Effect Of Energy Dissipation Research Articles

Robust, anti-freezing and conductive bonding of chitosan-based double-network hydrogels for stable-performance flexible electronic

Unstable hydrogel-substrate interfaces and defunctionalization at low temperature severely restrict versatile applications of hydrogel-based systems. Herein, various chitosan-polyacrylamide double-network (CS-PAM DN) ionic hydrogels were chemically linked with diverse substrates to construct robust and anti-freezing hydrogel-substrate combination, wherein the destructible CS physical network rendered effective energy dissipation mechanism to significantly enhanced the cohesion of hydrogels and the covalent linkage between PAM network with substrate surface strongly improved the interfacial adhesion. The synergistic effects enabled the CS-PAM DN hydrogels to be tightly bonded on diverse metals and inorganics. Impressively, the hydrogel-substrate combinations were freezing tolerant to well-maintain high interfacial toughness at low temperature. Notably, due to the high toughness and conductivity of hydrogel-metal interface, the hydrogel-metal combination can be utilized as a multi-model flexible sensor to detect strain and pressure within broad temperature range. This work may provide a platform for construction and emerging application of robust, anti-freezing and stable-performance hydrogel-based systems.

Study on the Impact of Hydraulic Fracturing on Surrounding Ancillary Buildings considering SSI

Hydraulic fracturing is a key technology in the development of unconventional oil and gas reservoirs. With the continuous industrialization and large-scale development of shale gas production in China, the workload of hydraulic fracturing is also increasing rapidly, and the induced seismic events are also increasing gradually, resulting in different degrees of damage to the surrounding ancillary buildings. In order to study the impact of hydraulic fracturing on ancillary buildings, the finite element software ABAQUS was used to establish a three-dimensional model of middle and high-rise isolated structures to simulate the earthquake triggered by hydraulic fracturing. Then, considering the SSI (soil-structure interaction) effect of soil-based structure, the nonlinear dynamic response of the structure under the action of ground motion was analyzed. Through the adoption of different types of soil and the foundation depth, the influence of various parameters is discussed. The study found that in the case of not considering SSI, basal shear force, and displacement between floors of the seismic-isolation structure significantly greater than considering SSI, using hard soil layer, base shear displacement is greater than the soft soil layer and interlayer, shows that due to the effect of hydraulic fracturing, making fluid diffusion in soil, the seismic energy dissipation effect. It is also found that the period, base shear, peak displacement, and interlayer displacement of deep foundation pit are increased compared with shallow foundation pit considering SSI effect.

Structural properties of superior design solutions of steel buildings associated with BRBs

A design algorithm is proposed for rational seismic design solutions of steel buildings associated with buckling restrained braces (BRB). The strengths and locations of BRBs in addition to the section sizes of structural members are considered as discrete design variables. The steel volume including BRBs is minimized as an objective function under various practical design constraints. A seven-story office building is examined for application in two different types of structural systems, i.e. one mainly consisting of lateral frames and the other with limited utilization of lateral frames typically in perimeter separately from gravity frames. The derived solutions, defined as superior design solutions (SDSs), satisfy serviceability and limit-state constraints, taking into consideration the seismic energy dissipation effect of BRBs using the calculation of resistance and limit-state method. Their rationale is validated with response history analysis. Furthermore, the influences in SDSs by the seismic demand levels and elastic member constraint are investigated. The structural characteristics of SDSs associated with BRBs are objectively evaluated using the proposed design algorithm.

Optimal placement of viscous wall dampers in RC moment resisting frames using metaheuristic search methods

Viscous wall dampers (VWDs) are one of the most effective energy dissipation devices for the seismic performance enhancement of buildings. The number of VWDs as well as their positions in the building directly affects the seismic performance. In this study, two of the metaheuristic algorithms were employed for the optimal placement of VWDs in a reinforced concrete (RC) special moment resisting frame (SMRF) in order to achieve a safe yet cost effective solution. Bat algorithm (BA) and dragonfly algorithm (DA) were adopted to achieve the minimum number of VWDs by placing them in the most suitable positions of a 15 story RC SMRF. The floor accelerations and inter-story drift ratios (ISDRs) are considered as the constraints for the position optimization of VWDs with the objective of minimum number of VWDs. The application-programming interface (API) was employed for the interaction and data transfer between the structural analysis program ETABS and the Matlab program for optimization operations. Nonlinear response history analyses (NRHA) were conducted using recorded earthquake ground motions. Optimal placement for the minimum number of VWDs was achieved by using metaheuristic search algorithms. The additional damping provided by VWDs is effective in reducing the max ISDRs. However, higher damping ratios do not always result in the minimum floor accelerations. Therefore, an optimum damping ratio provided by VWDs needs to be sought for achieving minimum floor accelerations.

Energy dissipation and Hall effect on MHD convective flow of nanofluid within an asymmetric channel with arbitrary wall thickness and conductance

Energy dissipation and Hall effect on MHD convective flow of nanofluid within an asymmetric channel with arbitrary wall thickness and conductance

Anti-plane impact of a composite wedge with radial cracks

The Laplace transform of stress field in a cylindrically anisotropic elastic wedge, fixed at an edge and traction-free at the other, containing a screw dislocation with time-dependent Burgers vector is obtained by means of integral transform method. Energy dissipation in the wedge is modeled by viscous damping. Furthermore, solution to an intact wedge subjected to the dynamic anti-plane point load is obtained. These solutions are utilized to construct integral equations for a wedge weakened by several radial cracks subject to anti-plane impact loads. The integral equations are of Cauchy singular type. The stress analysis around a crack tip in cylindrically anisotropic material reveals that power of stress singularity depends upon the ratio of material stiffness coefficients. Therefore, a general definition for crack Stress Intensity Factor (SIF) is rendered for any power of stress singularity at a crack tip. Moreover, the numerical procedure for the solution to Cauchy integral equations is extended to solve integral equations with general power of singularity of solution. The procedure is utilized to obtain Laplace transform of the cracks SIFs. In the case of a cracked wedge under impact loads the inverse Laplace transforms of SIFs are determined numerically. To verify the formulation the quasi-static case of all the examples is solved by means of a different procedure. The results of latter case are compared with the dynamic solutions as time tends to infinity. Interaction between cracks, effects of structural energy dissipation, and wedge geometry on cracks SIFs are studied.

Numerical Simulation of Imported Sediment in a Stilling Basin

Sediment buildup at the bottom of a stilling basin can result in premature drainage of spillway structures and can even lead to dam failure in severe cases. Such failures pose ecological and human safety hazards to downstream areas. To evaluate the sudden discharge and potential dam failure associated with sediment buildup, we developed a two-dimensional two-phase flow simulation model built on a particle-based force balance equation. We compared the flow patterns and energy dissipation effects in the stilling basin at different inlet flows (2, 3, 4.5, and 6.75 m2/s), and the subsequent bottom deposition was compared across different sand discharge mass flow rates (0.1, 0.2, and 0.3 kg/s). The results show that the turbulent energy increased with the increasing inlet unit width flow rate. When more vortices were generated and the flow velocity was reduced significantly, the energy dissipation was more effective. The sediment deposition at the bottom of the stilling basin gradually increased with the decrease of inlet unit width flow and the decrease of the sediment mass flow rate. Meanwhile, at a fixed inlet shape, the change in inlet unit width flow had little effect on the maximum sedimentation height at the bottom of the basin. In addition, the average deposition rate at the bottom of the stilling basin was positively correlated with the inlet sedimentation concentration, and the correlation coefficient could be as high as 0.97. In this two-phase flow method, the error of the simulated value over the theoretical value was less than 10%. This simulation of sediment deposition at the bottom of the stilling basin provides a practical reference for dam managers.

Mechanical Properties of Solution-Blended Graphene Nanoplatelets/Polyether-Ether-Ketone Nanocomposites.

A lightweight composite with outstanding damping effects and impact resistance is significant for the design of functional structures in advanced equipment, such as aircraft and space vehicles. In this paper, the mechanical properties of solution-blended graphene nanoplatelets (GNPs)/polyether-ether-ketone (PEEK) nanocomposites were characterized by both experimental and numerical methods. It can be found that the layer number and packing configuration of graphene layers are critical to the efficiency of energy dissipation in the composite, while a pack of six- layer graphene and the perpendicular arrangement to the shockwave direction provide the most outstanding energy dissipation ability. The reflection of shockwave caused by graphene reinforcements in the nanocomposite was found to be the dominating reason for the enhanced energy dissipation effect. Physical mechanisms of energy dissipation are investigated by a molecular modeling method to provide insights into the cross-scale design of graphene-reinforced nanocomposites as structural materials.

Numerical model of the spatio-temporal dynamics in a water strider group

The water strider group demonstrates a very complex dynamics consisting of competition for the food items, territoriality and aggression to the conspecific individuals, escaping from the predators, etc. The situation is even more complex due to the presence of different instars, which in most water strider species live in the same habitat and occupy the same niche. The presented swarm model of water striders demonstrates the realistic population dynamics. For the swarm formation in the model, attraction and repulsion forces were used. Animal motion in the model takes into account inertia and kinetic energy dissipation effects. The model includes three different rates related to the growth of individuals: food appearance rate, food assimilation rate, and stored energy loss rate. The results of our modeling show that the size distribution of individuals seems to be an adequate measure for population status, and it has a characteristic shape for different model parameter combinations. Distribution of the distances between nearest neighbors is other important measure of the population density and its dynamics. Parameters of the model can be tuned in such a way, that the shape of both distributions in a steady phase coincides with that shape observed in a natural population, which helps to understand the factors leading to particular momentary distribution of both parameters (size and distance) in the population. From this point of view, the model can predict how both distributions can further develop from certain state depending on particular combination of factors.

Quality factor trimming method using thermoelastic dissipation for multi-ring resonator

In this paper, a novel quality factor trimming method for a 2-axis mode-matched resonator using thermoelastic dissipation (TED) is reported. A disk resonator was designed so that the Q-factor is mainly limited by TED, in which the effect of energy dissipation can be tuned by mechanical trimming. The trimming location are carefully chosen to independently modify the Q-factors of each axis. In addition, the trimming structure is designed not to affect the resonant frequencies. From the numerical experiment, the Q-factor trimming as much as 108% could be achieved while the frequency change was 4.7% at the maximum.

Toughening polyisoprene rubber with sacrificial bonds: The interplay between molecular mobility, energy dissipation and strain-induced crystallization

Sacrificial bonds have been utilized to improve the mechanical properties of self-reinforced rubbers with strain-induced crystallization (SIC) behavior. However, the influence of sacrificial bonds on the SIC behavior under quasistatic and dynamic processes is rarely reported. Herein, weak hydrogen bonds and strong metal coordination bonds are introduced as sacrificial bonds to toughen polyisoprene rubber (IR). Compared with the sample containing only hydrogen bonds, the further introduction of coordination bonds form denser network and impose stronger restriction on the molecular mobility, leading to higher energy dissipation. The hydrogen bonds suppress the crystallization rate and crystallinity of SIC, due to the suppressed molecular mobility and orientation of amorphous chains. By contrast, the coordination bonds lead to smaller onset crystallization strain and partially recovered crystallinity, as they are difficult to relax during stretching and thus can maintain a higher degree of chain orientation. However, under dynamic cyclic loading, both the hydrogen and metal coordination bonds obviously retard the SIC and reduce the crystallinity after the first loading cycle, which is unfavorable for the dynamic mechanical properties. Despite this fact, the synergistic effect of SIC and energy dissipation significantly improves the quasistatic mechanical properties of the modified IR containing both hydrogen and metal coordination bonds.

A Comparative Study of Fatigue Energy Dissipation of Additive Manufactured and Cast AlSi10Mg Alloy

In this paper, the fatigue energy dissipation of Gravity Casting (GC) and Laser-based Powder Bed Fusion (LPBF) AlSi10Mg alloys under cyclic loading are investigated. The increase in surface temperature related to the energy dissipation effect is decoupled and used to predict the fatigue limits of GC and LPBF AlSi10Mg alloys as being 55.8% UTS and 33.9% UTS, respectively. The energy dissipation rate is obtained by solving the one-dimensional thermal diffusion problem. This energy dissipation is separated into related and unrelated fatigue damage using polynomial function fitting. The energy dissipation related to fatigue damage for LPBF specimens is observed to be higher than that of GC specimens, which indicates worse fatigue performance. The fatigue damage entropy is employed to predict the fatigue life of both GC and LPBF AlSi10Mg alloys, which has a good agreement with the results of a traditional fatigue experiment.

Optimization of Damping Configurations in a Plate Embedded with ABH Array

Owing to its broadband and lightweight features, the Acoustic Black Hole (ABH) effect has attracted increasing interests in the structural dynamics and vibration-acoustic communities in recent years. And damping material is essential to achieve effective ABH phenomena. To explore effective vibration and noise control in thin-walled structures such as vehicle body panel using ABH effect, aiming at the plate embedded with two-dimensional ABH array, this paper investigates the coupling between ABH structure and damping material. First, the energy dissipation mechanism of viscoelastic damping material is analyzed to obtain the deformation characteristic that leads to effective energy dissipation. Next, the bending deflection of a plate with a single ABH under harmonic excitation is investigated, and the damping material configuration is optimized to obtain an optimal vibration suppression. Finally, the above-mentioned configuration is applied to a plate embedded with the ABH array and compared with the conventional damping arranging method. And the advantages of this damping material configuration scheme in vibration and noise control are investigated and summarized. This paper provides a reference for the damping material configuration and optimization of the thin plates embedded with ABHs.

Structure Evolution and Hoop-Reinforcing Mechanism of Bionic-Inspired Off-Axial Glass Fiber-Reinforced High-Density Polyethylene Pipes Fabricated via Rotating Co-extrusion

Triple-layer rotating co-extrusion is employed to fabricate hoop-enhanced polyethylene composite pipes with bionic off-axial glass fiber (GF)-reinforced high-density polyethylene (HDPE) middle layer. One kind of super-“hybrid shish-kebab”-like structures formed by GFs and interfacial lamellae tend to spirally align with a fiber deviation angle of 55.7° as the rotation rate reaches 20 rpm. Encouragingly, the hoop strength and hydraulic damage resistance are improved by 25.5 and 24.1%, respectively, even with a low fiber aspect ratio, which can be attributed to the enhanced hoop loading capacity and the energy dissipation effect of crack bifurcation contributed by deviated hybrid structures. Innovatively, the relationship between processing field and structure evolution has been systematically investigated by the simulation of melt flow track, shear rate, and flow rate, indicating that fiber deviation is closely related to the shear rate. This work develops a feasible strategy with both academic value and industrial application prospect for the hoop enhancement of fiber-reinforced HDPE pressure pipes and improves its adaptability to service requirements as well.

Energy dissipation enhancement through multi-toggle brace damper systems for mitigating dynamic responses of structures

A novel energy dissipation system named multi-toggle brace damper (MTBD) system is proposed in this paper. A theoretical mechanism for analysing the magnification factor of the MTBD system is established. Based on the finite element models (FEMs) simulated by ABAQUS, several single-story two-dimensional frame models with fluid viscous damper are investigated and compared with the theoretical mechanism. The magnification factors of the MTBD systems are compared with those of the traditional toggle brace damper (TTBD) systems. In addition, the dynamic responses of several three story three-dimensional reinforced concrete frame structures with different brace damper systems under various earthquake excitation levels are considered and investigated. The results show that the theoretical mechanism of the MTBD system is almost identical with the FEMs. Compared with the concrete frame with the TTBD system, the MTBD system has a larger amplification factor, a fuller hysteresis loop and a more obvious energy dissipation effect. The roof maximum displacements of the concrete frame structures with MTBD system are reduced by 41.1% on average. The MTBD system can significantly enhance the vibration control effect and reduce the dynamic response of the superstructures.

Automated simulation techniques for uncovering high-performance bioinspired cellular structures under blast loads

Trabecular bone possesses a complex hierarchical structure of plate- and strut-like elements, which is analogous to structural systems encountered in engineering practice. In this work, key structural features of trabecular bone are mimicked to uncover effective energy dissipation mechanisms under blast loading. To this end, several key design parameters were identified to develop a bone-like unit cell. A computer script was then developed to automatically generate bone-like finite element models with many combinations of these design parameters, which were simulated under blast loading. The optimal structure was identified and its performance was benchmarked against traditional engineered cellular structures, including those with hexagonal, re-entrant and square cellular geometries. The bone-like structure showed superior performance over its engineered counterparts using the peak transmitted reaction force and energy dissipation as the key performance criteria.

Synergistic damping effect mechanism of magneto-mechanical hysteresis and dislocations energy dissipation in FeMnCrCo high entropy alloys

The Fe65-xMn20Cr15Cox (x = 0, 5, 10, 15) high entropy alloys (HEAs) were prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effects of the configurational entropy on the microstructure, magnetic properties, and damping behaviors were investigated in this paper. As the Co content increased, the configurational entropy of the HEAs was increased from 0.88R to 1.23R, the magnetology performance was reduced significantly, but the peak of internal friction (IF) Q-1 increased monotonously. The maximum internal friction (IF) Q-1max achieved 0.073 when 15 at% Co element was added. With the configurational entropy increasing, in addition to the ferromagnetic damping mechanism, the dislocation damping mechanism was introduced in the HEAs. The synergistic effect of magneto-mechanical hysteresis and dislocation energy dissipation ensured the FeMnCrCo HEAs maintained high damping performance in a wide strain amplitude. Through the regulation of the microstructure, the possibility of application of the damping alloy under extreme conditions can be expanded.

Increasing the stability of the spring loaded inverted pendulum model of running with a wobbling mass

Human running can be simulated using a simple model called the spring-loaded inverted pendulum (SLIP). The SLIP model predicts some aspects of running including the self-stabilizing properties of running. In human locomotion energy is dissipated due to the passive motion of the soft tissue. However, little is known about the effects of this energy dissipation on the dynamics of running. This study utilizes a SLIP model with an additional spring-mass-damper system to study the effects of energy dissipation due to an additional wobbling mass on the self-stabilizing properties of human running. It was found that the additional spring-mass-damper system increased the self-stabilizing properties of the SLIP model and increased its robustness to perturbations. This suggests that increasing stability is one of the effects of energy dissipation due to the passive motion of a wobbling mass during human running.

Hysteretic and seismic performance of dual self-centering variable friction damper braces

A novel dual self-centering variable friction damper (DSC-VFD) brace was introduced to achieve greater post-yield stiffness and a better energy dissipation capability. To evaluate its hysteretic response with a novel flag shape, a new uniaxial material with different loading and unloading stiffnesses was developed based on the OpenSees platform in this study. The actual initial stiffness of the DSC-VFD brace was significantly lower than the theoretical value because of the tube length and pin diameter tolerances. The initial stiffness modification coefficients of the DSC-VFD brace were defined, and their calculation equations were established. Because of the uneven gap openings along the friction plates, the matrix displacement method was applied to determine the different gap openings under the tension and compression stages. Then, the hysteretic response of the DSC-VFD brace was calculated with the user-defined model; the model results were in good agreement with the experimental result, verifying the reliability of the proposed model. Simulation models were used to study the crucial parameters for the hysteretic response of the DSC-VFD brace. Finally, nonlinear dynamic analyses of a four-story braced frame were conducted to study the seismic performance of the DSC-VFD brace with a novel flag shape. The results showed that the DSC-VFD brace with a larger post-yield stiffness provided stable self-centering behavior and an effective energy dissipation capability. The high loading stiffness and energy dissipation ability effectively decreased the deformations of the braced structures and improved their seismic responses.

Polyurethane as high-functionality crosslinker for constructing thermally driven dual-crosslinking plant protein adhesion system with integrated strength and ductility

Wood products have gained considerable interest for use in furniture and construction materials; however, adhesives for bonding wood components are mainly formaldehyde-based resins, which release hazardous substances and can cause serious health concerns during service. The development of plant protein adhesives is in high demand to satisfy requirements for green wood-based composites and stringent environmental regulations. However, their practical application is hindered by the trade-off between high mechanical strength and good adhesion toughness. Herein, a biomimetic branched polyurethane is synthesised initially using a blocking agent of dopamine and sodium bisulfite to form a thermally driven dual-functionalised elastomer (PUSD). The prepared PUSD is employed as a novel dual-crosslinker for the improvement of soy protein (SP) adhesives. Because of the deblocking effect of sodium bisulfite under the thermal stimulus during hot pressing, the isocyanate groups are exposed and further cooperates with catechol groups to induce the construction of a thermally responsive dual-crosslinking network within the SP system. These structures not only promote the optimisation of the crosslinking density for a rigid system but also improve the intermolecular interaction patterns, thereby achieving effective energy dissipation. Consequently, the modified SP adhesives exhibit an integrated improvement in adhesive strength, adhesion toughness, and water resistance compared to the untreated adhesive. The outcome of this work enables the utilisation of plant proteins instead of traditional wood adhesives, thus addressing health and environmental concerns.