PERFORMANCE EVALUATION OF A 1kW VARIABLE PITCH-STRAIGHT BLADE VERTICAL AXIS WIND TURBINE | Journal of Energy Resources Technology | ASME Digital Collection
This research work represents a study of the design, analysis and experimental study of a 1kW Variable Pitch-Straight Blade Vertical Axis Wind Turbine using Natural Fiber Reinforced Composite. Wind turbine which is an emerging technology is of great interest for researchers nowadays. The Vertical Axis Wind Turbine (VAWT) was chosen for this study because of its numerous advantages over Horizontal Axis Wind Turbine (HAWT). A new concept of Variable Pitch was implemented by the introduction of a pitching mechanism associated to the turbine blades which helps the blade to maximize the generation of torque and power....
3 juin 2020
1 juin 2020
J. Compos. Sci. | Free Full-Text | Strain State Detection in Composite Structures: Review and New Challenges
J. Compos. Sci. | Free Full-Text | Strain State Detection in Composite Structures: Review and New Challenges
Developing an advanced monitoring system for strain measurements on structural components represents a significant task, both in relation to testing of in-service parameters and early identification of structural problems. This paper aims to provide a state-of-the-art review on strain detection techniques in composite structures. The review represented a good opportunity for direct comparison of different novel strain measurement techniques. Fibers Bragg grating (FBG) was discussed as well as non-contact techniques together with semiconductor strain gauges (SGs), specifically infrared (IR) thermography and the digital image correlation (DIC) applied in order to detect strain and failure growth during the tests. The challenges of the research community are finally discussed by opening the current scenario to new objectives and industrial applications. View Full-Text
Developing an advanced monitoring system for strain measurements on structural components represents a significant task, both in relation to testing of in-service parameters and early identification of structural problems. This paper aims to provide a state-of-the-art review on strain detection techniques in composite structures. The review represented a good opportunity for direct comparison of different novel strain measurement techniques. Fibers Bragg grating (FBG) was discussed as well as non-contact techniques together with semiconductor strain gauges (SGs), specifically infrared (IR) thermography and the digital image correlation (DIC) applied in order to detect strain and failure growth during the tests. The challenges of the research community are finally discussed by opening the current scenario to new objectives and industrial applications. View Full-Text
26 mai 2020
Influence of matrix systems on the deformation behavior of adaptive fiber-reinforced plastics - Moniruddoza Ashir, Chokri Cherif,
Influence of matrix systems on the deformation behavior of adaptive fiber-reinforced plastics - Moniruddoza Ashir, Chokri Cherif,
Adaptive structures contain actuators that enable the controlled modification of system states and characteristics. Furthermore, their geometric configuration as well as physical properties can be varied purposefully. The geometric configuration of adaptive fiber-reinforced plastics can be changed by varying the bending modulus of the matrix material. Hence, this research work presents the influence of thermosetting matrix material with different bending moduli on the deformation behavior of adaptive fiber-reinforced plastics. Firstly, shape memory alloys were converted into shape memory alloy hybrid yarn in order to realize this goal. Subsequently, shape memory alloy hybrid yarn was textile-technically integrated into reinforcing fabrics by means of weaving technology. The bending modulus of the thermosetting matrix material was changed by mixing modifier into it. The Seemann Corporation Resin Infusion Molding Process was used for infusion. Later, the deformation behavior of adaptive fiber-reinforced plastics was characterized. Results revealed that the maximum deformations of adaptive fiber-reinforced plastics with resin and modifier at a mixing ratio of 9:1 and 8:2 were increased to 34% and 63%, respectively, compared to adaptive fiber-reinforced plastics infiltrated by the reference resin. The maximum deformation speed during heating and cooling of adaptive fiber-reinforced plastic with the mixing ratio of resin and modifier at a value of 8:2 were 41.17 mm/s and 26.89 mm/s, respectively.
Adaptive structures contain actuators that enable the controlled modification of system states and characteristics. Furthermore, their geometric configuration as well as physical properties can be varied purposefully. The geometric configuration of adaptive fiber-reinforced plastics can be changed by varying the bending modulus of the matrix material. Hence, this research work presents the influence of thermosetting matrix material with different bending moduli on the deformation behavior of adaptive fiber-reinforced plastics. Firstly, shape memory alloys were converted into shape memory alloy hybrid yarn in order to realize this goal. Subsequently, shape memory alloy hybrid yarn was textile-technically integrated into reinforcing fabrics by means of weaving technology. The bending modulus of the thermosetting matrix material was changed by mixing modifier into it. The Seemann Corporation Resin Infusion Molding Process was used for infusion. Later, the deformation behavior of adaptive fiber-reinforced plastics was characterized. Results revealed that the maximum deformations of adaptive fiber-reinforced plastics with resin and modifier at a mixing ratio of 9:1 and 8:2 were increased to 34% and 63%, respectively, compared to adaptive fiber-reinforced plastics infiltrated by the reference resin. The maximum deformation speed during heating and cooling of adaptive fiber-reinforced plastic with the mixing ratio of resin and modifier at a value of 8:2 were 41.17 mm/s and 26.89 mm/s, respectively.
21 mai 2020
Spiral: Computational modelling of dynamic delamination in morphing composite blades and wings
Spiral: Computational modelling of dynamic delamination in morphing composite blades and wings
Morphing blades have been promising in lifting restrictions on rated capacity of wind turbines and improving lift-to-drag ratio for aircraft wings at higher operational angles of attack. The present study focuses on one aspect of the response of morphing blades viz. dynamic delamination. A numerical study of delamination in morphing composite blades is conducted. Both components i.e. the composite part and the stiffener are studied. The eXtended Finite Element Method (XFEM) and nonlocal continuum mechanics (peridynamics) have both been used to study fracture in the isotropic stiffener used in conjunction with the blade. As for the composite morphing blade, cohesive elements are used to represent the interlaminar weak zone and delamination has been studied under dynamic pulse loads. Intraply damage is studied using the nonlocal model as the peridynamic model is capable of addressing the problem adequately for the necessary level of sophistication. The differences and similarities between delamination patterns for impulsive, dynamic, and quasi-static loadings are appreciated and in each case detailed analyses of delamination patterns are presented. The dependence of delamination pattern on loading regime is established, however; further parametric studies are not included as they lie beyond the scope of the study. Through the use of fracture energy alone the nonlocal model is capable of capturing intra- and interlaminar fractures. The proposed modelling scheme can thus have a major impact in design applications where dynamic pulse and impact loads of all natures (accidental, extreme, service, etc.) are to be considered and may therefore be utilised in design of lightweight morphing blades and wings where delamination failure mode is an issue.
Morphing blades have been promising in lifting restrictions on rated capacity of wind turbines and improving lift-to-drag ratio for aircraft wings at higher operational angles of attack. The present study focuses on one aspect of the response of morphing blades viz. dynamic delamination. A numerical study of delamination in morphing composite blades is conducted. Both components i.e. the composite part and the stiffener are studied. The eXtended Finite Element Method (XFEM) and nonlocal continuum mechanics (peridynamics) have both been used to study fracture in the isotropic stiffener used in conjunction with the blade. As for the composite morphing blade, cohesive elements are used to represent the interlaminar weak zone and delamination has been studied under dynamic pulse loads. Intraply damage is studied using the nonlocal model as the peridynamic model is capable of addressing the problem adequately for the necessary level of sophistication. The differences and similarities between delamination patterns for impulsive, dynamic, and quasi-static loadings are appreciated and in each case detailed analyses of delamination patterns are presented. The dependence of delamination pattern on loading regime is established, however; further parametric studies are not included as they lie beyond the scope of the study. Through the use of fracture energy alone the nonlocal model is capable of capturing intra- and interlaminar fractures. The proposed modelling scheme can thus have a major impact in design applications where dynamic pulse and impact loads of all natures (accidental, extreme, service, etc.) are to be considered and may therefore be utilised in design of lightweight morphing blades and wings where delamination failure mode is an issue.
Strain sensing and progressive failure monitoring of glass-fiber-reinforced composites using percolated carbon nanotube networks - IOPscience
Strain sensing and progressive failure monitoring of glass-fiber-reinforced composites using percolated carbon nanotube networks - IOPscience
This paper presents a study on incorporation of carbon nanotubes (CNTs) in fiber-reinforced plastics for real-time structural health monitoring. CNTs dispersed in a solvent were uniformly spray-coated on the surfaces of glass fiber fabrics, which were then layed-up and impregnated with an unsaturated polyester resin using vacuum-assisted resin transfer molding to form composite samples. Prior to resin infusion, electrodes were embedded on the periphery as well as between the plies for electrical resistance monitoring. The composite sample was subjected to three-point bending, during which the changes in resistances between various electrode pairs were measured and recorded. Experimental results revealed the dependence of resistance change on the loading conditions, amount of CNTs coated, measured directions, and presence of structural failure. In particular, the percolated CNT networks enabled real-time identification of various failure modes, including delamination, fiber breakage, and in-plane compression. The proof-of-concept was demonstrated by fabricating and testing with a scaled-down wind turbine blade.
This paper presents a study on incorporation of carbon nanotubes (CNTs) in fiber-reinforced plastics for real-time structural health monitoring. CNTs dispersed in a solvent were uniformly spray-coated on the surfaces of glass fiber fabrics, which were then layed-up and impregnated with an unsaturated polyester resin using vacuum-assisted resin transfer molding to form composite samples. Prior to resin infusion, electrodes were embedded on the periphery as well as between the plies for electrical resistance monitoring. The composite sample was subjected to three-point bending, during which the changes in resistances between various electrode pairs were measured and recorded. Experimental results revealed the dependence of resistance change on the loading conditions, amount of CNTs coated, measured directions, and presence of structural failure. In particular, the percolated CNT networks enabled real-time identification of various failure modes, including delamination, fiber breakage, and in-plane compression. The proof-of-concept was demonstrated by fabricating and testing with a scaled-down wind turbine blade.
Cure-induced residual stresses for warpage reduction in thermoset laminates - Giacomo Struzziero, Davide Nardi, Jos Sinke, J J E Teuwen,
Cure-induced residual stresses for warpage reduction in thermoset laminates - Giacomo Struzziero, Davide Nardi, Jos Sinke, J J E Teuwen,
The paper addresses the role played by the cure stage of a vacuum assisted resin transfer molding process in residual stresses generation. The Airstone 780E epoxy resin and Hardener 785H system broadly used in the wind turbine blade industry has been used in this study. The viscous–elastic properties of the resin have been characterized and implemented in a thermo-mechanical FE model. The model has been validated against manufactured [0/90]4 asymmetric laminates. Analysis of residual stresses generation highlighted that compressive stresses generation occurs when the cure is shrinkage dominated and tensile stresses when expansion dominated in the 0° plies. The finding points out that 10% reduction in warpage and 33% reduction in process time can be obtained by selecting cure cycle parameters that allow tensile stresses development during the cure process in the 0° plies.
The paper addresses the role played by the cure stage of a vacuum assisted resin transfer molding process in residual stresses generation. The Airstone 780E epoxy resin and Hardener 785H system broadly used in the wind turbine blade industry has been used in this study. The viscous–elastic properties of the resin have been characterized and implemented in a thermo-mechanical FE model. The model has been validated against manufactured [0/90]4 asymmetric laminates. Analysis of residual stresses generation highlighted that compressive stresses generation occurs when the cure is shrinkage dominated and tensile stresses when expansion dominated in the 0° plies. The finding points out that 10% reduction in warpage and 33% reduction in process time can be obtained by selecting cure cycle parameters that allow tensile stresses development during the cure process in the 0° plies.
20 mai 2020
Pultruded materials and structures: A review - Alexander Vedernikov, Alexander Safonov, Fausto Tucci, Pierpaolo Carlone, Iskander Akhatov,
Pultruded materials and structures: A review - Alexander Vedernikov, Alexander Safonov, Fausto Tucci, Pierpaolo Carlone, Iskander Akhatov,
Currently, the application of pultruded profiles is increasing owing to their advantages, such as light weight, high strength, improved durability, corrosion resistance, ease of transportation, speed of assembly, and nonmagnetic/nonconductive characteristics. This review analyzes the main application fields of elements produced by pultrusion manufacturing processes: bridges and bridge decks, cooling towers, building elements and complete building systems, marine construction, transportation, and energy systems. Analysis of the scientific literature in relation to the mechanical behavior of pultruded elements is presented as well. Finally, this review outlines the future study possibilities, giving the researchers and practitioners the directions for deeper investigation of specific features and exploration of new ones concerning the mentioned aspects of pultruded fiber-reinforced polymer composites.
Currently, the application of pultruded profiles is increasing owing to their advantages, such as light weight, high strength, improved durability, corrosion resistance, ease of transportation, speed of assembly, and nonmagnetic/nonconductive characteristics. This review analyzes the main application fields of elements produced by pultrusion manufacturing processes: bridges and bridge decks, cooling towers, building elements and complete building systems, marine construction, transportation, and energy systems. Analysis of the scientific literature in relation to the mechanical behavior of pultruded elements is presented as well. Finally, this review outlines the future study possibilities, giving the researchers and practitioners the directions for deeper investigation of specific features and exploration of new ones concerning the mentioned aspects of pultruded fiber-reinforced polymer composites.
Classification and prediction of multidamages in smart composite laminates using discriminant analysis: Mechanics of Advanced Materials and Structures: Vol 0, No 0
Classification and prediction of multidamages in smart composite laminates using discriminant analysis: Mechanics of Advanced Materials and Structures: Vol 0, No 0
A supervised machine learning framework is proposed for local assessments of delamination and transducer debonding in smart composite laminates while using their low-frequency structural vibrations. Load independent discriminative features were identified through a system identification algorithm and several supervised machine learning algorithms were employed to distinguish between the healthy and damaged structures. Linear discriminant analysis was shown to outperform other classifiers. The issue of overfitting of the training data was addressed by evaluating the predictive performance of the classifier on independent test cases. The proposed approach could help provide insightful guidelines for the assessment of multidamages in smart composite laminates.
A supervised machine learning framework is proposed for local assessments of delamination and transducer debonding in smart composite laminates while using their low-frequency structural vibrations. Load independent discriminative features were identified through a system identification algorithm and several supervised machine learning algorithms were employed to distinguish between the healthy and damaged structures. Linear discriminant analysis was shown to outperform other classifiers. The issue of overfitting of the training data was addressed by evaluating the predictive performance of the classifier on independent test cases. The proposed approach could help provide insightful guidelines for the assessment of multidamages in smart composite laminates.
18 mai 2020
Simulation mésoscopique des polymères : Dossier complet | Techniques de l’Ingénieur
Simulation mésoscopique des polymères : Dossier complet | Techniques de l’Ingénieur
Les polymères représentent un grand intérêt pour les industries chimiques et des matériaux, mais le coût associé à leur mise sur le marché reste un facteur qui limite leur développement. Pourtant, l’industrie recherche des mélanges de polymères ou la synthèse de copolymères possédant des propriétés spécifiques, comme la rigidité, la dureté et la résistance à la chaleur. Les techniques de simulation moléculaire permettent à moindre frais d’effectuer les meilleurs compromis et de retenir les compositions de polymères les plus prometteurs. Les méthodes mésoscopiques, situées entre les niveaux de représentation macroscopique et atomistique, correspondent au niveau de détail associé à la morphologie, et pour cette raison répondent parfaitement à ce besoin.
13 mai 2020
Spinning finite element analysis of longitudinally stiffened horizontal axis wind turbine blade for fatigue life enhancement - ScienceDirect
Spinning finite element analysis of longitudinally stiffened horizontal axis wind turbine blade for fatigue life enhancement - ScienceDirect
In this study, a proof-of-concept is presented for extending the fatigue life of modern multi-megawatt wind turbine blades. For this purpose, spinning finite element model of the blade is investigated which has longitudinal stiffener (i.e. a tendon along its length) made of shape memory alloy. The material behaviour of the tendon is characterized by Liang and Rogers constitutive model in combination with thermodynamic principles. Modal analysis of the stiffened blade shows significant improvement of bending stiffness. The response of the blade with and without the stiffener are simulated using aerodynamic loads, which are evaluated following modified blade element momentum theory from the wind field generated by TurbSim. The impact of the proposed longitudinal stiffener on the stress profile and fatigue life of the blade are presented to show its performance. A sensitivity analysis on the reduction of peak stress and fatigue life for different diameters of the tendon are also presented.
In this study, a proof-of-concept is presented for extending the fatigue life of modern multi-megawatt wind turbine blades. For this purpose, spinning finite element model of the blade is investigated which has longitudinal stiffener (i.e. a tendon along its length) made of shape memory alloy. The material behaviour of the tendon is characterized by Liang and Rogers constitutive model in combination with thermodynamic principles. Modal analysis of the stiffened blade shows significant improvement of bending stiffness. The response of the blade with and without the stiffener are simulated using aerodynamic loads, which are evaluated following modified blade element momentum theory from the wind field generated by TurbSim. The impact of the proposed longitudinal stiffener on the stress profile and fatigue life of the blade are presented to show its performance. A sensitivity analysis on the reduction of peak stress and fatigue life for different diameters of the tendon are also presented.
12 mai 2020
Mécanique de la rupture de fibres dans les composites stratifiés : Dossier complet | Techniques de l’Ingénieur
Mécanique de la rupture de fibres dans les composites stratifiés : Dossier complet | Techniques de l’Ingénieur
Cet article propose une présentation de la mécanique de la rupture appliquée à la rupture translaminaire des composites stratifiés. Ce phénomène est particulièrement important dans le cadre de la certification des structures composites à la tolérance aux dommages. Après un bref rappel des concepts de la mécanique de la rupture, les différents essais expérimentaux caractérisant ces grandeurs seront présentés et commentés. Une revue détaillée des différents endommagements translaminaires sera ensuite effectuée puis quelques valeurs caractéristiques de ténacité à rupture de fibres seront discutées. Enfin la dissipation d’énergie lors du crash, l’énergie spécifique absorbée (SEA), sera abordée.
Cet article propose une présentation de la mécanique de la rupture appliquée à la rupture translaminaire des composites stratifiés. Ce phénomène est particulièrement important dans le cadre de la certification des structures composites à la tolérance aux dommages. Après un bref rappel des concepts de la mécanique de la rupture, les différents essais expérimentaux caractérisant ces grandeurs seront présentés et commentés. Une revue détaillée des différents endommagements translaminaires sera ensuite effectuée puis quelques valeurs caractéristiques de ténacité à rupture de fibres seront discutées. Enfin la dissipation d’énergie lors du crash, l’énergie spécifique absorbée (SEA), sera abordée.
9 mai 2020
FASTIGUE: A Computationally Efficient Approach for Simulating Discrete Fatigue Crack Growth in Large-scale Structures - ScienceDirect
FASTIGUE: A Computationally Efficient Approach for Simulating Discrete Fatigue Crack Growth in Large-scale Structures - ScienceDirect
The renaissance of digital twin technology heralded by recent advancements in machine learning raises the demand for structural analysis tools for real time predictions of the structural performance and ultimately the remaining lifetime. This paper proposes a novel approach – FASTIGUE - for computationally super-efficient discrete fatigue crack growth analysis of large structures particularly for bondlines with high aspect ratios. The computational speed is considerably increased by outsourcing the finite element analysis into a pre-processing step in which the numerical model is solved for a comparatively small number of crack stages; providing the Stress Intensity Factors (SIFs) for a set of auxiliary crack tip location permutations. 3D surface fitting of the auxiliary data provides the SIF ranges as continuous functions of the crack lengths. The fatigue crack growth simulation is performed independently from finite element analysis by utilising the SIF-functions within an explicit growth prediction scheme. The method is applied to a trailing edge crack in a 14.3 m wind turbine blade model and further validated against an analytical solution. It is demonstrated that the computation speed outperforms conventional fatigue analysis approaches relying on update-and-rerun schemes.
The renaissance of digital twin technology heralded by recent advancements in machine learning raises the demand for structural analysis tools for real time predictions of the structural performance and ultimately the remaining lifetime. This paper proposes a novel approach – FASTIGUE - for computationally super-efficient discrete fatigue crack growth analysis of large structures particularly for bondlines with high aspect ratios. The computational speed is considerably increased by outsourcing the finite element analysis into a pre-processing step in which the numerical model is solved for a comparatively small number of crack stages; providing the Stress Intensity Factors (SIFs) for a set of auxiliary crack tip location permutations. 3D surface fitting of the auxiliary data provides the SIF ranges as continuous functions of the crack lengths. The fatigue crack growth simulation is performed independently from finite element analysis by utilising the SIF-functions within an explicit growth prediction scheme. The method is applied to a trailing edge crack in a 14.3 m wind turbine blade model and further validated against an analytical solution. It is demonstrated that the computation speed outperforms conventional fatigue analysis approaches relying on update-and-rerun schemes.
Effects of environmental exposure on the mechanical properties of composite tidal current turbine - ScienceDirect
Effects of environmental exposure on the mechanical properties of composite tidal current turbine - ScienceDirect
In order to meet the growing demand for energy and also to fight against global warming, Renewable Marine Energies (RME) appeared as a great opportunity for a real ecological and industrial choice. Tidal current turbines are used to extract this energy and installed on the seabed at locations where the nozzle can be prone to the accidental impact and critical loads. The principal objective of this research is to investigate the effects of environmental exposure on the mechanical properties of composite tidal current turbine, the most advanced features currently available in finite element (FE) Abaqus/Explicit have been employed to simulate the behavior of the composite nozzle under static and dynamic loading conditions. To investigate this situation, a parametric analysis is conducted which deals with the effect of velocity and geometry of the impactor. The mechanical behavior has been analyzed as both kinematic effect due to deflection of the composite structure and dynamic effect caused by the interaction between the impactor and the hydrodynamic and hydrostatic pressures over the loading. The stress and the deformation distribution are presented. On the other hand, damage modeling was formulated based on Hashin criteria for intra-laminar damage. This has been accomplished by forming a user-created routine (VUMAT) and executing it in the Abaqus software.
In order to meet the growing demand for energy and also to fight against global warming, Renewable Marine Energies (RME) appeared as a great opportunity for a real ecological and industrial choice. Tidal current turbines are used to extract this energy and installed on the seabed at locations where the nozzle can be prone to the accidental impact and critical loads. The principal objective of this research is to investigate the effects of environmental exposure on the mechanical properties of composite tidal current turbine, the most advanced features currently available in finite element (FE) Abaqus/Explicit have been employed to simulate the behavior of the composite nozzle under static and dynamic loading conditions. To investigate this situation, a parametric analysis is conducted which deals with the effect of velocity and geometry of the impactor. The mechanical behavior has been analyzed as both kinematic effect due to deflection of the composite structure and dynamic effect caused by the interaction between the impactor and the hydrodynamic and hydrostatic pressures over the loading. The stress and the deformation distribution are presented. On the other hand, damage modeling was formulated based on Hashin criteria for intra-laminar damage. This has been accomplished by forming a user-created routine (VUMAT) and executing it in the Abaqus software.
1 mai 2020
A review of advances in the preparation and application of polyaniline based thermoset blends and composites
A review of advances in the preparation and application of polyaniline based thermoset blends and composites
For several decades, forming blend and composite of polyaniline (PANI) with insulating polymers has been a widely studied research area because of the potential applications of such blends, which have a unique combination of mechanical properties, the processability of conventional polymers and the electrical property of conducting polymers. The current review paper will emphasize PANI composites or blends with thermosetting polymer matrices. The enhanced electro-mechanical properties of the blends and composites depend on the uniform dispersion of the PANI particle in polymer matrix. Therefore, considerable studies have focused on improving the distribution of PANI particles within the thermoset matrices. In this review paper, all the parameters and conditions that influence the surface morphology and application of PANI thermoset blends and composites will be described systematically. Recent progress on PANI based thermoset system with multifunctional ternary composites research will be highlighted in this paper. Furthermore, encouraging applications of different PANI thermoset composites and blends are discussed, such as flame-retardant materials, lightning damage suppression, metal ion removal, anticorrosive coating, electromagnetic shielding, conductive adhesives, and sensing materials.
For several decades, forming blend and composite of polyaniline (PANI) with insulating polymers has been a widely studied research area because of the potential applications of such blends, which have a unique combination of mechanical properties, the processability of conventional polymers and the electrical property of conducting polymers. The current review paper will emphasize PANI composites or blends with thermosetting polymer matrices. The enhanced electro-mechanical properties of the blends and composites depend on the uniform dispersion of the PANI particle in polymer matrix. Therefore, considerable studies have focused on improving the distribution of PANI particles within the thermoset matrices. In this review paper, all the parameters and conditions that influence the surface morphology and application of PANI thermoset blends and composites will be described systematically. Recent progress on PANI based thermoset system with multifunctional ternary composites research will be highlighted in this paper. Furthermore, encouraging applications of different PANI thermoset composites and blends are discussed, such as flame-retardant materials, lightning damage suppression, metal ion removal, anticorrosive coating, electromagnetic shielding, conductive adhesives, and sensing materials.
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