Description

The unique properties - the shape memory effect and super-elasticity - of shape memory alloys (SMAs) are used in numerous engineering applications ranging from biomedical to aerospace. These special properties are the result of solid-solid phase transformation, the main feature of which - hysteresis - is widely studied for the industrial applications it enables. In particular, the hysteresis of SMAs (involving energy dissipation) has been used to absorb the energy of mechanical vibrations and thus protect structures. It is well established that the damping capacity of AMF structures is influenced by several phenomena such as thermomechanical coupling [1-4]. With the rapid development of the new Additive Manufacturing (AM) process, it is possible to considerably improve the damping capacity of AMF devices by combining the 'smart' properties intrinsic to AMF (super-elasticity, one-way and two-way shape memory effect, etc.) and the optimization of the AMF microstructure using the AMF process (architected materials and cellular structures).
This thesis aims to develop a new concept for an SMA damping device not only to improve damping efficiency (higher damping capacity and lower mass) but also to minimize permanent plastic deformation in the devices, enabling recovery of their initial shapes after shock/oscillation ('self-centering' using the shape memory effect). To achieve these objectives, the PhD student will study and model the FA process of SMA, and characterize the thermomechanical properties of the FA-derived SMA [5]. Finally, a new dynamic constitutive law for architected shape memory materials will be proposed to evaluate/predict the performance of the 'smart' damping device.

Skills required

Mechanics of continuous media, plasticity, numerical analysis

Bibliography

[1] Z. Moumni, Wael Zaki and Q.S. Nguyen, 2008, Theoretical and numerical modeling of solid-solid phase change: Application to the description of the thermomechanical behavior of shape memory alloys, International Journal of Plasticity, vol. 24, n°6, p. 14-645.
[2] W. Zaki and Z. Moumni 2007, A three-dimensional model of the thermomechanical behavior of shape memory alloys, Journal of the Mechanics and Physics of Solids, vol. 55, p. 2455-2490.
[3] H. Yin, Y.J. He, Q.P. Sun, “Effect of deformation frequency on temperature and stressoscillations in cyclic phase transition of NiTi shape memory alloy”, Journal of the Mechanics and Physics of Solids 67, 100–128(2014).
[4] L. Zheng, Y.J. He, Z. Moumni “Investigation on fatigue behaviors of NiTi polycrystalline strips under stress-controlled tension via in-situ macro-band observation” International Journal of Plasticity 90, 116-145 (2017).
[5] Z. Moumni, F. Roger and T. Ngoc, 2010, Theoretical and numerical modeling of the thermomechanical and metallurgical behavior of welded steel. International Journal of Plasticity,vol. 27, n°3, p. 414-439.

Keywords

Smart materials, Additive manufatcuring, Architected materials , Topology optimization