Development of a double-tee flange connection using shape memory alloy rods

This study investigated the out-of-plane shear performance of a newly developed shape memory alloy (SMA) connector and a commonly used shear/alignment connector. The innovation lies in developing a durable and easily installed and maintained flange-to-flange connector between precast concrete double-tee members. The proposed connector consists of a superelastic SMA curved bolt inserted into a duct that is then cast into the precast concrete member. Two types of sealant materials were used: polyurethane elastomeric sealant and nonshrink cementitious grout. The shear/alignment and SMA connectors were tested under monotonic vertical shear. The tests were conducted on 4 ft × 4 ft × 4 in. (1.2 m × 1.2 m × 100 mm) slab specimens. The resulting capacities and associated damage were summarized. Higher stiffness and lower ductility were observed for the SMA connector with nonshrink grout compared with the shear/alignment connector with polyurethane elastomeric sealant. The average stiffnesses of the SMA and shear/alignment connector specimens were 116,681 lb/in. (20,434 kN/m) and 31,300 lb/in. (5481 kN/m), respectively. The ductility of the SMA connector was improved when using polyurethane elastomeric sealant; however, more tests should be done to confirm this behavior. The SMA rod was reused in several tests through reheating of the SMA element. The shear/alignment connector cannot be reused.

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Buckling Strengths of Composite Plate Using Shape Memory Alloy under In-Plane Shear

Turkish Journal of Computer and Mathematics Education (TURCOMAT) ◽

10.17762/turcomat.v12i2.1509 ◽

2021 ◽

Vol 12 (2) ◽

pp. 1729-1738

Author(s):

Yatendra Saraswat, Et. al.

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Composite Plate ◽

Shear Deformation Theory ◽

Shear Load ◽

Plane Shear ◽

Alloy Plate ◽

First Order ◽

Circular Cutout ◽

Ansys Workbench

In this article, we analyze the strength and buckling response in the plane shear load fixed at the corner of the composite plate. The fem is formulated is done on the basis of first-order shear deformation theory and assumptions of von Karman. The Newton-Raphson technique is considered to analyze the non-linearity algebraic equation. The effect of shape memory alloy in shear load and buckling response is discussed. In this study we analyze the two cases in the first simple carbon/epoxy plate is analyze and then we use the shape memory wire embedded in the plate which is about 1% of the volume of the plate and studies the buckling response effect on the plate. In the second case we use Shape Memory Alloy plate and loading but a circular cutout at the middle of the plate this case we analyze for both with the use of shape memory alloy and without the use of shape memory. It is observed that the shape memory alloy increases the strength of the plate in both cases. The whole simulations are done using Ansys workbench software v 2020R2.

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Maximum Attainable Deflections of Shape Memory Alloy-Layered Microcantilever

Journal of Microelectronics and Electronic Packaging ◽

10.4071/1551-4897-5.2.52 ◽

2008 ◽

Vol 5 (2) ◽

pp. 52-61

Author(s):

P. Majumder ◽

A. Bhattacharyya

Keyword(s):

Phase Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Case Analysis ◽

Nickel Titanium ◽

Surveillance Systems ◽

Computational Results ◽

Heating And Cooling ◽

Out Of Plane ◽

Cantilever Surface

Finite element modeling of a shape memory alloy (SMA)-layered microcantilever is reported herein. It is assumed that the SMA layer is “two-way–trained,” such that alternate heating and cooling of the SMA layer will cause a phase transformation in the SMA layer and deform the cantilever out-of-plane and back. For a nickel–titanium (NiTi) layer on a glass substrate, computational results indicate that a uniform 4% two-way strain along the length of a SMA layer spanning the full length of a 100-μm cantilever translates to a tip deflection of 29.5 μm, and a sweep of approximately 30° from the flat “rest” state. As well, 40% of the cantilever surface (measured from its free end) is flat and can be used as a flat reflective surface for micromirror applications. A “worse-case” analysis is presented where only 50% of the SMA length is able to undergo phase transformation, resulting in deflections of about 10 μm with a 12° sweep. Finally, it is shown that deflections are about two orders of magnitude higher than what would be possible if the SMA layer did not undergo phase transformations (but underwent pure thermal expansion only). One possible area of application could be in the area of continuously rotating micromirrors, suitable for surveillance systems.

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Fabrication and Characterization of Nanoscale Shape Memory Alloy MEMS Actuators

Advanced Functional Materials ◽

10.5772/intechopen.92762 ◽

2020 ◽

Author(s):

Cory R. Knick

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Martensite Phase ◽

Radius Of Curvature ◽

Curvature Radius ◽

Thermal Actuators ◽

Mems Actuators ◽

Out Of Plane

The miniaturization of engineering devices has created interest in new actuation methods capable of large displacements and high frequency responses. Shape memory alloy (SMA) thin films have exhibited one of the highest power densities of any material used in these actuation schemes and can thermally recovery strains of up to 10%. Homogenous SMA films can experience reversible shape memory effect, but without some sort of physical biasing mechanism, the effect is only one-way. SMA films mated in a multi-layer stack have the appealing feature of an intrinsic two-way shape memory effect (SME). In this work, we developed a near-equiatomic NiTi magnetron co-sputtering process and characterized shape memory effects. We mated these SMA films in several “bimorph” configurations to induce out of plane curvature in the low-temperature Martensite phase. We quantify the curvature radius vs. temperature on MEMS device structures to elucidate a relationship between residual stress, recovery stress, radius of curvature, and degree of unfolding. We fabricated and tested laser-irradiated and joule heated SMA MEMS actuators to enable rapid actuation of NiTi MEMS devices, demonstrating some of the lowest powers (5–15 mW) and operating frequencies (1–3 kHz) ever reported for SMA or other thermal actuators.

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