Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation最新文献
The demand for clean and sustainable energy sources continuously increases. One of the promising ways to provide electrical power is using fuel cells. Polymer electrolyte membrane fuel cell (PEMFC) represents the most common type of fuel cells. However, PEMFCs have not yet been fully commercialized because of the high cost and low performance. A main part of PEMFC, which significantly contributes to the cost and weight is the bipolar plate (BPP). The US Department of Energy (DOE) has recommended some physical properties for BPP for sustainable commercialization of PEMFC. Those set properties have yet to be met. Conductive polymer composites (CPCs) use conductive fillers such as carbon nanotube (CNT), carbon fiber (CF), and graphite (Gr) to impart electrical and thermal conductivities and can potentially provide an optimum combination of weight, cost, mechanical properties and conductivity characteristics for BPPs. In the current work, CPCs of polycarbonate (PC) filled with singular filler of CNT, binary fillers of CNT and CF and ternary fillers of CNT, CF and Gr were fabricated using melt mixing method followed by compression molding. The through-plane and in-plane electrical conductivities of the CPCs were investigated. The results showed that the electrical percolation thresholds for the PC-CNT is ∼1 wt. % CNT in both the through-plane and in-plane directions. Addition of 3 wt. % CNT to PC composites with 10 - 30 wt. % CF improved the conductivity performance. It was noticed increasing CF content from 20 to 30 wt. % did not yield a big change in conductivity, so that at 20 wt. % CF, the through-plane and in-plane electrical conductivities are 0.11 S.cm−1 and 6.4 S.cm−1 respectively. Moreover, using 20 wt. % CF will allow for higher loading of graphite. To further enhance the conductivities towards the DOE recommendations, 30 wt. % Gr was introduced to the PC composite with binary filler (i.e., 3 wt. % CNT and 20 wt. % CF). The results showed that the through-plane and in-plane electrical conductivities were increased to 1.5 S.cm−1 and 13.5 S.cm−1, respectively. These properties recommend a potential application of polycarbonate based CPCs for BPP manufacturing.
{"title":"Melt Processed Conductive Polycarbonate Composites With Ternary Fillers Towards Bipolar Plate Applications","authors":"A. Naji, P. Pötschke, A. Ameli","doi":"10.1115/SMASIS2018-8046","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8046","url":null,"abstract":"The demand for clean and sustainable energy sources continuously increases. One of the promising ways to provide electrical power is using fuel cells. Polymer electrolyte membrane fuel cell (PEMFC) represents the most common type of fuel cells. However, PEMFCs have not yet been fully commercialized because of the high cost and low performance. A main part of PEMFC, which significantly contributes to the cost and weight is the bipolar plate (BPP). The US Department of Energy (DOE) has recommended some physical properties for BPP for sustainable commercialization of PEMFC. Those set properties have yet to be met. Conductive polymer composites (CPCs) use conductive fillers such as carbon nanotube (CNT), carbon fiber (CF), and graphite (Gr) to impart electrical and thermal conductivities and can potentially provide an optimum combination of weight, cost, mechanical properties and conductivity characteristics for BPPs.\u0000 In the current work, CPCs of polycarbonate (PC) filled with singular filler of CNT, binary fillers of CNT and CF and ternary fillers of CNT, CF and Gr were fabricated using melt mixing method followed by compression molding. The through-plane and in-plane electrical conductivities of the CPCs were investigated. The results showed that the electrical percolation thresholds for the PC-CNT is ∼1 wt. % CNT in both the through-plane and in-plane directions. Addition of 3 wt. % CNT to PC composites with 10 - 30 wt. % CF improved the conductivity performance. It was noticed increasing CF content from 20 to 30 wt. % did not yield a big change in conductivity, so that at 20 wt. % CF, the through-plane and in-plane electrical conductivities are 0.11 S.cm−1 and 6.4 S.cm−1 respectively. Moreover, using 20 wt. % CF will allow for higher loading of graphite. To further enhance the conductivities towards the DOE recommendations, 30 wt. % Gr was introduced to the PC composite with binary filler (i.e., 3 wt. % CNT and 20 wt. % CF). The results showed that the through-plane and in-plane electrical conductivities were increased to 1.5 S.cm−1 and 13.5 S.cm−1, respectively. These properties recommend a potential application of polycarbonate based CPCs for BPP manufacturing.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"788 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":"116133830","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) are often used for robotic, biomedical, and aerospace applications because of their unique ability to undergo large amounts of stress and strain during thermomechanical loading compared to traditional metals. While SMAs such as NiTi have been used in wire, plate, and tubular forms, NiTi as a woven dry fabric has yet to be analyzed for use as protective materials and actuators. Applications of SMA fabric as a “passive” material include shields, seatbelts, watchbands and window screens. Applications as an “active” material include robotic actuators, wearable medical and therapy devices, and self-healing shields and screens. This paper applies a macro-mechanical model from composites analysis to NiTi plain woven fabric to determine the effective elastic constants. The fabric model is based on actual weave geometry, including the presence of open gaps and wire cross-sectional area, and with the same diameter and alloy in the warp and weft. A woven NiTi ribbon has been manufactured (Figure 1) using a narrow weaving machine and has been tested in uniaxial tension. Planar fabric constants were measured at a range of temperatures. The analytically and experimentally derived constants for various weave patterns and cover factor combinations are presented and compared. It was determined that in uniaxial tension the fabric behaves like a collection of unidirectional wires, but has 78% of the rigidity, on average, across all test temperatures. This result is predicted by the fabric model with a 16% error, demonstrating that the proposed analytical model offers a useful tool for design and simulation of SMA fabrics.
{"title":"Design and Analysis of SMA Woven Fabric","authors":"Amanda Skalitzky, A. Gurley, D. Beale, K. Kubik","doi":"10.1115/SMASIS2018-8206","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8206","url":null,"abstract":"Shape Memory Alloys (SMAs) are often used for robotic, biomedical, and aerospace applications because of their unique ability to undergo large amounts of stress and strain during thermomechanical loading compared to traditional metals. While SMAs such as NiTi have been used in wire, plate, and tubular forms, NiTi as a woven dry fabric has yet to be analyzed for use as protective materials and actuators. Applications of SMA fabric as a “passive” material include shields, seatbelts, watchbands and window screens. Applications as an “active” material include robotic actuators, wearable medical and therapy devices, and self-healing shields and screens. This paper applies a macro-mechanical model from composites analysis to NiTi plain woven fabric to determine the effective elastic constants. The fabric model is based on actual weave geometry, including the presence of open gaps and wire cross-sectional area, and with the same diameter and alloy in the warp and weft. A woven NiTi ribbon has been manufactured (Figure 1) using a narrow weaving machine and has been tested in uniaxial tension. Planar fabric constants were measured at a range of temperatures. The analytically and experimentally derived constants for various weave patterns and cover factor combinations are presented and compared. It was determined that in uniaxial tension the fabric behaves like a collection of unidirectional wires, but has 78% of the rigidity, on average, across all test temperatures. This result is predicted by the fabric model with a 16% error, demonstrating that the proposed analytical model offers a useful tool for design and simulation of SMA fabrics.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"1 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":"115227392","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}
Graphene nanoplatelets (GNPs) have the same chemical structures as carbon nanotubes but their internal structure consists of multiple layers of graphene with thicknesses of only a few nanometers. Due to their increased thickness, GNPs are less prone to agglomeration and entanglement when they are used as nanofillers in composite materials. Although it has been shown that self-sensing cementitious composites can be fabricated using GNPs, further studies are needed to reveal effect of various factors on the performance of such composites. Here, a fabrication method that mainly employs polycarboxylate-based superplasticizers together with high-speed shear mixing to disperse GNPs in cement composites is used to prepare GNP-reinforced mortar composites. The molecular structure of polycarboxylate-based superplasticizer can considerably affect the performance of GNP-cement composites. Therefore, two commercially available polycarboxylate-based superplasticizers that possess varying backbone and side-chain lengths are systematically incorporated to prepare GNP-reinforced multifunctional composites. In addition, the effects of mixing durations on the electrical properties of the developed composites are assessed. Another essential challenge in the development of multifunctional cement composites is to improve the interfacial interaction between GNPs and the hydration products of cement such as calcium-silicate-hydrates (CSH). Here, incorporation of supplementary materials such as silica fume into the matrix is studied to improve the bond between a cementitious matrix and nano reinforcement. The bulk resistivity of the mortar specimens is measured using the four-probe measurement method. The piezoresistive behavior and sensing ability of the GNP-reinforced mortar composites are investigated through compressive tests at quasi-static.
{"title":"Evaluation of Various Factors on Electrical Properties of GNP-Reinforced Mortar Composites","authors":"O. Ozbulut, Zhangfan Jiang, G. Xing","doi":"10.1115/SMASIS2018-8062","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8062","url":null,"abstract":"Graphene nanoplatelets (GNPs) have the same chemical structures as carbon nanotubes but their internal structure consists of multiple layers of graphene with thicknesses of only a few nanometers. Due to their increased thickness, GNPs are less prone to agglomeration and entanglement when they are used as nanofillers in composite materials. Although it has been shown that self-sensing cementitious composites can be fabricated using GNPs, further studies are needed to reveal effect of various factors on the performance of such composites. Here, a fabrication method that mainly employs polycarboxylate-based superplasticizers together with high-speed shear mixing to disperse GNPs in cement composites is used to prepare GNP-reinforced mortar composites. The molecular structure of polycarboxylate-based superplasticizer can considerably affect the performance of GNP-cement composites. Therefore, two commercially available polycarboxylate-based superplasticizers that possess varying backbone and side-chain lengths are systematically incorporated to prepare GNP-reinforced multifunctional composites. In addition, the effects of mixing durations on the electrical properties of the developed composites are assessed. Another essential challenge in the development of multifunctional cement composites is to improve the interfacial interaction between GNPs and the hydration products of cement such as calcium-silicate-hydrates (CSH). Here, incorporation of supplementary materials such as silica fume into the matrix is studied to improve the bond between a cementitious matrix and nano reinforcement. The bulk resistivity of the mortar specimens is measured using the four-probe measurement method. The piezoresistive behavior and sensing ability of the GNP-reinforced mortar composites are investigated through compressive tests at quasi-static.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"7 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":"114357761","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 investigate the coupled band gaps created by the locking phenomenon between the electrical and flexural waves in piezoelectric composite plates. To do that, the distributed piezoelectric materials should be interconnected via a ‘global’ electric network rather than the respective ‘local’ impedance. Once the uncoupled electrical wave has the same wavelength and opposite group velocity as the uncoupled flexural wave, the desired coupled band gap emerges. The Wave Finite Element Method (WFEM) is used to investigate the evolution of the coupled band gap with respect to propagation direction and electric parameters. Further, the bandwidth and directionality of the coupled band gap are compared with the LR and Bragg gaps. An indicator termed ratio of single wave (RSW) is proposed to determine the effective band gap for a given deformation (electric, flexural, etc.). We show that the coupled band gap, despite directional, can be much wider than the LR gap with the same overall inductance. This might lead to an alternative to create sub-wavelength band gaps.
{"title":"Coupled Band Gaps in the Piezoelectric Composite Plate With Interconnected Electric Impedance","authors":"Lin Li, Zhou Jiang, Yu Fan, Jun Li","doi":"10.1115/SMASIS2018-7948","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7948","url":null,"abstract":"In this paper, we investigate the coupled band gaps created by the locking phenomenon between the electrical and flexural waves in piezoelectric composite plates. To do that, the distributed piezoelectric materials should be interconnected via a ‘global’ electric network rather than the respective ‘local’ impedance. Once the uncoupled electrical wave has the same wavelength and opposite group velocity as the uncoupled flexural wave, the desired coupled band gap emerges. The Wave Finite Element Method (WFEM) is used to investigate the evolution of the coupled band gap with respect to propagation direction and electric parameters. Further, the bandwidth and directionality of the coupled band gap are compared with the LR and Bragg gaps. An indicator termed ratio of single wave (RSW) is proposed to determine the effective band gap for a given deformation (electric, flexural, etc.). We show that the coupled band gap, despite directional, can be much wider than the LR gap with the same overall inductance. This might lead to an alternative to create sub-wavelength band gaps.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"40 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133036825","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 reduction of low-frequency noise transmission through thin-walled structures is a topic of research for many years now. Due to large wavelengths and the mass law, passive solutions usually gain low performance in the frequency range below 500 Hz. Active systems promised to fill the gap and to achieve significant reductions of transmitted sound. Nevertheless, experiments showed the outstanding performance of such specialized systems, but also demonstrated the computational and hardware effort of such solutions. The upcoming additive manufacturing technology enabled new multi-material designs of complex structures. Based on this technology, acoustic metamaterials emerged in the laboratories and in literature. Arrays of miniaturized locally resonant structures are able to change the noise transmission of thin walled structures beyond the limits of the given mass law in certain frequency bands. For future aircraft contra-rotating open rotor (CROR) engines are a promising technology to reduce their CO2 footprint. Since the contribution of CROR engines to the cabin noise is higher than for jet engines, new strategies for the reduction of noise transmissions for frequency bands below 200 Hz are necessary. For the tonal noise of the CROR engines, acoustic metamaterials seem to be an appropriate solution. In this paper a 110 × 110 × 1 mm3 thin-walled sample plate is presented. It is covered with a 5 × 5 array of multi-material resonant structures, which are printed as mass on a beam. The rubber-like beam material combines a low Young’s modulus with a high material damping, leading to a low eigenfrequency of the resonators. The design of the resonators using simulations and experimental data is shown. To explore the potential of the design, an acoustic test box is manufactured. Starting with all resonators unblocked the emitted sound intensity of the plate is measured. Sequential blocking of selected resonators proves the concept. Additional laser scanning vibrometer measurements give insights into the vibration behavior of single resonators.
{"title":"Reduction of Low-Frequency Sound Transmission Using an Array of 3D-Printed Resonant Structures","authors":"S. Algermissen, H. Monner","doi":"10.1115/SMASIS2018-7985","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7985","url":null,"abstract":"The reduction of low-frequency noise transmission through thin-walled structures is a topic of research for many years now. Due to large wavelengths and the mass law, passive solutions usually gain low performance in the frequency range below 500 Hz. Active systems promised to fill the gap and to achieve significant reductions of transmitted sound. Nevertheless, experiments showed the outstanding performance of such specialized systems, but also demonstrated the computational and hardware effort of such solutions. The upcoming additive manufacturing technology enabled new multi-material designs of complex structures. Based on this technology, acoustic metamaterials emerged in the laboratories and in literature. Arrays of miniaturized locally resonant structures are able to change the noise transmission of thin walled structures beyond the limits of the given mass law in certain frequency bands.\u0000 For future aircraft contra-rotating open rotor (CROR) engines are a promising technology to reduce their CO2 footprint. Since the contribution of CROR engines to the cabin noise is higher than for jet engines, new strategies for the reduction of noise transmissions for frequency bands below 200 Hz are necessary. For the tonal noise of the CROR engines, acoustic metamaterials seem to be an appropriate solution. In this paper a 110 × 110 × 1 mm3 thin-walled sample plate is presented. It is covered with a 5 × 5 array of multi-material resonant structures, which are printed as mass on a beam. The rubber-like beam material combines a low Young’s modulus with a high material damping, leading to a low eigenfrequency of the resonators. The design of the resonators using simulations and experimental data is shown. To explore the potential of the design, an acoustic test box is manufactured. Starting with all resonators unblocked the emitted sound intensity of the plate is measured. Sequential blocking of selected resonators proves the concept. Additional laser scanning vibrometer measurements give insights into the vibration behavior of single resonators.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"53 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":"115838266","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. Benouhiba, K. Rabenorosoa, P. Rougeot, M. Ouisse, N. Andreff
In the growing field of origami engineering, self-folding is of a high regard. The latter is regularly used by nature as an efficient approach for autonomous growing and reorganizing. In this work, we present a self-folding approach based on Electro-Active Polymer (EAP), especially Conductive Polymers (CP). This approach proposes lightweight, compact and energy efficient self-folding structures, as well as large angle and reversible folding. We study the behavior of a three-segment milli-structure containing two passive segments made of paper, separated by an active segment made of CP. The folding motion of the structure was modeled and experimentally validated. Furthermore, as a proof of concept, a self-folding origami cube is presented.
{"title":"Electro-Active Polymer Based Self-Folding Approach Devoted to Origami-Inspired Structures","authors":"A. Benouhiba, K. Rabenorosoa, P. Rougeot, M. Ouisse, N. Andreff","doi":"10.1115/SMASIS2018-8153","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8153","url":null,"abstract":"In the growing field of origami engineering, self-folding is of a high regard. The latter is regularly used by nature as an efficient approach for autonomous growing and reorganizing. In this work, we present a self-folding approach based on Electro-Active Polymer (EAP), especially Conductive Polymers (CP). This approach proposes lightweight, compact and energy efficient self-folding structures, as well as large angle and reversible folding. We study the behavior of a three-segment milli-structure containing two passive segments made of paper, separated by an active segment made of CP. The folding motion of the structure was modeled and experimentally validated. Furthermore, as a proof of concept, a self-folding origami cube is presented.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"116 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":"132216109","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}
Yisheng Zheng, Zhen Wu, Xinong Zhang, Kon-Well Wang
In this paper, we present a piezoelectric metamaterial integrated with bistable circuits to realize adaptive non-reciprocal elastic wave transmission. Dynamics of the bistable circuit and the piezoelectric metamaterial are investigated numerically to analyze the wave transmission characteristics of the proposed system. Results reveal that when the excitation amplitude exceeds certain threshold, wave energy is able to propagate even with excitation frequency inside the local-resonance bandgap of the piezoelectric metamaterial. This bandgap transmission phenomenon is also known as supratransmission. It is shown that by introducing spatial asymmetry, the system could exhibit different supratransmission thresholds when it is actuated in opposite directions, and hence there exists an excitation range within which wave energy is only able to propagate in one direction. Furthermore, this excitation range to facilitate non-reciprocal energy transmission is adaptable by adjusting the stable equilibria of the bistable circuits, which can be conveniently tuned utilizing only DC voltage sources. Additionally, it is shown that by adjusting the stable equilibria, the wave propagation direction, analogous to the forward direction of an electrical diode, can be easily reversed. Lastly, in contrast to many nonlinearity enabled non-reciprocal systems, the proposed system is able to realize non-reciprocal elastic energy transmission with majority of the transmitted energy preserved at the original input frequency. Overall, these results illustrate a new means of utilizing nonlinear piezoelectric metamaterial to manipulate elastic wave transmission.
{"title":"A Piezoelectric Metamaterial With Bistable Circuit Shunts for Adaptive Non-Reciprocal Elastic Wave Transmission","authors":"Yisheng Zheng, Zhen Wu, Xinong Zhang, Kon-Well Wang","doi":"10.1115/SMASIS2018-7924","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7924","url":null,"abstract":"In this paper, we present a piezoelectric metamaterial integrated with bistable circuits to realize adaptive non-reciprocal elastic wave transmission. Dynamics of the bistable circuit and the piezoelectric metamaterial are investigated numerically to analyze the wave transmission characteristics of the proposed system. Results reveal that when the excitation amplitude exceeds certain threshold, wave energy is able to propagate even with excitation frequency inside the local-resonance bandgap of the piezoelectric metamaterial. This bandgap transmission phenomenon is also known as supratransmission. It is shown that by introducing spatial asymmetry, the system could exhibit different supratransmission thresholds when it is actuated in opposite directions, and hence there exists an excitation range within which wave energy is only able to propagate in one direction. Furthermore, this excitation range to facilitate non-reciprocal energy transmission is adaptable by adjusting the stable equilibria of the bistable circuits, which can be conveniently tuned utilizing only DC voltage sources. Additionally, it is shown that by adjusting the stable equilibria, the wave propagation direction, analogous to the forward direction of an electrical diode, can be easily reversed. Lastly, in contrast to many nonlinearity enabled non-reciprocal systems, the proposed system is able to realize non-reciprocal elastic energy transmission with majority of the transmitted energy preserved at the original input frequency. Overall, these results illustrate a new means of utilizing nonlinear piezoelectric metamaterial to manipulate elastic wave transmission.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"35 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":"127463666","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}
Aircraft wing design optimization typically requires the consideration of many competing factors accounting for both aerodynamics and structures. To address this, research on morphing aircraft has shown its potential by providing large benefits on aircraft performance. In particular, by adapting wing lift distribution, morphing winglets are capable to improve aircraft aerodynamic efficiency in off-design conditions and reduce wing loads at critical flight points. For those reasons, it is expected that these devices will be applied to the aircraft of the very next generation. In the study herein presented, a preliminary failure analysis and structural design of a morphing winglet are presented. The research is collocated within the Clean Sky 2 Regional Aircraft IADP, a large European programme targeting the development of novel technologies for the next generation regional aircraft. The safety-driven design of the proposed kinematic system includes a thorough examination of the potential hazards associated with the system faults, by taking into account the overall operating environment and functions. The mechanical system is characterized by movable surfaces sustained by a winglet skeleton and completely integrated with a devoted actuation system. Such a load control device requires sufficient operational reliability to operate on the applicable flight load envelope in order to match the needs of the structural design. One of the most critical failure modes is assessed to get key requirements for the system architecture consistency. Possible impacts of the defined morphing outline on the FHA analysis are investigated. The structural design process is then addressed in compliance with the demanding requirements posed by the implementation on regional airplanes. The layout static robustness is verified by means of linear stress analyses at the most critical conditions, including possible failure scenarios. Results focus on the assessment of the device static and dynamic structural response and the preliminary definition of the morphing system kinematics, including the integrated actuator system.
{"title":"Preliminary Failure Analysis and Structural Design of a Morphing Winglet for Green Regional Aircraft","authors":"I. Dimino, S. Ameduri, A. Concilio","doi":"10.1115/SMASIS2018-8236","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8236","url":null,"abstract":"Aircraft wing design optimization typically requires the consideration of many competing factors accounting for both aerodynamics and structures. To address this, research on morphing aircraft has shown its potential by providing large benefits on aircraft performance. In particular, by adapting wing lift distribution, morphing winglets are capable to improve aircraft aerodynamic efficiency in off-design conditions and reduce wing loads at critical flight points. For those reasons, it is expected that these devices will be applied to the aircraft of the very next generation. In the study herein presented, a preliminary failure analysis and structural design of a morphing winglet are presented. The research is collocated within the Clean Sky 2 Regional Aircraft IADP, a large European programme targeting the development of novel technologies for the next generation regional aircraft. The safety-driven design of the proposed kinematic system includes a thorough examination of the potential hazards associated with the system faults, by taking into account the overall operating environment and functions. The mechanical system is characterized by movable surfaces sustained by a winglet skeleton and completely integrated with a devoted actuation system. Such a load control device requires sufficient operational reliability to operate on the applicable flight load envelope in order to match the needs of the structural design. One of the most critical failure modes is assessed to get key requirements for the system architecture consistency. Possible impacts of the defined morphing outline on the FHA analysis are investigated. The structural design process is then addressed in compliance with the demanding requirements posed by the implementation on regional airplanes. The layout static robustness is verified by means of linear stress analyses at the most critical conditions, including possible failure scenarios. Results focus on the assessment of the device static and dynamic structural response and the preliminary definition of the morphing system kinematics, including the integrated actuator system.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"34 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":"131625850","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}
There has been increasing focus in the area of in-situ structural health monitoring since the advent of embedded nano-composites. This experimental research investigates the structural health monitoring abilities of polymer bonded energetics embedded with a uniformly dispersed but randomly oriented carbon nanotube (CNT) sensing network within the polymer binder. A common formulation of the recent solid propellants consists of ammonium perchlorate (oxidizer) and aluminum powder (combustive fuel)-often shaped using a polymer binder, rather than the older techniques of power pressing. Since this study focuses on the structural health of the material and not its thermal properties, monoclinic sugar crystals were used as a substitute for ammonium perchlorate as it has very similar mechanical properties and is much safer in terms of material handling. Thus, a combination of sugar crystals and aluminum powder bound by a Polydimethylsiloxane (PDMS) binder is fabricated in varying concentrations to simulate actual solid rocket propellants. The main focus of this study lies in characterizing the mechanical and electrical properties of the CNT embedded energetic material through subjecting it under mechanical loads; followed by a detailed observation and study of the real time electro-mechanical response under tension and compression. The addition of carbon nanotubes to the polymer binder, thus translates to a real time sensing technique for detection of multi-scale damage in polymer bonded energetics. The results of this study aim to establish a proof of concept for CNT embedded structural health monitoring systems.
{"title":"Structural Health Monitoring of Solid Rocket Propellants Using Piezoresistive Properties of Dispersed Carbon Nano-Tube Sensing Networks","authors":"N. Shirodkar, S. Rocker, G. Seidel","doi":"10.1115/SMASIS2018-8250","DOIUrl":"https://doi.org/10.1115/SMASIS2018-8250","url":null,"abstract":"There has been increasing focus in the area of in-situ structural health monitoring since the advent of embedded nano-composites. This experimental research investigates the structural health monitoring abilities of polymer bonded energetics embedded with a uniformly dispersed but randomly oriented carbon nanotube (CNT) sensing network within the polymer binder. A common formulation of the recent solid propellants consists of ammonium perchlorate (oxidizer) and aluminum powder (combustive fuel)-often shaped using a polymer binder, rather than the older techniques of power pressing. Since this study focuses on the structural health of the material and not its thermal properties, monoclinic sugar crystals were used as a substitute for ammonium perchlorate as it has very similar mechanical properties and is much safer in terms of material handling. Thus, a combination of sugar crystals and aluminum powder bound by a Polydimethylsiloxane (PDMS) binder is fabricated in varying concentrations to simulate actual solid rocket propellants. The main focus of this study lies in characterizing the mechanical and electrical properties of the CNT embedded energetic material through subjecting it under mechanical loads; followed by a detailed observation and study of the real time electro-mechanical response under tension and compression. The addition of carbon nanotubes to the polymer binder, thus translates to a real time sensing technique for detection of multi-scale damage in polymer bonded energetics. The results of this study aim to establish a proof of concept for CNT embedded structural health monitoring systems.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"108 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":"124301971","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 a multi-segment beam, in what is called an inertial four-point loaded configuration, is proposed and its dynamic response is analyzed. In this configuration, two symmetrical overhanging free segments extend beyond the pinned supports, and two tip masses are attached to these free segments yielding symmetrical inertial loading at the tips. By varying the configuration parameters of this multi-segment beam, such as support locations and tip loading, the dynamic response of the system can be significantly altered. The harmonically excited transverse vibration of a piezocomposite beam with four-point loaded boundary conditions is analyzed as a function of the support location and tip mass. Experimental data for several support locations is presented for validation of the analytical model and the predicted relationship between the system natural frequency, support locations, and tip masses. Comparisons are also made between the multi-point loaded cases and a reference cantilevered beam. The analytical and experimental results demonstrate that the natural frequency of a multi-point loaded beam can be continuously adjusted in a relatively wide range using the configuration changes investigated.
{"title":"A Multi-Point Loaded Piezocomposite Beam: Mechanics and Response to Harmonic Excitation","authors":"P. S. Heaney, O. Bilgen","doi":"10.1115/SMASIS2018-7940","DOIUrl":"https://doi.org/10.1115/SMASIS2018-7940","url":null,"abstract":"In this paper a multi-segment beam, in what is called an inertial four-point loaded configuration, is proposed and its dynamic response is analyzed. In this configuration, two symmetrical overhanging free segments extend beyond the pinned supports, and two tip masses are attached to these free segments yielding symmetrical inertial loading at the tips. By varying the configuration parameters of this multi-segment beam, such as support locations and tip loading, the dynamic response of the system can be significantly altered. The harmonically excited transverse vibration of a piezocomposite beam with four-point loaded boundary conditions is analyzed as a function of the support location and tip mass. Experimental data for several support locations is presented for validation of the analytical model and the predicted relationship between the system natural frequency, support locations, and tip masses. Comparisons are also made between the multi-point loaded cases and a reference cantilevered beam. The analytical and experimental results demonstrate that the natural frequency of a multi-point loaded beam can be continuously adjusted in a relatively wide range using the configuration changes investigated.","PeriodicalId":392289,"journal":{"name":"Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation","volume":"14 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":"125302634","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 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation
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