Experimental and theoretical investigations of macro fiber composite actuation degradation induced by the mechanical load

Macro Fiber Composite (MFC) demonstrates promising application in morphing structure actuation and structural vibration active control. MFC patches are subject to mechanical loads in conjunction with the structure, which may result in actuation performance degradation. The actuation may not proceed as intended after the degradation. However, the actuation degradation of MFC under mechanical loading has been rarely addressed. In this study, the actuation degradation of MFC under mechanical loads respectively at room and higher temperatures is first investigated by experiments. The experimental results indicate that the mechanical-induced MFC actuation degradation exhibits a nonlinear trend, and compressive loads show a trivial impact on the actuation degradation. Mechanical-induced actuation degradation becomes more significant with the increase of the tensile load and temperature. Further, a finite element model based on a damage evolution model is proposed for the sake of time and economic cost. The predictions align well with the experimental data. The experimental evidence and theoretical predictions show that the mechanical-induced actuation degradation arises from the MFC stiffness degradation and irreversible degradation of piezoelectric properties. The finite element model further verifies that the microcracks accumulation before the creation of the visible cracks contributes to the great initial degradation.