Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies最新文献
Knitted Textiles made from Nickel-Titanium (NiTi) shape memory alloy wires are a new structural element with enhanced properties for a variety of applications. Potential advantages of this structural form include enhanced bending flexibility, tailorable in-plane, and through-thickness mechanical performance, and energy absorption and damping. Inspection of the knit pattern reveals a repeating cell structure of interlocking loops. Because of this repeating structure, knits can be evaluated as cellular structures that leverage their loop-based architecture for mechanical robustness and flexibility. The flexibility and robustness of the structure can be further enhanced by manufacturing with superelastic NiTi. The stiffness of superelastic NiTi, however, makes traditional knit manufacturing techniques inadequate, so knit manufacturing in this research is aided by shape setting the superelastic wire to a predefined pattern mimicking the natural curve of a strand within a knit fabric. This predefined shape-set geometry determines the outcome of the knit’s mechanical performance and tunes the mechanical properties. In this research, the impact of the shape setting process on the material itself is explored through axial loading tests to quantify the effect that heat treatment has on a knit sample. A means of continuously shape setting and feeding the wire into traditional knitting machines is described. These processes lend themselves to mass production and build upon previous textile manufacturing technologies. This research also proposes an empirical exploration of superelastic NiTi knit mechanical performance and several new techniques for manufacturing such knits with adjustable knit parameters. Displacement-controlled axial loading tests in the vertical (wale) direction determined the recoverability of each knit sample in the research and were iteratively increased until failure resulted. Knit samples showed recoverable axial strains of 65–140%, which could be moderately altered based on knit pattern and loop parameters. Furthermore, this research demonstrates that improving the density of the knit increases the stiffness of the knit without any loss in recoverable strains. These results highlight the potential of this unique structural architecture that could be used to design fabrics with adjustable mechanical properties, expanding the design space for aerospace structures, medical devices, and consumer products.
{"title":"Manufacture of Ultra-Dense Knitted Superelastic Structures","authors":"Henry Koon, J. Laven, J. Abel","doi":"10.1115/SMASIS2018-8225","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8225","url":null,"abstract":"Knitted Textiles made from Nickel-Titanium (NiTi) shape memory alloy wires are a new structural element with enhanced properties for a variety of applications. Potential advantages of this structural form include enhanced bending flexibility, tailorable in-plane, and through-thickness mechanical performance, and energy absorption and damping. Inspection of the knit pattern reveals a repeating cell structure of interlocking loops. Because of this repeating structure, knits can be evaluated as cellular structures that leverage their loop-based architecture for mechanical robustness and flexibility. The flexibility and robustness of the structure can be further enhanced by manufacturing with superelastic NiTi. The stiffness of superelastic NiTi, however, makes traditional knit manufacturing techniques inadequate, so knit manufacturing in this research is aided by shape setting the superelastic wire to a predefined pattern mimicking the natural curve of a strand within a knit fabric. This predefined shape-set geometry determines the outcome of the knit’s mechanical performance and tunes the mechanical properties. In this research, the impact of the shape setting process on the material itself is explored through axial loading tests to quantify the effect that heat treatment has on a knit sample. A means of continuously shape setting and feeding the wire into traditional knitting machines is described. These processes lend themselves to mass production and build upon previous textile manufacturing technologies. This research also proposes an empirical exploration of superelastic NiTi knit mechanical performance and several new techniques for manufacturing such knits with adjustable knit parameters. Displacement-controlled axial loading tests in the vertical (wale) direction determined the recoverability of each knit sample in the research and were iteratively increased until failure resulted. Knit samples showed recoverable axial strains of 65–140%, which could be moderately altered based on knit pattern and loop parameters. Furthermore, this research demonstrates that improving the density of the knit increases the stiffness of the knit without any loss in recoverable strains. These results highlight the potential of this unique structural architecture that could be used to design fabrics with adjustable mechanical properties, expanding the design space for aerospace structures, medical devices, and consumer products.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"149 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115304406","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}
Conductive nanofiller-modified composites have received a lot of attention from the structural health monitoring (SHM) research community in recent years because these materials are piezoresistive (i.e. they have deformation and damage-dependent electrical conductivity) and are therefore self-sensing. To date, the vast majority of work in this area has utilized direct current (DC) interrogation to identify and/or localize damage. While this approach has been met with much success, it is also well known that nanofiller-modified composites possess frequency-dependent electrical behavior. This behavior can be roughly modeled as a parallel resistor-capacitor circuit. However, much less work has been done to explore the potential this frequency-dependent behavior for damage detection. To this end, the work herein presented covers some preliminary results which leverage high-frequency electrical interrogation for damage detection. More specifically, carbon nanofiber (CNF)/epoxy specimens are produced and connected to an external inductor in both series and parallel configurations. Because the CNF/epoxy electrically behaves like a resistor-capacitor circuit, the inclusion of an inductor enables electrical resonance to be achieved. Changes in resonant frequency are then used for rudimentary damage detection. These preliminary results indicate that the potential of SHM via the piezoresistive effect in nanofiller-modified composites can be considerably expanded by leveraging alternating current (AC) interrogation and resonant frequency principles.
{"title":"Damage Detection in Nanofiller-Modified Composites With External Circuitry via Resonant Frequency Shifts","authors":"T. Tallman","doi":"10.1115/SMASIS2018-8008","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8008","url":null,"abstract":"Conductive nanofiller-modified composites have received a lot of attention from the structural health monitoring (SHM) research community in recent years because these materials are piezoresistive (i.e. they have deformation and damage-dependent electrical conductivity) and are therefore self-sensing. To date, the vast majority of work in this area has utilized direct current (DC) interrogation to identify and/or localize damage. While this approach has been met with much success, it is also well known that nanofiller-modified composites possess frequency-dependent electrical behavior. This behavior can be roughly modeled as a parallel resistor-capacitor circuit. However, much less work has been done to explore the potential this frequency-dependent behavior for damage detection. To this end, the work herein presented covers some preliminary results which leverage high-frequency electrical interrogation for damage detection. More specifically, carbon nanofiber (CNF)/epoxy specimens are produced and connected to an external inductor in both series and parallel configurations. Because the CNF/epoxy electrically behaves like a resistor-capacitor circuit, the inclusion of an inductor enables electrical resonance to be achieved. Changes in resonant frequency are then used for rudimentary damage detection. These preliminary results indicate that the potential of SHM via the piezoresistive effect in nanofiller-modified composites can be considerably expanded by leveraging alternating current (AC) interrogation and resonant frequency principles.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123322552","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}
Silicon anodes in lithium ion batteries have high theoretical capacity and large volumetric expansion. In this paper, both characteristics are used in a segmented unimorph actuator consisting of several Si composite anodes on a copper current collector. Each unimorph segment is self-actuating during discharge and the discharge power can be provided to external circuits. With no external forces and zero current draw, the unimorph segments will maintain their actuated shape. Stress-potential coupling allows for the unimorph actuator to be self-sensing because bending changes the anodes’ potential. An analytical model is derived from a superposition of pure bending and extensional deformation forces and moments induced by the cycling of a Si anode. An approximately linear relationship between axial strain and state of charge of the anode drives the bending displacement of the unimorph. The segmented device consists of electrically insulated and individually controlled segments of the Si-coated copper foil to allow for variable curvature throughout the length of the beam. The model predicts the free deflection along the length of the beam and the blocked force. Tip deflection and blocked force are shown for a range of parameters including segment thicknesses, beam length, number of segments, and state of charge. The potential applications of this device include soft robots and dexterous 3D grippers.
{"title":"Analytical Modeling of a Multifunctional Segmented Lithium Ion Battery Unimorph Actuator","authors":"Cody Gonzalez, Jun Ma, M. Frecker, C. Rahn","doi":"10.1115/SMASIS2018-8123","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8123","url":null,"abstract":"Silicon anodes in lithium ion batteries have high theoretical capacity and large volumetric expansion. In this paper, both characteristics are used in a segmented unimorph actuator consisting of several Si composite anodes on a copper current collector. Each unimorph segment is self-actuating during discharge and the discharge power can be provided to external circuits. With no external forces and zero current draw, the unimorph segments will maintain their actuated shape. Stress-potential coupling allows for the unimorph actuator to be self-sensing because bending changes the anodes’ potential. An analytical model is derived from a superposition of pure bending and extensional deformation forces and moments induced by the cycling of a Si anode. An approximately linear relationship between axial strain and state of charge of the anode drives the bending displacement of the unimorph. The segmented device consists of electrically insulated and individually controlled segments of the Si-coated copper foil to allow for variable curvature throughout the length of the beam. The model predicts the free deflection along the length of the beam and the blocked force. Tip deflection and blocked force are shown for a range of parameters including segment thicknesses, beam length, number of segments, and state of charge. The potential applications of this device include soft robots and dexterous 3D grippers.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123410549","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}
Shape Memory Alloys (SMAs), known as an intermetallic alloys with the ability to recover its predefined shape under specific thermomechanical loading, has been widely aware of working as actuators for active/smart morphing structures in engineering industry. Because of the high actuation energy density of SMAs, compared to other active materials, structures integrated with SMA-based actuators has high advantage in terms of tradeoffs between overall structure weight, integrity and functionality. The majority of available constitutive models for SMAs are developed within infinitesimal strain regime. However, it was reported that particular SMAs can generate transformation strains nearly up to 8%–10%, for which the adopted infinitesimal strain assumption is no longer appropriate. Furthermore, industry applications may require SMA actuators, such as a SMA torque tube, undergo large rotation deformation at work. Combining the above two facts, a constitutive model for SMAs developed on a finite deformation framework is required to predict accurate response for these SMA-based actuators under large deformations. A three-dimensional constitutive model for SMAs considering large strains with large rotations is proposed in this work. This model utilizes the logarithmic strain as a finite strain measure for large deformation analysis so that its rate form hypoelastic constitutive relation can be consistently integrated to deliver a free energy based hyper-elastic constitutive relation. The martensitic volume fraction and the second-order transformation strain tensor are chosen as the internal state variables to characterize the inelastic response exhibited by polycrystalline SMAs. Numerical experiments for basic SMA geometries, such as a bar under tension and a torque tube under torsion are performed to test the capabilities of the newly proposed model. The presented formulation and its numerical implementation scheme can be extended in future work for the incorporation of other inelastic phenomenas such as transformation-induced plasticity, viscoplasticity and creep under large deformations.
{"title":"A Three-Dimensional Constitutive Model for Polycrystalline Shape Memory Alloys Under Large Strains Combined With Large Rotations","authors":"Lei Xu, T. Baxevanis, D. Lagoudas","doi":"10.1115/SMASIS2018-8050","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8050","url":null,"abstract":"Shape Memory Alloys (SMAs), known as an intermetallic alloys with the ability to recover its predefined shape under specific thermomechanical loading, has been widely aware of working as actuators for active/smart morphing structures in engineering industry. Because of the high actuation energy density of SMAs, compared to other active materials, structures integrated with SMA-based actuators has high advantage in terms of tradeoffs between overall structure weight, integrity and functionality. The majority of available constitutive models for SMAs are developed within infinitesimal strain regime. However, it was reported that particular SMAs can generate transformation strains nearly up to 8%–10%, for which the adopted infinitesimal strain assumption is no longer appropriate. Furthermore, industry applications may require SMA actuators, such as a SMA torque tube, undergo large rotation deformation at work. Combining the above two facts, a constitutive model for SMAs developed on a finite deformation framework is required to predict accurate response for these SMA-based actuators under large deformations.\u0000 A three-dimensional constitutive model for SMAs considering large strains with large rotations is proposed in this work. This model utilizes the logarithmic strain as a finite strain measure for large deformation analysis so that its rate form hypoelastic constitutive relation can be consistently integrated to deliver a free energy based hyper-elastic constitutive relation. The martensitic volume fraction and the second-order transformation strain tensor are chosen as the internal state variables to characterize the inelastic response exhibited by polycrystalline SMAs. Numerical experiments for basic SMA geometries, such as a bar under tension and a torque tube under torsion are performed to test the capabilities of the newly proposed model. The presented formulation and its numerical implementation scheme can be extended in future work for the incorporation of other inelastic phenomenas such as transformation-induced plasticity, viscoplasticity and creep under large deformations.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"02 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129708947","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}
Shengyuan Li, Peigang Li, Yang Zhang, Xuefeng Zhao
High-speed railway plays critical roles in public safety and the country’s economy. Visual detection of components and damages can reflect the health conditions of high-speed railway. Human-based visual inspection is a difficult and time-consuming task and its detection results significantly rely on subjective judgement of human inspectors. Image-based detection methods abandon the weakness of human-based visual inspection. However, in practice, the complex real-world situations, such as lighting and shadow changes, can lead to challenges to the wide adaptability of image process techniques. To overcome these challenges, this paper provides a Faster Region-based Convolutional Neural Network (Faster R-CNN)-based detection method of component types and track damage for high-speed railway. To realize the method, a database including 575 images labeled for three component types and one track damage type of high-speed railway is built. A Faster R-CNN architecture based on ZF-Net is modified, then trained and validated using the built database. The performance of the trained Faster R-CNN is evaluated using 50 new images which are not be used for training process. The results show that the proposed method can indeed detect the component types and track damage for high-speed railway.
{"title":"Detection of Component Types and Track Damage for High-Speed Railway Using Region-Based Convolutional Neural Networks","authors":"Shengyuan Li, Peigang Li, Yang Zhang, Xuefeng Zhao","doi":"10.1115/SMASIS2018-8223","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8223","url":null,"abstract":"High-speed railway plays critical roles in public safety and the country’s economy. Visual detection of components and damages can reflect the health conditions of high-speed railway. Human-based visual inspection is a difficult and time-consuming task and its detection results significantly rely on subjective judgement of human inspectors. Image-based detection methods abandon the weakness of human-based visual inspection. However, in practice, the complex real-world situations, such as lighting and shadow changes, can lead to challenges to the wide adaptability of image process techniques. To overcome these challenges, this paper provides a Faster Region-based Convolutional Neural Network (Faster R-CNN)-based detection method of component types and track damage for high-speed railway. To realize the method, a database including 575 images labeled for three component types and one track damage type of high-speed railway is built. A Faster R-CNN architecture based on ZF-Net is modified, then trained and validated using the built database. The performance of the trained Faster R-CNN is evaluated using 50 new images which are not be used for training process. The results show that the proposed method can indeed detect the component types and track damage for high-speed railway.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128355853","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}
A novel bridged-microfluidic for cell-based assays was developed by combining a microstructured optical fiber (MOF) with a microfluidic network with the purpose of continuously monitoring the state of hepatocellular carcinoma (HepG2) cells. In this configuration a solid core MOF with channels in the cladding serves as a bridge for cell transport as well as an evanescent wave-based monitoring system to detect cells labeled with fluorescent nanomaterials. The device was fabricated by positioning an MOF to bridge two polydimethylsiloxane (PDMS) microfluidic networks. Alignment strategies and pressurization considerations to produce this system are presented. Pump systems that support fluid transport through the MOF demonstrated the tendency of flow rate fluctuations even for constant microfluidic pump rates. Spectroscopic measurements confirm the delivery and motion of cells between the two neighboring microfluidic chips. The linewidth of the spectra demonstrated oscillations that were consistent with pressure broadening caused by hydrodynamic fluctuations. Fluctuations in the microfluidic flow ranging from 0.005 to 0.016 Hz were observed. These results are consistent with theoretical principles and provide important information regarding syringe pump artifacts, i.e. fluctuations, observed during spectroscopic measurements in MOF/microfluidic systems.
{"title":"Fabrication Considerations for Bridged Microfluidic Cell Cultures","authors":"R. Wynne, Sabrina Ahmed","doi":"10.1115/SMASIS2018-7983","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7983","url":null,"abstract":"A novel bridged-microfluidic for cell-based assays was developed by combining a microstructured optical fiber (MOF) with a microfluidic network with the purpose of continuously monitoring the state of hepatocellular carcinoma (HepG2) cells. In this configuration a solid core MOF with channels in the cladding serves as a bridge for cell transport as well as an evanescent wave-based monitoring system to detect cells labeled with fluorescent nanomaterials. The device was fabricated by positioning an MOF to bridge two polydimethylsiloxane (PDMS) microfluidic networks. Alignment strategies and pressurization considerations to produce this system are presented. Pump systems that support fluid transport through the MOF demonstrated the tendency of flow rate fluctuations even for constant microfluidic pump rates. Spectroscopic measurements confirm the delivery and motion of cells between the two neighboring microfluidic chips. The linewidth of the spectra demonstrated oscillations that were consistent with pressure broadening caused by hydrodynamic fluctuations. Fluctuations in the microfluidic flow ranging from 0.005 to 0.016 Hz were observed. These results are consistent with theoretical principles and provide important information regarding syringe pump artifacts, i.e. fluctuations, observed during spectroscopic measurements in MOF/microfluidic systems.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128689228","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 study uses the finite element method to analyze the sliding contact behavior between a rigid cylinder and a shape memory alloy (SMA) semi-infinite half-space. An experimentally validated constitutive model is used to capture the pseudoelastic effect exhibited by these alloys. Parametric studies involving the maximum recoverable transformation strain and the transformation temperatures are performed to analyze the effects that these parameters have on the stress fields during indentation and sliding contact. It is shown that, depending on the amount of recoverable transformation strain possessed by the alloy, a reduction of almost 40 % of the maximum stress in the pseudoelastic half-space is achieved when compared to the maximum stress in a purely elastic half-space. The studies also reveal that the sliding response is strongly temperature dependent, with significant residual stress present in the half-space at temperatures below the austenitic finish temperature.
{"title":"Plane Strain Sliding Contact Between a Rigid Cylinder and a Pseudoelastic Shape Memory Alloy Half-Space","authors":"R. Fernandes, J. Boyd, D. Lagoudas, S. El-Borgi","doi":"10.1115/SMASIS2018-8243","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8243","url":null,"abstract":"This study uses the finite element method to analyze the sliding contact behavior between a rigid cylinder and a shape memory alloy (SMA) semi-infinite half-space. An experimentally validated constitutive model is used to capture the pseudoelastic effect exhibited by these alloys. Parametric studies involving the maximum recoverable transformation strain and the transformation temperatures are performed to analyze the effects that these parameters have on the stress fields during indentation and sliding contact. It is shown that, depending on the amount of recoverable transformation strain possessed by the alloy, a reduction of almost 40 % of the maximum stress in the pseudoelastic half-space is achieved when compared to the maximum stress in a purely elastic half-space. The studies also reveal that the sliding response is strongly temperature dependent, with significant residual stress present in the half-space at temperatures below the austenitic finish temperature.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"166 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123199693","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 special piezoelectric energy harvester system which is obtained by separating the end of the upper piezoelectric layer of the traditional piezoelectric cantilever beam from its basic layer. A mass I is located at the end of the separated upper piezoelectric layer (SUPL), a mass II and a permanent magnet I are located at the end of the separated lower piezoelectric beam (SLPB) and a permanent magnet II is added in the opposite position of the permanent magnet I and they face each other with same polarities. A nonlinear magnetic force which can broaden the frequency bandwidth of the system is generated mutually on the two permanent magnets. Studies find that this special piezoelectric energy harvester has extremely high energy capture efficiency. In order to further explore the reason of high efficiency, experimental research on its dynamic behavior is carried out. The experimental results show that the vibrations of the SUPL and the SLPB are relatively simple. The dynamic behaviors of the SUPL, the SLPB and the unseparated part are different. The unseparated part of the piezoelectric shows relatively complex nonlinear phenomenon due to the interaction of nonlinear magnetic force and the collision. With the increase of the external excitation frequency, period doubling motion and almost periodic motion appear alternately.
{"title":"Nonlinear Dynamics of a Special Piezoelectric Energy Harvester With a Special Bistable Piezoelectric Cantilever Beam","authors":"M. Yao, W. Xia, Wei Zhang, J. Jiao","doi":"10.1115/SMASIS2018-7967","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7967","url":null,"abstract":"This paper presents a special piezoelectric energy harvester system which is obtained by separating the end of the upper piezoelectric layer of the traditional piezoelectric cantilever beam from its basic layer. A mass I is located at the end of the separated upper piezoelectric layer (SUPL), a mass II and a permanent magnet I are located at the end of the separated lower piezoelectric beam (SLPB) and a permanent magnet II is added in the opposite position of the permanent magnet I and they face each other with same polarities. A nonlinear magnetic force which can broaden the frequency bandwidth of the system is generated mutually on the two permanent magnets. Studies find that this special piezoelectric energy harvester has extremely high energy capture efficiency. In order to further explore the reason of high efficiency, experimental research on its dynamic behavior is carried out. The experimental results show that the vibrations of the SUPL and the SLPB are relatively simple. The dynamic behaviors of the SUPL, the SLPB and the unseparated part are different. The unseparated part of the piezoelectric shows relatively complex nonlinear phenomenon due to the interaction of nonlinear magnetic force and the collision. With the increase of the external excitation frequency, period doubling motion and almost periodic motion appear alternately.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":" 50","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113952688","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}
F. Welsch, Susanne-Marie Kirsch, Nicolas Michaelis, Paul Motzki, Marvin Schmidt, A. Schütze, S. Seelecke
Elastocaloric cooling is a novel environment-friendly alternative to vapor compression-based cooling systems. This solid-state cooling technology uses NiTi shape memory alloys (SMAs) as cooling medium. SMAs are well known for lightweight actuator systems and biomedical applications, but in addition, these alloys exhibit excellent cooling properties. Due to the high latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by a small required work input, this also leads to a high coefficient of performance superior to vapor compression-based systems. In order to access the potential of these alloys, the development of suitable thermodynamic cooling cycles and an efficient system design are required. This paper presents a model-based design process of an elastocaloric air-cooling device. The device is divided into two parts, a mechanical system for continuously loading and unloading of multiple SMA wire bundles by a rotary motor and a heat transfer system. The heat transfer system enables an efficient heat exchange between the heat source and the SMA wires as well as between the SMA wires and the environment. The device operates without any additional heat transfer medium and cools the heat source directly, which is an advantage in comparison to conventional cooling systems. The design of this complex device in an efficient manner requires a model approach, capable of predicting the system parameters cooling power, mechanical work and coefficient of performance under various operating conditions. The developed model consists of a computationally efficient, thermo-mechanically coupled and energy based SMA model, a model of the system kinematics and a heat transfer model. With this approach, the complete cooling system can be simulated, and the required number of SMA wires as well as the mechanical power can be predicted in order to meet the system requirements. Based on the simulation results a first prototype of the elastocaloric cooling system is realized.
{"title":"Elastocaloric Cooling: System Design, Simulation, and Realization","authors":"F. Welsch, Susanne-Marie Kirsch, Nicolas Michaelis, Paul Motzki, Marvin Schmidt, A. Schütze, S. Seelecke","doi":"10.1115/SMASIS2018-7982","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7982","url":null,"abstract":"Elastocaloric cooling is a novel environment-friendly alternative to vapor compression-based cooling systems. This solid-state cooling technology uses NiTi shape memory alloys (SMAs) as cooling medium. SMAs are well known for lightweight actuator systems and biomedical applications, but in addition, these alloys exhibit excellent cooling properties. Due to the high latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by a small required work input, this also leads to a high coefficient of performance superior to vapor compression-based systems. In order to access the potential of these alloys, the development of suitable thermodynamic cooling cycles and an efficient system design are required. This paper presents a model-based design process of an elastocaloric air-cooling device. The device is divided into two parts, a mechanical system for continuously loading and unloading of multiple SMA wire bundles by a rotary motor and a heat transfer system. The heat transfer system enables an efficient heat exchange between the heat source and the SMA wires as well as between the SMA wires and the environment. The device operates without any additional heat transfer medium and cools the heat source directly, which is an advantage in comparison to conventional cooling systems. The design of this complex device in an efficient manner requires a model approach, capable of predicting the system parameters cooling power, mechanical work and coefficient of performance under various operating conditions. The developed model consists of a computationally efficient, thermo-mechanically coupled and energy based SMA model, a model of the system kinematics and a heat transfer model. With this approach, the complete cooling system can be simulated, and the required number of SMA wires as well as the mechanical power can be predicted in order to meet the system requirements. Based on the simulation results a first prototype of the elastocaloric cooling system is realized.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128042680","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}
Y. Yang, Y. Fu, C. T. Chen, S. C. Lin, J. Shieh, M. Veidt, W. Wu
In this paper, a high performance micro piezoelectric energy harvester (PEH) fabricated on stainless substrates is presented. A PZT piezoelectric active layer with a thickness of about 10 μm was deposited on a stainless steel substrate by the aerosol deposition method. The cantilever beam-shaped PEH was then fabricated by metal-MEMS processing of the PZT/stainless steel composite structure. The size of the cantilever PEH transducer developed was about 1 cm2 and a proof mass was attached to tune its resonant frequency to around 120 Hz for harvesting mechanical vibrations from direct drive AC motors. The PEH transducer showed an output voltage and an output power of 8.9 Vp-p and 107.8 μW, respectively, when connected with optimal load and excited under 0.5 g acceleration level. In order to realize the fatigue behavior and reliability of the PEH in field applications, the PEH transducer was driven at its own resonant frequency and tested under 1.0 g acceleration level for millions of cycles and the vibration modes were measured with a laser scanning vibrometer. The PEH transducer had an operating lifetime of about 1.8 million cycles at 1.0 g cyclic loading based on the shift of its resonant frequencies and the decrease in electrical output. The experimental results show the resonant frequencies of the first, second and third modes were all shifted to lower frequencies with increasing operation cycle number due to the development of microcracks in the ceramic PZT active layer. However, the same PEH transducer could survive millions of cycles (in the high millions) at 0.5 g cyclic loading without any significant changes in the resonant frequencies and electrical output. The results confirm the operating limits of the PEH transducer and suggest further protection and reinforcement are required for the transducer to operate at high acceleration loadings.
{"title":"The Reliability Testing and Fatigue Behavior Study of Micro Piezoelectric Energy Harvester","authors":"Y. Yang, Y. Fu, C. T. Chen, S. C. Lin, J. Shieh, M. Veidt, W. Wu","doi":"10.1115/SMASIS2018-8022","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8022","url":null,"abstract":"In this paper, a high performance micro piezoelectric energy harvester (PEH) fabricated on stainless substrates is presented. A PZT piezoelectric active layer with a thickness of about 10 μm was deposited on a stainless steel substrate by the aerosol deposition method. The cantilever beam-shaped PEH was then fabricated by metal-MEMS processing of the PZT/stainless steel composite structure. The size of the cantilever PEH transducer developed was about 1 cm2 and a proof mass was attached to tune its resonant frequency to around 120 Hz for harvesting mechanical vibrations from direct drive AC motors. The PEH transducer showed an output voltage and an output power of 8.9 Vp-p and 107.8 μW, respectively, when connected with optimal load and excited under 0.5 g acceleration level. In order to realize the fatigue behavior and reliability of the PEH in field applications, the PEH transducer was driven at its own resonant frequency and tested under 1.0 g acceleration level for millions of cycles and the vibration modes were measured with a laser scanning vibrometer. The PEH transducer had an operating lifetime of about 1.8 million cycles at 1.0 g cyclic loading based on the shift of its resonant frequencies and the decrease in electrical output. The experimental results show the resonant frequencies of the first, second and third modes were all shifted to lower frequencies with increasing operation cycle number due to the development of microcracks in the ceramic PZT active layer. However, the same PEH transducer could survive millions of cycles (in the high millions) at 0.5 g cyclic loading without any significant changes in the resonant frequencies and electrical output. The results confirm the operating limits of the PEH transducer and suggest further protection and reinforcement are required for the transducer to operate at high acceleration loadings.","PeriodicalId":117187,"journal":{"name":"Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131734864","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}
Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies
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