Elaboration and study of the fatigue behavior of a multifunctional composite material with embedded copper insert: The effect of thickness and electrical voltage

Abstract

The behavior of multifunctional composite material with an embedded copper foil strip under cyclic loading was investigated. Materials able to bare charge as well as conduct electricity are crucial in various applications in high-tech industries. The effects of applied stress, voltage levels and the dimensions of the insert on the material response were analyzed. Two types of composites were prepared: one with a 0.1 mm thick copper (GFC0.1) and another with a thickness of 0.05 mm (GFC0.05). Both materials were subjected to tensile and fatigue tests. The results revealed that the dimensions of the insert had an impact on the Maximum Tensile Resistance (MTR). The examination of the fatigue-damaged composite gave important insights about the evolution of the de-bonding area of the interface copper/composite under different loading conditions. Fatigue test results allow the plotting of fatigue curves and establishing the fatigue equation specific to each material under each voltage level (U = 5, 9, and 12 ± 0.3 V). These results also showed that when tested at the same voltage, there is one stress level for which both GFC0.1 and GFC0.05 have the same fatigue resistance; above this stress value, GFC0.1 has a better resistance, and below it, GFC0.05 will be the one resisting better. Epoxy resin was chemically dissolved to restore the damaged copper Nicked-eye inspection along with scanning electron microscope (SEM) observations revealed interesting facts about the metallic insert behaviors, including the nature of the rupture and the effect of the voltage on the fractured surface aspect.