A cyclic integrated microstructural-mechanical model for a shape memory alloy

Bellini, Costanzo; Berto, Filippo; Cocco, Vittorio Di; Iacoviello, Francesco

doi:10.1016/j.ijfatigue.2021.106473

Cited by 9 publications

(8 citation statements)

References 24 publications

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“…10a). However, most of the heat is conducted out of the plate at the temperature Dirichlet boundaries due to the small size of the plate and the long simulated time 5 . Subsequently, after unloading, the plate does not transform back, which is shown in Fig 10b . Finally, when increasing the temperature at both ends, the martensite is transformed back to austenite, leading to a recovery of the initial shape (see Fig.…”

Section: Plate With a Holementioning

confidence: 99%

“…Afterward, at 4 the shape memory alloy reaches A f and the martensite is transformed back to austenite, which makes the actuator deflect up. Finally, when we remove the source at 5 , the polymer hardens before M f is reached. Thus, depending on the polymer thickness, the polymer may hold the actuators shape or release some of it's stroke.…”

Section: Influence Of the Polymer Thicknessmentioning

confidence: 99%

“…Therefore, we try to maximize the difference in stroke between states A and B . In turn, one must choose a sufficient polymer thickness, such that the actuator does not release too much stroke at 5 . For example, 0.1mm of PMMA is not thick enough to hold the shape, while 0.3 mm holds the shape perfectly (see Fig.…”

Section: Influence Of the Polymer Thicknessmentioning

confidence: 99%

“…On the other hand, models employing a multiplicative split are computationally more elaborate, but can represent finite stretches well (see, e.g., Reese and Christ [38], Arghavani et al [1] or Wang et al [49]). Additionally, there exist many new models considering geometric nonlinearities, which are limited to superelasticity (see, e.g., Bellini et al [5], Wang et al [48] and Rezaee-Hajidehi et al [39]). Furthermore, some models also consider transformation induced plasticity (see, e.g., Hartl et al [19], Xu et al [53] and it's extension to partial phase transformations by Scalet et al [41]).…”

Section: Introductionmentioning

confidence: 99%

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A thermomechanical finite strain shape memory alloy model and its application to bistable actuators

Sielenkämper

Wulfinghoff

2022

Acta Mech

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This work presents a thermomechanical finite strain shape memory alloy model that utilizes a projection method to deal with the incompressibility constraint on inelastic strains. Due to its finite strain formulation, it is able to accurately predict the behavior of shape memory alloys with high transformation strains. The key feature of this model is the thermomechanical modeling of the shape memory effect and superelastic behavior by optimizing a global, incremental mixed thermomechanical potential, the variation of which yields the linear momentum balance, the energy balance, the evolution equations of the internal variables as well as boundary conditions of Neumann- and Robin-type. The proposed thermal strain model allows to properly capture transformation induced volume changes, which occur in some shape memory alloys. A finite strain dissipation potential is formulated, which incorporates the disappearance of inelastic strains upon austenite transformation. This important property is consistently transferred to the time-discrete potential using a logarithmic strain formulation. Yield and transformation criteria are derived from the dual dissipation potential. The implementation based on an active set search and the algorithmically consistent linearization are discussed in detail. The model is applied in three-dimensional simulations of a bistable actuator design to explore its capabilities.

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Section: Plate With a Holementioning

confidence: 99%

Section: Influence Of the Polymer Thicknessmentioning

confidence: 99%

Section: Influence Of the Polymer Thicknessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A thermomechanical finite strain shape memory alloy model and its application to bistable actuators

Sielenkämper

Wulfinghoff

2022

Acta Mech

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“…making them suitable for potential applications in medicine, engineering, aerospace, or automobiles [14][15][16]. Nowadays, one of the leading research deals with the smartification of materials and structures using smart materials with sensing capabilities [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Fe–Mn–Ga shape memory glass-coated microwire with sensing possibilities

Galdun¹,

Vidyasagar²,

Hennel³

et al. 2021

J. Phys. D: Appl. Phys.

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The structural phase transformation in a non-stoichiometric shape memory Fe 42.8 Mn 27.6 Ga 29.6 Heusler glass-coated microwire was experimentally observed using indirect magnetic, permeability, and electrical resistance measurements. While the temperature dependence of magnetization revealed hysteresis of magnetization during the heating and cooling process, magnetic hysteresis loops point to the change in the direction of the easy magnetization axis of the low-and high-temperature phase. Additionally, the unusual behavior of the permeability and electrical resistance measurements are in good agreement with the magnetic measurements. The x-ray diffraction profile measured at room temperature revealed the coexistence of a high-temperature L2 1 phase (a = 5.88 Å) and low-temperature phase with the L1 2 structure (a = 3.71 Å) and can be considered as another proof of the shape memory effect that is expected in the Fe-Mn-Ga-based Heusler alloys. In the presented glass-coated microwire, it is not only possible to shift the transformation temperature with the external magnetic field, but from its initial permeability value, it is possible to determine whether the alloy has undergone the structural transformation. Therefore, the presented Fe-Mn-Ga-based glass-coated microwire may be considered a suitable candidate for microactuators with sensory capabilities.

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