scholarly journals New Insights Into Shape Memory Alloy Bimorph Actuators Formed by Electron Beam Evaporation

2018 ◽  
Author(s):  
Hao Sun ◽  
Jianjun Luo ◽  
Ming Lu ◽  
Dmytro Nykypanchuk ◽  
Yong Shi
Keyword(s):  
Electron Beam ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Precision ◽  
Deposition Rate ◽  
Annealing Process ◽  
Element Analysis ◽  
Finite Element Analysis Simulation ◽  
Lift Off ◽  
Beam Deposition

In order to create shape memory alloy (SMA) bimorph microactuators with high-precision features, a novel fabrication process combined with electron beam (E-beam) evaporation, lift-off resist and isotropic XeF2 dry etching method was developed. To examine the effect of E-beam deposition and annealing process on nitinol (NiTi) characteristics, the NiTi thin film samples with different deposition rate and overflow conditions during annealing process were investigated. With the characterizations using scanning electron microscope and x-ray diffraction, the results indicated that low E-beam deposition rate and argon employed annealing process could benefit the formation of NiTi crystalline structure. Besides, SMA bimorph microactuators with high-precision features as small as 5 microns were successfully fabricated. Furthermore, the thermomechanical performance was experimentally verified and compared with finite element analysis simulation results.

Shape Memory Alloy Bimorph Microactuators by Lift-Off Process

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Hao Sun ◽  
Jianjun Luo ◽  
Zhongjing Ren ◽  
Ming Lu ◽  
Dmytro Nykypanchuk ◽  
...  
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Precision ◽  
Sem Images ◽  
Element Analysis ◽  
Heating And Cooling ◽  
Finite Element Analysis Simulation ◽  
Micro Actuators ◽  
Lift Off

Abstract This study aims to develop a new fabrication process to create high-precision patterned shape memory alloy (SMA) bimorph micro-actuators by the e-beam evaporation technique. To examine the effect of the annealing process on nitinol (NiTi) thin film characteristics, the as-deposited and annealed NiTi thin films are, respectively, investigated. X-ray diffraction (XRD) results demonstrate the crystallization of NiTi thin films after annealing at 600 °C. The transformation behaviors of NiTi thin films during heating and cooling are studied using the differential scanning calorimeter (DSC). Furthermore, scanning electron microscopy (SEM) images indicate that SMA bimorph micro-actuators with high-precision features can be fabricated by the lift-off process, without any wet or dry etching procedures, and their thermomechanical behaviors are experimentally verified by comparing them with that of finite element analysis simulation results.

scholarly journals Low carbon content NiTi shape memory alloy produced by electron beam melting

2004 ◽  
Vol 7 (2) ◽  
pp. 263-267 ◽  
Author(s):  
Jorge Otubo ◽  
Odair Doná Rigo ◽  
Carlos de Moura Neto ◽  
Michael Joseph Kaufman ◽  
Paulo Roberto Mei
Keyword(s):  
Electron Beam ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Carbon Content ◽  
Electron Beam Melting ◽  
Niti Shape Memory Alloy ◽  
Low Carbon

Experimental and numerical studies on a novel shape-memory alloy wire–woven trusses capable of undergoing large deformation

2019 ◽  
Vol 30 (15) ◽  
pp. 2283-2298
Author(s):  
Zhixiang Rao ◽  
Xiaojun Yan ◽  
Xiaoyong Zhang ◽  
Bin Zhang ◽  
Jun Jiang ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Large Deformation ◽  
Residual Deformation ◽  
Shape Memory Alloy Wire ◽  
Static Compression ◽  
Recoverable Strain ◽  
Alloy Wire ◽  
Assembly Method ◽  
Finite Element Analysis Simulation

Currently, most wire-woven trusses are fabricated with traditional metals such as steel and aluminum, thus the deformation ability is constrained due to the low yield strain of common metals. Shape-memory alloy is a kind of smart material which can bear large recoverable strain while producing hysteresis. Due to the unique capacity of large deformation and remarkable damping property of the shape-memory alloy, a novel lattice trusses assembled by superelastic shape-memory alloy coil springs was proposed. Furthermore, the treatment processes to prepare the shape-memory alloy coil springs and the assembly method to fabricate the shape-memory alloy wire–woven trusses were also introduced. The quasi-static compression under different maximum deformation and temperatures was performed to investigate the mechanical and thermal responses of the proposed shape-memory alloy wire–woven trusses. Cyclic compression tests were also performed to study the functional fatigue of the shape-memory alloy wire–woven trusses. The proposed wire-woven trusses can undergo up to 80% deformation by compression and recover without evident residual deformation after unloading. Finite element analysis simulation of representative volume element under different deformation was presented. Analytical modeling of the stiffness of shape-memory alloy wire–woven trusses was also carried out. Both the numerical and analytical methods can predict the stiffness within a small deviation.

Development of a Shape Memory Alloy Actuator for a Micromechanical Sterilization Cycle Counter

2020 ◽  
Author(s):  
Kenny Pagel ◽  
Jonas Esch ◽  
Daniel Hoffmann ◽  
Heiko Trautner ◽  
Simon Herrlich ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Medical Device ◽  
System Development ◽  
Temperature Limit ◽  
Saturated Steam ◽  
Steam Sterilization ◽  
Element Analysis ◽  
Additional Energy ◽  
Fea Model

Abstract The steam sterilization of reusable medical instruments is a critical process. Standardized treatments with hot, saturated steam at maximum temperatures of up to 138 °C often represent a significant thermal load, which is repeated with varying number of cycles depending on the medical device. Until now, there is no possibility for medical device manufacturers to monitor how often a product has been sterilized. However, this is necessary for both safety and warranty issues, since according to the European Medical Device Regulation (EU-MDR), the manufacturer must specify how often a product can be sterilized. In this paper the actuator approach for a micromechanical “sterilization cycle counter” is presented. It is designed to autonomously record, count and store steam sterilizations directly on the instrument by combining silicon micromechanics with shape memory alloy (SMA) actuators. This enables an autonomous operation without additional energy sources such as batteries. During the steam sterilization cycle, a certain temperature limit is exceeded once and detected by the SMA. The system development aims at the heterogeneous integration of standard SMA wires into a silicon microstructure. The transformation temperatures of the SMA is thereby increased to the relevant range by prestressing. In detail, the paper first describes the approach of the counting mechanism and the possibilities and limitations of implementing and pretensioning of SMA wires in silicon microstructures. Based on that, the development of the SMA actuator geometry using an SMA Finite Element Analysis (FEA) model according to the approach of Aurichio is described. The model is validated using an up-scaled test bench of the system, in which various geometric parameters can be varied. Finally, the results will be discussed in particular regarding the MEMS process chain to be carried out in the next step.

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