composites (Laminated and layered structures)
C1.1: Foam Sandwich Laminates
•	Key researchers: M. Hoffman, T. Vodenitcharova, M. Idris, K. Kabir, D. Moore
Progress towards targets in the research projects of the Centre
The project had the following targets for 2007. All have been achieved:
•	Determination of deformation process of foam under quasi-static contact load.
•	Determination of the effect of ‘typical’ brittle and ductile skins upon quasi-static contact damage.
•	Development of experimental relationship between contact damage and residual strength under bending.
Technical Report
Experimental work:
•	Aluminium metal foam–only (ALPORAS) panels have been tested to uniaxial compression, to obtain the working stress-strain diagram needed for the modelling of the crushing force.
•	Local damage of various shape and volume was experimentally simulated by indentations with various indenters – long flat-end punch, long cylindrical punch, bottom-end cylindrical punches, and hemispherical punches.
•	The failure modes were determined.
Figure C1 - Deformation modes of aluminium foams subjected to localised contact damage, showing cell crushing and cell wall tearing.
Modelling and analysis:
•	The crushing force was numerically modelled. The tear energy was defined, and the absorbed energy and indentation pressure were calculated.
•	The results were analysed. Relationships were found between the absorbed energy, tear energy and indentation pressure, and the indenter shape/ size and foam density.
•	The flat-end punch indentation was simulated using the Finite Element Method.
Key items of infrastructure acquired during the project includes LS–DYNA software (finite element software with implicit solver for dynamic loading solutions).
C1.1.1: Metal foam based hybrid structures laminated with fabric face sheets
•	Key researchers: M. Hoffman, M.Idris, T. Vodenitcharova
Technical Report
•	The failure modes were determined in indentation and bending.
	Analysis of deformation response of sandwich panels – undamaged and damaged with spherical indenters – to three-point bending, was carried out.
•	Relationships were found between the bending strength, and the indenter sizes and beams span.
•	The response of the sandwich to indentation will be modelled analytically, as well as using FEA.
Figure C2 - Deformation of aluminium foam laminate with carbon fibre skin following bending.
Figure C3 - Contact deformation of aluminium foam laminates with carbon fibre skin on surface (a) and (c), and cross-section (b) and (d).
C1.1.2: Metal foam based hybrid structures laminated with aluminium face sheets
•	Key researchers: M. Hoffman, K. Kabir, T. Vodenitcharova
Technical report
•	Sandwich panels of ALPORAS foam and Aluminium face sheets were bent in three-point and four-point bending.
•	Failure modes were determined.
•	Results were analysed and the bending strength was evaluated as a function of the beam span and the panel thickness.
•	The absorbed energy was calculated up the failure point.
•	Indentation experiments were also carried out. The failure modes were determined.
Figure C4 - Deformation of aluminium foam/aluminium skin sandwich panel following bending to high strain.
C1.1.3: Indentation response of sandwich panels under impact load, and bending strength of the damaged sandwich structures
Only training in using the impact tester has been undertaken.
C1.2: Nano-micro laminated composites
C1.2.1: Development of nanolayered systems
Key researchers: P. Dayal, N. Savvides (CSIRO), M. Hoffman
Currently, there is intense world-wide interest in enhancing the mechanical properties of Aluminium-based light metals. Recent advancement in nanotechnology has given us the ability to tailor material properties at atomic scale. One good example of such synthetic materials is nanolayered material. Nanolayered material can be defined as the specimen consisting of alternate nano-layers of two different materials. Over the past few years, it has been shown that these nanolayered materials exhibit enhanced mechanical properties compared to that of individual constituent layers. In the similar trend, Al-based nanolayered light metals are expected to show better mechanical strength compared to pure aluminium. Also, at the current stage of world-wide research on nanolayered materials, exact mechanism of strengthening is not well understood. Better knowledge of strengthening mechanism might help in designing future advanced materials including Al-based light metals. In this project, we are trying to fabricate Al-based nanolayered light metals and study its deformation behaviour to get better understanding of strengthening mechanism.
At the current stage of this project, Al-based nanolayered thin films have been fabricated successfully using magnetron sputtering facility at CSIRO. Exact material system cannot be disclosed at this moment because results are not yet published. After fabrication, these thin films were characterised using nanoindentation for their mechanical properties. Result showed significant enhancement in mechanical properties compared to that of pure Al film. Currently, advanced characterisation techniques such as X-Ray Diffraction (XRD), nanoindentation, Focussed Ion Beam milling (FIB), and High Resolution Transmission Electron Microscopy (HRTEM) are being used to understand the structure-property relationship and deformation behaviour for these nanolayered thin films.
C1.2.2: Numerical modeling of laminate deformation
Key researchers: S. Ringer, G. Ranzi, C. Moy
The following 2007 goals were partially achieved:
•	Development of initial model in Abaqus based on linear-elastic material properties.
•	Initial implementation of different constitutive models for individual layers.
•	A numerical model has been developed for the direct analysis of layered samples including elastic, plastic and hardening material properties.
Specifically, an inverse analysis technique has been set-up using the direct analysis to identify material parameters of the different layers using experimentally observed measurements from nano-indentation tests. This approach has been tested against computer generated experiments considering elastic and plastic properties of samples with alternating layers.