Session B6: Particulate, Porous and Composite Materials I: Foams and Composites

Dynamic Crushing Response of Closed-cell Aluminium Foam at Variable Strain Rates

The impact response of aluminium foams is essential for assessing their crashworthiness and energy absorption capacity for potential applications. The dynamic compactions of closed-cell aluminium foams (CYMAT) have been tested at variable strain rates. Microstructural characterization has also been carried out. The low strain rate impact test has been carried out using drop weight experiments while the high strain compaction test has been carried out via plate impact experiments. The post impacted samples have been examined using optical and electron microscopy to observe the microstructural changes during dynamic loading. This combination of dynamic deformation during impact and post impact microstructural analysis helped to evaluate the pore collapse mechanism and impact energy absorption characteristics.   

Impact and damage of an armor composite

The use of carbon fiber composites under shock and impact loading in aerospace, defense and automotive applications is increasingly important. Therefore prediction of the composite behavior and damage in these conditions is critical. Influence of anisotropy, fiber orientation and the rate of loading during the impact is considered in the present study and validated by comparison with experiments. The experiments deal with the plane, ballistic and Taylor impacts accompanied by high-speed photography observations and tomography of recovered samples. The CTH hydrocode is employed as the modeling platform with an advanced rate sensitive material model used for description of the deformation and damage of the transversely isotropic composite material.   

An Investigation of The Reticulated Foam - Perforated Steel Sheet Sandwich Structure As A Blast Mitigation Media

Explosions have always been the main cause of injuries during battles and conflicts, with improvised explosive devices (IEDs) becoming more and more common nowadays. In this paper, the interaction between blast waves and sandwich structures of reticulated foam and perforated sheets, with varying thickness and configuration, is studied using an air-driven shock tube apparatus. The mitigation effects for primary blast injuries of these structures are discussed in terms of pulse shape, pressure magnitude as well as shock impulse. Schlieren photography together with other high-speed imaging was also used to visually investigate the matter. The results show that lower open area of perforated sheet and increased thickness of foam offer best protection. However, below a threshold thickness, no mitigation is seen.   

On~the compression of Aluminium foam structures under shock

Foam-based materials have an important role as both blast and impact mitigators, with their extended sub-surface structures providing multiple redundant routes for load management and distribution in the event of failure.~ In order to further elucidate underlying stress management mechanisms at high strain-rates, here, a series of Aluminium foams manufactured via rapid prototyping techniques were investigated via the plate-impact technique.~ These experiments allowed the material to be loaded under a quasi one-dimensional state of strain. ~The nature of pore collapse was monitored via manganin stress gauges at the target rear surface, with resultant data related back to changes in microstructure via microstructural and topographical analysis of both un-impacted and recovered target material.