۴D printing of cellular structure damper of iron base shape memory alloy using wire arc additive manufacturing

Recently, Jafarabadi et al [۱] explored seismic dampers fabricated from Fe-SMAS via powder bed fusion additive manufacturing. Their evaluation of two Fe-SMA compositions revealed significant potential for energy absorption in seismic-protection applications [۱]. The present study focuses on the fabrication, process optimization, and mechanical evaluation of architected structures made from Fe-based shape memory alloy (Fe-SMA) using Wire Arc Additive Manufacturing (WAAM). The work includes wire production, optimization of parameters, design of deposition path strategies, heat treatment of printed walls, and compression-testing-based mechanical assessment of the carbon steel and Fe-SMA specimens. Feedstock preparation began by reducing the diameter of ۱۸-mm Fe-SMA rods through hot forging and hot shape rolling to approximately ۵ mm, followed by wire drawing to obtain a final diameter of ۰.۸ mm suitable for WAAM processing. WAAM parameters including current, voltage, travel speed, and wire feed rate were optimized by printing multiple single-layer tracks of carbon steel and Fe-SMA. After final deposition path strategies refinement, carbon steel and Fe-SMA specimens were successfully printed with final heights of approximately ۱۳ mm and ۱۱ mm, respectively. Printed Fe-SMA walls were subjected to two heat-treatment conditions: aging at ۷۵۰ _x۰۰۱۷_۶C for ۶ h and double-aging at ۴۸۵ _x۰۰۱۷_۶C for ۶ h. Tensile and bending specimens extracted from these walls were tested under both conditions. Results were used to select the suitable heat-treatment route for damper fabrication. Mechanical evaluation of the printed dampers was performed through cyclic compression testing. Fe-SMA specimen reached a displacement of approximately ۱۴ mm under continuous loading. In cyclic tests, both carbon steel and Fe-SMA dampers were compressed to ۱۰ mm for six repeated cycles, and Digital Image Correlation (DIC) was used to monitor strain distribution during loading. After each cycle, Fe-SMA specimen was thermally recovered at ۲۰۰ _x۰۰۱۷_۶C for ۳۰ min to restore their original geometry. Force-displacement data were used to calculate energy absorption versus nominal strain, as well as energy absorption and energy dissipation per unit volume versus compressive strength. The comparison between carbon steel and Fe-SMA dampers provided input for refining geometric parameters for larger-scale designs.

کلیدواژه ها:

۴D Printing ، Cellular Structure ، Shape Memory Alloys ، Wire Arc Additive Manufacturing (WAAM)