Influence of internal stress on magnetostrain effect in Ni–Mn–Ga/polymer composite

• Main Authors: Pimpet Sratong-on, Volodymyr Chernenko, Hideki Hosoda
• Format: Article
• Language: English
• Published: Elsevier 2019-09-01
• Series: Results in Materials
• Subjects: Ni–Mn-Ga/Silicone composite; Ferromagnetic shape memory alloys; Finite element analysis; X-ray micro-CT; Recoverable magnetostrain; Internal stress reversal
• Online Access: http://www.sciencedirect.com/science/article/pii/S2590048X19300378

The outstanding role of internal stress in the silicone matrix driving a magnetostrain reversal of embedded particles of the Ni–Mn-Ga ferromagnetic shape memory alloy after removal of magnetic field, has been disclosed by finite element (FE) simulations and validated by experiment. For simulations, the three case studies have been considered: an isolated particle, and the particles pairs aligned parallel or perpendicularly to the applied magnetic field. The isolated particle provided a 0.4 ​MPa of the reverse stress accumulated in a matrix that was insufficient to recover the composite shape after the removal of magnetic field. Simulations revealed that the strong elastic inter-particle interactions are needed to enhance both the local effective stiffness of composite and the reverse stress. The case where the particles pairs with the optimized inter-particle distance are aligned perpendicularly to the applied magnetic field, is more favorable to obtain the largest magnetostrain recovery. Simulation results demonstrate a 1.8% of the compressive magnetostrain of the 30 ​vol%Ni–Mn-Ga/silicone composite under the field applied parallel to the particles chains, which is in agreement with the experiment. The criteria for a selection of matrix, facilitating a large reversible magnetostrain of composite, have been determined.