The relationship between the symmetry breaking and the energy dissipation of dynamic systems is the foundation of the geometric mechanics, the investigation of which will establish a bridge between ...the structure-preserving theory and the assessment approach of the structure-preserving property for the employed numerical scheme. In this letter, two typical factors inducing the symmetry breaking for the infinite-dimensional dynamic system, including the symmetry breaking of the coefficient matrices and the space–time dependence of the Hamiltonian function, are investigated in detail. Based on the multi-symplectic theory, the local energy variations for dynamic systems with the mentioned symmetry breaking factors are deduced and the specific forms of which for a flexible cantilever with the variable bending rigidity under an external excitation are presented, which shows the local energy dissipation explicitly and provides the possibility of reproduction the local energy dissipation for the infinite-dimensional dynamic system in the numerical simulation.
The gradient-distributed binders have better energy dissipation and stress relief capabilities under stress to maintain stability of Si electrode.
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Silicon is considered as a promising ...alternative to traditional graphite anode for lithium-ion batteries. Due to the dramatic volume expansion of silicon anode generated from the insertion of Li+ ions, the binder which can suppress the severe volume change and repeated massive stress impact during cycling is required greatly. Herein, we design a gradient-distributed two-component binder (GE-PAA) to achieve excellent cyclic stability, and reveal the mechanism of high energy dissipative binder stabilized silicon electrodes. The inner layer of the electrode is the polyacrylic acid polymer (PAA) with high Young’s modulus, which is used as the skeleton binder to stabilize the silicon particle interface and the electrode structure. The outer layer is the gel electrolyte polymer (GE) with lower Young’s modulus, which releases the stress generated during the lithiation and de-lithiation process effectively, achieving the high structural stability at the molecular level and silicon particles. Due to the synergistic effect of the gradient binder design, the silicon electrode retains a reversible capacity of 1557.4 mAh g-1 after 200 cycles at the current density of 0.5 C and 1539.2 mAh g-1 at a high rate of 1.8 C. This work provides a novel binder design strategy for Si anode with long cycle stability.
Cellular plastics have been widely used in transportation, aerospace, and personal safety applications owing to their excellent mechanical, thermal, and acoustic properties. It is highly desirable to ...impart them with a complex porous structure and composition distribution to obtain specific functionality for various engineering applications, which is challenging with conventional foaming technologies. Herein, it is demonstrated that this can be achieved through the controlled freezing process of a monomer/water emulsion, followed by cryopolymerization and room temperature thawing. As ice is used as a template, this method is environmentally friendly and capable of producing cellular plastics with various microstructures by harnessing the numerous morphologies of ice crystals. In particular, a cellular plastic with a radially aligned structure shows a negative Poisson’s ratio under compression. The rigid plastic shows a much higher energy dissipation capability compared to other materials with similar negative Poisson’s ratios. Additionally, the simplicity and scalability of this approach provides new possibilities for fabricating high‐performance cellular plastics with well‐defined porous structures and composition distributions.
Cellular plastics with complex porous structure and composition distribution are in great demand for various engineering applications, yet are challenging to realize through conventional foaming technologies. An ice‐templating approach, involving a controlled freezing process of a monomer/water emulsion, followed by cryopolymerization and room‐temperature thawing, is developed to fabricate such cellular plastics in a scalable and environmentally friendly manner.
We describe the in-plane compressive performance of a new type of hierarchical cellular structure created by replacing cell walls in regular honeycombs with triangular lattice configurations. The ...fabrication of this relatively complex material architecture with size features spanning from micrometer to centimeter is facilitated by the availability of commercial 3D printers. We apply to these hierarchical honeycombs a thermal treatment that facilitates the shape preservation and structural integrity of the structures under large compressive loading. The proposed hierarchical honeycombs exhibit a progressive failure mode, along with improved stiffness and energy absorption under uniaxial compression. High energy dissipation and shape integrity at large imposed strains (up to 60%) have also been observed in these hierarchical honeycombs under cyclic loading. Experimental and numerical studies suggest that these anomalous mechanical behaviors are attributed to the introduction of a structural hierarchy, intrinsically controlled by the cell wall slenderness of the triangular lattice and by the shape memory effect induced by the thermal and mechanical compressive treatment.
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•A new class of hierarchical honeycombs was designed and fabricated using 3D printing technique.•The hierarchical honeycomb exhibits a progressive failure mode under uniaxial compression.•Compared with regular honeycombs, improved stiffness and energy absorption have been achieved simultaneously.•High energy dissipation at large imposed strains (up to 60%) have also been observed under cyclic loading.
Dipolarization fronts (DFs) are important for energy conversion, particle acceleration, and flux transport in the magnetotail. The partition of energy conversion between ions and electrons and the ...energy dissipation at DFs are not well understood. In this paper, we present a statistical study of energy conversion and dissipation of 122 DFs observed by Magnetospheric Multiscale mission in the magnetotail. Statistically, electromagnetic energy transfers to plasma at DF. The released energy is mainly transferred to ions rather than electrons. On average, ions gain energy across the whole DF, while electrons gain energy at the leading part but lose energy at the trailing part of DFs. Joule dissipation J · (E+ve × B) can be either positive or negative at DFs, and its average value is very small. The kinetic energy dissipation parameter Pi − D does not exhibit clear signatures at the DFs; hence, it is not suitable for quantifying the energy dissipation at DF.
Key Points
Statistical study of the energy conversion and dissipation at DFs observed by MMS
Electromagnetic energy released at DF mainly goes to heat and accelerate ions
Average Joule dissipation across DF is very small, and the parameter Pi − D is not suitable for quantifying the energy dissipation at DF
•Initial granular topologies drastically affect the time-bandwidth results.•Optimal particle impact dampers work effectively over a broad energy range.•High nonlinear bandwidth is got by using ...multiple granules in collect-and-collect regime.•Time-bandwidth limit is broken owing to inelastic collisions and frictional effects.
The dissipative capacity as quantified by the nonlinear bandwidth measure of impulsively loaded linear primary resonators or primary structures (PSs) coupled to particle impact dampers (PIDs) is assessed. The considered PIDs are designed by initially placing different numbers of spherical, linearly viscoelastic granules at various 2D initial topologies and clearances. The strongly nonlinear and highly discontinuous dynamics of the PIDs are simulated via the discrete element method taking Hertzian interactions, slipping friction caused by granular rotations into account. An extended definition of nonlinear bandwidth is used to evaluate the energy dissipation capacity of the integrated PS-PID systems. To this end, the time-bandwidth (T-B) product is defined by nonlinear bandwidth in tandem with characteristic time. The T-B product is studied as a measure of the capacity of these systems to store or dissipate vibration energy. It is found that the initial topologies of the granules in the PID drastically affect the T-B product, which, depending on shock intensity, may break the classical limit of unity of linear time-invariant dissipative resonators. The optimal PS-PID systems composed of multiple granules produce large nonlinear bandwidths, indicating strong dissipative capacity of broadband input energy by the PIDs. Moreover, the granular collect-and-collide regime yields high nonlinear bandwidth and efficient energy dissipation capacity, whereas the opposite is observed for the granular gaseous state regime. The relationship between energy dissipation by the PID and nonlinear bandwidth of the PS are discussed, and it is found that as the shock intensity increases these two measures tend to vary similarly. The implications of these findings on the study of the dissipative capacity of the PS-PID system are discussed, yielding a predictive methodology for designing PIDs to act as highly effective nonlinear energy sinks capable of rapid and efficient suppression of vibration induced by shocks.
•We derive that Cahn–Hilliard equation possesses a local energy dissipation law (LEDL).•Based on the observation, three LEDL schemes for the CH equation are derived.•Three schemes are independent of ...boundary conditions.•Such schemes are proven to conserve the LEDL in any local region.•Our schemes hold the total energy stable laws and the mass laws.
In this paper, we show that the Cahn–Hilliard equation possesses a local energy dissipation law, which is independent of boundary conditions and produces much more information of the original problem. To inherit the intrinsic property, we derive three novel local structure-preserving algorithms for the 2D Cahn–Hilliard equation by the concatenating method. In particular, when the nonlinear bulk potential f(ϕ) in the equation is chosen as the Ginzburg–Landau double-well potential, the method discussed by Zhang and Qiao (2012) 50 is a special case of our scheme II. Thanks to the Leibnitz rules and properties of operators, the three schemes are rigorously proven to conserve the discrete local energy dissipation law in any local time–space region. Under periodic boundary conditions, the schemes are proven to possess the discrete mass conservation and total energy dissipation laws. Numerical experiments are conducted to show the performance of the proposed schemes.
A controllable plastic hinge with bending moment-shear separation was developed according to the design concept of an earthquake-resilient structure using replaceable multi-slit energy dissipation ...devices. Furthermore, a novel precast concrete beam-column joint was proposed to achieve repair of the post-earthquake damage in prefabricated structures. Pseudo-static cyclic loading tests were conducted on three precast concrete exterior beam-column joints and one conventional monolithic joint specimen to investigate the seismic performance and validate the effectiveness of the proposed joint. The results revealed that when the maximum flexural capacity of the precast joint was close to that of the monolithic joint, the precast joints exhibited better seismic performance in terms of ductility, deformation, and energy dissipation capacity than that of the monolithic joint. Furthermore, the damage and failure of the precast joints were mainly concentrated in the multi-slit energy dissipation device. In contrast, the precast concrete beam and column components remained elastic, allowing for the control of damage locations at the precast joint and facilitating efficient post-earthquake repair. Finally, a theoretical relationship was established between the flexural capacity and deformation of the connection zone in the precast joint, serving as a theoretical reference for the design of multi-slit energy dissipation devices and shear connection keys.
•A new type of earthquake resilient precast joint is presented and investigated.•A connection form of plastic hinge with bending moment-shear separation is developed.•The theoretical method of the proposed bending moment-shear separation hinge is established.
Photocatalysis is a green technology to use ubiquitous and intermittent sunlight. The emerging S‐scheme heterojunction has demonstrated its superiority in photocatalysis. This article covers the ...state‐of‐the‐art progress and provides new insights into its general designing criteria. It starts with the challenges confronted by single photocatalyst from the perspective of energy dissipation by borrowing the common behaviors in the dye molecule. Subsequently, other problems faced by single photocatalyst are summarized. Then a viable solution for these problems is the construction of heterojunctions. To overcome the problems and mistakes of type‐II and Z‐scheme heterojunctions, S‐scheme heterojunction is proposed and the underlying reaction mechanism is summarized. Afterward, the design principles for S‐scheme heterojunction are proposed and four types of S‐scheme heterojunctions are suggested. Following this, direct characterization techniques for testifying the charge transfer in S‐scheme heterojunction are presented. Finally, different photocatalytic applications of S‐scheme heterojunctions are summarized. Specifically, this work endeavors to clarify the critical understanding on curved Fermi level in S‐scheme heterojunction interface, which can help strengthen and advance the fundamental theories of photocatalysis. Moreover, the current challenges and prospects of the S‐scheme heterojunction photocatalyst are critically discussed.
Emerging S‐scheme heterojunction has demonstrated its superiority in photocatalysis. This article covers the state‐of‐the‐art progress of S‐scheme heterojunction. Design principles for S‐scheme heterojunction are proposed and four types of S‐scheme heterojunctions are suggested. Direct characterization methods for electron transfer in S‐scheme heterojunction are presented. Different photocatalytic applications are summarized. Especially, the curved Fermi level in S‐scheme heterojunction interface is discussed.
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