Optimization of a shift in the natural frequency of a nitinol-reinforced composite beam

Many engineering applications are being developed using smart adaptive composites to tailor their static and dynamic performance. Shape Memory Alloy (SMA) reinforced composite can change its physical properties with respect to temperature, thus becoming adaptive to cope with changing operational conditions. Hence it is essential to know the optimum parameters of such reinforced composite to ensure the best performance during operation. This paper investigates different design parameters of composite reinforced with Nickel-Titanium Alloy(nitinol) for the maximum shift in stiffness and, consequently, the natural frequency during SMA phase change. The full factorial design of the experiment is used for selecting the L27 orthogonal array. The optimum parameters are selected after presenting the Technique for Order of Preference by Similarity to the Ideal Solution (TOPSIS) ranking and validated using the Taguchi method. The composite with a combination of optimum parameters has been fabricated for the confirmation test. The confirmation test shows good agreement with optimization results. The distance of reinforced nitinol wires from the neutral axis is the most influencing parameter, followed by the volume fraction of nitinol and its activation pattern. The study shows that the optimum parameters for the maximum shift in natural frequency are a volume fraction equal to 3.53%, the reinforced wires are at a neutral axis, and all wires are activated. The composite beam studied in this work can shift a maximum of 27.09% of the natural frequency.