Numerical simulation of the behavior of steel T-stubs connected by Fe-based shape memory alloy bolts

Abstract

The article focuses on the numerical simulation of the thermomechanical behavior of steel T-stubs connected by iron-based shape memory alloys bolts. The three-dimensional macroscopic model used in this work was previously developed by the authors considering different thermomechanical properties between austenite and martensite, and coupling between phase transformation and plasticity. The model is implemented in a UMAT code using an implicit time-discrete integration scheme that follows a “multisurface plasticity”-like approach. The numerical results show that the shape memory effect can be used to preload the bolt if the initial length of its shank is less than the total thickness of the flanges. For an initial shank length of 21.38 mm and a total flange thickness of 21.4 mm, the shape memory effect produced average contact forces of 101 N between the bolt head and the flange, and 37 N between the two flanges. The resulting average contact pressures were 210 and 25 MPa, respectively. The average bolt force after preload was approximately 22.6 kN. Subsequent application of 2 mm normal displacements at the top and bottom faces of the upper and lower webs induced local plastic deformation around the flange holes and phase transformation in the bolt. The reversibility of martensitic transformation and the confinement of the plastic deformation in a limited zone around the holes allowed nearly complete shape recovery by heating. The obtained results highlight the advantage of using low-cost iron-based shape memory alloys as alternatives to steel bolts for connecting T-stubs.

Self-centering of steel braced frames equipped with Fe-SMA TADAS dampers

“…FE-SMAs are less expensive and stiffer than NiTi SMAs (in the same order of the stiffness of steel), making them more suitable for structural control applications [22][23][24][25][26][27]. In addition, pure SMAs (Ni-Ti SMAs) are limited to wires/ fibers, while the Fe-SMAs can be manufactured in different shapes [24,28,29] In 2022, Wang and Zhu [27] conducted extensive research on the cyclic behavior of Fe-SMA bars with the aim of enhancing their suitability for high-performance seismic devices. They harnessed the SME property to recover partial residual deformations by applying controlled heating after unloading the bars from a compression strain of 4% and discussed that cyclic tension-compression loadings might have an adverse effect on the recovery capability of the SMA material in uniaxial behavior.…”

Development and implementation of an effective constitutive model for architected cellular iron-based shape memory alloys: Pressure dependency and transformation-plasticity interaction

“…For instance, Fe-Mn-Si-based SMAs have been successfully used in smart composites (Watanabe et al, 2002), reinforced concrete beams (Rojob and El-Hacha, 2017, 2018; Sawaguchi et al, 2006; Shahverdi et al, 2016), pipe joints (Tanahashi et al, 1994), crane rail fishplates (Maruyama et al, 2008), seismic dampers (Sawaguchi et al, 2016), and so on. In recent numerical works, Cissé et al (2017a) and Cissé et al (2018) investigated the feasibility of using Fe-SMAs as, respectively, smart cellular strucutral beams and self-healing bolts for steel T-stubs.…”