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Abstract\nHIGHLIGHTSThis paper focuses on the nonlinear vibration and snap-through behavior of bistable cantilever shell under in-plane foundation excitation. A combination of experimental and finite element analysis methods are used for an in-depth exploration. The experimental setup is built to accurately simulate the in-plane foundation excitation environment and measure the nonlinear responses of bistable cantilever shell. By adjusting excitation parameters, the dynamic behavior of the structure under different conditions is systematically observed, especially the snap-through process from one stable-state to the other. A corresponding finite element model is established based on ABAQUS software to verify the accuracy of the experimental results and further understand the motion mechanism, which takes into account factors such as material nonlinearity and geometric large deformation. By comparing the experimental results with the simulation data, a high degree of consistency is exhibited. This not only verifies the reliability of the experimental method but also demonstrates the accuracy and applicability of the established FEA model. The nonlinear vibration and snap-through behavior of bistable cantilever shell are quite sensitive to the excitation levers.The nonlinear vibration and snap-through behavior are investigated for bistable cantilever shell under in-plane foundation excitation.The experimental setup is built to simulate the in-plane foundation excitation and measure the nonlinear responses of the system.The dynamic behavior of the bistable cantilever shell is observed under different conditions by adjusting excitation parameters.The accuracy of the experimental results is compared with the finite element simulation results.The dynamic responses of bistable cantilever shell are quite sensitive to the excitation levers. [ABSTRACT FROM AUTHOR]

Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In a situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted, and pendulum modes of oscillation are found with an eigen-period of around 15 s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dynamic response analysis of multi-span beams is one of the important topics in the field of highway and railway engineering, which provides valuable guidance for the design, operation and maintenance of multi-span bridges. It is worth considering how to calculate the dynamic characteristics of multi-span beams quickly and conveniently. In this study, an effective analytical method is developed for the dynamic modeling and investigations of multi-span Timoshenko beams under moving loads by employing the assumed mode method (AMM). Based on Hamilton’s principle, the equation of motion of the Timoshenko multi-span beam subjected to moving loads is formulated and the natural frequencies are calculated. A comprehensive investigation is conducted on the dynamic responses of the multi-span Timoshenko beam considering different factors, including the length-to-thickness ratio, disorder degree, arrangement order, number of spans and related parameters of moving loads. In addition, the influence of the interval and velocity of the moving load series on the dynamic responses, including displacement, velocity and acceleration of the multi-span beam, are analyzed in detail. The theoretical calculation results of multi-span Timoshenko beams under moving loads are compared with numerical results obtained from ANSYS software, and the results are in good agreement. This demonstrates that the developed method, which utilizes the AMM to analyze the dynamic characteristics of multi-span beams subjected to moving loads, significantly simplifies the calculations and is well-suited for practical engineering applications. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvesters (PEHs) have drawn considerable attention due to their unique ability to convert ambient mechanical energy to electrical energy. These devices are widely implemented in numerous applications such as wearable technology, structural health monitoring, and renewable energy systems. In this work, a novel approach that seamlessly integrates arbitrary metastructures into the substrate layer of cantilever beam‐based PEHs is presented. The corresponding performance of each PEH design is evaluated via an experimentally validated finite element model. This is the first systematic study to explore 3D metastructures with various unit cell configurations, unit cell numbers, and porosity levels. Compared with the existing PEH designs, implementation of a 3D auxetic metastructure with 85% porosity single unit cell design can demonstrate a substantial enhancement in output power, reaching 48.16 mW, and a high normalized power density (NPD) of 2.1131 µW mm−3 g−2 Hz−1. Results show that there are competing requirements for improving the performance of PEHs. On one hand, low metastructure stiffness is preferred to achieve high power output at low resonant frequency. On the other hand, metastructures designs with low stiffness may induce excessive distortion in the substrate layer, leading to mechanical energy loss. This deformation mechanism adversely affects the mechanical to electrical energy conversion efficiency. Detailed guidelines for designing and manufacturing high‐performance PEHs are discussed in this work. [ABSTRACT FROM AUTHOR]

Owing to the simplification of the wind turbine, it is difficult to accurately simulate the interaction between the rotor system and the supporting structure using the decoupling finite element method. Therefore, when using this method for safety assessment and dynamic response research of the offshore wind turbine (OWT), there is a deviation between the simulation result and the real response of the OWT. In this study, an improved decoupled finite element analysis method is proposed based on a theoretical derivation. A simplified finite element model of a 10 MW jacket OWT with an equivalent substructure was established, and the dynamic response of the OWT under wind and waves was studied. By comparing the results of the fully coupled analysis method and the traditional finite element method, the applicability of the traditional finite element analysis method to the dynamic analysis of an OWT under typical winds and waves is discussed. The limitations of using the traditional finite element method to study or evaluate an OWT complex dynamic system were revealed, and the effectiveness and applicability of the improved method proposed in this study were qualitatively and quantitatively verified. Subsequently, based on the proposed improved decoupled finite element analysis method, a numerical calculation corresponding to a fully coupled test was performed. Compared with the numerical results obtained by the traditional finite element method, the improved decoupled finite element method proposed in this study obtained more consistent results with the fully coupled test. [ABSTRACT FROM AUTHOR]

Purpose: The time-dependent deflection characteristics of intact/damaged hybrid curved shell panels have been analyzed numerically under external loading and verified subsequently using experimentation. The effect of damage on structural integrity has been examined in order to identify practical implications. Methods: The damaged hybrid structure (Luffa-CNT) has been modeled numerically in a computer code in MATLAB utilizing higher-order mid-plane kinematics based on a variational approach and finite element technique. Results: The concurrence behavior and model validity have been confirmed by associating the outcomes with the results available in the literature. This study also analyzed experimentally and numerically generated material properties from the DIGIMAT platform, further increasing the depth and precision of the analysis. Finally, several instances are provided to demonstrate the effect of damage, including several geometrical input parameters on the transient responses of the curved shell hybrid structure (HS). Conclusion: The consequences obtained from this detailed approach are thoroughly investigated and addressed. The presence of damage weakens the structure's stiffness by causing the laminate's integrity to erode. [ABSTRACT FROM AUTHOR]

Shallow-buried cavities and underground structures are inevitably subjected to transient perturbation from earthquakes or engineering activities during their life circle, leading to the occurrence of dynamic failure. The investigation presented by this paper concentrates on the dynamic responses triggered by an aperiodic transient P wave around a circular lined tunnel with an imperfect interface in a half-space and the spring model is employed to describe the interface between rock mass and liner. Resorting to the wave function expansion scheme, the large arc assumption, the Graf's addition theorem and the numerical inversion algorithm of Laplace transformation, the dynamic responses around a circular shallow lined tunnel with an imperfect interface are evaluated theoretically. The good agreement of time–history curves and contour snapshots for stress between the theoretical solutions and the numerical counterparts validates the analytical scheme. The effect of disturbance direction, embedment depth, thickness of liner and interface coefficients on the dynamic responses around the shallow-buried lined tunnel is analyzed. The results indicate that the positions of peak hoop dynamic stress concentration factor (DSCF) are approximately perpendicular to the perturbation direction. The DSCF distributions converge to be stable when the ratio of embedment depth to excavation radius exceeds 10.0. The thickness of the liner mainly affects the dynamic responses around the interface. Increase of elastic coefficient induces a decreasing DSCF in rock mass and an increasing counterpart in the liner. The results may provide the theoretical basis for the transient responses and aseismic design of underground tunnels. [ABSTRACT FROM AUTHOR]

To study the influence of the Chinese high-speed railway ballastless track spectrum and the German low-interference spectrum on riding comfort, a long-span highway-railway suspension bridge is studied as an example, and a passenger–train–bridge coupling model is established based on the structural dynamics. The vibration responses of the passenger–train–bridge system during the CRH2C train running on the bridge are studied by a combination of the self-written computer program and general finite element software, considering the hunting movement, and the riding comfort of trains and passengers is evaluated using NMV and ISO-2631 standard, respectively. The results show that track irregularity has a few effects on the lateral vibration of the bridge. Compared with the German low-interference spectrum, the Chinese high-speed railway ballastless track spectrum has less exciting effects on the vibration of the passenger–train–bridge system and better riding comfort. Passengers in the middle of the train and on the middle seats of the same train have better riding comfort, and with the increase of train speed, the riding comfort of passengers will gradually reduce. Instead of passenger responses, the riding comfort classification based on the car body is overestimated. [ABSTRACT FROM AUTHOR]

Summary: The columned‐supported reinforced concrete silo models with different filling conditions considering soil‐structure dynamic interaction (SSI) are established based on the finite element program ANSYS to thoroughly investigate the complex interaction mechanism of the soil–pile–silo structure with granular solid. The dynamic characteristics and seismic responses of the SSI system and fixed‐base condition are analyzed and compared when the filling conditions are empty‐filled state, half‐filled state and full‐filled state. The numerical results reveal that the SSI effect reduces the seismic acceleration response of columned‐supported silos effectively. However, in terms of displacement, the SSI effect often amplifies the relative deformation of the supporting column and the cylindrical silos. Furthermore, the SSI effect often increases the relative dynamic lateral pressure of the storage material in the half‐filled silo condition. In the full‐filled silo condition, the relative dynamic lateral pressure at the top and bottom of the storage material is increased by the SSI effect; while it is decreased in the middle part of the granular solid, demonstrating that the SSI effect could change and increase the seismic responses of the silo structure in certain areas. Therefore, the investigation provides a comprehensive insight into the interaction mechanism of the pile–soil–silo structure with different filling conditions. [ABSTRACT FROM AUTHOR]

Summary: In this study, a viscoelastic damper (VED) employing an additional amplification device is proposed to enhance the stiffness as well as energy dissipation. The mechanical model of the amplified viscoelastic damper (AVED) is developed and the amplification efficiency is explored. The mechanical behaviors of AVED and the traditional VED are experimentally investigated. By adopting a leverage system, the stiffness and the dissipated energy of AVED are significantly improved and the amplification factors are confirmed. Meanwhile, the seismic responses and structural damages are addressed through a numerical study on a frame attached to the AVEDs and VEDs. The AVED reinforced building employing fewer dampers has close seismic responses compared with VED reinforced building. Furthermore, the installation of AVEDs significantly reduces the risk of structural damage. [ABSTRACT FROM AUTHOR]

This study addresses the limitations of current tonometry techniques by exploring vibroacoustic properties for estimating intraocular pressure (IOP), a key diagnostic parameter for monitoring glaucoma—a significant risk factor for vision loss. Utilizing vivo porcine eyeballs, we investigated the relationship between IOP and the nonlinear vibration transfer function ratio (NVTFR). Through applying varying vibration levels and analyzing responses with transfer function analysis and univariate regression, we identified a strong negative correlation between NVTFR and IOP, evidenced by a Pearson correlation coefficient of −0.8111 and significant results from generalized linear model (GLM) regression (p-value < 0.001). These findings indicate the potential of NVTFR as a vital indicator of IOP changes. Our study highlights the feasibility of using vibroacoustic properties, specifically NVTFR, to measure IOP. While further refinement is necessary for in vivo application, this approach opens new possibilities for non-invasive and patient-friendly IOP monitoring, potentially enhancing ophthalmology diagnostic techniques and providing a foundation for future research and development in this critical area. [ABSTRACT FROM AUTHOR]

Strengthening using large-rupture-strain fiber-reinforced polymer (LRS-FRP) laminates can effectively enhance the deformation and energy absorption capacity of reinforced concrete (RC) components under static and seismic loads. This study explores the application of LRS-FRP, particularly polyethylene terephthalate FRP (PET-FRP), to increase the impact resistance of RC columns in instances wherein high deformability and energy absorption capacity are necessary. Six RC column specimens, preloaded axially with heavy blocks and laterally impacted using a pendulum apparatus, were wrapped with PET-FRP. The dynamic responses of the columns, including the impact force, axial force, and lateral and axial displacements, were carefully recorded. Local strengthening schemes applied at the impact points of the columns and ends effectively enhanced their anti-impact performance without transferring damage to unstrengthened areas. As regards middle-impact specimens, PET-FRP wrapping changed the failure mode from shear to flexure failure, thereby increasing the lateral-impact resistance and deformation recovery capacity and preventing collapse owing to the axial bearing capacity loss. In bottom-impact specimens, PET-FRP improved ductility in the shear failure mode and maintained a consistent trend in the damage degree of flexure and shear failure columns across varying axial compressive ratios. Within an axial compression ratio of < 0.32, the axial force reduced flexural and shear damages. However, excessive axial preloading (axial compression ratio = 0.64) increased the flexural deformation because of the P-delta effect and shear damage owing to the increased risk of FRP debonding. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Civil Engineering & Architecture is the property of Journal of Beijing University of Civil Engineering & Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractEngineering problems, such as fire and explosion caused by mechanical damage, have restricted the further development of lithium-ion batteries (LIBs). The paper aims to present an effective method for studying the impact responses of cylindrical LIBs under localized impact loadings. An impact model in which the cell is simplified to a beam is developed considering the interaction between bending and stretching. The membrane factor (fn) of the beam with a circular cross-section is introduced, and then the motion control equations for the cell with large deformation are derived. The accuracy of the theoretical method is verified based on the results from the mass block impact experiment and finite element simulation. A method for cell failure detection is established based on the force-displacement-voltage response from the impact experiment. It is shown that higher impact velocities and smaller punch widths increase cell deformation. Moreover, a larger punch mass results in greater displacement when the impact energy remains unchanged, and the strengthening tendency increases with the punch width. The research will provide theoretical guidance for the safety assessment and dynamic optimization design of LIBs. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic responses and damage evolution of two types of conformal radome composites (CRCs), namely single‐window conformal radome (SWCR) and multi‐window conformal radome (MWCR), under blast loading, were investigated using numerical methods. The results show that the local dynamic response of the conformal window is dominating. The window deformation of SWCR is larger than that of MWCR under the same scaled distance, and the MWCR exhibits better blast resistance. The increase in window size causes the reduction of the bending stiffness of CRCs. The obvious stress concentration appears in the notch of carved foam cores, caused by the window effect. The conformal windows are weak parts for the CRCs under the blast loading. It was revealed that the damages of CRCs are mainly concentrated at the edges, center, and diagonal areas of the conformal windows. Highlights: Designed two types of conformal radome composites with hierarchical configuration.Established the finite element (FE) models of two types of conformal radome compositesRevealed the dynamic responses and damage evolution of conformal radome composites under blast loading. [ABSTRACT FROM AUTHOR]

Track irregularities induce potential risks to the safety and stability of railway track systems. This paper proposes a novel methodology to identify vertical and lateral track irregularities. The method involves measuring system-based attitude calculation and a model-based unknown input observer estimator, based on the dynamic responses of distributed multi-sensors on the vehicle and bogie. First, a mechanical model of wheel-rail contacts is built with dynamic methods. The model considers the different directions of motion for a railway vehicle and consists of two bogies and four wheelsets. Based on the multi-sensor acceleration measurement, the vertical and lateral acceleration signals of the vehicle and bogies are integrated into the displacement signal. Then a state-space description of the vehicle suspension model is established for inverse dynamical analysis to extract the input signals. A suitable unknown input observer is constructed to estimate the track irregularities by transforming the state space equations of the vehicle into an augmented system that can monitor the track irregularities in-service. This method provides an opportunity to reduce the costs of the monitoring infrastructure and provide quicker and more reliable information about the status of a track. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of the dynamic responses of machine foundations, both block and pile foundations, on stratified residual soils in Duri and Ulubelu, Indonesia. The evaluation was conducted using two widely recognized methods: the lumped mass method (LMM) and the finite element method (FEM). LMM and FEM were performed by utilizing DYNA and ABAQUS, respectively. The analysis results showed that LMM generally predicted more conservative displacements compared to FEM. This conservatism in predicted displacement was more pronounced for pile group foundations, which are inherently more flexible than block foundations. Additionally, this study found that the resonance frequencies obtained through both analysis methods were not the same. Furthermore, this paper includes a parametric study and presents its results to assess the influence of key factors, i.e., pile cap thickness, pile diameter, number of piles, and vertical dynamic loads, on displacement. [ABSTRACT FROM AUTHOR]

Background: Tuned liquid dampers (TLDs) have been successfully installed on different types of structures for vibration mitigation against wind or earthquake forces. However, the effectiveness of TLDs in mitigating the dynamic responses of buildings with large mass eccentricity has not been well investigated. Method: In this study, a scaled-down one-bay 3-story structure with a 1 m span length and a total height of 2.65 m was constructed and subjected to free vibration and harmonic excitations. TLDs with mass ratios ranging from 1 to 5% were installed on the roof of the building. Moreover, to impose in-plane torsional moments to the reference structure, the location of floors' mass was shifted 0.15 m and 0.3 m away from the geometric centroid. The peak displacement and acceleration responses (PDR and PAR) were measured at the roof level of the reference structure with and without the effect of the torsional moment. Results: The obtained results indicated that, at the resonance frequency (RF), TLDs could successfully mitigate the PDRs and PARs even at the presence of torsional moments. Moreover, TLDs reduced the PDRs more than the PARs. Besides, an increase in the mass ratio up to 5% enhanced the effectiveness of TLDs in reducing the peak responses. [ABSTRACT FROM AUTHOR]

Purpose: The rich dynamic responses and complex dissipation behaviors of metamaterials with different loading speeds and specific stiffness are investigated. To our knowledge, this work studies systematically for the first time the mutual interaction among these mechanical parameters. Methods: The metamaterials composed of PCBs (prefabricated curved beams) are modeled as a corresponding NDT (nonlinear damping tandem) model, where the PCB is depicted as a nonlinear spring, the structural mass is simplified as lumped mass, and the energy dissipation is described by equivalent viscous damping. Results: The external low-frequency/speed energy can be transformed into high-frequency vibrations via the fully elastic buckling of unstable elements and dissipated, distinguishing it from plastic dissipation. The dissipation process appears to be instantaneous under quasi-static conditions as well as dynamic loadings, which is in sharp contrast to the viscoelastic effect. Conclusion: The dynamic responses and dissipation behaviors depend crucially on the mutual interactions of loading speed and specific stiffness under dynamic loadings. [ABSTRACT FROM AUTHOR]

Modern potentiometric sensors based on polymeric membrane ion‐selective electrodes (ISEs) have achieved new breakthroughs in sensitivity, selectivity, and stability and have extended applications in environmental surveillance, medical diagnostics, and industrial analysis. Moreover, nonclassical potentiometry shows promise for many applications and opens up new opportunities for potentiometric biosensing. Here, we aim to provide a concept to summarize advances over the past decade in the development of potentiometric biosensors with polymeric membrane ISEs. This Concept article articulates sensing mechanisms based on non‐equilibrium measurement techniques. In particular, we emphasize new trends in potentiometric biosensing based on attractive dynamic approaches. Representative examples are selected to illustrate key applications under zero‐current conditions and stimulus‐controlled modes. More importantly, fruitful information obtained from non‐equilibrium measurements with dynamic responses can be useful for artificial intelligence (AI). The combination of ISEs with advanced AI techniques for effective data processing is also discussed. We hope that this Concept will illustrate the great possibilities offered by non‐equilibrium measurement techniques and AI in potentiometric biosensing and encourage further innovations in this exciting field. [ABSTRACT FROM AUTHOR]

The dynamic responses of both underground structures and their surrounding geoformations induced by tamped spherical detonation have been recognised as one of the key topics in both defence engineering and civil engineering. Proper understanding and evaluation of tamped detonation-induced particle movement, spherical stress wave propagation/attenuation, and dynamic crack propagation in geoformations require effective experimental methods and numerical tools. To capture the main characteristics of the spherical shock waves, including the wave propagation and attenuation, a systematic tamped spherical detonation test technique on PMMA has been designed in this study. A mini-explosive sphere with a diameter of 4 mm is generated to produce a small-scale explosion within the PMMA specimen. To monitor the movement of particles during explosion, an electronic measurement system consisting of embedded particle velocity sensors and high-intensity magnetic field generators, has been developed. For the modelling of tamped spherical detonation, a modified multibody failure criterion, equation of state (EOS), and Johnson–Holmquist–Beissel (JHB) model have been implemented in a four-dimensional lattice spring model, thus forming an improved JHB-4DLSM model (M-JHB-4DLSM). It is capable of reproducing the effects of large Poisson's ratios, the strain rate and the high ratio of uniaxial compressive strength to the uniaxial tensile strength values (UCS/T). The developed M-JHB-4DLSM model has been validated through modelling the dynamic responses of both granite and PMMA. Results indicate that the dynamic process and fracturing patterns reproduced by M-JHB-4DLSM are consistent with experimental observations. M-JHB-4DLSM model is then applied to investigate the impact effects of tunnels subjected to close-in buried blasting. Highlights: A systematic experimental technique has been developed for the tamped spherical denotation test. A M-JHB-4DLSM model has been proposed for more realistic modelling of brittle materials subjected to blasting load. The proposed model has been validated through modelling the dynamic responses of both PMMA and granite. [ABSTRACT FROM AUTHOR]

The yaw damper is of great significance to the dynamic performance of high-speed trains. In this work, the influence of different installation angles of yaw dampers on dynamic responses and wheel wear is investigated. Firstly, the detailed dynamic model of a high-speed train is developed, which includes all kinds of nonlinear factors, such as wheel/rail contact relationship and nonlinear characteristics of various damping, and the influence of the installation angle of the yaw damper on dynamic performances of railway vehicles is investigated. Then the wheel wear prediction procedure is also proposed to obtain the effect of the installation angle of the yaw dampers on wheel wear evolution. The results show that the nonlinear critical speed of railway vehicles gradually increases with the increasing lateral distance of the yaw damper at the frame side. While critical velocity gradually decreases with increasing vertical installation distance of the yaw damper at the car body side. The maximum wheel wear depth will also gradually increase with increasing vertical distance at the car body side and increasing lateral distance of the yaw damper at the frame side when the vehicle runs on the tangent track. Moreover, it is also noticed that the wear depth of the wheel on both sides will gradually increase with the increasing vertical installation distance of the yaw damper at the car body side when the vehicle runs on a curved track. When the lateral installation angle of the yaw damper is less than 0°, the wheel wear rate remains constant and the wear sensitivity of the wheel to lateral installation angle is low, if the lateral installation angle of the yaw damper is greater than 0°, wheel wear rate increases significantly with increasing lateral installation angle of the yaw damper. [ABSTRACT FROM AUTHOR]

The mechanical behavior of single-layer graphdiyne (SLGDY) subjected to high-velocity micro-ballistic impacts is analyzed by molecular dynamics (MD) simulations. The ballistic limits of SLGDY is obtained for the first time. The temperature deterioration effects of the impact resistance are also investigated. The results show that the ballistic limits can reach 75.4% of single-layer graphene (SLGR) at about 1/2 density, leading to approximately the same specific energy absorption (SEA) as SLGR. The ballistic limits of SLGDY and SLGR with single atomic thickness agree with the predictions of macroscopic penetration limits equations, implying the applicability of continuum penetration theories for two-dimensional (2D) materials. In addition, the dynamic responses involving stress wave propagation, conic deformation, and damage evolution are investigated to illuminate the mechanisms of the dynamic energy dissipation. The superior impact resistance of SLGDY and SLGR can be attributed to both the ultra-fast elastic and conic waves and the excellent deformation capabilities. This study provides a deep understanding of the impact behavior of SLGDY, indicating it is a promising protective material.

With increasing demand for planting space, a new type of large-span pipe-framed plastic greenhouse has been developed in recent years. However, as the span increases, new problems in structural analysis arise. Compared with small-span plastic greenhouses, large-span pipe-framed plastic greenhouses are more likely to be damaged under wind and snow loads. In this study, the static and dynamic characteristics of a large-span pipe-framed plastic greenhouse were investigated using static analysis and the time history method, respectively. First, a 3-D finite element model of the greenhouse was established using ANSYS software. Second, the static characteristics of the greenhouse under three load cases were investigated along with and the failure mechanisms under the most unfavourable load case. Finally, the dynamic characteristics of the greenhouse were analysed using the time history method. The numerical results showed that the greenhouse was mainly subjected to bending stress, and the axial stress values were small. Compared with uniform snow loads, the pipe-framed plastic greenhouse structure was more sensitive to non-uniform snow loads. The maximum displacement of the greenhouse structure under non-uniform snow loads was approximately 2.2 times that under uniform snow loads. A comparative analysis showed that the maximum displacement and bending stress obtained from the time history method were 1.7 and 1.5 times greater, respectively, than those obtained from the static equivalent method. This study provides a reference for the design and analysis of large-span pipe-framed plastic greenhouse structures. • Large-span pipe-framed plastic greenhouses are sensitive to non-uniform snow loads. • The greenhouse is mainly subjected to bending stress under wind and snow loads. • The response under pulsating wind loads is greater than that under static wind loads. • Load-carrying capacity decreases as the geometric imperfection amplitude increases. • The secondary frame is more susceptible to failure than the primary frame. [ABSTRACT FROM AUTHOR]

Timely inspection of structures is necessary to prevent damage progression and ensure the safety and efficiency of structures at the lowest cost. The existence of defects and partial failures in structures is the source of general failures and threats to the behavior of structures. In many cases, impending failure may not be apparent from its appearance. Hence, the study of structural failure is one of the essential areas of research that helps increase the structure's life and control the failure of structures. This research aims to investigate an approach for detecting damage in the structure, especially in the plates. An efficient method utilizing the Grasshopper Optimization Algorithm (GOA) as an optimization solver is presented here to detect the multiple-damage of structural systems. Accelerations changes of a structure are considered as a criterion for damage occurrence. The structural damage detection problem is first transmuted into a standard optimization problem dealing with continuous variables. Then the GOA is utilized to solve the optimization problem for finding the site and severity of structural damage. To assess the performance of the proposed method for damage identification, numerical examples with considering measurement noise are considered. All the results demonstrate the effectiveness of the proposed method for accurately determining the site and severity of multiple-damage. Also, the performance of the GOA for damage detection compared to the differential evolution algorithm (DEA) is confirmed by a numerical example. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Composite double-arrow auxetic structures were designed and fabricated. The local impact experiments were carried out on the auxetic structures to explore the dynamic responses and failure modes. The effects of relative density and impulse level on the impact properties were analyzed and discussed. As the relative density increased, the local deformation of the auxetic structures and the damage of the core layer decreased, and the overall response of the auxetic structure increased. The finite element model was used to simulate the impact responses of the auxetic structures, and the numerical simulation results were in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Past major earthquakes have witnessed extensive pile-supported transmission tower-line systems (PSTLs) failing, which highlights the great susceptibility of PSTLs to damage from earthquakes. However, a comprehensive literature review in seismic analysis of PSTLs reveals that two critical aspects, i.e. soil–structure interaction (SSI) and depth-varying spatial ground motions (DVSGMs), have been completely overlooked in numerous previous studies. To be specific, pile-supported transmission towers are generally assumed to be fixed to the ground surface and are excited using uniform ground motion inputs. Such analytical schemes may result in severe misestimates of seismic response predictions of PSTLs. Within this context, the main objective of the present study is to accurately assess the seismic performance of PSTLs by considering SSI and using DVSGMs as inputs. For this purpose, an existing prototype PSTL is firstly selected and the corresponding three-dimensional finite element model is created in ABAQUS software, in which SSI is simulated by the Beam on Nonlinear Winkler Foundation (BNWF) model. Then, the three-dimensional DVSGMs are stochastically synthesized based on the computed ground motion transfer functions (GMTFs) of local sites. Next, seismic performance of the PSTL with SSI, including dynamic responses, ultimate bearing capacity, and failure mechanism, is assessed using the generated DVSGMs as seismic inputs. Finally, a parametric study is conducted to comprehensively examine and discuss the influences of SSI, seismic excitation types, coherence loss, and local site conditions on seismic performance of the PSTL. Numerical results show that seismic performance of PSTLs can be affected significantly by the above mentioned influencing factors. This research is expected to offer a meaningful reference to seismic performance assessments of PSTLs. [ABSTRACT FROM AUTHOR]

In waterway regulation engineering, submerged reefs are quite susceptible to the repetitive oblique strike from drop hammer and impact drilling, leading to a repetitive compression–shear impacting. Understanding the dynamic responses and failure mechanism of saturated rocks subjected to repetitive compression–shear impacting is thus of great significance for the efficient removal of submerged reefs. In this study, using the split Hopkinson pressure bar (SHPB) apparatus, the repetitive compression–shear impacting tests were conducted on the saturated and dry sandstone specimen from the harbor excavation project in Guoyuan Port (Chongqing, China). Our experimental results indicate that the increasing loading rate or shear component in the dynamic loading has a negative influence on the bearing capacity of saturated sandstone subjected to repetitive impacting. The deformability of saturated rocks increases as the impacting number or the shear component in the dynamic loading. The energy absorption ability as well as the energy utilization of the saturated rocks is highly improved by implementing repetitive compression–shear impacting, and such improvement yields an ascension limit with the increasing shear component in the dynamic loading. As the shear component introduces into the repetitive impacting loading, the failure patterns of rocks change from the relative tensile mode with a large deformation band along the loading direction to the combined compression–shear mode with two parallel large deformation bands inclined to the loading direction, the water content between the mineral grains promotes the shear failure in rock dynamic testing. These results can provide a better understanding of the dynamic responses and failure properties of saturated rocks subjected to repetitive compression–shear impacting. Highlights: Illustrated influences of repetitive compression–shear impacting on the bearing capacity and deformability of saturated and dry rocks. Investigated energy dissipation of saturated and dry rocks under repetitive combined compression–shear impacting. Revealed failure patterns of saturated and dry rocks under repetitive combined compression–shear impacting. [ABSTRACT FROM AUTHOR]

Networked dynamical systems, i.e., systems of dynamical units coupled via nontrivial interaction topologies, constitute models of broad classes of complex systems, ranging from gene regulatory and metabolic circuits in our cells to pandemics spreading across continents. Most of such systems are driven by irregular and distributed fluctuating input signals from the environment. Yet how networked dynamical systems collectively respond to such fluctuations depends on the location and type of driving signal, the interaction topology and several other factors and remains largely unknown to date. As a key example, modern electric power grids are undergoing a rapid and systematic transformation towards more sustainable systems, signified by high penetrations of renewable energy sources. These in turn introduce significant fluctuations in power input and thereby pose immediate challenges to the stable operation of power grid systems. How power grid systems dynamically respond to fluctuating power feed-in as well as other temporal changes is critical for ensuring a reliable operation of power grids yet not well understood. In this work, we systematically introduce a linear response theory (LRT) for fluctuation-driven networked dynamical systems. The derivations presented not only provide approximate analytical descriptions of the dynamical responses of networks, but more importantly, also allow to extract key qualitative features about spatio-temporally distributed response patterns. Specifically, we provide a general formulation of a LRT for perturbed networked dynamical systems, explicate how dynamic network response patterns arise from the solution of the linearised response dynamics, and emphasise the role of LRT in predicting and comprehending power grid responses on different temporal and spatial scales and to various types of disturbances. Understanding such patterns from a general, mathematical perspective enables to estimate network responses quickly and intuitively, and to develop guiding principles for, e.g., power grid operation, control and design. [ABSTRACT FROM AUTHOR]