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Tuesday, May 18, 2010

Simulated and Experimental Damping PROPERTIES of A SMA/Fiber Glass Laminated COMPOSITES

S. Arnaboldi, P. Bassani, A. Tuissi, CNR IENI Istituto per l'Energetica e le Interfasi, Lecco, Italy; M. Carnevale, C. Biffi, A. Lo Conte, B. Previtali, N. Lecis, Politecnico di Milano (Technical University of Milan), Milan, Italy

Shape memory alloys (SMA) posses high damping capacity due to their shape memory effect, pseudo-elasticity, and damping capacity of the martensitic phase. Through the combination of these important functional properties of shape memory alloy with the mechanical properties of the glass fiber reinforced polymer, it could be possible to design smart and light weight composites for the vibrations control of mechanical systems.

In this paper an advanced laminated composite is developed, with a epoxy fiber glass core covered by two thin patterned sheet of SMA material, respectively covered by two layer of epoxy fiber glass. The patterning enhance the interface between matrix and SMA insert. Moreover, increasing locally the SMA strain amplitude an increasing the amount of the vibration energy transmitted to the damping alloy, the patterning allows to optimally use the damping capacity of the SMA thin sheet.

A Ni40Ti50Cu10 alloy was used for the pattered insert. The alloy has been hot and cold rolled in order to obtain 20mm x 200mm samples with thickness 0.15mm. Damping properties at different amplitude and frequency on full scale sample (20mmx200mm), were investigated at room temperature with an MTS machine, through dynamic tension tests .

Temperature dependence of damping properties was investigated with dynamic mechanical analyzer (DMA) experiments, on smaller sample, with heating/cooling rate of 1K/min.

Experimental results were used in conjunction with FEM analysis to optimize the pattern of the insert. The patterned laminae of the SMA alloys were obtained by mean of an innovative pulsed active fiber laser source. The bars of the laminated composite were assembled and cured in autoclave. Experimental decay tests have been carried out on the fabricated bars in order to identify the non dimensional damping value related to their first flexural mode.


Summary: In this paper an advanced laminated composite is developed, with a epoxy fiber glass core covered by two thin patterned sheet of SMA material, respectively covered by two layer of epoxy fiber glass. The patterning enhance the interface between matrix and SMA insert. Moreover, increasing locally the SMA strain amplitude an increasing the amount of the vibration energy transmitted to the damping alloy, the patterning allows to optimally use the damping capacity of the SMA thin sheet.