V. Degiorgi, P. Finkel, Lauren M. Garten, M. Staruch
Recently NRL researchers have embarked on a basic research effort “Tuning Giant Magnetoelectric Properties in Phase Transformation Multiferroics” focused on multifunctional materials for energy transduction and conversion. Multiferroic materials combine at least two coupled ferroic properties and are used in multiple applications including magnetic field sensors, energy harvesting devices, non-volatile memory and antennas. There are very few single phase multiferroic materials, and they normally have relatively low magnetoelectric (ME) coupling coefficient. In contrast, engineered materials such as ME composites fabricated from piezoelectric and magnetostrictive materials can show multiple orders of magnitudes increase in the ME coupling coefficient. The optimal design of ME composites would lead to conditions of maximum response (strain, induced voltage, or field) with minimum applied electric or magnetic fields, providing advanced materials for transduction, sensing, energy harvesting and other applications. That is why NRL researchers are working on piezoelectric materials with enhanced properties due to a phase transformation that would minimize the stimuli needed to achieve large strains. Key to the successful design and fabrication of ME composites is an understanding of interface characteristics as well as individual material components. In this paper we will review the current status of work at NRL on engineered multiferroic composites comprised of piezoelectric and magnetostrictive materials coupled through strain. There are still many open questions about the interfacial properties as well as the individual component materials. Details will be presented from recent work on material characterization under repetitive cycling, interface characteristics, and stress/electric/thermal effects on driving the phase transition in a relaxor ferroelectric single crystal.
{"title":"Transduction Using Functional Materials: Basic Science and Understanding at the U. S. Naval Research Laboratory","authors":"V. Degiorgi, P. Finkel, Lauren M. Garten, M. Staruch","doi":"10.1115/smasis2019-5501","DOIUrl":"https://doi.org/10.1115/smasis2019-5501","url":null,"abstract":"\u0000 Recently NRL researchers have embarked on a basic research effort “Tuning Giant Magnetoelectric Properties in Phase Transformation Multiferroics” focused on multifunctional materials for energy transduction and conversion. Multiferroic materials combine at least two coupled ferroic properties and are used in multiple applications including magnetic field sensors, energy harvesting devices, non-volatile memory and antennas. There are very few single phase multiferroic materials, and they normally have relatively low magnetoelectric (ME) coupling coefficient. In contrast, engineered materials such as ME composites fabricated from piezoelectric and magnetostrictive materials can show multiple orders of magnitudes increase in the ME coupling coefficient. The optimal design of ME composites would lead to conditions of maximum response (strain, induced voltage, or field) with minimum applied electric or magnetic fields, providing advanced materials for transduction, sensing, energy harvesting and other applications. That is why NRL researchers are working on piezoelectric materials with enhanced properties due to a phase transformation that would minimize the stimuli needed to achieve large strains. Key to the successful design and fabrication of ME composites is an understanding of interface characteristics as well as individual material components. In this paper we will review the current status of work at NRL on engineered multiferroic composites comprised of piezoelectric and magnetostrictive materials coupled through strain. There are still many open questions about the interfacial properties as well as the individual component materials. Details will be presented from recent work on material characterization under repetitive cycling, interface characteristics, and stress/electric/thermal effects on driving the phase transition in a relaxor ferroelectric single crystal.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131263069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work focuses on a surrogate predictive model, conceived to estimate the impact on blade twist law of a Shape Memory Alloy actuation system. The basic idea is to integrate the pre-existing blade structure with a pre-twisted SMA tube. Due to the specific property of recovering deformation during phase transition, the SMA element can transmit angular deformations and alter the original twist to improve performance when required. The model includes two main modules. The first one targets the SMA actuator and simulates the transmission of twist against some critical parameters (tube extension and location along the blade span and level of activation). The second module receives as input the modified twist law and the updated mechanical features due to the SMA and gives in output an estimate of the performance produced by the system. After an overview on input and output parameters and their cross link, a description of the SMA predicting core is provided. A parameterization is then organized to illustrate the impact of the morphing system onto the blade and on the twist law. On this basis, an additional parameterization is implemented, now focusing on the effects on performance of the proposed system.
{"title":"An FE Based Surrogate Model for Predicting the Impact of a SMA Twist System on the Helicopter Performance","authors":"S. Ameduri, A. Concilio, Rohin K. Majeti","doi":"10.1115/smasis2019-5574","DOIUrl":"https://doi.org/10.1115/smasis2019-5574","url":null,"abstract":"\u0000 This work focuses on a surrogate predictive model, conceived to estimate the impact on blade twist law of a Shape Memory Alloy actuation system.\u0000 The basic idea is to integrate the pre-existing blade structure with a pre-twisted SMA tube. Due to the specific property of recovering deformation during phase transition, the SMA element can transmit angular deformations and alter the original twist to improve performance when required.\u0000 The model includes two main modules. The first one targets the SMA actuator and simulates the transmission of twist against some critical parameters (tube extension and location along the blade span and level of activation). The second module receives as input the modified twist law and the updated mechanical features due to the SMA and gives in output an estimate of the performance produced by the system.\u0000 After an overview on input and output parameters and their cross link, a description of the SMA predicting core is provided. A parameterization is then organized to illustrate the impact of the morphing system onto the blade and on the twist law. On this basis, an additional parameterization is implemented, now focusing on the effects on performance of the proposed system.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134312752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Structures and mechanisms in soft robotics are primarily based on chemically versatile species such as hydrogels, polymers, or elastomers, thus offering great potential for the design of adaptive core properties. In particular, tunable rigidity is highly desirable to enable control of soft grippers or for advanced robot locomotion. However, most of the strategies explored so far rely on mechanisms, such as phase transitions or shape memory effects, that require heavy external hardware or have a limited range of tunable rigidity. In this work, we propose a novel strategy inspired by the sea cucumber dermis mechanism. High aspect ratio carbon nanotubes (CNTs) are reversibly interconnected by DNA oligonucleotides within a polyacrylamide (PAAm) hydrogel. The combination of the excellent mechanical properties of CNTs and the reversible hybridization of DNA strands into a stable double-helicoidal structure allowed the reversible tunability of mechanical properties over one order of magnitude (from ∼100 Pa to ∼1 kPa) within minutes by increasing the temperature beyond the melting temperature of DNA strands (∼50 °C). First, the functionalization strategy of CNTs with DNA strands is described and characterized. The aggregation of CNTs driven by the DNA hybridization is then demonstrated. The mechanical properties of hydrogels functionalized with CNTs are finally analyzed using rheology measurements.
{"title":"DNA Nanotechnologies for the Design of Bio-Inspired Soft Nanocomposites With Reversible Rigidity","authors":"T. Calais, T. Stalin, V. S. Joseph, P. Alvarado","doi":"10.1115/smasis2019-5568","DOIUrl":"https://doi.org/10.1115/smasis2019-5568","url":null,"abstract":"\u0000 Structures and mechanisms in soft robotics are primarily based on chemically versatile species such as hydrogels, polymers, or elastomers, thus offering great potential for the design of adaptive core properties. In particular, tunable rigidity is highly desirable to enable control of soft grippers or for advanced robot locomotion. However, most of the strategies explored so far rely on mechanisms, such as phase transitions or shape memory effects, that require heavy external hardware or have a limited range of tunable rigidity.\u0000 In this work, we propose a novel strategy inspired by the sea cucumber dermis mechanism. High aspect ratio carbon nanotubes (CNTs) are reversibly interconnected by DNA oligonucleotides within a polyacrylamide (PAAm) hydrogel. The combination of the excellent mechanical properties of CNTs and the reversible hybridization of DNA strands into a stable double-helicoidal structure allowed the reversible tunability of mechanical properties over one order of magnitude (from ∼100 Pa to ∼1 kPa) within minutes by increasing the temperature beyond the melting temperature of DNA strands (∼50 °C). First, the functionalization strategy of CNTs with DNA strands is described and characterized. The aggregation of CNTs driven by the DNA hybridization is then demonstrated. The mechanical properties of hydrogels functionalized with CNTs are finally analyzed using rheology measurements.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133130729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a summary on the ongoing research and development of a solid-state piezoelectric composite rotor design for use in rotary systems. The paper focuses on the theoretical analysis of a two-bladed rotor with varying parameters such as flight speed, blade pitch angle, and rotational speed. XROTOR, a blade element method based software, is used for analysis. The two-dimensional aerodynamic characteristics are acquired from the previous research on a Macro-Fiber Composite actuated simply supported thin airfoil. A set of simulations are conducted to determine the best geometric configuration, so the piezoelectric increase in thrust is maximized. The proposed hub-rotor system has the potential to be implemented in unmanned-aerial-vehicles such as single-rotor, tandem-rotor, multi-copter, and ducted-fan rotorcraft, or other rotating systems such as wind turbines, turbine engines, and marine propellers. This paper presents a summary of previous findings on a solid-state rotor prototype, and a new investigation on the theoretical aerodynamic behavior.
{"title":"A Piezocomposite Solid-State Rotor: Theoretical Analysis of Thrust and Efficiency Metrics","authors":"Taís Carneiro Ferreira de Castro, O. Bilgen","doi":"10.1115/smasis2019-5558","DOIUrl":"https://doi.org/10.1115/smasis2019-5558","url":null,"abstract":"\u0000 This paper presents a summary on the ongoing research and development of a solid-state piezoelectric composite rotor design for use in rotary systems. The paper focuses on the theoretical analysis of a two-bladed rotor with varying parameters such as flight speed, blade pitch angle, and rotational speed. XROTOR, a blade element method based software, is used for analysis. The two-dimensional aerodynamic characteristics are acquired from the previous research on a Macro-Fiber Composite actuated simply supported thin airfoil. A set of simulations are conducted to determine the best geometric configuration, so the piezoelectric increase in thrust is maximized. The proposed hub-rotor system has the potential to be implemented in unmanned-aerial-vehicles such as single-rotor, tandem-rotor, multi-copter, and ducted-fan rotorcraft, or other rotating systems such as wind turbines, turbine engines, and marine propellers. This paper presents a summary of previous findings on a solid-state rotor prototype, and a new investigation on the theoretical aerodynamic behavior.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133472733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Samuel I. Mattern-Schain, Mary-Anne Nguyen, Tayler M. Schimel, J. Manuel, Joshua J. Maraj, D. Leo, E. Freeman, S. Lenaghan, S. A. Sarles
This work draws inspiration from totipotent cellular systems to design smart materials whose compositions and properties can be learned or evolved. Totipotency refers to the inherent genetic potential of a single cell to adapt and produce all types of differentiated cells within an organism. To study this principal and apply it synthetically, tissue-like compartmentalized assemblies are constructed via lipid membrane-separated aqueous droplets in a hydrophobic medium through the droplet interface bilayer (DIB) method. Within our droplets, we explore synthetic totipotency via cell-free reactions including actin polymerization and cell free protein synthesis (CFPS). The transcription and translation of our CFPS reactions are controlled by stimuli-responsive riboswitches (RS). Via this scheme, adaptable material properties and functions are achieved in vitro via protein production from cell-free machinery administered through RS governance. Here, we present thermally or chemically-triggered riboswitches for orthogonal production of representative fluorescent protein products, as well functional proteins. To characterize the material properties of target proteins, we study the formation of polymerized actin shells to stabilize organically-encased droplets and span DIBs. We present a modified protocol for chemically-triggered actin polymerization as well as a thermally triggered actin RS. We characterize theophylline (TP)-triggered production of alpha hemolysin (α-HL) through CFPS and synthesized an organic-soluble trigger that can be sensed from the oil phase by a RS in an aqueous bioreactor droplet. We also demonstrate increased droplet conductivity when CFPS α-HL products are incorporated in DIBs. This interdisciplinary work involves cell culture, gene expression, organic synthesis, vesicle formation, protein quantification, tensiometry, droplet aspiration, microplate fluorescence/absorption experiments, fluorescent microscopy, and electrophysiology. This project is an essential design analysis for creating smart, soft materials using synthetic biology and provides motivation for artificial tissues capable of adapting in response to external stimuli.
{"title":"Totipotent Cellularly-Inspired Materials","authors":"Samuel I. Mattern-Schain, Mary-Anne Nguyen, Tayler M. Schimel, J. Manuel, Joshua J. Maraj, D. Leo, E. Freeman, S. Lenaghan, S. A. Sarles","doi":"10.1115/smasis2019-5745","DOIUrl":"https://doi.org/10.1115/smasis2019-5745","url":null,"abstract":"\u0000 This work draws inspiration from totipotent cellular systems to design smart materials whose compositions and properties can be learned or evolved. Totipotency refers to the inherent genetic potential of a single cell to adapt and produce all types of differentiated cells within an organism. To study this principal and apply it synthetically, tissue-like compartmentalized assemblies are constructed via lipid membrane-separated aqueous droplets in a hydrophobic medium through the droplet interface bilayer (DIB) method. Within our droplets, we explore synthetic totipotency via cell-free reactions including actin polymerization and cell free protein synthesis (CFPS). The transcription and translation of our CFPS reactions are controlled by stimuli-responsive riboswitches (RS). Via this scheme, adaptable material properties and functions are achieved in vitro via protein production from cell-free machinery administered through RS governance. Here, we present thermally or chemically-triggered riboswitches for orthogonal production of representative fluorescent protein products, as well functional proteins. To characterize the material properties of target proteins, we study the formation of polymerized actin shells to stabilize organically-encased droplets and span DIBs. We present a modified protocol for chemically-triggered actin polymerization as well as a thermally triggered actin RS. We characterize theophylline (TP)-triggered production of alpha hemolysin (α-HL) through CFPS and synthesized an organic-soluble trigger that can be sensed from the oil phase by a RS in an aqueous bioreactor droplet. We also demonstrate increased droplet conductivity when CFPS α-HL products are incorporated in DIBs. This interdisciplinary work involves cell culture, gene expression, organic synthesis, vesicle formation, protein quantification, tensiometry, droplet aspiration, microplate fluorescence/absorption experiments, fluorescent microscopy, and electrophysiology. This project is an essential design analysis for creating smart, soft materials using synthetic biology and provides motivation for artificial tissues capable of adapting in response to external stimuli.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129636333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The possibilities of a technical application of the shape memory effect are comprehensive and widespread. Besides the usage of arbitrary geometries, e.g. in the medical sector, especially wires are of great interest for unlocking mechanisms or other kinds of actuators. One of the challenges of the application of shape memory alloys (SMA) is the small deformation factor that prevents actuations with large travels. A second property that is usually seen as a disadvantage is the thermal dependence of the position. It leads to the necessity of comparably high electrical power for holding a location, as the cooling has to be compensated constantly. Therefore, SMA are usually not in use for such applications. For special environments, this effect can still be an advantage. By using an SMA driven positioning actuator in vacuum, the low loss of heat leads to a very precise and low power consuming alignment. Such actuators can be used for example in satellites. This paper presents an analysis of the properties under atmospheric conditions in comparison to the behavior in vacuum. Along with a comprehensive interpretation of the experimental results, further characteristics, like the functional and structural fatigue, are presented in detail.
{"title":"Feedback Control of SMA-Wires for Position Determination: A Comparison of the Behavior Under Vacuum and Standard Conditions","authors":"R. Roj, P. Dültgen, F. Schummer, S. Langbein","doi":"10.1115/smasis2019-5503","DOIUrl":"https://doi.org/10.1115/smasis2019-5503","url":null,"abstract":"\u0000 The possibilities of a technical application of the shape memory effect are comprehensive and widespread. Besides the usage of arbitrary geometries, e.g. in the medical sector, especially wires are of great interest for unlocking mechanisms or other kinds of actuators. One of the challenges of the application of shape memory alloys (SMA) is the small deformation factor that prevents actuations with large travels. A second property that is usually seen as a disadvantage is the thermal dependence of the position. It leads to the necessity of comparably high electrical power for holding a location, as the cooling has to be compensated constantly. Therefore, SMA are usually not in use for such applications. For special environments, this effect can still be an advantage. By using an SMA driven positioning actuator in vacuum, the low loss of heat leads to a very precise and low power consuming alignment. Such actuators can be used for example in satellites. This paper presents an analysis of the properties under atmospheric conditions in comparison to the behavior in vacuum. Along with a comprehensive interpretation of the experimental results, further characteristics, like the functional and structural fatigue, are presented in detail.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128278582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article discusses an approach to develop innovative carbon fiber composites that have the capability to change shape according to a prescribed input. The approach is based on the study of specific stacking sequences of unidirectional fiber plies cured on a curved mold. The effects of the above-mentioned aspects are investigated on the manufactured specimen. The combined thermo-mechanical response is investigated by performing mechanical tests at various prescribed temperatures and the intensity of the shape change is evaluated together with the corresponding stiffness variation. The experimental campaign is mostly devoted to characterize the response of the manufactured sample and demonstrate the great capability of the proposed approach to develop a smart material with enhanced shape and stiffness variation according the prescribed input.
{"title":"Towards Highly Reconfigurable Carbon Fiber Composite","authors":"A. Casalotti, G. Lanzara, Matthew P. Snyder","doi":"10.1115/smasis2019-5677","DOIUrl":"https://doi.org/10.1115/smasis2019-5677","url":null,"abstract":"\u0000 This article discusses an approach to develop innovative carbon fiber composites that have the capability to change shape according to a prescribed input. The approach is based on the study of specific stacking sequences of unidirectional fiber plies cured on a curved mold.\u0000 The effects of the above-mentioned aspects are investigated on the manufactured specimen. The combined thermo-mechanical response is investigated by performing mechanical tests at various prescribed temperatures and the intensity of the shape change is evaluated together with the corresponding stiffness variation.\u0000 The experimental campaign is mostly devoted to characterize the response of the manufactured sample and demonstrate the great capability of the proposed approach to develop a smart material with enhanced shape and stiffness variation according the prescribed input.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123773426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Knitted textiles manufactured from shape memory alloy (SMA) monofilaments possess advanced capabilities for distributed and complex actuation and are suited for a range of emerging needs in aerospace, biomedical, and robotics applications. In general, high currents for short periods of time provide sufficient electroresistive (Joule) heat to cause SMA wires to transform to austenite. However, SMA knitted textiles are difficult to electroresistively heat because the interlocking knit structure short-circuits the flow of current, causing localized overheating and isolating the transformation of the material along the current path. One approach for heating SMA knitted textiles is to drive pulses of high current between pairs of electrodes positioned across horizontal courses (rows) of knitted loops. This research presents a preliminary experimental investigation of the effects of factors related to electroresistive heating for SMA knitted textiles. A design of experiments analysis with two levels of four factors was conducted using a 24–1 fractional factorial design. The factors included the voltage of the power supply connected to the current amplifiers; a geometric factor defining the horizontal spacing of the electrodes attached to the knit sample; and two waveform factors: On Cycles and Off/On Cycles, which defined the length of time each current amplifier was enabled and disabled. Actuation performance was quantified by the actuation displacement and actuation force of the knit sample. Preliminary results suggest that voltage is the most influential factor, but also indicate that interactions between the geometric and waveform factors have significant effects on the heating and actuation performance. The characterization of these factor interactions has the potential to inform optimal electroresistive heating approaches for SMA knitted textiles, enabling integration into applications such as wearable technologies where convective heating is not practical.
{"title":"Preliminary Experimental Investigation of Control Parameters for the Electroresistive Heating of SMA Knitted Textiles","authors":"Rachel Marbaker, B. Utter, K. Eschen, J. Abel","doi":"10.1115/smasis2019-5666","DOIUrl":"https://doi.org/10.1115/smasis2019-5666","url":null,"abstract":"\u0000 Knitted textiles manufactured from shape memory alloy (SMA) monofilaments possess advanced capabilities for distributed and complex actuation and are suited for a range of emerging needs in aerospace, biomedical, and robotics applications. In general, high currents for short periods of time provide sufficient electroresistive (Joule) heat to cause SMA wires to transform to austenite. However, SMA knitted textiles are difficult to electroresistively heat because the interlocking knit structure short-circuits the flow of current, causing localized overheating and isolating the transformation of the material along the current path. One approach for heating SMA knitted textiles is to drive pulses of high current between pairs of electrodes positioned across horizontal courses (rows) of knitted loops. This research presents a preliminary experimental investigation of the effects of factors related to electroresistive heating for SMA knitted textiles. A design of experiments analysis with two levels of four factors was conducted using a 24–1 fractional factorial design. The factors included the voltage of the power supply connected to the current amplifiers; a geometric factor defining the horizontal spacing of the electrodes attached to the knit sample; and two waveform factors: On Cycles and Off/On Cycles, which defined the length of time each current amplifier was enabled and disabled. Actuation performance was quantified by the actuation displacement and actuation force of the knit sample. Preliminary results suggest that voltage is the most influential factor, but also indicate that interactions between the geometric and waveform factors have significant effects on the heating and actuation performance. The characterization of these factor interactions has the potential to inform optimal electroresistive heating approaches for SMA knitted textiles, enabling integration into applications such as wearable technologies where convective heating is not practical.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127085404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper we present the development, implementation and testing of a compact system for diagnosis and control of actuators based on metallic shape memory alloys (SMA). Using NiTi-SMA, very compact, cost-effective and lightweight actuation systems can be realized. In applications where the SMA is activated by internal Joule heating or its condition is diagnosed by the self-sensing of its electrical resistance, an electrical system capable of reliably measuring very small resistance changes (< 1 ohm) without affecting the phase-state of the SMA is required. In addition, the system must offer the possibility to evaluate the nonlinear, hysteresis-afflicted behavior of the SMA and to handle this difficulty, e.g. utilizing a model-based control. This paper presents a simple compact and adaptive system based on a microcontroller that meets these requirements. Detailed functional tests were carried out with the system to establish a correlation between the change in electrical resistance in the range < 200 mOhm and the current strain state of the actuator. For this purpose, a first series of tests was performed, with the SMA wires working against a constant load. In a second tests series, the SMA wires worked against springs of different stiffness. The use of a microcontroller enables simple implementation of different control strategies. The control system for the non-linear resistance change utilizes a fuzzy logic which divides the control algorithm into three regimes. In the regime of the martensitic phase transformation a PI-controller is used. The state of actuators with an absolute electrical resistance < 1 Ohm and a resistance change < 200 mohm associated with the phase transformation can be precisely measured and controlled with an accuracy < 10 mohm. The system can be configured with little effort for different tasks and shape memory systems of different sizes. Furthermore, it is possible to implement more complex control algorithms up to model-based controllers.
{"title":"Implementation and Investigation of a Compact, Powerful System for Diagnosis and Control of Shape Memory Alloys in Technical Applications","authors":"M. Kaiser, Nils Neblung, M. Gurka","doi":"10.1115/smasis2019-5551","DOIUrl":"https://doi.org/10.1115/smasis2019-5551","url":null,"abstract":"\u0000 In this paper we present the development, implementation and testing of a compact system for diagnosis and control of actuators based on metallic shape memory alloys (SMA). Using NiTi-SMA, very compact, cost-effective and lightweight actuation systems can be realized. In applications where the SMA is activated by internal Joule heating or its condition is diagnosed by the self-sensing of its electrical resistance, an electrical system capable of reliably measuring very small resistance changes (< 1 ohm) without affecting the phase-state of the SMA is required. In addition, the system must offer the possibility to evaluate the nonlinear, hysteresis-afflicted behavior of the SMA and to handle this difficulty, e.g. utilizing a model-based control. This paper presents a simple compact and adaptive system based on a microcontroller that meets these requirements. Detailed functional tests were carried out with the system to establish a correlation between the change in electrical resistance in the range < 200 mOhm and the current strain state of the actuator. For this purpose, a first series of tests was performed, with the SMA wires working against a constant load. In a second tests series, the SMA wires worked against springs of different stiffness. The use of a microcontroller enables simple implementation of different control strategies. The control system for the non-linear resistance change utilizes a fuzzy logic which divides the control algorithm into three regimes. In the regime of the martensitic phase transformation a PI-controller is used. The state of actuators with an absolute electrical resistance < 1 Ohm and a resistance change < 200 mohm associated with the phase transformation can be precisely measured and controlled with an accuracy < 10 mohm. The system can be configured with little effort for different tasks and shape memory systems of different sizes. Furthermore, it is possible to implement more complex control algorithms up to model-based controllers.","PeriodicalId":235262,"journal":{"name":"ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127985264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Erika Magnafico, F. Poli, A. Casalotti, G. Lanzara
In recent years carbon nanotubes (CNTs) have been widely used for the realization of polymeric matrix nanocomposites for strain monitoring applications in civil, biomedical and aerospace engineering. In fact, by embedding CNTs in an insulated polymer matrix, it is possible to realize a conductive nanocomposite with piezoresistive behaviour which allows to monitor the occurring strains through an electrical resistance change. In this work a conductive coating made of Multi-Walled Carbon Nanotubes (MWNTs) and PolymethylMethacrilate (PMMA) is fabricated and is applied onto a fiberglass structure surface. In order to characterize the electrical behaviour of the coating and its capability to sense strain, an experimental campaign is carried out by applying a voltage to the manufactured coating. Its variations throughout the surface in the longitudinal and transverse directions are then evaluated to identify the electric field distribution and its dependence on strain.
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