An experimental and theoretical fatigue study on macro fiber composite (MFC) under thermo-mechanical loadings

Macro fiber composite (MFC) is widely used for various applications especially in the area of sensors, actuator, structural health monitoring and vibration control due to its improved electro-mechanical coupling and flexibility. While being used for these applications, the MFCs might be subjected to cyclic mechanical load at various operating temperatures leading to the deterioration in the sensing performance. Hence, to study the life of the MFCs (d31&d33 type) as a sensor, an experimental setup is devised and tests are performed for various thermo-mechanical loading conditions. Experiments involve huge investment in terms of cost and time. Therefore, in the present work, a theoretical model consisting of non-linear finite analysis integrated with the cumulative damage theory is derived to predict the fatigue behaviour of the MFC. The degradation in the piezoelectric coupling coefficient obtained using the present model is able to capture the non-linear trend observed from the experimental observations and the values are in good comparison. The non-linear FE model is also extended to predict the degradation of stiffnesses and strengths of the MFCs due to various thermo-mechanical loading conditions.