Specific Load Research Articles

Fabrication of PVDF membranes via γ-ray irradiation and investigation into their membrane formation mechanisms and water treatment properties

Polyvinylidene fluoride (PVDF) membrane is a cheap and commonly used separation material, but its inherent hydrophobicity results in significant membrane contamination, which limits its engineering application and further development. The hydrophilic PVDF-g/co-NVP membrane was prepared through low-dose γ-ray irradiation and using N-vinyl-2-pyrrolidinone (NVP) as a modifier in this study. The effects of γ-ray dose and incorporating NVP additive on the microstructure, hydrophilicity, anti-fouling capability, and mechanical capacity of membranes were discussed. Molecular dynamics (MD) simulation method was used to comprehensively investigate the impact of the NVP on the physicochemical characteristics of membrane structure. Under a specific NVP load, the water contact angle of the membrane decreases from 87.92° to 52.66°. The pure water permeance reaches 362.1 L/m2 h, and the porosity increases to 55.21 %±1.29 %, which indicates that γ-ray irradiation with NVP addition can effectively adjust the pore structure and hydrophilicity of the membrane. During anti-fouling test against bovine serum albumin (BSA), the modified membrane exhibits remarkable anti-fouling characteristics, including reduced BSA accumulation, enhanced flux recovery, lower irreversible contamination level, and extended cleaning cycle compared with the original pure PVDF membrane because of its higher hydrophilicity and positive zeta-potential value. This study elucidates the mechanism underlying γ-ray graft modification of PVDF membranes, thereby providing valuable insights into the development of efficient functional membrane materials.

Physiological and cognitive responses to load carriage in the cold

Load carriage is a vital role related task for military, emergency service, and search and rescue personnel, through the transport of critical equipment. From an external validity perspective, a common oversight in previous research is the effect of multiple stressors during load carriage; for example, the inclusion of adverse environmental conditions and/or concurrent cognitive tasks. Therefore, this study aimed to quantify physiological and cognitive changes over time during military specific fast-paced lower-weight load carriage in a cold environment. With approval from the University of Chichester’s Ethics Committee, nine participants completed a load carriage task consisting of 20 min walking at 5.1 km∙h-1, 40 min walking at 6.5 km∙h-1, followed by 8 × 9 s shuttles running at 11 km∙h-1 in an environmental temperature of −10°C. Participants wore overalls whilst carrying 16 kg of external load (10 kg belt-webbing, 6 kg body armour). Throughout, measurements were taken of heart rate, core and skin temperatures, expired gas (VO2), and ratings of physical exertion and thermal comfort. Six military-specific auditory n-back tasks (MSANT) were completed across the trial. The rating scale of mental effort (RSME) quantified mental exertion during the load carriage task. Statistical differences within variables were evaluated using a one-way repeated measures ANOVA with post-hoc analysis employed to identify differences between timepoints. Heart rate and VO2 behaved as expected, with increases after the 5.1 to 6.5 km∙h-1 speed escalation (Pbonf< 0.001); heart rate also increased during the shuttles compared to the first 6.5 km∙h-1 collection (Pbonf = 0.003). A main effect rise for core temperature was evident (Pbonf < 0.001), increasing after 25 min at 6.5 km∙h-1 (Pbonf = 0.009). Skin temperature presented a main effect (Pbonf < 0.001) with an initial decrease and plateau occurring after 15 min. There was no main effect for MSANT or RSME at MSANT completion timepoints (P’s= 0.935 and 0.368 respectively). However, during non-MSANT completion timepoints, RSME was greater from 25 min onwards compared to 5 min (Pbonf < 0.05) signifying an increase in inter-task cognitive demand, oppose to a period of relative mental recovery. This reduced efficiency could be exacerbated during concurrent or extended physical and cognitive tasks. This study is the first to examine physiological and cognitive responses to fast-paced lower-weight load carriage in the cold, progressing understanding of occupational performance in representative environments. These performance data can inform training protocols and operation approaches by highlighting higher inter-task cognitive demand, potentially emphasising an avenue for mitigation strategies.

Modeling the nonlinear dynamic behavior of filled elastomers: Application to the vibration of structures with large preloads

This study offers a global mechanical approach from filled rubber characterization and modeling to how this behavior affects vibratory structural simulations. This work focuses on the characterization and the modeling of the dynamic behavior of a filled rubber. Particularly the effects of frequency, static preload and amplitude of cyclic loading (i-e Payne effect) are studied. A new hyper-viscoelastic constitutive model is proposed and its linearization for a specific loading case in order to obtain a straight-forward stress–strain relationship in the frequency domain. After validation of the implementation, this model is used in vibratory cantilever beam simulations of CFRP (Carbon Fiber Reinforced Polymer) laminates containing constrained rubber layers. Damping capability is then linked to the non-linear behavior of the rubber material.

A semi-empirical model for time-domain tower Vortex induced Vibration load simulations of wind turbines

A new method for simulating aeroelastic resonances between vortex shedding and structural eigenfrequencies of a wind turbine tower is presented in this publication. This aero-elastic effect of Vortex induced Vibrations (ViV) has the potential to disrupt installation processes and cause fatigue and extreme loads on the tower. Despite this issue, there are no established simulation methods available in literature, able and sufficiently efficient to predict the ViV in turbulent and site specific design load conditions. This state-of-the-art is extended by introducing an efficient semi-empirical, time-domain simulation method, which is capable of analyzing the tower ViV excitations and aeroelastic responses in wind turbine load simulations of the isolated tower or the full turbine for fatigue and extreme loads. The method is based on an adaptive harmonic equation, which is automatically tuned to the instantaneous tower motions.

Distributed Energy Dispatch for Geo-Data Centers Port Microgrid

With the development of port automation and artificial intelligence, coordination with multi-geographic data centers (Geo-DCs) has become a viable solution to address the issue of limited port computing resources. This study proposes a distributed energy dispatch method for the port microgrid coordinated with Geo-DCs (Geo-DCPM), aimed at reducing port carbon emissions and operational costs. Consider the single point of failure problem and high construction costs of centralized data centers. Geo-DCs are first introduced to solve the problem of insufficient computing resources in ports. An energy consumption calculation model for Geo-DCs is established, considering the data load delay constraint and the data space transfer constraint caused by specific delay-sensitive loads in the port microgrid. Then, an energy dispatch model (EDM) is constructed for the Geo-DCPM, taking into account carbon capture costs. Moreover, based on mixed-integer linear programming, a distributed algorithm is proposed to solve the EDM problem. Finally, the simulation results verify the effectiveness of the proposed method. Compared with the centralized algorithm, the packet loss rate of the distributed algorithm combined with Geo-DCs is significantly lower, reduced by about 70%.

Features of multi-agent evaluation of of microgrid systems efficiency in parallel operation with the power system according to the reliability criterion

Ensuring reliable electricity supply to consumers in the face of destruction of critical energy infrastructure and shortage of generating capacities in Ukraine requires the development of distribution systems and their management systems. The purpose of the study was to substantiate the development of models for ensuring the optimal structure of electrical distribution networks under the conditions of connecting micro-networks according to the reliability criterion in conditions of limited investments. The paper uses a method for assessing the structural reliability of complex electrical systems with microgrid structures and forms a rational power distribution of such structures according to the criterion of optimising the reliability indicators of the studied electric power system. A mathematical optimisation model based on a computational system was proposed, designed to solve non-convex problems with minimising integral reliability indicators, considering financial constraints and the investment efficiency curve. Based on the research, the possibilities of optimisation using the BARON solver available on the NEOS server were examined. The results of the model’s performance are demonstrated using examples, considering the parameters of distribution system objects and their limitations on network components. An algorithm and programme for solving the problem of targeting power flows of microgrid structures in multi-node regional power systems are proposed. Algorithms and scenarios for the response of dispatching services are developed, provided that investments are limited, which will ensure the survivability of the power system as a whole. It is established that the development of rational electricity flows of microgrid structures will minimise the under-supply of electric energy by specific load nodes and determine their shares in covering the demand of the energy island in conditions of power shortage. The findings can be used in the operational management of power systems

Investigation on PFAS Sources and Removal in a Municipal Wastewater Treatment Plant

PFAS (per- and poly-fluoroalkyl substances) is a complex family of manmade highly fluorinated aliphatic organic chemicals including thousands of chemical structures identified. PFASs were first synthesized in the 1940s and their physical and chemical properties such as oil and water repellency, temperature resistance, and friction reduction were then used in a wide range of products and industrial applications. Awareness about the possible health and environmental risks related to exposure to these substances has only risen in recent years and is resulting in the inclusion of such compounds in the Proposal for the recast of the Directive of the European Parliament and of the Council concerning urban wastewater treatment.A research was carried out at a municipal wastewater treatment plant (MWWTP) in Northern Italy to define the inflowing load of PFAS, the main load sources and the removal efficiency of the treatment processes.First, the contribution of the water supplied to the local population was excluded by means of specific chemical analyses. Then, the 100 industrial settlements served by the MWWTP were examined for the raw materials used, the final products and the productive cycle and 8 of them were selected as potential sources. A sampling campaign was carried out and the specific PFAS load was calculated. The total PFAS load entering the MWWTP was calculated from the analytical results and the flow. The percent contribution of each of the selected settlements to the total PFAS load was then calculated. 40% derives from a textile dyeing industry and 32% from a waste platform receiving also landfill leachates. 89% of the total PFAS load comes from the sum of such contributions and two other activities: the processing of slaughterhouse wastes and the production of chemicals for agriculture.Specific investigations lead to attribute an important role also to fire drills and fire extinguishing, using Aqueous Film Forming Foams (AFFF) containing PFAS. So, domestic contribution can be held as negligible.The removal in the WWTP was null and, in some cases, negative. As also reported in the literature some precursors can be transformed in PFAS during the biological process and some sludge accumulated compounds can be released.

An experimental study on aging effects of fuel-cut events including sound optimized torque reduction on modern three-way catalysts

Continuously increasing country-specific emission standards for passenger vehicles demand additional development steps in complex exhaust gas aftertreatment systems for a more effective reduction of harmful gases. The efficiency of the aftertreatment system declines over its lifecycle due to specific load profiles and other boundary conditions, resulting in increasing emissions over vehicle mileage. As a result, the durability of the exhaust system becomes more important. Fuel cut is an intended, temporary interruption of the fuel supply of modern combustion engines of passenger cars to reduce fuel consumption and emissions. During this fuel reduction event, unconsumed oxygen of rich and cool fresh air is introduced to the combustion chamber and to the exhaust system. Besides a catalyst cool down, oxidation effects are provoked by enhanced oxygen reactions processes within the catalyst’s washcoat and surface layers. In this publication, specific aging cycles with a variation of fuel-cut programs were examined on their effects on a modified modern eight-cylinder turbo-charged engine, especially on their oxidation effects correlating to catalyst aging. Light-off curves and conversion heat maps were used to evaluate possible damaging impacts of fuel-cut events on the aging behavior of the catalyst systems. Results indicate that higher frequency of fuel-cut events results in a reduced catalyst conversion efficiency, whereas thermal sintering might be reduced due to overall lower temperature load. Temporary oxidation processes on catalyst’s surfaces occur only in a short timespan after changing the air fuel ratio to lean, resulting in a weaker thermal sintering during longer fuel-cut events. Sound optimized torque reduction functions, used in sports cars for a better drivability and powertrain response, exhibit a stronger aging influence due to additional thermal shock effects on the catalysts front face, as demonstrated via optical infrared sensor technology during catalyst aging cycles on the modified engine bench setup. A theoretical calculation of aging processes as a combination of thermal sintering by Arrhenius equation as well as oxidation process is discussed to describe an aging classification induced via oxidation processes. Additional physisorption measurements of different catalyst probes support the results which indicate the direction of future experimental approaches.

Economic predictive control-based sizing and energy management for grid-connected hybrid renewable energy systems

Hybrid renewable energy systems (HRES) comprise a group of different energy sources and storage units that feed a specific load, efficiently. This research paper aims to develop a new methodology that provides the optimal size of the proposed HRES and runs it efficiently. Bi-level mixed-integer nonlinear programming (BMINLP) optimization approach is used to combine the sizing task and the energy management strategy (EMS) established utilizing the economic model predictive control (EMPC) method. The sizing task (upper layer) is formulated as mixed integer nonlinear programming (MINLP) optimization that has been implemented by the solver: multi-objective genetic algorithm (MOGA). EMS task (lower layer) is represented as a constraint embedded within the upper layer and executed as mixed integer linear programming (MILP) per each applied solution of the sizing task. The principal findings indicate that the total cost of the system is about 114,224 $. In detail, the annual fixed operation and maintenance, investment, and operating costs are 15,090 $, 28,351 $, and 70,783 $, correspondingly. Furthermore, around 90 % of the overall produced power is imported from the grid, while the load power represents about 95 % of the total demanded power.

Threshold investigation of shell thickness for enhanced mechanical and tribological performance in 3D-printed curved sandwich structures

Global prominence has been attained by additive manufacturing technology in recent years, driven by its environmental benefits and machining advantages when compared to traditional subtractive methods. Fused deposition modeling (FDM) technology, primarily utilized in polymer and polymer composite 3D printing, allows for precise control of material distribution within components. In this study, mechanical and tribological behaviors of 3D-printed structures are investigated, yielding valuable insights applicable to practical scenarios. The study identifies threshold limits for layer thickness ratios in three-layered curved sandwich structures, which directly impact their specific load capacity. Stress distribution within 3D-printed PLA discs can be accurately predicted by a saturation function dependent on shell thickness, with material-specific constants. Beyond a critical shell thickness, the impact of increased shell thickness on local tribological properties is found to be negligible. These findings generalize effectively to structures characterized by robust outer shells and weaker inner infills. Connections are drawn between tribological behavior and contact mechanical properties, opening avenues for future research involving nonlinear material modeling and advanced simulations. This study contributes to a deeper understanding of 3D printing and polymer tribology while highlighting the transformative potential of additive manufacturing in various industries, offering cost-effective and resource-efficient solutions for optimized mechanical performance.

Analysis of Specific Electrical Loads of Cottage Settlements

Analysis of Specific Electrical Loads of Cottage Settlements

Optimization of fibre orientation for composite reinforcement of circular hollow section KT-joints

PurposeComposite materials are effective alternatives for rehabilitating critical members of offshore platforms, bridges, and other structures. The structural response of composite reinforcement greatly depends on the orientation of fibres in the composite material. Joints are the most critical part of tubular structures. Various existing studies have identified optimal reinforcement orientations for a single load component, but none has addressed the combined load case, even though most practical loads are multiplanar.Design/methodology/approachThis study investigates the optimal orientation of composite reinforcement for reducing stress concentration factors (SCF) of tubular KT-joints. The joint reinforcement was modelled and simulated using ANSYS. A parametric study was carried out to determine the effect of the orientations of reinforcement in the interface region on SCF at every 15° offset along the weld toe using linear extrapolation of principal stresses. The impact of orientation for uniplanar and multiplanar loads was investigated, and a general result about optimum orientation was inferred.FindingsIt was found that the maximum decrease of SCF is achieved by orienting the fibres of composite reinforcement along the maximum SCF. Notably, the optimal direction for any load configuration was consistently orthogonal to the weld toe of the chord-brace interface. As such, unidirectional composites wrapped around the brace axis, covering both sides of the brace-chord interface, are most effective for SCF reduction.Originality/valueThe findings of this study are crucial for adequate reinforcement of tubular joints using composites, offering a broader and universally applicable optimum orientation that transcends specific joint and load configuration.

Risk Analysis of Electricity Demand at Public Electric Vehicle Charging Stations (SPKLU): CVaR Model Approach

The electricity demand at Public Electric Vehicle Charging Stations (SPKLUs) exhibits significant volatility, which is driven by several aspects including electricity demand patterns at specific time intervals, load variability, SPKLU capacity, and other related factors. The variability of these swings can present hazards for SPKLU operators in relation to energy administration as well as operational and financial hazards. The objective of this study is to assess the risk associated with energy demand fluctuation at SPKLUs by employing the Conditional Value-at-Risk (CVaR) model technique. CVaR, or Conditional Value at Risk, is a quantitative measure of risk that calculates the predicted loss value in the most unfavorable situation. It is commonly employed to enhance the risk management approach of SPKLUs. The electricity demand at SPKLU exhibits significant volatility, with an average fluctuation of 10.15% and a standard deviation of 49.67%. The CVAR, calculated at -121.19% for a confidence interval of 1%, represents the maximum potential loss that could be experienced during worst-case electrical demand conditions, highlighting the substantial fluctuations in demand. The study initially implemented the CVaR model to analyze power demand at SPKLU, providing novel perspectives on risk reduction for critical infrastructure and proposing unique strategies for managing demand fluctuations in a reliable and efficient manner. The results also offer comprehensive insights into risk exposure and facilitate the formulation of well-informed and strategic risk management plans.

Lightweight Potential of Anisotropic Plate Lattice Metamaterials

Additive manufacturing enables the production of lattice structures, which have been proven to be a superior class of lightweight mechanical metamaterials whose specific stiffness can reach the theoretical limit of the upper Hashin–Shtrikman bound for isotropic cellular materials. To achieve isotropy, complex structures are required, which can be challenging in powder bed additive manufacturing, especially with regard to subsequent powder removal. The present study focuses on the Finite Element Method simulation of 2,5D anisotropic plate lattice metamaterials and the investigation of their lightweight potential. The intentional use of anisotropic structures allows the production of a cell architecture that is easily manufacturable via Laser Powder Bed Fusion (LPBF) while also enabling straightforward optimization for specific load cases. The work demonstrates that the considered anisotropic plate lattices exhibit high weight-specific stiffnesses, superior to those of honeycomb structures, and, simultaneously, a good de-powdering capability. A significant increase in stiffness and the associated surpassing of the upper Hashin–Shtrikman bound due to anisotropy is achievable by optimizing wall thicknesses depending on specific load cases. A stability analysis reveals that, in all lattice structures, plastic deformation is initiated before linear buckling occurs. An analysis of stress concentrations indicates that the introduction of radii at the plate intersections reduces stress peaks and simultaneously increases the weight-specific stiffnesses and thus the lightweight potential. Exemplary samples illustrate the feasibility of manufacturing the analyzed metamaterials within the LPBF process.

Effectiveness of double cutout on lateral buckling analysis of fiber reinforced composites

AbstractLateral buckling, an essential mechanical phenomenon observed in composite beams subjected to specific external loads and boundary conditions, is influenced by various factors including cutout dimension, shape, position, and beam thickness in woven fabric laminated composite cantilever beams. The investigation focused on examining the lateral buckling behavior of beams containing two square or circular cutouts and comparing the experimental critical buckling loads of beams without any cutouts, which yielded results demonstrating a significant level of agreement. Through the experimental analysis, it was determined that square cutouts exhibit superior lateral buckling behavior when compared to circular cutouts.Highlights The effects of cutout shapes on lateral buckling analysis on fiber reinforced composites. The effects of cutout location on lateral buckling load on fiber reinforced composites. Comparison of the lateral buckling performances of fiber reinforced composites in relation to the type and position of cutouts.

Amorphous ribbons for GMI detection of stray fields FeOx magnetic filler of epoxicomposites

Magnetoimpedance (MI) effect in stress-annealed Co-based amorphous ribbon was studied in the states without and in presence of the magnetic epoxy composite of cylindrical shape. Iron oxide FeOx magnetic microparticles of different concentrations (0–70 wt.%) were used as a magnetic filler. The condition of stress annealing (350 °C, 1 h and 250 MPa specific load) were selected in order to insure the high MI sensitivity with respect to external magnetic field in the field of a few Oersted. The MI responses were modified in the presence of the magnetic epoxy composites due to the contribution of the stray fields of embedded microparticles. It was experimentally found that degree of the MI curves modification depended on the microparticles concentration. The MI characteristics were also dependent on the length-to-width ratio of the MI element. The most sensitive MI element under study showed a linear dependence with a 1 %/weightpercent microparticle concentration slope. Mathematical modeling using finite elements (FEM) protocol for the properties of short MI elements confirmed the results and highlighted the non-monotonic contribution of high-concentration composites to the MI responses.

Innovative Coastal Structure Solutions And The Role Of Physical Modelling In The Design Process (Dawlish Mog2 Casino)

With the increase in storminess due to climate change induced sea level rise, coastal protection solutions need to be able to contend with larger storms, resulting in larger incident waves, on a more regular basis. Many traditional coastal protection systems like vertical seawalls are proving to be expensive to design for the increased overtopping associated with this change in coastal conditions. As such, engineers are developing more bespoke and innovative design solutions, such as the use of bullnoses and the use of multiple seawalls located one behind the other. Examples of the former can be found in the new Dawlish seawall (see Figure 1) built to replace the old seawall that was damaged during a storm surge in February 2012. For the later, recent examples include the Middelkerke CASINO stilling basin (see Figure 2) and the new energy island being developed by Elia in Belgium (MOG2). The latter consists of two vertical seawalls (see Figure 3), each with a bullnose to reduce overtopping rates. CASINO and MOG2 have in common the novel approach of allowing significant overtopping of the first seawall but instead using the second wall as the safety line, to ensure safe overtopping limits are achieved at this location, thus reducing the required height of the front wall. Moving towards alternative design solutions is associated with its own set of design challenges. The primary challenge is the lack of consistent design guidelines within the field of coastal structures. In Europe, EurOtop is commonly used for overtopping estimates in design (van der Meer et al., 2018). In the US, the Coastal Engineering Manual is used instead (USACE, 2002). Both of these guidelines rely on empirical equations and the variations between the two are primarily a question of preference. However, the empirical equations can have large variations in their solutions (a factor of 3 for the overtopping rate is commonly accepted), the value of which can be heavily dependant on the geometric configuration being used for the seawall, toe protection and bathymetry, limiting their applicability to novel solutions. There is limited research currently available investigating novel geometries such as bullnoses (Dong et al., 2021, Castellino et al., 2018) and stilling basins, and much of the existing literature is limited in scope, thus limiting its wider applicability. In the case of MOG2 and CASINO, the use of the two seawall configuration, combined with drainage solutions, means that there is no suitable guidance in neither of the aforementioned design guides. As a result, coastal designers often turn to physical modelling in order to identify the specific design loads and overtopping values of their proposed design. Physical modelling performed in collaboration with research organisations allows design engineers to benefit from the expertise of researchers working with state-of-the-art techniques informed by the most recent research. However, the physical modelling phase is often not fully integrated into the design process meaning that is it not fully utilised. Integrating physical modelling fully into the design cycle can help to optimise the design as well as identifying the structural loading and verifying the overtopping performance.

Failure evaluation mechanism of cement sheath sealing integrity under casing eccentricity during multistage fracturing

A microannulus (MA) is the primary reason for sustained casing pressure in multi-stage fractured-shale gas wells. However, the effect of the casing eccentricity on the long horizontal section has not been considered. In this study, a full-scale integrity tester for cement sheaths is adopted to measure the cumulative plastic deformation. Numerical models are applied to evaluate the development of the cumulative plastic deformation and quantify the MA width considering casing centralization and eccentricity in the context of multiple loading and unloading cycles. Subsequently, the influences of the eccentricity distance and angle, cement-sheath mechanical variables, and different well depths on the cumulative sheath plastic deformation and sheath MA development are explored. The research results demonstrate that casing eccentricity significantly increases the cumulative sheath plastic deformation compared with that of the casing-centered condition. Consequently, the risk of sealing integrity failure increases. The accumulated plastic deformation increases when the eccentricity distance increases. In contrast, the initial plastic deformation increases as the eccentricity angle increases. However, the cumulative plastic deformation decreases after a specific loading and unloading cycle count. Affected by the coupled influence of the internal casing pressure and fracturing stages, the width of the MA in the horizontal section increased from the toe to the heel, and the casing eccentricity significantly increased the MA width at each stage, thus increasing the risk of gas channeling. Finally, an engineering case is considered to study the influence of casing eccentricity. The results show that cement slurries that form low and high elastic moduli can be applied to form a cement sheath when the fracturing stage is lower or higher than a specific value, respectively. The results of this study offer theoretical references and engineering support for the integrity control of cement sheath sealing.

Control of Power Converters in Micro Grids

Owing to several operational drawbacks in the existing power management schemes for interlinked AC-DC micro grids which are either concerned about only on sharing power or regulation of voltage but not on both, so as to overcome these issues this paper is proposed. This proposed autonomous power management scheme will consider the specific loading condition of the DC micro grid before importing power from the interlinked AC microgrid. This strategy not only enables voltage regulation in the DC micro grid but also reduces the number of converters in operation which will in turn reduces the power transfer losses. Theproposed scheme is fully self governed as it holds on the plug-nplay features for generators and tie-converters. The performance of the proposed control scheme has been validated under different operating scenarios. The results reveal the usefulness of the proposed scheme in managing the shortcoming of power in the DC microgrid efficiently and autonomously, on the other hand maintaining the better voltage regulation in the DC micro grid. In this project a DG interfacing network and its control also to be simulated to analyze the system stability The results are verified through MATLAB/SIMULINK environment.

Origami-based bidirectional self-locking system for energy absorption

When a periodic cellular structure is subjected to high-intensity loading, lateral splashing can occur, significantly decreasing macro mechanical properties. Periodic structures with self-locking properties can overcome this inherent flaw and achieve excellent performance characteristics, including high energy absorption efficiency. In this regard, thin-walled periodic self-locking dissipative structures have been extensively studied recently. Most existing bend-dominated self-locking dissipative systems are two-dimensional and can only achieve self-locking under specific loading conditions. This paper describes a three-dimensional origami-based bidirectional self-locking system that can achieve self-locking under normal and shear loading. Furthermore, a plastic hinge model revealed the energy absorption mechanism of the origami-based cells, whose specific energy absorption (SEA) is higher than that of other existing bend-dominated self-locking cells. The bidirectional self-locking of the origami-based system was demonstrated through compression, bending and impact tests. This origami-based system has high energy absorption efficiency, and the novel bidirectional self-locking mechanism can significantly broaden the design space for periodic dissipative metamaterials.