Engineering Applications and Devices: Session 4
Program Organizers: Alan Pelton, G.RAU Inc.
Thursday 10:20 AM
July 13, 2017
Location: Hyatt Regency Chicago
Session Chair: Eckhard Quandt, University of Kiel
The Thermomechanical Hingeless Actuation based on Shape Memory Alloy Plate: Velaphi Msomi1; Graeme Oliver1; 1Cape Peninsula University of Technology
The non biological applications of shape memory alloys(SMA) material has drawn much attention from researchers across the globe. The SMA application in the engineering field is classified as one of the non biological application. In most cases, SMAs are employed to replace the existing structures or to improve the performance of the existing systems. SMAs are preferred for actuation applications due to their lightness in weight and their quickness in response. This paper is aiming at demonstrating the hingeless actuation based on SMA plate. The structure resembling the top part of aerofoil was constructed through aluminium plate and trained SMA plate. The leading edge was constructed using trained SMA plate while the trailing edge was constructed through aluminium plate. This structure was constructed with the purpose of studying the vertical deflection that the structure can produce and also to look at the response time. The results were obtained and analysed.
SMA Microactuators for In situ TEM Strain Analysis: Christoph Chluba1; Ulrich Schürmann1; Niklas Wolff1; Rodrigo Lima de Miranda2; Daria Smazna1; Rainer Adelung1; Lorenz Kienle1; Eckhard Quandt1; 1University of Kiel; 2Acquandas GmbH
In situ straining TEM analysis is a useful tool in materials science to investigate deformation mechanisms and stress induced transformations on the atomistic scale. Here we present a simple method for in situ straining experiments by using micro SMA actuators implemented in a TEM grid fabricated by thin film technology and sputter deposition of NiTi-based alloy compositions. Actuation during the experiment is performed by a slight temperature change (~40 K) of the grid which is either conducted by using a conventional heating holder or by local resistive heating. Depending on the microactuator design displacements of several 100 µm with forces up to 0.5 N can be achieved. Moreover a linear actuation movement with temperature change is observed which facilitates the strain control. To demonstrate the capability of this new concept first in situ straining TEM experiments for different materials like e.g. ZnO are presented.
Microstructure and Properties of Electron Beam Welded TiNi-based Shape Memory Alloys: Haichang Jiang1; Dan Yang1; Mingjiu Zhao1; Lijian Rong1; 1Institute of Metal research, Chinese Academy of Sciences
The microstructure and properties of the electron beam welding joints of TiNi binary, TiNiNb ternary and TiNiNbMo quarternary shape memory alloys have been studied. The coarse columnar structure formed in the fusion zone of TiNi binary shape memory alloy and grew towards the center line of the fusion zone with a <100> preferred orientation. The Nb and Mo elements in TiNiNb(Mo) alloy could refine the equiaxed grains of the fusion zone and the Mo would promote the supersaturation of Nb atoms in the matrix.The high cooling speed in the fusion zon led to the strain glass transition in the fusion zone. As a result of cointeraction of Nb and Mo elements, the tensile strength of welding joint of TiNiNbMo alloys at room temperature reached 94% of the base metal, the maximum recoverable strain reached 8.0%, and the strain recovery rate was 97% after 10% pre-deformation.
Development of a Shape Memory Actuator for Aircraft Engine Turbine Blades: Richard Blocher1; Muthuvel Murugan2; Anindya Ghoshal2; Luis Bravo2; Peter Anderson1; 1The Ohio State University; 2Army Research Laboratory
Existing aircraft engines feature turbine blades that are fixed at an optimal angle for a single flight condition. However, changes in flight conditions affect the optimal blade pitch angle. Articulating turbine rotors and stators, which maintain the optimum fluid-structure interaction for different flight conditions, would significantly increase the efficiency of aircraft engines. The implementation of shape memory blade actuators in aircraft turbine engines would increase the efficiency and customizability of engine performance.Computational Fluid Dynamics (CFD) simulation results for simulated flow over turbine blades during actuation about the leading edge have been carried out on Army Research Laboratory’s High Performance Computing center Excalibur using CONVERGE CFD software. Pressure outputs from CONVERGE will be used in conjunction with a Microstructural Finite Element SMA code to simulate the phase transition behavior of an SMA actuator during engine operation.
Effects of Austenite Grain Size on the Athermal Martensite Start Temperature Detected by Spontaneous Magnetic Emission (SME): Hélio Goldenstein1; E. A. Huallpa1; J. C. Sanchez2; 1University of Sao Paulo; 2Universidad de Oriente
The effects of austenite grain size on the start of martensite formation (Ms) in Fe-–Ni-–C alloy have been studied using Spontaneous Magnetic Emission (SME), a recently described phenomenon that can function as a tool to monitor the martensitic transformation. The SME phenomenon is more sensitive than other global measurements like resistivity , dilatometry, etc., as it does not require a critical volume of transformation and is able to detect signals from individual growing plates. The Ms as detected by SME decreases as the grain size decreases, a result opposite to the results found using resistivity or dilatometry, but in agreement with results obtained by acoustic emission.This is probably due to smaller grains contain more dislocations and more grain boundaries, i.e., more martensite nucleation sites than larger grains and are more likely to start transforming. Global measurements that depend on a large critical transformation volume fail to detect smaller bursts,
Elastocaloric Cooling: Mechanisms, Materials, and Systems: Huilong Hou1; Ichiro Takeuchi1; 1University of Maryland, College Park
We are actively developing prototypes of elastocaloric cooling systems using mechanisms based on compression of shape memory alloys. We are compressing bundles of NiTi tubes while heat exchange fluid flows through the tubes. A key component is a heat recovery system implemented to maximize efficiency of heat exchange. We have observed cooling DeltaT of 4.5 K at 70 W, as directly measured in cooled water. A latest prototype was designed to deliver 400 W. We have demonstrated when properly loaded, NiTi tubes can survive up to at least ~ 0.3 million cycles without any degradation in cooling capacity. We carry out combinatorial investigation of ternary and quaternary alloys to identify new compositions with enhanced latent heat and reduced critical stress. Our material optimization processes include developing understanding the effect of atomic structure and microstructure on latent heat and fatigue. This project is funded by DOE ARPA-E and DOE EERE CaloriCool.