A micromechanical model for shape memory alloy fiber reinforced plastics considering cyclic hygrothermal damage

This study presents a micromechanical constitutive model for Shape Memory Alloy Fiber Reinforced Plastics (SMA-FRP) that considers cyclic hygrothermal damage. The SMA-FRP composite consists of SMA fiber inclusions embedded in a polymer matrix, leveraging the advantageous properties of both smart alloys and multifunctional composites. The model introduces a thermal cycling damage factor for the SMA fiber and a hygrothermal cycling damage factor for the resin matrix, establishing a constitutive framework that highlights how the combined effects of moisture and temperature significantly accelerate material damage accumulation. To enhance the characteristics of this composite, a homogenization process for the mechanical response is applied using the Mori-Tanaka method, which is based on Eshelby’s equivalent inclusion theory and incorporates hygrothermal effects. This process includes the homogenization of the effective overall elastic strain tensor, the average phase transformation strain tensor from the SMA inclusion, the average thermal strain tensor from the inclusion and matrix, as well as the average hygroscopic strain tensor from the matrix, providing a comprehensive view of the super-elastic hysteresis under hygrothermal conditions. The thermodynamic constitutive model for the SMA inclusion is highly compatible with the proposed homogenization approach for SMA-FRP, offering computational efficiency. This model effectively quantifies the influence of external factors on SMA-FRP.