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Multiphysics models were used to simulate the deformational characteristics experienced by paper under metering blades. Paper is found to slip microscopically at the backing roll interface and subsequently buckle either side of the blade during metering operations. Micro-slippage of the paper at the interface is a linear function of the separation height incurred during buckling. The effects of altering the static coefficient of friction as well as the properties of the backing roll material are studied. Increasing the coefficient of static friction reduces the extent of buckling while a non-linear relationship is found to arise on increasing the elastic modulus of the backing roll material. The mechanisms involved in micro-buckling deformation are explicated herein. [Copyright &y& Elsevier]

SiC/SiC composites are candidates of interest for fuel cladding applications in pressurized light-water reactors. In this study, fuel cladding tubes were made by filament winding and the matrix was deposited by CVI (Chemical Vapour Infiltration), which results in surface irregularities and waviness defects. This paper examines the influence of grinding steps on the mechanical behavior of tube specimens. Different depths of inner and outer surface grinding are carried out from a reference grade. Cyclic tensile tests are then performed. Elastic behavior analysis shows that the machining of tubes does not cause pre-damage. Analysis of unload-reload cycles indicates that the internal slippage does not depend on the seal coat thickness and that the surface quality weakly influences damage in the loading direction. Damage in the shear plane and ultimate failure strength strongly depend on the inner seal coat thickness. [ABSTRACT FROM AUTHOR]

This paper investigates the effective elastic constants of the perforated fibre-reinforcement damping membrane, taking into account the variations in perforation array and ply orientation angle using the homogenization method and the off-axis stress-strain relation. The equations for the free vibration of the composite beam with multi-layer perforated fibre-reinforcement damping membranes are derived using the first-order shear deformation theory and the Hamilton principle. These equations are then solved using the Navier method. The novelty of this paper lies in the achievement of an effective elastic constants model and vibration analysis for the multi-layer composite beam under simply supported boundary conditions. The calculated results are then compared with experimental values and finite element results to validate the theoretical model and method. Furthermore, the paper explores the graphical variation of mechanical performance with system parameters, providing a theoretical foundation for future researchers in the composite field. • Analysis of effective elastic constant using homogenization method. • Free vibration response of a multi-layer perforated damping beam is studied. • The fibre angle strongly affects the equivalent elastic constant of perforated beam. • Assessed for mechanical analysis of perforated beam. [ABSTRACT FROM AUTHOR]

• The LRBFCM is extended to a 3D dental elastic problem. • The direct method and fictitious node method are used to solve the derivative instability in the LRBFCM. • The maximum von Mises stress of the molar is fully studied by considering different situations. In this paper, the local radial basis function collocation method (LRBFCM) is presented to analyze 3D elastic problems of complex geometries. In particular, a real tooth domain built by cone beam computer tomography (CBCT) data is considered. The reconstruction process of a tooth shape, the choice of the local influence domain in the LRBFCM, as well as the treatments of the boundary conditions are detailed described in this paper. Linear elastic analyses of five different examples are carried out to validate the effectiveness of the proposed approach. The stress difference between a tooth with the dental caries and a healthy tooth is investigated and discussed by the 3D elastic deformation and stress analysis. [ABSTRACT FROM AUTHOR]

Single-loop elastic rings can be folded into multi-loop equilibrium configurations. In this paper, the stability of several such multi-loop states which are either circular or straight are investigated analytically and illustrated by experimental demonstrations. The analysis ascertains stability by exploring variations of the elastic energy of the rings for admissible deformations in the vicinity of the equilibrium state. The approach employed is the conventional stability analysis for elastic conservative systems based on the second variation of the system energy which differs from most of the analyses that have been published on this class of problems, as will be illustrated by reproducing and elaborating on several problems in the literature. In addition to providing solutions to two basic problems, the paper analyses and demonstrates the stability of six-sided rings, curved-sided hexagrams, that fold into straight configurations. [ABSTRACT FROM AUTHOR]

In this study, we aimed to construct a system to perform statistical analyses for educational improvement while preserving privacy. Various probabilistic statistical algorithms have been developed for data agitation. However, one of the major challenges in using these algorithms is determining appropriate parameters. To address this issue, our previous research proposed the "α-criterion" as a criterion that must be satisfied by appropriate parameters. This paper outlines a system that calculates the parameters that satisfy the α-criterion while performing real-time data agitation on the given aggregate data. To verify that our implementation actually works, we show a use case with sample data on kibana-Elastic log analysis provided by Elastic N. V. [ABSTRACT FROM AUTHOR]

Clay concrete is the main material of the embankment dam impervious wall, and its linear elastic property has significant influence on safe operation of dam impervious system. To deeply study the linear elastic property of clay concrete, this paper combines the multi-scale and multi-phase structure characteristics of the material and proposes a multi-scale analyses method to conduct the material research at the mechanism level. In this paper, the clay concrete material is firstly divided into several scales based on the scale information of different phases inside the material. Afterwards, on the basis of micro hydration law of clay and cement, a random adjoint growth model is established for the reconstruction of microscopic RVE of clay concrete. And reconstruction of the mesoscopic and macroscopic RVEs of clay concrete are conducted by randomly placing spherical inclusions in the research area. To establish the relationship between the linear elastic properties of each scale model, the homogenization method is applied to calculate the equivalent linear elastic property on the coarse scale according to the reconstruction of the fine scale model. And the macro-scale linear elastic property of the clay concrete can finally be obtained by the progressive homogenization process from the micro-scale model to the macroscopic model. [ABSTRACT FROM AUTHOR]

With the rapid development of China's industrialization, the extensive development of industrial models has led to increasing environmental pressure. In this paper, we use China as an example, combined with the Tapio elastic analysis method (Tapio model), modified gravity model, social network analysis (SNA), quadratic assignment procedure (QAP) regression and logit model, to explore a network effect on the decoupling of industrial waste gas emissions and industrial added value (industrial GDP). We use the special network structure of industrial waste gas emissions and industrial GDP to capture the network effect. The results show the following: (1) For industrial sulfur dioxide (SO 2), nitrogen oxide (NO x) and soot (dust) (SD), most provinces in China show obvious strong decoupling, and provinces with faster economic growth, such as the eastern coastal areas, have a larger proportion of strong decoupling than provinces with poor economic development. (2) According to the network analysis of the industrial GDP, SO 2 , NO x and SD, economically developed provinces such as Shanghai, Jiangsu, Zhejiang, Beijing and Guangdong are generally located at the core of the network and have a strong spatial spillover effect on other provinces; (3) The QAP regression results show that the spillover effects of industrial SO 2 , NO x and SD are largely influenced by industry structural similarities, geographic proximity, and the development of economy. (4) The logit regression results show that the decoupling of industrial waste gas emissions will be greatly affected by the spatial network structure of industrial waste gas emissions and industrial GDP. The provinces at the core of the network are more likely to undergo strong decoupling. Finally, based on the research results, this paper provides some recommendations. • A network effect on decoupling of industrial emissions and industrial added value. • The modified gravity model is used to build the network. • Provinces with faster economic development are more prone to pollution decoupling. • Provinces at the core of the network are more prone to pollution decoupling. [ABSTRACT FROM AUTHOR]

• The static behaviour of notched PPS/GF specimens was investigated. • V-shaped notched specimens were manufactured and tested. • Different notch root radii and manufacturing processes were considered. • Different approaches for the static strength assessment were compared. In this paper the static behaviour of polyphenylenesulfide reinforced by 40% wt. short glass fibre net-shaped plain and notched specimens was investigated. The specimen geometries were obtained by injection moulding and the experimental results were compared with data obtained from machined specimens with the same material and geometries. All data were reanalysed according to several models available in the literature for orthotropic materials, to find a rapid and efficient assessment tool for predicting the strength of short glass fibre reinforced materials in the early design stages. To this end, approaches based on orthotropic linear elastic stress analysis were considered, namely the linear elastic peak stress criterion, the nominal net-stress criterion, the point stress criterion, the average stress criterion, the strain energy density criterion, the generalized stress intensity factor-based approach, the inherent flaw model, the damaged zone criterion and the Hitchen criterion. Among the models, the average stress criterion and the generalized stress intensity factor-based approach provided the most accurate predictions of the static strength, ranging from −10% to +9% and from −19% to +2%, respectively, compared to the experimental data. [ABSTRACT FROM AUTHOR]

Peridynamics theory is a nonlocal continuum mechanics theory. The peridynamic material correspondence formulation provides passage for direct incorporation of any material constitutive models from the classical local continuum mechanics theory. The performance of the material correspondence formulation heavily relies on the influence function whose currently used form is spherical and depends only on the bond length. Together with the way how the nonlocal deformation gradient is constructed based on the material point horizon, this results in the well-known issue of material instability in the conventional peridynamic material correspondence formulation. In this paper, a generalized peridynamic material correspondence formulation that enables use both spherical and non-spherical influence functions is developed. A recently proposed class of parameterized non-spherical influence functions that depend on both the bond length and bond direction is used in the generalized formulation. Numerical examples including wave dispersion, small and finite deformation and linear elastic fracture analyses are studied to check the material stability, convergence characteristic, prediction accuracy and applicability to fracture problems without singularity issue of the proposed formulation. It is found that the proposed formulation is inherently stable, possesses linear convergence rate, yields highly accurate predictions for both small and finite deformation problems, and small horizon can be used to improve computational efficiency. • A material correspondence model uses non-spherical influence function was proposed. • A family of non-spherical influence functions was used and it is materially stable. • The proposed formulation possesses linear convergence rate. • Small horizon can be used to improve computational efficiency. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) techniques have been used in several fields of science and industry, and fabrication techniques are being updated. For this fact, especially, for industrial use, mechanical property evaluation methodologies for AM products and standards for product quality assessment should also be well established. In this paper, a probabilistic evaluation of the homogenized elastic properties of a resin product fabricated by a material extrusion-based AM technique is attempted by considering the randomness of both material and microscopic geometrical quantities. This AM method fabricates a resin structure by piling up melted resin, and to decrease consumed material and influence of thermal deformation, the inner structure of the fabricated products will include many pores and its geometry is difficult to be well controlled. From this fact, the products will be regarded as a heterogeneous material with complex random microstructure. This will cause difficulty in the evaluation of its apparent material properties and therefore a probabilistic homogenization analysis is attempted for their quantitative estimation in this study. In particular, to investigate probabilistic properties of microscopic geometry, a random field modeling technique is employed for the evaluation of autocorrelation of the microscopic geometrical parameter, and the results of the autocorrelation identified by experimental observation are introduced to the probabilistic homogenization analysis. The two-dimensional or three-dimensional random field modeling is attempted, and the effectiveness of this approach is investigated by comparing it with the experimental result. • The spatial variation of the random microstructure in AM products is identified. • A probabilistic multiscale elastic analysis of AM resin specimens is performed. • The random field of the apparent elastic modulus of the specimens is computed. • The estimation accuracy is improved by considering the 3D random spatial variation. [ABSTRACT FROM AUTHOR]

Achieving full integration of inspection and monitoring data with finite element models for structural condition assessment remains a persistent challenge in engineering. This paper introduces a novel approach aimed at enhancing structural analysis by amalgamating inspection and monitoring data with finite element models. On one hand, a hybrid substructure method was proposed. Initially, mathematical equations linking monitoring data with finite element mechanical information are established. Subsequently, a self-adaptive sparsity matching tracking algorithm is employed to attain highly accurate interface constraints for critical regions. Consequently, Finite element model updating was carried out in key areas based on monitoring data. On the other hand, an interacting analysis theory between substructures and the main structure is developed. This enables nonlinear analysis of substructures and equivalent linear elastic analysis of the main structure, ultimately achieving refined structural assessment. The feasibility of this analysis method is confirmed through experiments of concrete beam and steel arch bridge models. This approach enables a comprehensive integration of monitoring data with finite element models, facilitating detailed substructure analysis and refined overall structural assessment. • A new framework is proposed that combines targeted sensing data with finite element models. • Hybrid substructure modeling method integrating inspection and monitoring data. • An interacting analysis theory between substructures and the main structure is developed. • An adaptive sparsity matching tracking algorithm is proposed to get the high-precision key area interface constraint for substructures. [ABSTRACT FROM AUTHOR]

In this paper, a phenomenon of rolling stiffness variation in contact surface when two contact particles undergo relative rolling is introduced, and a formula of variable rolling stiffness is proposed. In the conventional discrete element method (DEM), the rolling stiffness is generally set to be a constant. However, it was observed that the rolling particles swing back and forth before coming to rest, and the frequency of swinging gradually increased. The swinging occurred before the rolling particles came to rest, was inconsistent with the results obtained from regular DEM simulations. Therefore, the rolling stiffness is hypothesized to be a variable that varies with the rolling displacement of particles. Subsequently, based on elastic mechanics analysis, it was found that the change in the length of the contact surface between particles is the reason for the variable rolling stiffness. Hence, a formula for the variation of rolling stiffness with rolling displacement was derived. This formula can be used to calculate the rolling stiffness of circular particles. Finally, the influence of surface defects on real particles in the experiment was analyzed, and an improved variable rolling stiffness formula was established. The variable rolling stiffness model was applied to DEM for simulation and the results were compared with experiments. The comparison shows that the hypothesis of variable rolling stiffness is applicable. [Display omitted] • The theoretical formulas and mechanical model for rolling stiffness variation were proposed. • A method for identifying rolling stiffness is proposed based on the swing process of particles. • The swing frequency in experiments could be simulated well by the proposed model in DEM. [ABSTRACT FROM AUTHOR]

• Study of ultrasonic wave propagation in a mesoscale model of concrete. • Numerical modelling of elastic waves using the discrete element method. • A novel methodology for the construction of a DEM model of concrete. • Calibration process of the mechanical parameters of the DEM model. This paper deals with the accurate modelling of ultrasonic wave propagation in concrete at the mesoscopic level. This was achieved through the development of a discrete element method (DEM) model capable of simulating elastic wave signals comparable to those measured experimentally. The main objective of the work was to propose a novel methodology for constructing a meso-scale model of concrete dedicated to the analysis of elastic wave propagation. All the material parameters necessary to prepare a numerical DEM model of concrete at the mesoscopic level were explored and explained. Calibration of the mechanical parameters of the DEM model to match the experimental values involved linking the local, micro-parameters between particles with the global response of the whole sample. The developed numerical model was further used to simulate the propagation of elastic waves in a cubic concrete sample, in the frequency range of 100–500 kHz. The results of the DEM calculations showed good agreement with the experimental ultrasonic signals. [ABSTRACT FROM AUTHOR]

Most species of bipeds walk with "bouncing gait" in nature, which plays an important role in their rapid and energy-saving movement. From the perspective of bionics, the "bouncing gait" for an ostrich-like one-leg is introduced in this paper, the bouncing characteristics of the leg is analyzed, the effect law of elastic component on the bouncing performance of the one-leg is revealed, and the forms and mechanisms of failure of the elastic component is obtained. This study provides theoretical references for the selection of elastic components in the ostrich-like robot, and gives an optimization scheme for improving its bouncing performance. [ABSTRACT FROM AUTHOR]

This is the second of two papers introducing the underpinning structural analyses and reliability studies that implement the system-based design-by-analysis method of steel rack frames, referred to as the Direct Design Method (DDM). The present paper presents the reliability analyses and derivation of system reliability index (β) versus system resistance factors (ϕ s) curves. Results are presented for nominal system strengths as per Australian Standard AS4084 for several nominal models, including models that exclude sectional imperfections, and models without member and sectional imperfections. The effect of model uncertainty is also assessed. A detailed example of the DDM applied to the design of a rack frame is presented and the benefits of the DDM are demonstrated when compared to the traditional design approach which is based on elastic analysis. • System reliability index versus system resistance factor curves are obtained through reliability analyses. • The effect of different nominal models and model uncertainty on the system resistance factor is assessed. • Different reliability categories are identified based on the reliability characteristics of the failure modes. • A design example is presented to compare the Direct Design Method with the traditional component-based LRFD method. [ABSTRACT FROM AUTHOR]

Interaction of two solitons with different structures is exhibited. By adjusting the corresponding parameters, distinct solitons and their interaction can be achieved. It can also simulate a process of energy concentration of solitons at different times. [Display omitted] • We investigated a two-dimensional Gross-Pitaevskii equation with time-varying trapping potential in the Bose-Einstein condensation. • The Hirota bilinear method is established to solve the two-dimensional Gross-Pitaevskii equation and its parabolic soliton, line-soliton and dromion-like structure can be exhibited via some appropriate parameters chosen. Their interaction structures are discussed. • The interaction of two-soliton solutions is investigated through asymptotic analysis. The Gross-Pitaevskii equation is a class of the nonlinear Schrödinger equation, whose exact solution, especially soliton solution, is proposed for understanding and studying Bose-Einstein condensate and some nonlinear phenomena occurring in the intersection field of Bose-Einstein condensate with some other fields. It is an important subject to investigate their exact solutions. We give multi-soliton of a two-dimensional Gross-Pitaevskii system which contains the time-varying trapping potential with a few interactions of multi-soliton. Through analytical and graphical analysis, we obtain one-, two- and three-soliton which are affected by the strength of atomic interaction. The asymptotic expression of two-soliton embodies the properties of solitons. We can give some interactions of solitons of different structures including parabolic soliton, line-soliton and dromion-like structure. By constructing an appropriate Hirota bilinear form, the multi-soliton solution of the system is obtained. The soliton elastic interaction is analyzed via asymptotic analysis. The results in this paper theoretically provide the analytical bright soliton solution in the two-dimensional Bose-Einstein condensation model and their interesting interaction. To our best knowledge, the discussion and results in this work are new and important in different fields. The study enriches the existing nonlinear phenomena of the Gross-Pitaevskii model in Bose-Einstein condensation, and prove that the Hirota bilinear method and asymptotic analysis method are powerful and effective techniques in physical sciences and engineering for analyzing nonlinear mathematical-physical equations and their solutions. These provide a valuable basis and reference for the controllability of bright soliton phenomenon in experiments for high-dimensional Bose-Einstein condensation. [ABSTRACT FROM AUTHOR]

In this paper, the effective elastic behavior of three-layer quasicrystal composite plates are forecasted. Firstly, effective properties of the first and third layers quasicrystal composite plates containing ellipsoidal inclusions are obtained according to the Mori-Tanaka model. Secondly, the three-layer composite plates effective behavior parameters are computed by employing the general matrix approach. The numerical examples reveal the influence of the inclusions geometry and volume fraction on the three-layer quasicrystal composite plates effective behavior parameters. The findings indicate that changing the elastic constants of the phason field and phonon-phason coupling field of inclusions will affect the effective behavior parameters of the three-layer quasicrystal composite plates. The increase in layers to some extent reduces the effective behavioral parameters. [ABSTRACT FROM AUTHOR]

Abstract In the processes of lowering down or raising up the legs of a floating structure, the legs are neither touch with the sea bed nor completely lift up, and the structure is situated in the condition of freely floating on the waves. The existing of the legs equipped on the structure leads to the property different hydroelastic responses from the ordinary floating structures. To investigate the variation of the length of the legs underwater affecting the hydroelastic responses, a plate-cell model is proposed, and the basin tests using the elastic model in waves are carried out. Based on the length of the legs under water, the model is set as 2 cases. The attenuation tests in calm water and test in the regular wave at zero speed in various of the wave conditions are carried out. According to the plate-cell model, a numerical model is constructed to simulate the hydroelastic responses of the 2 cases based on the theory of the three-dimensional (3-D) linear hydroelasticity. Both the experimental and numerical results demonstrate that the legs have significant influences on the hydroelastic responses of the structure. Highlights • A new hydroelastic experimental method is introduced for researches on floating structure with legs. • The significant influences of the length of underwater legs are investigated by experimental and numerical simulations. • Not only the conclusions of this paper, but also the experimental methods introduced in this paper have valuable references to relevant researches. [ABSTRACT FROM AUTHOR]

The use of elastic analysis is prevalent in the design of building structures even under loading conditions where inelasticity would be expected. Accordingly, geometric and material properties used in the elastic analyses must be carefully selected to maintain accuracy. Steel-concrete composite columns experience different forms of inelasticity. Concrete cracking is the source of much of the inelasticity and occurs at relatively low levels of load, but partial yielding of the steel, slip between concrete and steel, and concrete crushing also contribute to losses in stiffness. In this paper, the behavior of composite columns is characterized at the cross section and member levels through comparisons between inelastic and elastic analyses. Then, through a broad parametric study, specific practical design recommendations are developed for the elastic flexural rigidity of composite columns for the determination of lateral drifts under service loads. The recommendations in this paper provide simple and robust values for the stiffness of composite columns to be used for drift computations involving lateral loads. [ABSTRACT FROM AUTHOR]

Recent developments have demonstrated that the behaviour of segmental grey cast iron (GCI) tunnel linings can be simulated accurately with sophisticated 3D numerical models where the geometry of the segments and joints is considered explicitly. Such a 3D model is, however, impractical for geotechnical numerical analyses where the tunnel lining is usually simulated with simpler, structural elements. In this paper, a novel tunnel joint model specifically developed for simulating the behaviour of GCI longitudinal joints with beam elements in geotechnical finite element analysis is introduced. Unlike existing models, the model considers the contribution of the bolts to the joint response and the nonlinear decay of the rotational stiffness after joint opening as well as the dependency on the compression level. After calibration of the model parameters, the model was utilised in a series of parametric analyses replicating the elastic continuum model using 2D beam elements. The response of the segmental GCI lining was essentially equivalent to that predicted by an advanced 3D model which validated the new modelling approach. The development of the joint beam model enables the nonlinear behaviour of segmental GCI tunnel linings to be accounted for in routine geotechnical numerical analyses. • A new model is proposed to represent the bending moment-rotation behaviour of tunnel joints. • The bending moment-rotation relationship is dependent on the axial force and characterised by a hyperbolic expression. • The joint model captures the bending moment-rotation behaviour as predicted with 3D modelling. • The behaviour of segmental grey cast iron tunnel linings can successfully be simulated with beam elements. [ABSTRACT FROM AUTHOR]

• An international 'round-robin' exercise with 29 submissions. • Computational benchmark: buckling of a WTST metal shell. • A moment of truth for the international shell buckling community. • Increasing dispersion in submitted results, at most for GMNIA. • Case made for need for standardisation of meshing protocols and GMNIA interpretation. An assessment of the elastic-plastic buckling limit state for multi-strake wind turbine support towers poses a particular challenge for the modern finite element analyst, who must competently navigate numerous modelling choices related to the tug-of-war between meshing and computational cost, the use of solvers that are robust to highly nonlinear behaviour, the potential for multiple near-simultaneously critical failure locations, the complex issue of imperfection sensitivity and finally the interpretation of the data into a safe and economic design. This paper reports on an international 'round-robin' exercise conducted in 2022 aiming to take stock of the computational shell buckling expertise around the world which attracted 29 submissions. Participants were asked to perform analyses of increasing complexity on a standardised benchmark of an 8-MW multi-strake steel wind turbine support tower segment, from a linear elastic stress analysis to a linear bifurcation analysis to a geometrically and materially nonlinear buckling analysis with imperfections. The results are a showcase of the significant shell buckling expertise now available in both industry and academia. This paper is the first of a pair. The second paper presents a detailed reference solution to the benchmark, including an illustration of the Eurocode-compliant calibration of two important imperfection forms. Full details are here: https://doi.org/10.1016/j.engfailanal.2023.107133. [ABSTRACT FROM AUTHOR]

In rotary compressors, adding one cylinder to the conventional two in the axial direction without increasing the flow rate and load per cylinder can be expected to be an effective means for further increasing the capacity without deteriorating efficiency and reliability. This paper presents the prototype design with three different specifications for a three-cylinder rotary compressor, their performance measurement results, and their efficiency analysis. To investigate a bending deformation of the crankshaft, we have performed an axis behavior analysis as the elastic body and used the results for the efficiency analysis. Our efficiency analysis finds that the three-cylinder rotary compressor requires a middle bearing between the cylinders to reduce leakage in the compression chamber. The three-cylinder prototype demonstrates a higher COP than two-unit operation of the two-cylinder conventional models in almost the entire refrigeration capacity range and a great advantage in the medium capacity range especially. [ABSTRACT FROM AUTHOR]

• The closed-form solutions of an elastic half-plane subjected to a moving load under plane strain condition are obtained. • Two design schemes for periodic wave barriers are proposed and validated for vibration isolation of underground structures. • Some inherent properties of soil under a moving load are discovered. Most investigations on the control of ambient vibration caused by moving loads are partial to the ground buildings rather than underground structures. With the rapid development of rail transit, the effects of ambient vibration caused by moving loads on underground structures such as important underground military facilities or underground railway stations have been got wide attention in recent years. This paper focuses on the vibration attenuation of underground structures by periodic barriers under a single frequency moving concentrated force. First, under the assumption of plane strain and taking the Doppler effect into account, the closed-form solutions of an elastic half-plane subjected to a moving load on the surface are obtained, and are validated by numerical simulations. The frequency characteristics of the present solutions are comprehensively discussed. The isolation mechanism of periodic wave barriers under a moving load is revealed. Second, based on the characteristics of soil's frequency response under a moving load, two different schemes for designing wave barriers are provided for load speed less than S-wave speed of soil mass. The effectiveness of the proposed design schemes is verified through numerical simulations for different types of traffic loads. This study shows that the periodic wave barriers can play a great role in vibration isolation of underground engineering, and the design schemes proposed in this paper work very well. The present study provides a new insight for vibration attenuation of underground structures caused by moving loads. [ABSTRACT FROM AUTHOR]

Due to the air gap between stator and rotor, magnetically suspended control moment gyro (MSCMG) should be equipped with locking/unlocking device (LUD) to sustain launch vibration and impact. Current LUDs are not repeatable, reliable and compact enough for gyro applications. In this paper, a repeatable locking/unlocking device (RLUD) with several elastic brackets as clamping/releasing mechanism is proposed. Based on the equivalent beam model, static and dynamic analyses of the brackets are carried out, and the maximum stress, the locking/unlocking force and the resonance frequency are obtained. Subsequently, the optimization design using non-linear programming by quadratic Lagrangian (NLPQL) algorithm is implemented, and structural parameters of the optimized brackets are calculated. The maximum stress and first resonance frequency are simulated through finite element method (FEM), and the results are in good agreement with those of the elastic beam analyses. Finally, a MSCMG rotor system with the designed RLUD is fabricated. The environmental mechanics tests including sine sweep and random vibration are performed, which verifies the locking protection effect for MSCMG rotor. • A novel compact RLUD with flexible brackets was designed for MSCMG launch. • Static & dynamic analyses and optimization design of the RLUD were proposed in detail. • A series of environmental mechanics tests were conducted to prove the protection effect. • The design scheme and optimization method were successfully applied to a MSCMG rotor system. [ABSTRACT FROM AUTHOR]

We present a first-order stabilization-free virtual element method (VEM) for three-dimensional linear elastic problems in this paper. VEM has been increasingly used in various fields of engineering, but the need of stabilization yields a method that cannot be used without care, e.g. in nonlinear engineering applications. In this work, by increasing the order of the strain model, a new virtual element formulation is constructed for three-dimensional problems that does not require any stabilization term. The core concept involves adapting the virtual element space to enable the computation of a higher-order L 2 projection operator, guaranteeing an accurate representation of the element energy in terms of strain and stress. This work describes the calculation process of the original H 1 projection operator and the higher-order L 2 projection operator for three-dimensional problems. Eigenvalue analysis allows to derive an approximate relation between the polynomial order and the number of element vertices. Some benchmark problems illustrate the capability of the stabilization-free VEM for three-dimensional linear elastic problems. [ABSTRACT FROM AUTHOR]

This paper deals with elastic shear buckling behavior of infill panels in sinusoidally corrugated steel plate shear walls, and fitting equations predicting the shear buckling loads are presented. Firstly by using finite element analyses (FEA), the previous formulae for bending rigidities of sinusoidally corrugated plates are revised, then pure shearing model are established to study the effects of key parameters on elastic shear buckling of sinusoidally corrugated infill panels, such as the aspect ratio, corrugation ratio, corrugation depth to plate thickness ratio and corrugation repeating number. Based on extensive FEA numerical results, fitting equations with good accuracy are proposed to estimate elastic shear buckling loads of sinusoidally corrugated panels, which are improved much compared with the solutions in previous studies. It is found that, the formulae for bending rigidities of corrugated plates revised in this paper are accurate compared with the previous ones. For sinusoidal corrugated infill panels, only global buckling and local buckling can be observed in the lowest buckling mode of eigenbuckling analysis, while interaction buckling is not obvious. The parameter of corrugation repeating number has a significant influence on elastic shear buckling loads, whereas it was neglected in previous studies. [ABSTRACT FROM AUTHOR]

Brittleness is a key factor in identifying intervals and areas for fracking in tight oil and gas reservoirs. The brittleness index of reservoir rocks can be calculated by elastic properties, but laboratory measurement of elastic properties is usually expensive and time consuming. In this paper, a method is proposed to predict the brittleness from known mineralogy and applied to assess the upper Three Forks formation in the Williston basin. In this method, a correlation between the elastic properties of the formation rock and mineralogy was first established based on rule of mixture. This correlation was verified by the measured elastic properties of the middle Bakken member. Then the correlating approach was used to predict the elastic property-based brittleness index of the upper Three Forks formation. The results indicate that the upper Three Forks formation should be conducive to reservoir stimulation as its predicted brittleness index ranges from 53 to 67 in the direction parallel to the bedding plane and 58 to 70 in the direction perpendicular to the bedding plane. Its brittleness is comparable to that of the middle Bakken member, which has been already successfully stimulated. The correlating method presented in this paper is also applicable to other major tight reservoirs. [ABSTRACT FROM AUTHOR]

This paper presents the elastic buckling and static bending analysis of shear deformable functionally graded (FG) porous beams based on the Timoshenko beam theory. The elasticity moduli and mass density of porous composites are assumed to be graded in the thickness direction according to two different distribution patterns. The open-cell metal foam provides a typical mechanical feature for this study to determine the relationship between coefficients of density and porosity. The partial differential equation system governing the buckling and bending behavior of porous beams is derived based on the Hamilton’s principle. The Ritz method is employed to obtain the critical buckling loads and transverse bending deflections, where the trial functions take the form of simple algebraic polynomials. Four different boundary conditions are considered in the paper. A parametric study is carried out to investigate the effects of porosity coefficient and slenderness ratio on the buckling and bending characteristics of porous beams. The influence of varying porosity distributions on the structural performance is highlighted to shed important insights into the porosity design to achieve improved buckling resistance and bending behavior. [ABSTRACT FROM AUTHOR]

The deformation performance and settlement failure mechanism of geosynthetics-reinforced soil (GRS) walls are the two key points of engineering design under the differential settlement. This paper presents model tests of deformation performance and failure mechanism of the GRS wall with and without lateral restriction under differential settlement conditions. The observation and measurement results, including force and vertical displacement of geosynthetics and lateral deformation of facing panels, indicate good settlement control performance of GRS wall during construction and under differential settlement. Results indicate that the influence of the stress state of facing panels on the settlement control performance of GRS wall cannot be ignored. And the differential settlement failure of GRS wall is likely to occur in the joint of facing panels and geosynthetics. For good illustrations, two analytical approaches about deformation and stress of geosynthetics were proposed based on elastic cable theory, in GRS wall with and without lateral restriction. The expressions exclude the necessity to carry out sophisticated numerical analyses to stress and deformation and may help to develop the design guidelines for such GRS wall. • Deformation and stress distribution are obtained by the mechanical analysis of elastic cable theory. • The critical stress value of geosynthetics is indicative of geosynthetic-reinforced soil wall destroy. • Failure of geosynthetic-reinforced soil wall is mainly caused by "stress concentration-fracture-separation" of geosynthetics. • The maximum stress is concentrated at the joint of facing panels and geosynthetics. [ABSTRACT FROM AUTHOR]

• 3-dimensional elastic beam model for form-finding and analysis of gridshells. • 6DOFs at node for defining axial, bending, and torsional deformation. • Unit normal vector at node for defining deformation of beam connected by hinge. • Energy-based formulation for residual forces for dynamic relaxation and optimization. • Good agreement with the results by finite element method. In this paper, we present a 3-dimensional elastic beam model for the form-finding and analysis of elastic gridshells subjected to bending deformation at the self-equilibrium state. Although the axial, bending, and torsional strains of the beam elements are small, the curved beams connected by hinge joints are subjected to large-deformation. The directions and rotation angles of the unit normal vectors at the nodes of the curved surfaces in addition to the translational displacements are chosen as variables. Based on the 3-dimensional elastic beam model, deformation of an element is derived from only the local geometrical relations between the orientations of elements and the unit normal vectors at nodes without resorting to a large rotation formulation in the 3-dimensional space. Deformation of a gridshell with hinge joints is also modeled using the unit normal vectors of the surface. An energy-based formulation is used for deriving the residual forces at the nodes, and the proposed model is implemented within dynamic relaxation method for form-finding and analysis of gridshells. The accuracy of the proposed method using dynamic relaxation method is confirmed in comparison to the results by finite element analysis. The results are also compared with those by optimization approach for minimizing the total potential energy derived using the proposed formulation. [ABSTRACT FROM AUTHOR]

• The method performs elastic SBFE analyses to determine collapse load of structures. • Quadtree polygon SBFE algorithm models inelastic structures with complex geometry. • The method incorporates the actual nonlinear elastoplastic material properties. • The accuracy of the method is validated through a number of 2D and 3D benchmarks. • Examples address lower-bound limits for sufficiently-fine structural discretization. The paper proposes a novel numerical approach that incorporates the use of a modified elastic compensation method, within a polygon scaled boundary finite element framework, to determine the maximum load capacity of structures at plastic collapse. The distinctive feature of the proposed scheme is its effective computational ability in performing a series of successive elastic analyses by systematically adjusting elastic material properties of structures up to failure. The quadtree structural discretization within a polygon scaled boundary finite element platform enables model construction of sophisticated geometries at modest computing effort and thus the effective analysis of large-scale structures. The approach overcomes the challenges associated with stress singularity and locking phenomena under incompressibility conditions, even in the presence of high-order nonlinear yield loci. The robustness and accuracy of the proposed scheme are validated through a number of benchmarks and available practical engineering applications in 2D and 3D spaces. These illustrate the influences of some key algorithmic parameters, and the satisfaction of a lower-bound limit given by the present analysis method for a sufficiently fine discretization. [ABSTRACT FROM AUTHOR]

Cloud computing, with its various extensions, is a significant IT evolution aiming to provide on-demand IT services with an efficient resource usage, but still ensuring service availability and Quality of Service (QoS). Resource elasticity is an effective feature to deal with such issues; it provides the ability to adjust rapidly the deployed resource capacity according to the time-varying workload in order to meet the intended QoS requirements. However relying only on service provider strategies as horizontal and vertical elasticity, seems insufficient to ensure the QoS requirements, since resource usage patterns in Elastic Cloud Systems (ECS) are inherently non-deterministic. This causes difficulties while selecting the elasticity strategy to be applied with respect to QoS parameters. In this paper, we supply solutions for the challenging task of managing ECSs by quantifying the non-determinism on the basis of QoS parameters. Therefore, we define a formal model for specifying cloud systems structure and its dynamics in terms of quality driven elasticity strategies. Besides, a quantitative analysis is performed to evaluate the effectiveness of the proposed model with regard to QoS parameters. [ABSTRACT FROM AUTHOR]

• Elastic stress and displacement solutions around blunt V-notches were revisited. • Asymptotic solutions taking account of higher order terms were derived. • Coefficients of asymptotic series were calculated using least square method. • Classical singular term solution can be of significant errors even along notch border. This paper presents the in-plane asymptotic displacement and stress fields for blunt V-notched components based on Kolosov–Muskhelishvili's approach. In the first part, the displacement and stress components in the polar coordinate system are determined by choosing appropriate complex potential functions. In order to construct the notch geometry, the Neuber's mapping relation is utilized. Then, the notch boundary conditions are imposed to calculate the free parameters of the stress distribution. Eventually, the stress and displacement components are calculated in the Cartesian and polar coordinates in the forms of series expansion. In the second part, the coefficients of series expansions are computed by using the least square method (LSM). The blunt V-notched Brazilian disk (BV-BD) specimen under mixed mode loading is used as an example to verify the proposed procedure. The stress components in arbitrary distances and directions are determined for different blunt V-notches in order to evaluate the accuracy of the calculated stress series solutions and their associated coefficients. The numerical results indicate that a single-term solution can lead to considerable errors, and to achieve good accuracy in the stress field calculation, one should take account of at least three terms in the stress series solution. [ABSTRACT FROM AUTHOR]

• An energy flow model of two-dimensional panels in supersonic airflow is developed. • Equivalent damping due to supersonic airflow is introduced to derive the energy flow model. • The impedance of the panel in supersonic airflow is derived to calculate the input power. • Supersonic airflow leads to different equivalent damping for elastic waves propagating in different directions. • An energy finite element method for high-frequency analysis of elastic waves with different damping is developed. Many energy flow models have been proposed for high-frequency forced vibration analysis of structures. In this paper, a novel energy flow model is developed to predict the high-frequency vibration response of panels in supersonic airflow and quantify the effects of supersonic airflow on high-frequency forced vibration characteristics. The additional damping due to supersonic airflow is derived from the motion equation of a two-dimensional panel. The relationship between the wavenumber and the group velocity is introduced to describe the energy transmission property considering the effects of supersonic airflow. Then the energy density governing equation (i.e. energy flow model) is established and solved by the energy flow analysis (EFA) and the energy finite element method (EFEM). Finally, comparing the vibration responses obtained by the present energy flow model with the corresponding exact analytical solutions, the developed energy flow model is verified to be effective for high-frequency vibration analysis of panels in supersonic airflow. Furthermore, the numerical simulations indicate that supersonic airflow can affect the equivalent damping of the propagating elastic waves, and thus change the energy density distribution of the panel. [ABSTRACT FROM AUTHOR]

• A novel two-level nesting smoothed meshfree method (NSMM) is proposed. • The NSMM is applied for structural dynamic analysis. • The NSMM is directly extended to solving dynamic fracture problems. • The NSMM is efficient, accurate and stable. This paper presents a novel two-level nesting smoothed meshfree method (NSMM), which significantly improves the computational efficiency of the meshfree Galerkin methods without losing their accuracy, thus facilitates the employment of meshfree methods in applications where background integration cells would be prohibitively expensive. In the NSMM, the system stiffness matrix is calculated using the general smoothing strain technique over the two-level nesting smoothing sub-domains where fewer integration points are used and the costly derivative computation of meshfree shape functions is avoided. The accuracy, efficiency and stability of the present method are assessed by virtue of several numerical examples for problems involving free and forced vibration analysis of the linear elastic continua and dynamic crack response of elastic solid. The results reveal that the NSMM stands out and achieves better performance compared to other existing approaches in the literature. [ABSTRACT FROM AUTHOR]

• Novel wave irregularity mapping algorithm with the weighting (WIM-W). • Low-frequency (40 kHz) ACT-based damage imaging in composite structures. • Comparison of contact (PZT) and non-contact (ACT) elastic wave generation for a narrow band excitation. • Full non-contact wave generation and sensing. • Acousto-optic SLDV-based acoustic wave propagation measurement in the air. In this paper analyses of non-contact elastic wave generation based on an air-coupled transducer (ACT) are presented. Authors compared contact piezoelectric based (PZT) wave generation, with non-contact one using ACT for a narrow frequency band excitation. Elastic wave sensing was based in both cases on a scanning laser Doppler vibrometer. The problem of ACT slope angle for the effectiveness of elastic wave modes generation is analysed. It was shown that for an excitation frequency of 40 kHz it is possible to generate A 0 wave mode both in the case of PZT and ACT. Both methods of wave generation are compared based on an analysis of damage localisation results. For this purpose wave irregularity mapping (WIM) algorithm was utilised together with two attenuation compensation methods (based on energy normalisation and weighting function). Specimens in the form of simple square GFRP panel and bonded GFRP aerospace structure with omega stiffeners were investigated. The authors investigated simulated damage (Teflon inserts) and real delamination. In this research very cheap and popular, low-frequency ACT was utilised giving the possibility of realisation of low-cost excitation method. ACTs connected with a laser vibrometry sensing allows of realisation of full non-contact damage localisation method. Authors presented also non typical but very useful application of SLDV allowing to visualise the effect of acoustic wave generation in the air and determination of the pattern of generated acoustic waves. This was based on the photo-acoustic effect. [ABSTRACT FROM AUTHOR]

During the structure lifetime, the design loads can modify because of a changing in the use destination. In common practice, any architectural change of existing buildings, which modifies the magnitude of loads, requires the evaluation of the load-carrying capacity of structural members. To this aim a nonlinear analysis considering the rotation capacity of critical regions until the failure of the structure can be advantageous compared to a simple elastic analysis. Plastic deformations of ductile elements allow for attaining a more accurate evaluation of the ultimate load, once the strength of brittle mechanisms has been averted. Exploiting the actual rotation capacity of critical regions, where plastic hinges form, this paper presents new analytical closed-form equations to evaluate the ultimate load and the failure mode of an interior span of a multi-span moment resisting frame, as impacted by the strength of beam–column joints and the elastic and post-elastic structural response of adjacent elements. Taking advantage of derived equations, a retrofitting design procedure to identify the proper structural strengthening of critical regions is proposed. The accuracy of the method is checked through a comparison with numerical results. The procedure represents a new useful tool for engineers for the local strengthening of existing reinforced concrete buildings. • The failure load and mechanism of RC multi-span moment-resisting-frames are investigated. • Ductile post-elastic response of members and brittle failure of joints are considered. • Closed-form equations, to evaluate the ultimate load, are proposed. • The approach is validated through comparisons with numerical results (FEM). • To achieve a designed safety target, the proper structural strengthening is identified. [ABSTRACT FROM AUTHOR]

Time-consuming and costly computational analysis expresses the need for new methods for generalizing multiscale analysis of composite materials. Combining neural networks and multiscale modeling is favorable for bypassing expensive lower-scale material modeling, and accelerating coupled multi-scale analyses (FE2). In this work, neural networks are used to replace the time-consuming micromechanical finite element analysis of unidirectional composites, representing the local material properties of yarns in woven fabric composites in a multiscale framework. Leveraging the fast multiscale data generation procedure, we presented a second neural networks model to estimate the elastic engineering coefficients of a particular weave architecture based on a broad range of dry resin and fiber properties and yarn fiber volume fraction. As an outcome, this paper provides the user with a generalized, neural network-based approach to tackle the balance of computational efficiency and accuracy in the multiscale analysis of elastic woven composites. • A multiscale ANN model is proposed for elastic behavior of woven composites. • Two different length scales are considered in the model. • The proposed model is accurate and computationally efficient. • A wide range of microstructural parameters is accommodated by the model. [ABSTRACT FROM AUTHOR]

• The rideability of mechanical elastic wheel is analyzed at first time. • Mechanical elastic wheel can be used in damaged conditions. • The rideability can be analyzed by the rigid-flexible coupling ring model with travelling mode superposition method. • The axisymmetric damage of the wheel is better than neighboring chain damage. • The simulation time cost of ring model is less than that of finite element model. In this paper, it is first time to study rideability of mechanical elastic wheel (MEW) in damaged conditions and discuss whether the wheel with local damage conditions will be failure during running. This paper is first time to propose a rideability evaluation method of damaged MEW. For getting the parameters about displacement acceleration of rings and tensile force of chains required from the evaluation method, a rigid-flexible coupling model 'ring model' of running MEW was established, the solution method of the model was also given by travelling mode superposition method. The ring model was compared with the experiment and finite element method to verify its accuracy. With using the verified ring model, the rideability simulation was analyzed under eight kinds of speeds and six kinds of damaged working conditions. The results show that: MEW with one or two damaged chains still has the receptible rideability and is not failure, and it provides security for the safe driving of vehicles in emergency situations; when damaging three chains, the wheel can be used to run at low speeds, the rideability of wheel at high speeds will deteriorate and the wheel will be failure; the rideability of MEW with axisymmetric chain damage is better than that with neighboring chain damage; it also finds that the simulation calculation time of ring model is much lower than that of finite element method, the time cost will be saved. [ABSTRACT FROM AUTHOR]

Abstract: This paper revisits the problem of excavation of a circular lined tunnel in an infinite elastic medium under plane strain conditions, subjected to non-uniform stresses, solved by Einstein and Schwartz in their article ‘Simplified Analysis for Tunnel Supports’ published in 1979 (ASCE J Geotech Eng Div, 106–7), and in related publications by Schwartz and Einstein. In contrast with the solution by Einstein and Schwartz from 1979 which considers that the support is installed at the very same time the tunnel is excavated, and also in contrast with related publications by Schwartz and Einstein which account for the delayed effect of support installation by multiplying the values of loads and displacements on the support by a reduction factor (in the same expressions from their 1979 article), this paper formulates the problem as two separate problems to account for the two-stage excavation process. In a first stage, the initial tractions on the periphery of the tunnel to be excavated are decreased (or ‘relaxed’) by a factor , to account for the presence of the tunnel front, as normally done in analysis of two dimensional sections of lined tunnels using commercial finite element software. For this first stage, the solution of the field quantities (stresses and displacements) in the ground are provided. In a second stage the support is installed, and the previously imposed tractions on the boundary of tunnel and support are removed, resulting in loading and deformation of the support as it interacts with the ground. For this second stage, the field quantities in the ground and the resulting values of load and displacements on the support are also provided. This paper shows that by decreasing the tractions on the tunnel periphery in a ratio of the initial ground stresses before the installation of the support (i.e., with ), the resulting final loads and displacements on the support are reduced in the same ratio , with respect to the corresponding loads and displacements computed by Einstein and Schwartz's solution (i.e., when considering the case ). This observation confirms the agreement of the two-stage procedure followed in this study and the procedure followed in publications by Schwartz and Einstein of multiplying the values of load and displacements on the support (for the case ) by a correction factor to account for the delayed installation of the support. The paper also shows that when the stresses and displacements in the ground for the first stage are subtracted from the corresponding ground stresses and displacements for the second stage (after the support is installed), the resulting values of stresses and displacements are reduced in exactly the same ratio . All governing equations, boundary conditions and steps needed to arrive to a dimensionless form of the two-stage analytical solution of Einstein and Schwartz problem are presented, including the solutions for stresses and displacements in the ground which were not included in publications by Einstein and Schwartz. Also, particular forms of the two-stage solution are presented, including cases of an infinitely soft support, an infinitely rigid support, and uniform initial far-field stresses, which are shown to be equivalent to the classical expressions known as Kirsch and Lamé solutions, respectively. Although the outstanding solution by Einstein and Schwartz published in 1979 is basically correct, Einstein and Schwartz dropped a term in the solution for bending moment because its effect is small in most of the situations (particularly when the thickness of the support is small compared with the radius of the tunnel). Since the two-stage solution for bending moment presented in this paper is equivalent to the Einstein and Schwartz's solution only when the missing term in their solution is included, this paper presents a revised form of the expressions by Einstein and Schwartz published in 1979 which include the missing term, and it examines what the effect of retaining or dropping the term is. Finally a comparison of results obtained with the two-stage analytical solution and the finite difference code FLAC3D is presented, together with the outline of a computer spreadsheet that implements the two-stage analytical solution of this fundamental problem of tunnel ground–support interaction analysis. [Copyright &y& Elsevier]