Real-Time Hybrid Simulation of Shape Memory Alloy Dampers
Final Report Abstract
The research project was concerned with superelastic shape memory alloys as new-type of SMA based maintenance free dampers with effective energy dissipation and full re-centering capacities. Therefore, experimental investigations on NiTi-SMA wires with different geometries and chemical compositions were conducted. Random vibration patterns, such as by earthquakes and wind, include not only changing strain rates but also different strain amplitudes. Therefore, a shaking table was utilized to investigate the material behavior of superelastic SMA wires for harmonic and stochastic loading conditions. The separated consideration of the strain rate and strain amplitude effect reveals new insights in the quasi-static and dynamic material behavior of SMAs. Based on the experimental findings, constitutive modeling approaches are proposed and applied to existing macroscopic, one-dimensional material models for superelastic SMAs. On the one hand, the strain rate effect is covered by strain rate dependent formulations of the thermal energy. In fact, both a rate dependent entropy change formulation and a rate dependent latent heat formulation are proposed. The formulations serve to make the the constitutive model more sensitive to rate changes. On the other hand, a solution scheme is proposed to cover the observed strain amplitude effect, which causes a shift of the hysteretic curve not only to positive strain direction but also to a lower stress level during reverse transition. All proposed formulations serve to calculate the hysteretic surface and thus the dissipated energy per load cycle more accurately. The accurate calculation of the hysteretic surface is important to assess the energy dissipation potential or structural damping potential of superelastic SMA wires. Furthermore, a multistory steel frame equipped with SMA wires is designed, built and investigated in cooperation with the Hydraulic Structure and Earthquake Engineering (HSEE) lab at Tsinghua University, Beijing, China. The behavior of the multistory shear frame equipped with SMA wires under harmonic and stochastic loading conditions is investigated with shaking table tests at the HSEE lab. Based on the experimental findings, a more degree of freedom 2D- frame model is implemented. A comparison of experimental and numerical results reveals that the the structural response can be calculated accurately. The multistory steel frame is further used to conduct real-time hybrid simulation tests on a highly nonlinear structure. Therefore, a RTHS-based cyber-physical methodology, which employs a numerical soil-foundation model and simultaneously tests the SMA-controlled structure on a shaking table is proposed. Thus, soil-structure interaction effects on the vibration control performance of SMA wires were investigated.
Publications
- Effects of Cyclic and Seismic Loading on the Superelastic Behavior of Shape Memory Alloys. In Proc. of the 7th World Conf. on Structural Control and Monitoring, Qingdao, China; 2018
Kaup A., Altay O., Wang J.T. and Klinkel S.
- Rate-Dependent Thermomechanical Modeling of Entropy Changes in Superelastic SMA. In: Benjeddou A, Mechbal N, Deü JF, eds. In Proc. of the 9th ECCOMAS Thematic Conf. on Smart Structures and Materials. Paris, France; 2019
Kaup A., Altay O. and Klinkel S.
- Macroscopic modeling of strain-rate dependent energy dissipation of superelastic SMA dampers considering destabilization of martensitic lattice. Smart Mater Struct. 2020;29(2):025005
Kaup A., Altay O. and Klinkel S.
(See online at https://doi.org/10.1088/1361-665X/ab5e42) - Seismic Assessment of Shape Memory Alloy Dampers Considering Soil-Structure Interaction by RTHS. In Proc. of the 17th World Conf. on Earthquake Engineering, 17WCEE. Sendai, Japan; 2020
Ding H., Kaup A., Wang J.T., Lu L.Q. and Altay O.
- Strain rate dependent formulation of the latent heat evolution of superelastic shape memory alloy wires incorporated in multistory frame structures. J Intel Mat Syst St. Dec. 2020
Kaup A., Ding H., Wang J. and Altay O.
(See online at https://doi.org/10.1177/1045389X20975473) - Rate dependent free energy formulations for dynamically excited superelastic SMA wires. Proc. Appl. Math. Mech. 2021. 20: e202000209
Kaup A., Altay O. and Klinkel S.
(See online at https://doi.org/10.1002/pamm.202000209) - Real-time hybrid simulation technique for performance assessment of engineering structures and their components. In Proc. of the 2nd International Conference on Seismic Design of Industrial Facilities. Munich (Online), Germany; 2021
Altay O., Kaup A., Wang J.T. and Klinkel S.
