Thermal cycling of (heated) fibre metal laminates

Abstract

Fibre metal laminates with integrated heater elements have a promising potential as de- or anti-icing systems in aircraft structures. The alternating metal and composite lay-up in fibre metal laminates seems ideal for the development of a multifunctional skin with embedded heater elements. However, the long term durability needs to be carefully examined.

A unique thermal cycling setup has been designed and built to investigate the effects of thermal cycling on the material properties of GLARE (glass fibre reinforced aluminium). Peltier elements were used to provide external heating and external cooling by inverting the direction of the electrical current. With the same setup, heated GLARE samples can be internally heated using the integrated heater elements and externally cooled using the Peltier elements.

Glass-fibre epoxy composite, GLARE, and heated GLARE samples have been thermal cycled for 4000, 8000 and 12,000 cycles with temperature differences of 120 °C. The interlaminar shear strength (ILSS) increased by 6.9% after 8000 cycles for the glass-fibre epoxy composite material compared to the non-cycled samples. The GLARE samples showed a maximum ILSS increase of 4.2% after 12,000 cycles. However, the heated GLARE samples showed a continuous decrease of the ILSS with a maximum decrease of 7.8% after 12,000 cycles.