Mesoscale Analysis of Flexural Behavior of SME SMA Fiber-Reinforced Mortar Beams Considering Fiber Geometry and Volume Fraction

This study examines the influence of the geometry of mortar beams reinforced with crimped shape memory alloy fibers on flexural behavior using the mesoscale finite element method. Moreover, the shape memory effect, induced by heating, which generates prestressing inside the mortar matrix was simulated and considered in this model. To this end, 240 mesoscale beams were modeled using fibers with diameters ranging from 0.3 mm to 1.0 mm; lengths of 20.0 mm, 30.0 mm, and 40.0 mm; and fiber volume fractions of 0.25%, 0.5%, 0.75%, 1.0%, and 1.25%. The mesoscale finite element method beams were generated using Python scripting and analyzed in a finite element environment. The results indicated that the flexural capacity and toughness of the beam were enhanced by increasing the volume fraction of the fibers. For the unheated models, the peak load ranged from 2.96 to 5.64 kN, whereas the heated models exhibited peak loads of 3.11–6.79 kN. Thermal activation increased the peak load by approximately 1.7–20.3%, with the average increase rising from 5.8% at a fiber volume fraction of 0.25% to 14.9% at 1.25%. Increasing fiber length and volume fraction generally improved peak load and toughness, whereas increasing fiber diameter severely reduced performance, particularly at diameters of 0.9 and 1.0 mm. Additionally, increasing the fiber length and the aspect ratio of fibers while maintaining the same volume fraction also improved both the flexural capacity and toughness of the beam. However, the heated beams, in which prestressing was induced by the shape memory effect showed a higher peak load than that of the non-heated case. Nevertheless, the heated beams showed a lower toughness capacity and disappearance of the initial crack point compared to the non-heated beam. Thus, the mesoscale finite element method can effectively examine the effects of the geometry of fibers on flexural behavior with acceptable results at low cost and reduced time compared to experimental tests. Moreover, the mesoscale finite element method model can feasibly and thoroughly investigate the stress distribution inside the fibers. Therefore, the authors strongly recommend using the mesoscale finite element method to analyze the beams reinforced with shape memory alloy fibers. It also suggested that the geometric parameters of the fibers significantly enhance the beam’s flexural performance. Nonetheless, further experimental and interface-level validation is required for stronger confirmation.