Abstract. This article reports on an ESF S3T EUROCORES sponsored networking activity called Roundrobin SMA modeling organized with the aim to compare capabilities of various thermomechanical models of shape memory alloys capable to simulate their functional responses for applications in smart engineering structures. Five sets of experimental data were measured in thermomechanical tests on thin NiTi filament in tension, torsion and combined tension/torsion. The data were provided to six teams developing advanced SMA models to perform appropriate simulations. Simulation results obtained by individual teams were compared with experimental results and presented on a dedicated Roundrobin SMA modeling website. The evaluation of the activity in terms of the assessment of the capability of individual models to deal with specific features of the experimentally measured SMA thermomechanical responses is provided in this article.
The continuing implementation of shape memory alloys (SMAs) as lightweight solid-state actuators in morphing structures has now motivated research into finding optimized designs for use in aerospace control systems. This work proposes methods that use iterative analysis techniques to determine optimized designs for morphing aerostructures and consider the impact of uncertainty in model variables on the solution. A combination of commercially available and custom coded tools is utilized. ModelCenter, a suite of optimization algorithms and simulation process management tools, is coupled with the Abaqus finite element analysis suite and a custom SMA constitutive model to assess morphing structure designs in an automated fashion. The chosen case study involves determining the optimized configuration of a morphing aerostructure assembly that includes SMA flexures. This is accomplished by altering design inputs representing the placement of active components to minimize a specified cost function. An uncertainty analysis is also conducted using design of experiment methods to determine the sensitivity of the solution to a set of uncertainty variables. This second study demonstrates the effective use of Monte Carlo techniques to simulate the variance of model variables representing the inherent uncertainty in component fabrication processes. This paper outlines the modeling tools used to execute each case study, details the procedures for constructing the optimization problem and uncertainty analysis, and highlights the results from both studies.
He also serves as the Director for the Texas Institute for Intelligent Materials and Structures (TiiMS). His research involves the design, characterization and modeling of multifunctional material systems at nano, micro and macro levels. During the past two decades he has published extensively on the subject of shape memory alloys with his students, postdoctoral associates and colleagues and several of his journal papers are now considered classic papers in the field. He served as an Associate Vice President for Research for Texas A&M University from 2001-2004, and as the first chair of the Materials Science and Engineering Program at TAMU. He has been involved with curriculum innovations and engineering education throughout his career, notably with the Foundation Coalition, where he focused on restructuring the sophomore year engineering curriculum.
The utilization of shape memory alloys (SMAs) as actuators in aerospace applications continues to show promise. These materials, when subjected to controlled changes in temperature, have the capability to provide motion while under loads that exceed thousands of times their own weight and can do so over tens of thousands of cycles. However, the rate of thermally-induced SMA transformation is significantly hindered by low thermal conductivity and latent heat effects observed in this material. The relatively long cooling times observed in SMA geometries such as beams and tubes make it difficult for controlled devices to operate with sufficiently high frequency. Therefore, the application of SMA beams as aerospace control actuators has been limited. Morphing structures such as flight control mechanisms require higher cyclic actuation frequencies than are commonly observed in SMAs, and thus have motivated the effort to increase thermal actuation rates attainable in SMA active components.This work presents an analytical study of a tapered beam actuator and discusses the possibility of using SMAs in conjunction with more conductive materials to enhance actuation performance, especially with regard to actuation cyclic frequency. The analysis involves computing the actuation work output over time of various loaded, thermally cycled active SMA beams using an accurate constitutive model implemented in a finite element framework. This set of analyses considers the solution to a transient thermomechanically coupled problem and includes the effects of latent heat of transformation on the energy balance. The study compares the effectiveness of aluminum, copper, and silver secondary material regions and their geometric configurations in altering the actuation power-to-mass ratio of the beam. An optimization scheme is used to determine the geometric distribution of each secondary material that results in the highest power-to-mass ratio. It is shown that aluminum, when optimally distributed, provides the best overall design solution of the three materials considered.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.