A numerical investigation of the nucleation and the propagation of NiTi martensitic transformation front under impact loading

• Published in: International journal of impact engineering 2021-06, Vol.152, p.103841, Article 103841
• Main Authors: Xiao, R., Hou, B., Sun, Q.P., Zhao, H., Li, Y.L.
• Format: Article
• Language: English
• Subjects: Elastic limit; Elastic waves; Finite element method; High strain rate; Impact loads; Impact tensile test; Impact velocity; Intermetallic compounds; Martensitic transformations; Mechanical tests; Nickel base alloys; Nickel titanides; NiTi superelastic SMA alloy; Nucleation; Numerical analysis; Numerical models; Numerical simulation; Phase transformation front propagation; Phase transitions; Shape memory alloys; Speed limits; Tensile tests; Thermodynamic models; Velocity
• ISSN: 0734-743X; 1879-3509
• DOI: 10.1016/j.ijimpeng.2021.103841

•Abaqus Explicit user's law implementation of a thermodynamic model of NiTi SMA.•Good agreement between experimental and numerical results for impact SHTB tests.•High strain level ahead of a transformation front is due to the loading conditions.•A virtual impulse without the rising time generates a single transformation front.•Simulated single front speed can exceed the shear wave speed at high impact speed. A numerical investigation of NiTi SMA alloy under impact loading is presented in this paper. It is aimed at better understanding the observed behavior of NiTi SMA specimen loaded at impact velocities (up to 50m/s). A phenomenological thermodynamic model with an explicit integration frame is chosen and implemented as a user's law in Abaqus explicit commercial code. The parameters of the model are determined from the usual thermal-mechanical testing data without any tuning. The comparison between numerical and experimental results shows a satisfactory agreement, which proves the pertinence of the proposed numerical model. Using this numerical model, the reason of the experimentally observed inconstant strain level ahead of the phase transformation front is found. Instead of a material feature of NiTi SMA under impact loading, such a phenomenon is only due to the loading condition. Virtual tests at very high impact velocities are performed. Steep impulses without a rising time is chosen in order to have only one transformation front propagating inside the specimen, knowing that it is not possible to obtain such a simple condition in a real tensile test. A steady transformation front is observed and there is an asymptotical speed limit of this propagating front when the impact velocity increases. This speed limit is higher than the shear elastic wave speed but lower than the longitudinal elastic wave speed.