Fabrication of a New Model Hybrid Material and Comparative Studies of its Mechanical Properties
Cluff, Daniel Robert Andrew
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A novel aluminum foam-polymer hybrid material was developed by filling a 10 pore per inch (0.39 pores per millimeter), 7 % relative density Duocel® open-cell aluminum foam with a thermoplastic polymer of trade name Elvax®. The hybrid was developed to be completely recyclable and easy to process. The foam was solution treated, air quenched and then aged for various times at 180˚C and 220˚C to assess the effect of heat treatment on the mechanical properties of the foam and to choose the appropriate aging condition for the hybrid fabrication. An increase in yield strength, plateau height and energy absorbed was observed in peak-aged aluminum foam in comparison with underaged aluminum foam. Following this result, aluminum foam was utilized either at the peak-aged condition of 4 hrs at 220˚C or in the as-fabricated condition to fabricate the hybrid material. Mechanical properties of the aluminum foam-polymer hybrid and the parent materials were assed through uniaxial compression testing at static ( de/dt = 0.008s-1 ) and dynamic ( de/dt = 100s-1 ) loading rates. The damping characteristics of aluminum foam-polymer hybrid and aluminum foam were also obtained by compression-compression cyclic testing at 5 Hz. No benefit to the mechanical properties of aluminum foam or the aluminum foam-polymer hybrid was obtained by artificial aging to peakaged condition compared to as-fabricated foam. Although energy absorption efficiency is not enhanced by hybid fabrication, the aluminum foam-polymer hybrid displayed enhanced yield stress, densification stress and total energy absorbed over the parent materials. The higher densification stress was indicative that the hybrid was a better energy absorbing material at higher stress than the aluminum foam. The aluminum foam was found to be strain rate independent unlike the hybrid where the visco-elasticity of the polymer component contributed to its strain rate dependence. The damping properties of both aluminum foam and the aluminum foam-polymer hybrid materials were found to be amplitude dependant with the hybrid material displaying superior damping capability.