Journal articles: 'Composite flexible hinges'

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Shi, Yunlai, Chengshu Lou, and Jun Zhang. "Investigation on a Linear Piezoelectric Actuator Based on Stick-Slip/Scan Excitation." Actuators 10, no. 2 (February 20, 2021): 39. http://dx.doi.org/10.3390/act10020039.

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To perform a high resolution and long stroke application in optical precision instruments, a linear piezoelectric actuator operated in stick-slip/scan modes for driving a linear motion table is presented. The proposed piezoelectric actuator is a piezoelectric composite structure, which includes a metal elastomer, a piezoelectric stack, and a frictional ball. The purpose of this paper is to describe the operation principle, design, and the running test and resolution test of the linear motion table driven by the proposed piezoelectric actuator. The notable feature is the flexible hinges of the actuator, including composite hinge, pre-pressure adjustment flexible hinge, and transmission flexible hinge, which are designed for decoupling the motion in the action direction of the piezoelectric stack and the direction in which the pre-pressure is applied. A prototype has been fabricated and two operation modes of the piezoelectric actuator, stick-slip and scan mode, were utilized to test the driving characteristics of the linear motion table. Experimental results show that the finest step resolutions in stick-slip mode and scan mode achieved 12 nm and 4 nm, respectively.

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Kwon, O.-Hyun, and Jin-Ho Roh. "Origami-inspired shape memory dual-matrix composite structures." Journal of Intelligent Material Systems and Structures 30, no. 17 (September 18, 2019): 2639–47. http://dx.doi.org/10.1177/1045389x19873429.

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A sandwiched morphing structure is developed using an Origami-inspired shape memory dual-matrix composite core and shape memory polymer composite skins. The geometric parameters of the morphing structure are designed to have a zero Poisson’s ratio. In addition, an analytical model is developed to analyze the three-dimensional morphing structure easily. The shape memory dual-matrix composites are fabricated with woven fabrics based on the shape memory polymers, and an epoxy matrix is used to ensure a flexible and shape-recoverable structure. The shape recoverability of the shape memory polymer composite skins is verified by measuring the shape recovery ratio at various temperatures. Based on the tensile tests for the shape memory polymer composite skins and shape memory polymer hinges, it is found that the morphing structure can be highly flexible depending on temperature. Finally, the bending and shape recovery behaviors of the morphing structure are demonstrated.

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Gao, Hang, James Lynch, and Nick Gravish. "Soft Molds with Micro-Machined Internal Skeletons Improve Robustness of Flapping-Wing Robots." Micromachines 13, no. 9 (September 7, 2022): 1489. http://dx.doi.org/10.3390/mi13091489.

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Mobile millimeter and centimeter scale robots often use smart composite manufacturing (SCM) for the construction of body components and mechanisms. The fabrication of SCM mechanisms requires laser machining and laminating flexible, adhesive, and structural materials into small-scale hinges, transmissions, and, ultimately, wings or legs. However, a fundamental limitation of SCM components is the plastic deformation and failure of flexures. In this work, we demonstrate that encasing SCM components in a soft silicone mold dramatically improves the durability of SCM flexure hinges and provides robustness to SCM components. We demonstrate this advance in the design of a flapping-wing robot that uses an underactuated compliant transmission fabricated with an inner SCM skeleton and exterior silicone mold. The transmission design is optimized to achieve desired wingstroke requirements and to allow for independent motion of each wing. We validate these design choices in bench-top tests, measuring transmission compliance, kinematics, and fatigue. We integrate the transmission with laminate wings and two types of actuation, demonstrating elastic energy exchange and limited lift-off capabilities. Lastly, we tested collision mitigation through flapping-wing experiments that obstructed the motion of a wing. These experiments demonstrate that an underactuated compliant transmission can provide resilience and robustness to flapping-wing robots.

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Monteleone, Angelo, Gianluca Rodonò, Antonio Gagliano, and Vincenzo Sapienza. "SLICE: An Innovative Photovoltaic Solution for Adaptive Envelope Prototyping and Testing in a Relevant Environment." Sustainability 13, no. 16 (August 4, 2021): 8701. http://dx.doi.org/10.3390/su13168701.

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The development of adaptive architectural envelopes is one of the goals of researchers that aim to improve the energy performance of buildings. Traditional devices often have drawbacks linked to the complexity of the kinetic systems used, as the mechanical systems for guaranteeing proper operation are complex and expensive (e.g., hinges). Adaptive envelopes require energy for driving the mechanical components and management systems. Thus, it is useful for such adaptive elements to be self-sufficient, generating the energy necessary for their functioning. This study presents a prototype of a lightweight and stand-alone component for dynamic envelopes, characterized by a flexible composite material integrated with high-efficiency photovoltaic cells called the Solar Lightweight Intelligent Component for Envelopes (SLICE). The management and control of the SLICE is based on the Arduino platform. This paper describes the multidisciplinary design process that led to the realization of the current prototypes, the laboratory test phases, as well as the results of the preliminary experiments carried out under real environmental conditions.

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Ying, Zhiping, Xudong Hu, Xiaoying Cheng, and Zhenyu Wu. "Numerical investigation on the effect of tow tension on the geometry of three-dimensional orthogonally woven fabric." Textile Research Journal 89, no. 18 (December 30, 2018): 3779–91. http://dx.doi.org/10.1177/0040517518821912.

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The fabric geometry determines the mechanical performance of a textile composite. This paper investigates the effect of tow tension on the fabric geometry during the weaving process. A numerical model at the fiber scale was established by representing the fiber as a chain of truss elements connected by fully flexible hinges and having strong tensile modules. Fabric samples were woven on a homemade loom under different tension configurations to verify the numerical model. The model results with respect to the tow cross-section and path are in good agreement with observations of the homemade fabric sample. The tow cross-section deformation is the consequence of fiber rearrangement due to the transverse force originating from Z-binder tension. It is also found that the crimps of weft tows are different to those of warp tows. For weft tows, appreciable crimping is found in the regions of intercrossing with the Z-binder tow. Meanwhile, fibers undulate at the edges and remain straight in the middle of warp tows.

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Yang, Run Lin, Jie Kong, and Juan Hua Zhou. "Impact-Resistant Analysis of Hinged Reinforced Concrete Beam with Composite Laminates." Applied Mechanics and Materials 501-504 (January 2014): 1000–1003. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1000.

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Under the impact loads, once the key load-bearing member is damaged, it will endanger the entire building structures. Hence, it is very important to study impact-resistant performance of structural members. In order to verify effectiveness of a new composite protective device proposed in the earlier time, a reinforced concrete beam hinged at both ends was choosen as the observed object. During the process of numerical simulation, the four different protective measures including the unprotected, the rigid, the flexible and the composite one were considered in sequence. Numerical results show that the proposed composite measure can achieve the best protective effect, and it may be considered as a new option for impact-resistant protection of structural memebers.

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Bowen, Aileen G., Giovanni Zucco, and Paul M. Weaver. "Flexible hinges in orthotropic cylindrical shells facilitated by nonlinear elastic deformations." Composite Structures 268 (July 2021): 113726. http://dx.doi.org/10.1016/j.compstruct.2021.113726.

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Yang, Run Lin, Li Zhao, and Juan Hua Zhou. "Impact-Resistant Performance Analysis of Composite Laminates for Reinforced Concrete Beam Fixed and Hinged at Different Ends." Applied Mechanics and Materials 482 (December 2013): 30–33. http://dx.doi.org/10.4028/www.scientific.net/amm.482.30.

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Structural members are vulnerable to be damaged under the impact loads. According to traditional design methods, the impact load is seldomly considered. However, recently this situation is changed gradually. In view of this, impact-resistant performance of a new composite protective device was analyzed. A reinforced concrete beam with composite laminates, which was fixed at one end and hinged at the other end, was studied. Totally, the four cases including the unprotected, the rigid, the flexible and the composite protective measures were considered. The protective effects of the different measures can be compared by observing the strain, the displacement, the acceleration and the impact force of the target beam. Simulation results show that the composite protective measure can improve the impact-resistant effect of the target beam significantly and its dynamic response is suppressed effectively.

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Li, Yan, Bo Liu, Wenjie Ge, and Xinxing Tong. "Optimization design of compliant focusing mechanism for space optical camera with light weight." Advances in Mechanical Engineering 14, no. 8 (August 2022): 168781322211197. http://dx.doi.org/10.1177/16878132221119707.

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Thermal radiation and vacuum lead to the deformation of bearing cylinder with carbon fiber composites which generates the defocus phenomenon for space optical camera. As heavier weight and higher complexity of the rigid focusing mechanism for the space optical camera, a novel compliant focusing mechanism with lighter weight and simple structure was designed and tested in this paper. In order to achieve stroke range and ensure image quality for the compliant focusing mechanism, micro driving displacement from the piezoelectric ceramics was amplified by two-stage flexible hinge lever-type mechanism. Taking the size parameters of the flexure hinges and beams as the design variables, an optimization model of the compliant focusing mechanism was established in which minimizing weight was considered as objection function under the stroke requirements. Consequently, optimal structure parameters of the compliant focusing mechanisms under different input forces can be obtained under the allowable stress and lighter weight. The effectiveness of the proposed compliant focusing mechanism was verified by the simulations and experiments. The results show that the compliant focusing mechanism can achieve a stroke of 2 mm for the focal plane assembly. The proposed method provided a new idea to design the focusing mechanism with lighter weight, simpler structure and higher reliability.

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Baur, Werner H. "Self-limiting distortion by antirotating hinges is the principle of flexible but noncollapsible frameworks." Journal of Solid State Chemistry 97, no. 1 (March 1992): 243–47. http://dx.doi.org/10.1016/0022-4596(92)90031-p.

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Qin, Feng, Liya Tian, Hu Huang, Jiru Wang, Tianwei Liang, Xinyu Zu, and Hongwei Zhao. "Actively controlling the contact force of a stick-slip piezoelectric linear actuator by a composite flexible hinge." Sensors and Actuators A: Physical 299 (November 2019): 111606. http://dx.doi.org/10.1016/j.sna.2019.111606.

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Arias-Ferreiro, Goretti, Ana Ares-Pernas, Aurora Lasagabáster-Latorre, Nora Aranburu, Gonzalo Guerrica-Echevarria, M. Sonia Dopico-García, and María-José Abad. "Printability Study of a Conductive Polyaniline/Acrylic Formulation for 3D Printing." Polymers 13, no. 13 (June 23, 2021): 2068. http://dx.doi.org/10.3390/polym13132068.

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There is need for developing novel conductive polymers for Digital Light Processing (DLP) 3D printing. In this work, photorheology, in combination with Jacobs working curves, efficaciously predict the printability of polyaniline (PANI)/acrylate formulations with different contents of PANI and photoinitiator. The adjustment of the layer thickness according to cure depth values (Cd) allows printing of most formulations, except those with the highest gel point times determined by photorheology. In the working conditions, the maximum amount of PANI embedded within the resin was ≃3 wt% with a conductivity of 10−5 S cm−1, three orders of magnitude higher than the pure resin. Higher PANI loadings hinder printing quality without improving electrical conductivity. The optimal photoinitiator concentration was found between 6 and 7 wt%. The mechanical properties of the acrylic matrix are maintained in the composites, confirming the viability of these simple, low-cost, conductive composites for applications in flexible electronic devices.

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Chen, Yuanzhou, Junlin Chen, Yingming Zhang, Ziyue Hu, Weijian Wu, Xiang Chen, and Zhifeng Hao. "Flexible Fiber Membrane Based on Carbon Nanotube and Polyurethane with High Thermal Conductivity." Nanomaterials 11, no. 10 (September 26, 2021): 2504. http://dx.doi.org/10.3390/nano11102504.

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The development of high thermally conductive polymer composites with low filler content remains challenging in the field of thermal interface materials (TIMs). Herein, we fabricated a series of flexible fiber membranes (TMMFM) with high thermally conductive based on thermoplastic polyurethane (TPU) and acidified multiwalled carbon nanotubes (a-MWCNTs) via electrospinning and ultrasonic anchoring method. The SEM and TEM results demonstrated that the a-MWCNTs aligned along the fiber orientation in the membrane and anchored on the membrane surface strongly, which can establish the heat conduction path both in the horizontal and vertical directions. With the incorporation of 10 wt% a-MWCNTs, the horizontal direction (λ∥) and vertical direction (λ⊥) thermal conductivity value of TMMFM-5 was 3.60 W/mK and 1.79 W/mK, respectively, being 18 times and 10 times higher compared to pure TPU fiber membranes. Furthermore, the TMMFM maintained favorable flexibility of the TPU matrix because the small amount of a-MWCNTs only slightly hinders the mobility of the TPU molecular chain. The performance of the obtained TMMFM unveils their potential as a promising choice of flexible TIMs.

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Xu, Huajun, Gang Chen, Fei Du, Xin Wang, Yohan Dall’Agnese, and Yu Gao. "Electrospun Ti₃C₂T _x MXene and silicon embedded in carbon nanofibers for lithium-ion batteries." Journal of Physics D: Applied Physics 55, no. 20 (February 18, 2022): 204002. http://dx.doi.org/10.1088/1361-6463/ac4e36.

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Abstract In spite of outstanding theoretical specific capacity (∼3590 mAh g−1), huge volume change during lithiation/delithiation and poor conductivity hinder the practical applications of pure Si anodes for lithium ion batteries (LIBs), requiring conductive additives and porous architectures. In this work, flexible and freestanding composite films made of two-dimensional Ti3C2T x MXene nanosheets and silicon particles embedded in carbon nanofiber (denoted as Ti3C2T x -Si@CNF) were prepared via electrospinning and used as LIB anodes. This new electrode design provides a 3D network architecture and high conductivity favorable for good electrochemical performance and long cycle life. Ti3C2T x -Si@CNF electrodes, containing 28% silicon retained high specific capacity of ∼1580 mAh g−1 after 100 cycles at 0.1 A g−1 and 720 mAh g−1 after 1000 cycles at 1 A g−1, and delivered a great rate performance with 289 mAh g−1 at a current density of 5 A g−1. This is a significantly enhanced performance compared with Si particles embedded in CNF without Ti3C2T x (denoted Si@CNF). This work proposes a scalable manufacturing strategy for developing high-performance silicon-based anodes, overcoming the low conductivity and volume expansion issues.

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Wu, Gaihong, Shuqiang Liu, Xiongying Wu, and Xuemei Ding. "The effect of carbon nanotubes-grafted lactide on the mechanical and thermal properties of poly (lactic acid) biocomposites." Journal of Reinforced Plastics and Composites 36, no. 9 (March 9, 2017): 655–66. http://dx.doi.org/10.1177/0731684417696155.

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Poly(lactic acid) (PLA) derived from renewable crops is a promising substitute for petroleum-based products. Although PLA exhibits positive features, it also possesses drawbacks, such as brittleness, which hinder its extension in specific applications. In this study, lactide (LA) was used to graft carbon nanotubes (CNTs) to reinforce PLA. Under catalysis, LA was polymerized into PLA through ring-opening polymerization and simultaneously was grafted onto CNTs to obtain CNTs modified by LA (LA/CNTs). And the modified CNTs were used to prepare PLA composite films (LA/CNTs/PLA). Analysis of the Fourier transform infrared spectra (FT-IR) of the modified CNTs indicated that LA was grafted with the nanotubes. The scanning electron microscopy images showed that the modified CNTs were compatible and homogeneously dispersed in the PLA matrix. The excellent dispersibility and compatibility of the CNTs led to good interfacial adhesion, which directly enhanced the mechanical properties of PLA. The addition of CNTs also improved the thermal properties of PLA. This research aims to ameliorate the mechanical and thermal properties of PLA and provides basis for flexible fabrication of bio-based PLA materials for a wide range of applications.

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Kumykov, Ruslan M., and Aslan A. Kyarov. "SYNTHESIS AND INVESTIGATION OF PROPERTIES OF POLYETHERNAFLUYLENEBENZIMIDAZOLES USING REACTION OF NUCLEOPHILIC POLYNITRO-SUBSTITUTION." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, no. 10 (October 29, 2019): 61–69. http://dx.doi.org/10.6060/ivkkt.20196210.5994.

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Soluble polyethernaftoylenbenzimidazoles (PENBI) not previously described are obtained by reacting bis (nitronaphthoylenbenzimidazole) arylene with bisphenols using nucleophilic polynitrosubstitution reaction. The synthesis conditions and the influence of the introduced "bridge" flexible ether, dichloroethylene and carbonyl groups between the phenyl cores of the central fragments of macromolecules on the solubility, thermal and strength properties of the synthesized polymers were studied. Improving melting and solubility (PENBI) without a significant effect on the thermal and strength characteristics is achieved by introducing naphthylamide cycles into them, in combination with flexible bridging fragments into macromolecules of target polymers. The initial bis (nitronaphthoylenbenzimidazole) arylenes were obtained on the basis of (3 or 4-nitronaphthalic anhydride) and bis (o-phenylene diamines), which are derivatives of chloral. In this aspect, the bis (o-phenylenediamine) and bis (nitronaphthoylenenbenzimidazole) arylenes synthesized by us are unique, both in terms of availability of raw materials and price. Bis (nitronaphthoylenbenzimidazole) arylenes were obtained by the interaction of two moles (3 or 4-nitronaphthalic anhydride) with one mole of bis (o-phenylenediamine) under conditions of high-temperature catalytic cyclocondensation in organic solvents. All reactions of the synthesis of bis (nitronaphthoylenbenzimidazole) arylene proceeded homogeneously and resulted in well-cyclized dinitro compounds. As a comonomer of bis (nitronaphtho-ylenbenzimidazole) arylenes, bis-phenols containing also flexible “bridge” groups between phenyl nuclei were used in the synthesis of polyethernaphthoylenbenzimidazoles. The synthesis of polyethernaphthoylenebenzimidazoles was carried out by the interaction of bis (3 or 4-nitronaphthylenebenzimidazole) arylenes with bis-phenols under mild conditions in dimethyl sulfoxide or its mixture with toluene at a temperature of 70 ° C for 2 h in an absolutely dry environment. The obtained composite polymers were well soluble in dipolar aprotic solvents and had a rather wide interval between the temperatures of active destruction and softening temperatures (~ 250-260 ° С). Analysis of the primary thermal characteristics of the obtained polymers showed that they are characterized by relatively high temperatures of destruction (510-550 ºС). Polyethernaphthoylenebenzimidazoles are amorphous: this fact, combined with the presence in the macromolecules of a large number of flexible and “hinged” groups, determine their increased solubility in chlorinated and phenolic solvents. The significant difference between the softening temperature and the temperature of active destruction determines the possibility of their processing into products by injection molding. An analysis of the fire resistance of polymers showed that the highest oxygen index is for polymers, where macromolecules contain more dichloroethylene groups (KI = 62), and the lowest - for polymers with a high oxygen content (OI = 38.3).

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Chau, Ngoc Le, Thanh-Phong Dao, and Van Thanh Tien Nguyen. "An Efficient Hybrid Approach of Finite Element Method, Artificial Neural Network-Based Multiobjective Genetic Algorithm for Computational Optimization of a Linear Compliant Mechanism of Nanoindentation Tester." Mathematical Problems in Engineering 2018 (October 31, 2018): 1–19. http://dx.doi.org/10.1155/2018/7070868.

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This paper proposes a new evolutionary multiobjective optimization technique for a linear compliant mechanism of nanoindentation tester. The mechanism design is inspired by the elastic deformation of flexure hinge. To improve overall static performances, a multiobjective optimization design was carried out. An efficient hybrid optimization approach of central composite design (CDD), finite element method (FEM), artificial neural network (ANN), and multiobjective genetic algorithm (MOGA) is developed to solve the optimization problem. In this procedure, the CDD is used to lay out the experimental data. The FEM is developed to retrieve the quality performances. And then, the ANN is developed as black box to call the pseudo-objective functions. Unlike previous studies on multiobjective evolutionary algorithms, most of which generating only one Pareto-optimal solution, this proposed approach can generate more than three Pareto-optimal solutions. Based on the user’s real-work problem, one of the best optimal solutions is chosen. The results showed that the optimal results were found at the displacement of 330.68 μm, stress of 140.65 MPa, and safety factor of 3.6. The statistical analysis is conducted to investigate the behavior of the MOGA. The sensitivity analysis was carried out to determine the significant contribution of each factor. The results revealed that the lengths and thickness almost significantly affect both responses. It confirms that the proposed hybrid optimization approach gains high robustness and effectiveness with flexible decision maker rules to solve complex optimization engineering problems.

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Yang, Manzhi, Zhenyang Lv, Chuanwei Zhang, Yizhi Yang, Gang Jing, Wei Guo, Zhengxiong Lu, et al. "Positioning Performance of a Sub-Arc-Second Micro-Drive Rotary System." Micromachines 12, no. 9 (August 31, 2021): 1063. http://dx.doi.org/10.3390/mi12091063.

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In the macro/micro dual-drive rotary system, the micro-drive system compensates for the position error of the macro-drive system. To realize the sub-arc-second (i.e., level of 1″–0.1″) positioning of the macro/micro dual-drive rotary system, it is necessary to study the positioning performance of the sub-arc-second micro-drive rotary system. In this paper, we designed a sub-arc-second micro-drive rotary system consisting of a PZT (piezoelectric actuator) and a micro rotary mechanism, and used simulation and experimental methods to study the positioning performance of the system. First, the micro-drive rotary system was developed to provide ultra-precise rotary motion. In this system, the PZT has ultrahigh resolution at a level of 0.1 nanometers in linear motion; a micro rotating mechanism was designed according to the composite motion principle of the flexible hinge, which could transform the linear motion of piezoelectric ceramics into rotating motion accurately. Second, the drive performance was analyzed based on the drive performance experiment. Third, kinematics, simulation, and experiments were carried out to analyze the transformation performance of the system. Finally, the positioning performance equation of the system was established based on the two performance equations, and the maximum rotary displacements and positioning error of the system were calculated. The study results showed that the system can provide precision motion at the sub-arc-second and good linearity of motion. This study has a certain reference value in ultra-precision positioning and micromachining for research on rotary motion systems at the sub-arc-second level.

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Dawadi, Sonika, Saurav Katuwal, Aakash Gupta, Uttam Lamichhane, Ranjita Thapa, Shankar Jaisi, Ganesh Lamichhane, Deval Prasad Bhattarai, and Niranjan Parajuli. "Current Research on Silver Nanoparticles: Synthesis, Characterization, and Applications." Journal of Nanomaterials 2021 (February 5, 2021): 1–23. http://dx.doi.org/10.1155/2021/6687290.

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Over the past couple of decades, nanomaterials have advanced the research in materials; biomedical, biological, and chemical sciences; etc., owing to their peculiar properties at the nanoregime compared to their bulk composition. Applications of nanoparticles in the fields like medicine and agriculture have been boosted due to the development of different methodologies developed to synthesize specific shapes and sizes. Silver nanoparticles have tunable physical and chemical properties, so it has been studied widely to improve its applicability. The antimicrobial properties of Ag NPs are finding their application in enhancing the activity of drugs (like Amphotericin B, Nystatin, Fluconazole) and composite scaffolds for controlled release of drugs and targeted delivery of drugs due to their low toxicity and biocompatibility. Similarly, their surface plasmon resonance property makes Ag NPs a top-notch material for developing (bio)sensors, for instance, in surface-enhanced Raman spectroscopy, for detecting biomarkers, diseases, pollutants, and higher catalytic activity in photochemical reactions. Besides these, highly conducting Ag NPs are used in wearable and flexible sensors to generate electrocardiographs. Physicochemical or biological approaches are used to prepare Ag NPs; however, each method has its pros and cons. The prohibitive cost and use of hazardous chemicals hinder the application of physicochemical synthesis. Likewise, biological synthesis is not always reproducible for extensive use but can be a suitable candidate for therapeutic activities like cancer therapy. Excess use of Ag NPs is cytotoxic, and their unregulated discharge in the environment may have effects on both aquatic and terrestrial biota. The research in Ag NPs has always been driven by the need to develop a technology with potential benefits and minimal risk to environmental and human health. In this review, we have attempted to provide an insight into the application of Ag NPs in various sectors along with the recent synthetic and characterization techniques used for Ag NPs.

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Jiang, Ning, Yulong Bai, Hengbin An, Huatian Zhang, Yongquan Chen, Guixin He, and Shifeng Zhao. "Sensitive angle–dependent magnetoelectric coupling in cluster–assembled flexible composites." Journal of Physics: Condensed Matter, April 12, 2022. http://dx.doi.org/10.1088/1361-648x/ac66b4.

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Abstract Flexible magnetoelectric device is one of the indispensable elements. However, the complicated fabrication process and low sensitivity hinders the practical applications. Here, flexible NiFe anisotropic magnetoelastic composites were prepared by cluster–supersonic expansion method assistant with polyvinylidene fluoride (PVDF) substrates. The NiFe/PVDF composites possess sensitive angle–resolution magnetoelectric coupling coefficient at room temperature, and the value can reach 0.66 μV/deg. The strong anisotropic magnetoelasticity phenomenon is reminiscent of the short–range ordered cluster structure. The anisotropic magnetoelastic coefficient can be deduced by temperature– and magnetic field strength–dependent anisotropic magnetoresistance. The magnetic torque results also prove the strong anisotropic magnetoelastic trait. The coupling between piezoelectricity and anisotropic magnetostrictive effect endows great possibilities toward flexible electronic compass. These results shed light on future in non–invasive tracking of vital biological health via wearable electronic devices.

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Hejna, Aleksander, Paulina Kosmela, Adam Olszewski, Łukasz Zedler, Krzysztof Formela, Katarzyna Skórczewska, Adam Piasecki, Mariusz Marć, Roman Barczewski, and Mateusz Barczewski. "Management of ground tire rubber waste by incorporation into polyurethane-based composite foams." Environmental Science and Pollution Research, January 26, 2023. http://dx.doi.org/10.1007/s11356-023-25387-w.

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AbstractRapid economic growth implicated the developing multiple industry sectors, including the automotive branch, increasing waste generation since recycling and utilization methods have not been established simultaneously. A very severe threat is the generation of enormous amounts of post-consumer tires considered burdensome waste, e.g., due to the substantial emissions of volatile organic compounds (VOCs). Therefore, it is essential to develop novel, environmentally friendly methods for their utilization, which would hinder their environmental impacts. One of the most promising approaches is shredding, resulting in the generation of ground tire rubber (GTR), which can be introduced into polymeric materials as filler. The presented work is related to the thermomechanical treatment of GTR in a twin-screw extruder with zinc borate, whose incorporation is aimed to enhance shear forces within the extruder barrel. Modified GTR was introduced into flexible polyurethane (PU) foams, and the impact of modification parameters on the cellular structure, static and dynamic mechanical performance, thermal stability, as well as thermal insulation, and acoustic properties was investigated. Emissions of VOCs from applied fillers and prepared composites were monitored and evaluated. Depending on the treatment parameters, beneficial changes in foams’ cellular structure were noted, which enhanced their thermal insulation performance, mechanical strength, and thermal stability. It was proven that the proposed method of GTR thermomechanical treatment assisted by zinc borate particles might benefit the performance of flexible PU foamed composites and hinder VOC emissions, which could broaden the application range of GTR and provide novel ways for its efficient utilization.

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Chang, Hao-Lin, and Wei-Jiun Su. "Design and development of a high-performance tensile-mode piezoelectric energy harvester based on a three-hinged force-amplification mechanism." Smart Materials and Structures, May 30, 2022. http://dx.doi.org/10.1088/1361-665x/ac7489.

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Abstract When considering durability and reliability, flexible piezoelectric materials, such as PVDF and MFC (macro-fiber composite), are preferable to piezoceramics due to the brittleness of piezoceramics. However, flexible piezoelectric materials cannot sustain compressive loads so they need to be operated in either tensile or bending mode. The tensile mode is preferred over the bending mode due to the uniform strain distribution under a tensile load. This study proposes a novel tensile-mode piezoelectric energy harvester based on a three-hinged force amplification mechanism. The proposed design consists of a solid beam and an elastic PVDF film connected via a revolute joint. The assembly is attached to a base via revolute joints with the PVDF film pre-stretched. The PVDF film bears a dynamic tensile load when the harvester is under harmonic excitations. A theoretical model of the proposed harvester is developed and experimentally validated. The simulation and experimental results show that the proposed design exhibits a strong hardening effect, caused by the nonlinear geometry of the three-hinged mechanism. Different settings of the preload and mass distribution are examined to determine their impact on the harvesting performance. It is shown that the rise of preload decreases the peak voltage and bandwidth of the harvester. The performance of the harvester can be enhanced by properly tuning the mass distribution. Compared with a bending-mode cantilevered harvester, the voltage output and harvesting bandwidth of the proposed harvester can be improved by 500% and 1250%, respectively.

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Wang, Xinyi, Yan Tao, Shaoshan Pan, Xue Fang, Congcong Lou, Yunqi Xu, Jianpeng Wu, et al. "Biocompatible and breathable healthcare electronics with sensing performances and photothermal antibacterial effect for motion-detecting." npj Flexible Electronics 6, no. 1 (November 21, 2022). http://dx.doi.org/10.1038/s41528-022-00228-x.

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AbstractWith the booming development of smart wearable devices, flexible multifunctional composites with high sensitivity and well health therapy have evoked great interest for next-generation healthcare electronics. However, the weak biocompatibility, low breathability, and narrow sensing range greatly hinder the development of healthcare sensors. Herein, a porous, flexible and conductive MXene/Polydimethylsiloxane/Polydopamine/Polyurethane Sponge (MXene/PDMS/PDA/PU) nanocomposite is developed as a promising motion-detecting device with good flexibility, breathability, sensing performance, photothermal therapy and antibacterial activity. Benefiting from the porous structure and biocompatible surface, this multifunctional sensor is further fabricated into a diagnostic and therapeutic system for monitoring human body motion and performing hot therapy/antibacterial treatment in the application of sports injury site. Moreover, both the wireless smart insole and cushion are constructed to gait monitoring and sit position detecting. This multifunctional hybrid sponge not only demonstrates great potential for motion monitoring sensors but also exhibits wide potential in wearable medical assistive and therapeutic systems.

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Zupa, Erik, Martin Würtz, Annett Neuner, Thomas Hoffmann, Mandy Rettel, Anna Böhler, Bram J. A. Vermeulen, Sebastian Eustermann, Elmar Schiebel, and Stefan Pfeffer. "The augmin complex architecture reveals structural insights into microtubule branching." Nature Communications 13, no. 1 (September 26, 2022). http://dx.doi.org/10.1038/s41467-022-33228-6.

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AbstractIn mitosis, the augmin complex binds to spindle microtubules to recruit the γ-tubulin ring complex (γ-TuRC), the principal microtubule nucleator, for the formation of branched microtubules. Our understanding of augmin-mediated microtubule branching is hampered by the lack of structural information on the augmin complex. Here, we elucidate the molecular architecture and conformational plasticity of the augmin complex using an integrative structural biology approach. The elongated structure of the augmin complex is characterised by extensive coiled-coil segments and comprises two structural elements with distinct but complementary functions in γ-TuRC and microtubule binding, linked by a flexible hinge. The augmin complex is recruited to microtubules via a composite microtubule binding site comprising a positively charged unordered extension and two calponin homology domains. Our study provides the structural basis for augmin function in branched microtubule formation, decisively fostering our understanding of spindle formation in mitosis.

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Liu, Xiaoyue, Pengwu Xu, Ruiyi Li, Haiyan Zhu, Xiaohao Liu, and Zaijun Li. "Synthesis of highly dispersed Nb2O5-graphene heterojunction composite using ethylene diamine tetraacetic acid and boron-functionalized graphene quantum dot for symmetrical flexible supercapacitors with ultrahigh energy density." New Journal of Chemistry, 2023. http://dx.doi.org/10.1039/d2nj05554f.

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Nb2O5 is a promising metal oxide electrode material for supercapacitors because of outstanding structural stability and wide electrochemical window, but low inherent conductivity hinders its many applications. The paper reports...

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Liu, Qing, LanlanWang, Min Luo, Qian Wu, Yong Kang, and Pibo Ma. "Stab resistance of flexible composite reinforced with warp-knitted fabric like scale structure at quasi-static loading." Journal of Industrial Textiles, January 5, 2022, 152808372110569. http://dx.doi.org/10.1177/15280837211056987.

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The stab-resistant fabric like scale structure has a promising application prospect for areas of stab prevention owing to its great flexibility and excellent stab-resistance performance. In this paper, a kind of novel stab-resistant fabric has been designed by coating with epoxy resin (ER) and silicon carbide (SiC) particles, which was based on the warp-knitted fabric like scale structure (WKFS). The uniformity of dispersion has been investigated with different diameter and mass fraction of SiC, and polymerization degree of polyglycols (PEG); the flexibility and quasi-static properties of different kinds of WKFS treated with different coating solution has been studied, and the coating solution was prepared by mixing SiC particles and ER at different ratios. The results showed that the dispersion uniformity of the dispersion was the best when the diameter of SiC is 1 μm, the content is 50%, and the polymerization degree of PEG is 600. The longitudinal flexibility of the stab-resistant fabric is greater than that of transverse due to the gap between the longitudinal scales, and the addition of SiC particles can increase the transverse and longitudinal flexibility of stab-resistant fabric, and the flexible properties were the greatest when SiC:ER = 50:30. In addition, the WKFS treated with SiC of 16.7% has fatigue resistance; the damage mechanism of the fabric treated with pure ER is thankful to the brittleness of the resin; the added SiC particles hinder the further crack propagation of the resin, and the failure mode is mainly in stretch.

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Fauzi, R. M. Qudsi, Meri Indri Hapsari, Sri Herianingrum, Sunan Fanani, and Tuti Kurnia. "The challenges of empowering waqf land in Indonesia: an analytical network process analysis." International Journal of Ethics and Systems, January 13, 2022. http://dx.doi.org/10.1108/ijoes-03-2021-0061.

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Purpose This paper aims to identify the factors that hinder the successful empowerment of waqf land in Indonesia empirically by applying the analytic networking process (ANP). Design/methodology/approach In this study, after the waqf land problem criteria were introduced, an ANP model was developed and applied to identify the main problem, solution and strategy as a framework to guide stakeholders to produce policy recommendations appropriately and optimally. Findings The results showed that the main priority of the problem is the nadzir aspect. Furthermore, each criterion’s problems are a low public trust, unprofessional nadzir (waqf manager), a huge number of idle waqf lands, the absence of waqf certificates and non-economic waqf lands utilisation. Meanwhile, the main priorities for each aspect of the solution are socialisation and education to the community, nadzir certification, utilisation of information technology for the administration of waqf land governance, waqf land certification and innovation of waqf land development projects. Then, the long-term strategic priority is optimising the community’s role in the empowerment of waqf land. Research limitations/implications The development of the ANP model would give the institutions a modest, flexible and convenient approach to evaluate the barriers present in waqf land. However, ANP requires greater effort because it is a highly complex methodology that compels a study to use more numerical calculations in assessing composite priorities. Originality/value Not many studies on waqf land issues in Indonesia have been discussed empirically. Most of these studies are in the form of descriptive studies. This study introduces the ANP approach to illustrate the main problems of waqf land empowerment in Indonesia. ANP is a new approach to the decision-making process through a process that produces a general framework for treating decisions without making assumptions regarding independence between elements.

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Journal articles on the topic 'Composite flexible hinges'

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