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Abstract: This paper presents a method to predict the through-thickness moisture content distribution and associated induced deformations of paper and cardboard sheets as they are subjected to relative humidity changes. The transient moisture diffusion problem is solved using a “natural” analytic approach that has previously been applied for solving transient heat conduction in multi-layer solids. The deformation behaviour of the sheet during the moisture diffusion process is predicted using a semi-analytical approach based on a Rayleigh–Ritz minimization of the total potential energy. Geometrically nonlinear effects are taken into account. Curvatures of the originally flat sheet are predicted as a function of time, as are the shapes of the sheet for steady-state condition. As multiple solutions exist, stability is studied. The developed model was used to study the deformation behaviour of one paper and two cardboard sheets. Comparisons with finite-element results demonstrate that the developed model provides accurate results. The displacements obtained for steady-state conditions are within +6%. Comparisons with previous steady-state analyses reveal important differences in the shape of one cardboard sheet. This suggests that the moisture diffusion process may influence the configuration assumed by the sheet at steady-state equilibrium. Hence, it may be necessary to take the moisture diffusion into account in the analysis to accurately predict the hygro-mechanical behaviour of paper or cardboard sheets. [Copyright &y& Elsevier]

This paper presents an efficient parallel computing strategy to solve large-scale structural vibration problems. The proposed approach utilises a novel direct method that operates using simplex-shaped space-time finite elements and allows for the direct decoupling of variables during the assembly of global matrices. The method uses consistent stiffness, inertia and damping matrices and deals with non-symmetric matrices. One significant advantage of this approach is that the computational cost remains unaffected by the bandwidth of the matrix in the traditional sense because only non-zero coefficients are retained. The speed of computations demonstrates a noticeable increase as the number of nodes and the problem's dimensionality grow. To demonstrate the effectiveness of the parallel space-time approach, a comparison with a sequentially executed code was conducted. The results indicate that the proposed method enables calculations at least 20 times faster than those achieved using the classical finite element method. Furthermore, the parallelisation algorithm was successfully implemented to solve a dynamics problem involving a large-scale, three-dimensional railway structure subjected to a moving load. Remarkably, the problem was solved in a reasonable amount of time using a relatively low-cost personal computer. • Strategy allows efficient parallel computing for large scale structural problems. • Direct method uses simplex-shaped space-time finite elements. • Variables are decoupled while assembling global matrices. • Computational cost is independent of the bandwidth. • Simulations of travelling load problems exhibit twenty times faster computations. [ABSTRACT FROM AUTHOR]

This paper proposes a robust finite element Kalman filter for the state estimation of flexible space tether systems, which are critical for space exploration and satellite missions. Due to the limited access to placing sensors along the flexible tether to measure them directly, the measurement of the state of these systems is challenging. To address this, a fully expandable, scalable, and robust approach is developed that fuses position/velocity sensors at tether ends, distributed fiber optic strain measurement along the tether, and a position/velocity estimation by a finite element-based Kalman filter to estimate the state of the tether system. The proposed estimator is mathematically proven to be observable, stable, and robust. The effectiveness of the estimator is demonstrated through numerical simulations of a space tether system in orbit, and the method can be extended to any flexible body system. The results of the simulations show that the proposed approach can accurately estimate the state of the tether system, even in the presence of disturbances and noise. • Expandable, scalable FE-Kalman state estimator for flexible space tether systems. • Data fusion with tether end position/velocity, distributed fiber optic strain measure, and estimated internal position/velocity. • Mathematically proven observability, stability, and robustness to noise of the estimator. [ABSTRACT FROM AUTHOR]

Linear transverse flux permanent magnet machines (LTFPMs) are categorized as high force density topologies, which are suitable candidates for direct drive and low-speed applications. This paper introduces a novel LTFPM topology, which also proposes advantages of the flux-switching machines. This proposed linear transverse flux switching PM machine (LTFSPM) has two long passive translators located at the armature's top and bottom sides. The topology offers a high value of force density, and also, it is a cost-effective topology due to its double-sided passive translator. Furthermore, the PMs are fully utilized in the magnetic circuit, the end winding length is negligible, and the iron cores can be laminated easily. In this paper, the operation principle of the topology is explained and its magnetic circuit is discussed. To reduce the computational time of optimization procedure, a double-layer method is adopted, which provides high robustness, low computational time, and high precision. Results of the finite element method indicate that the proposed machine can be considered a potential candidate for linear motion applications especially direct drive wave energy conversion systems, which require high force density values. [ABSTRACT FROM AUTHOR]

• The ASABH is proposed to attenuate AE reflection waves at the boundary. • The influence of geometric parameters of the ASABH have been revealed. • Compared to ABH, the ASABH has higher security and better adaptability. • The ASABH has a good effect on reducing the AE boundary reflection. Acoustic emission (AE) technology plays a crucial role in dynamic nondestructive testing. To investigate material properties, friction characteristics, damage features, and acoustic source localization, AE tests are commonly conducted on metal or composite plates. However, the reflection of AE waves at the boundary often generates strong interference, significantly impacting AE test results. In response to this challenge, this paper introduces an innovative solution: an additional Spiral Acoustic Black Hole (ASABH) affixed to the test plate's boundary. The ASABH is designed to mitigate the reflection of AE signals, enhancing the signal-to-noise ratio collected by the sensor. The study begins by establishing a finite element model of the ASABH to validate its efficacy in reducing boundary reflection waves. Subsequently, the paper explores the impact of structural geometric parameters—such as length, residual thickness, power exponent, pitch, and extended length—on the reduction effect. The investigation also delves into the variation of attenuation degree when connecting the ASABH to plates with different relative thickness, relative widths, and materials. Finally, the effectiveness of the ASABH in attenuating structural boundary reflection waves is verified through pencil-lead breaking tests conducted on both metal and composite plates. Results indicate that the proposed ASABH effectively mitigates the reflection of AE waves at the structural boundary, demonstrating adaptability and providing valuable insights for ASABH design. [ABSTRACT FROM AUTHOR]

This paper is devoted to the numerical analysis of a control constrained distributed optimal control problem subject to a time fractional diffusion equation with non-smooth initial data. The solutions of state and co-state are decomposed into singular and regular parts, and some growth estimates are obtained for the singular parts. By following the variational discretization concept, a full discretization is applied to the corresponding state and co-state equations by using linear conforming finite element method in space and piecewise constant discontinuous Galerkin method in time. Error estimates are derived by employing the growth estimates. In particular, graded temporal grids are adopted to obtain the first-order temporal accuracy. Finally, numerical experiments are performed to verify the theoretical results. [ABSTRACT FROM AUTHOR]

In order to understand the mechanism of lining failure caused by creep, it is significant to evaluate the three creep stages of lining materials. In this paper, the three stages creep curves of 3 MPa, 3.25 MPa and 3.5 MPa for high alumina bricks at 1350 °C were obtained by high temperature creep testing equipment. Then the K-R model, the Sinh model and the Liu-Murakami model combined with the Garofalo formula are used to fit the measured creep curves. The results show that all the three models are suitable for the description of the creep behavior and the creep life prediction of high alumina bricks, and the Sinh-Garofalo model has the best fitting effect. Therefore, the Sinh-Garofalo model is selected for finite element modeling. The reliability of the model is verified by comparing the simulated and analytical values. Finally, by comparing the model with/without considering the creep damage, it is found that the creep damage model can be used to characterize the creep damage evolution process and predict the life of structures, which can be further used in the failure study of furnace lining. [ABSTRACT FROM AUTHOR]

Twisted steel bars are often used to strengthen masonry buildings and, in particular, to improve the transverse connection between different structural elements. The performance of the retrofitted structure depends on several parameters such as the mechanical properties of the base material (masonry), the bar diameter, the pre-drilled hole diameter. The paper presents the numerical assessment of the tensile behavior of twisted stainless-steel bars installed in brickwork masonry. Nonlinear numerical models in Abaqus software were developed and validated on the basis of experimental results, considering different bar diameters (8, 10, 12 mm). A parametric study was conducted to examine the factors that could influence the performance, namely the embedment depth, the pre-hole diameter, and the mechanical properties of the base material. The outcomes reveal the sensitivity of the twisted bars to the aforementioned parameters. In particular, the twisted bars exhibited a higher capacity in stiffer base materials, with longer embedment and smaller pre-drilled hole. However, none of the above parameters proportionally affect the ultimate strength, but lead to a limited improvement in the ultimate capacity (up to 40% in the considered range). • A finite element model is developed to study the pull-out behavior of twisted bar. • Experimental results are used to validate the numerical model. • The influence of several design parameters is numerically investigated. • The most influent parameters are the base material properties and the hole diameter. [ABSTRACT FROM AUTHOR]

The main purpose of the present paper is to investigate the failure pressure and the remaining life of the corroded offshore pipelines utilizing code-based methods such as ASME B31G, modified ASME B31G, DNV RP-F101 and FFS Level-1. Besides, the results of these approaches are compared with the responses of Finite Element Method (FEM) using Artificial Neural Network (ANN) model. To this purpose, the probability distribution of the corrosion defect length and depth as well as the corrosion rate values are obtained from an In-Line Inspection (ILI) survey of an offshore pipeline project in the Persian Gulf. In addition, a 3D verified numerical model of a corroded pipeline is constructed to conduct the numerical analyses. Using the numerical analysis data, a Multi-Layer Perceptron (MLP) model is created to estimate the failure pressure of the pipeline with arbitrary defect dimensions. Moreover, the remaining life of the corroded pipeline is quantified in order to prevent the catastrophic consequences of the pipeline failure. The results show that the MLP model is capable of estimating the failure pressure of the corroded offshore pipeline with quite acceptable accuracy compared with the mentioned code-based methods. Furthermore, the calculated failure pressure of the corroded pipeline can be sorted in ascending order as: (1) FFS-Level 1 (2) ASME modified B31G (3 & 4) ASME B31G & DNV RP-F101 (5) FEM + MLP. In fact, the failure pressure and the remaining life calculated by DNV RP-F101 are closer to the FEM + MLP results for the defects with small and medium dimensions. Diversely, the DNV RP-F101 method underestimates the failure pressure of the corroded pipeline when the defect dimensions become larger. • The failure pressure of corroded offshore pipelines is investigated by different code-based methods such as ASME B31G and DNV RP-F101. • A combination of FEM along with ANN model is utilized. • The remaining life of corroded offshore pipelines is estimated. • The results of DNV RP-F101 are closer to the FEM and ANN for the defects with small and medium dimensions. • The results of ASME B31G are more exact for relatively large sized corrosion defects. [ABSTRACT FROM AUTHOR]

In this paper, the finite element method is utilized to evaluate the behavior of the armchair phosphorene nanotubes under the compressive loading. The energy equations of the molecular and structural mechanics are used to obtain the elemental properties. The critical compressive forces of various armchair phosphorene nanotubes are computed with clamped-clamped and clamped-free boundary conditions. Results show that the stability of armchair phosphorene nanotubes increases with increasing nanotube aspect ratio, particularly under clamped-clamped boundary conditions. Finally, the buckling mode shapes of armchair phosphorene nanotubes under different boundary conditions are compared. Our work offers valuable insights into how these nanotubes respond to mechanical stress, helps determine elemental properties, and investigates the effects of nanotube geometry and different boundary conditions on their stability. This knowledge has broad applications in fields like nanotechnology, materials science, and nanomechanics, advancing the understanding of nanoscale materials and their potential for various practical uses. The finite element method is utilized to evaluate the behavior of the armchair phosphorene nanotubes under the compressive loading. [Display omitted] • FE method is utilized to evaluate the behavior of the armchair PNTs under the compressive loading. • The elemental properties are obtained by the energy equations of the molecular and structural mechanics. • The buckling forces of the armchair PNTs with different radii and lengths are computed. • The stability of armchair PNTs increases by increasing the nanotube aspect ratio. • The clamped-clamped nanotubes are more stable than clamped-free ones. [ABSTRACT FROM AUTHOR]

In this paper, we propose a finite element method for solving viscoelastic hyperbolic integrodifferential equations with L 1 kernel, involving a nonlocal and nonlinear damped coefficient. Firstly, we discuss and deduce that the L 1 kernel is of positive type in two cases. Subsequently, based on the continuous Galerkin technique and the energy argument, we prove the global existence and uniqueness of the discrete solution. Finally, using the basic properties of the positive-type kernel, we derive the error estimates of the finite element solutions. [ABSTRACT FROM AUTHOR]

This paper presents the application of a thick-shell nonlinear finite element analysis procedure to estimate the punching shear resisting performance of reinforced concrete slab-column connections under variable connection shear stress conditions. In the analyses performed, varied connection shear stress conditions stem from slabs being supported by columns with different cross-section aspect ratios, being subjected to different distributions of gravity loading, being constructed with different planar reinforcement ratios in orthogonal directions, as well as the application of unbalanced bending moments. Forty-eight isolated slab-column connection specimens presented in the literature were modelled and analyzed using a thick-shell finite analysis procedure. All numerical results were developed using a predefined set of material models and analysis parameters, a consistent meshing procedure, and are shown to provide meaningful agreement with experimental data without the need for case-specific model calibration or the adoption of specialised failure criteria. The results show that thick-shell modelling methods can be suitable for estimating the punching shear response of slabs subjected to non-uniform shear stress development in connection regions, and can provide similar levels of precision to that obtained for the analysis of idealised slab-column connections typically used for design procedure and model development. • Low-cost shell FEA for punching shear assessment of reinforced concrete flat plates. • Analysis of 45 non-idealised connection specimens representative of real-world construction. • Good agreement between FEA simulations and reported results without model calibration. • Result accuracy comparable to that obtained for more typical idealised connection specimens. [ABSTRACT FROM AUTHOR]

• Design and validation of a sealing and closing system for a Sample Return mission. • Testing in relevant environment of a space mechanism for sample return missions. • Development of a scalable closing mechanism able to release a high pushing force. The present paper addresses the development of a closing and sealing system for a container which shall safely bring 100 g of regolith from the surface of Phobos, one of the moons of Mars. Based on a set of requirements defined by the ESA (European Space Agency), a design of the closing and sealing system was made and FEA (Finite Element Analysis) was employed to validate the design. The closing and sealing mechanism along with the Vault (container to be sealed) proved the capability to overcome the Robotic Arm misalignments, to ensure the Vault closing and to maintain the leak tightness (maximum admissible leak rate of 10−4 mbar*l/s Helium) during the trip back to Earth. All these features were validated following an extensive test campaign implying mechanical loads, shocks, thermal vacuum cycling, dust contamination, impact tests and several functional verifications. The mechanism demonstrated the targeted maturity level (TRL 5) and it can be further developed in order to be qualified for a specific mission/application. [ABSTRACT FROM AUTHOR]

Shear truss steel panels are the main constituents in the construction of modular steel Bailey bridges. Buckling characteristics, and ultimate capacity of the panels are the main design parameters to be rationally predicted. The present paper presents full-scale tests on two types of typical shear panels. In addition, two distinctive three-dimensional finite element models were developed to analyze the response of the tested shear panels using beam-column elements and shell elements, which represent the simplified macro and micro modeling techniques, respectively. Both the eigenvalues (buckling) analysis and the nonlinear response analysis were conducted to predict both the buckling characteristic, and ultimate capacities, respectively. Correlation between predicted buckling loads from different modeling techniques revealed that to introduce an adjustment length factor K in the AASHTO-LRFD standards to accommodate rational end conditions and lengths of the compression members. Furthermore, the study revealed that the conservative prediction of buckling load stemmed from the method employed to calculate the buckling length, which leads to a conservative estimate of the compressive strength. • Experimental and analytical investigation for shear panels of Bailey bridges. • Buckling analysis of the shear panels using beam-column element and shell elements FE modeling. • Evaluation of the effective length used in AASHTOO code provision according to the experimental and the numerical results. • Introducing correction factors for the buckling effective length. • Validating the response and load-carrying capacity of the shear panels using 3D FE modeling. [ABSTRACT FROM AUTHOR]

Applications of concrete-filled square (or circular) stainless-steel tubes keep increasing in cold-region coastal engineering structures. However, their behaviours under low-temperature bending have not been fully investigated, which brings obstacles to their engineering applications. To address this issue, this paper investigated flexural behaviours of concrete-filled square/circular stainless-steel tubular beams (CFSSSTBs/CFCSSTBs) at low temperatures through eight four-point bending tests. The main studied parameters were low temperatures (20∼−60 ℃) and cross-section type (circular or square shape). Test results showed that both CFSSSTBs and CFCSSTBs exhibited flexural failure and exhibited excellent ductility under low-temperature bending benefiting from the excellent ductility of stainless steel; bending resistances of CFSSSTBs and CFCSSTBs were improved by 5% and 22%, respectively. This study also developed finite element models (FEMs) for simulations on flexural behaviours of CFSSSTBs/CFCSSTBs at low temperatures. The FEMs considered both low-temperature material and geometric nonlinearities. Validations against eight tests proved the capacities of FEM simulations on low-temperature flexural behaviours of CFSSSTBs/CFCSSTBs. Finally, the code equations in Eurocode 4 and AISC 360 were used to predict the stiffness and ultimate bending resistances of CFSSSTBs/CFCSSTBs. Validations showed that the code equations underestimated the bending resistances of CFSSSTBs/CFCSSTBs. This study provided fundamental information on the flexural bending mechanism of CFSSSTBs/CFCSSTBs) at low temperatures. • Low-temperature flexural behaviors of concrete-filled stainless-steel tubular beams (CFSSTBs) are reported. • Low temperatures improve stiffness and bending resistances of CFSSTBs. • Bending resistances of circular CFSSTBs are more improved than square ones as T decreases. • Code equations conservatively predict low-temperature bending resistances of CFSSTBs. [ABSTRACT FROM AUTHOR]

Seismic fragility assessments that predicts the exceedance probabilities of predefined limit states of a structure subjected to earthquakes are widely used to reduce economic losses and casualties. This paper presents a probabilistic assessment of slopes based on the permanent displacements calculated from a suite of two-dimensional (2D) nonlinear dynamic analyses. The slopes are categorized into four groups based on static factor of safety (FS static). The centrifuge test measurements of a slope composed of granular soil are utilized to validate the 2D finite element numerical model. The Newmark displacements are calculated by integrating the stresses imposed on the sliding surface. The sliding surface is determined from the maximum accumulated strain contours, thereby accounting for the slope and input motion characteristics. The Newmark displacement is correlated with various earthquake intensity measures (IMs). The optimal IMs are selected based on the goodness of fit, efficiency, practicality, and proficiency. The fragility curves are developed using selected optimal IMs for three sliding displacement-based damage levels, which are minor, moderate, and severe. The results show that FS static , which contains information on both the slope geometry and the shear strength of soil, is an effective parameter to estimate the Newmark displacement. In addition, a suite of seismic fragility surfaces are developed using dual IMs. • We develop fragility curves and surfaces for probabilistic estimate of seismic slope performance. • We use the outputs from 2D nonlinear dynamic analyses to determine Newmark displacement (NM). • NM is developed from integration of stress across intensity and slope dependent sliding surface. • NM is highly dependent on the static factor of safety of slopes. • We recommend four intensity measures based on evaluation of 20 parameters. [ABSTRACT FROM AUTHOR]

An innovative cold-formed steel center-sheathed shear walls (CFSCSSWs) was proposed in this paper to improve the horizontal load-carrying capacity of conventional cold-formed steel walls. However, the fire behavior of this wall configuration was particularly worthy of attention because it was designed to be used in multi-story buildings, and there is still a lack of in-depth exploration of the fire performance and high-temperature horizontal load-bearing capacity of CFSCSSWs under combined loads. In this study, a compression test was first carried out to obtain the vertical load-carrying capacity of a full-scale CFSCSSW, followed by a fire test on a similar CFSCSSW subjected to combined vertical and horizontal loads to investigate the fire behavior of walls. Then, a finite element model was established and validated by test results to investigate the influence of various critical factors, including vertical and horizontal load ratios, height-width ratio, and sheathing thickness, on the fire behavior of the CFSCSSW. The results showed that the vertical load ratio presented a larger influence on the fire behavior of CFSCSSWs compared to the horizontal load ratio. The increasing aspect ratio can slightly improve the fire resistance of the wall under the same load ratio. The wall with a 0.8 mm thick sheathing exhibits better fire behavior under the same load ratio. A high-temperature horizontal load-carrying capacity calculation method for CFSCSSWs was proposed, and its good accuracy was found. • Load capacity of cold-formed steel center-sheathed shear wall was investigated experimentally and numerically. • Parametric analysis was conducted to investigate the influence of key parameters on the fire behavior of the wall. • A method for predicting high-temperature horizontal load capacity of the wall was proposed. [ABSTRACT FROM AUTHOR]

In this paper we present an investigation of the impact of cold-formed steel channel section columns when subjected to an axial impact by a rigid impactor. The work involves both the numerical simulations and experimental tests. The former was done by using nonlinear finite element analysis method and the latter was done by using drop hammer tests. In the present finite element analysis, material nonlinearity, strain rate effect, initial geometric imperfection, and interactions between the impactor and column are considered. It is shown that the impact deformation of the channel-section column under the axial impact of rigid impactor can be characterized initially by its axially compressive deformation, followed by the localized bending deformation in the region where the geometric imperfection is large. The validation of the numerical results using the drop hammer test results demonstrates the appropriateness of the numerical model developed in the paper. • It presents original experimental data of axial impact tests of CFS channel section columns. • FE analysis is provided to simulate axial impact tests of CFS channel section columns under different impact velocities. • Initial geometric imperfection of CFS columns and uses strain rate-dependent elstoplastic stress-strain equation. • The results show that impact velocity significantly affects the final residual deformation of columns. [ABSTRACT FROM AUTHOR]

This paper presents a detailed treatment of the formulation for buckling and free vibration analysis of Bi-Directional Functionally Graded (BDFG) Thin-Walled non-prismatic beams of generic open/closed cross section. The theory developed is limited to small strains, moderate deflections and small rotations. It is based on the assumption that the shear strain on the mid-surface contour of the cross section of the member is neglected. Using the membrane theory of shells rigorous expressions for strains are obtained by which the effect of nonlinear tapering is considered. The material properties are assumed to be graded both in the longitudinal and depth-wise directions of the plate segment of the thin-walled beams. The governing equations are developed defining the displacements with reference to any arbitrary point (say geometric centre) and get away with the usual shear centre and centroid. For computer solutions for classical buckling and vibration analyses, the Finite Element Method is used. Simpson's rule of numerical integration is adopted for the computation of axial, coupled and bending rigidities as well as inertial properties of the plate segment and the Gaussian Quadrature of numerical integration is used for the computation of flexural stiffness, geometric stiffness and mass matrices of an element over the length of the beam. Critical buckling loads and the natural frequencies and their corresponding buckled and mode shapes for various examples are obtained by solving as an eigen-value problem and compared with the published results in the companion paper. • Using Membrane theory of shells, rigorous expressions for strains have been developed. • The governing equations for BDFG thin-walled beams are arrived at defining displacements with respect to any arbitrary point. • Different material and geometric variations are considered in this paper. • Property constants are determined using Simpson's rule and elements of Stiffness, Mass matrix using Gaussian quadrature. • Static, Stability and Free vibration of BDFG tapered beam of generic open/closed sections can be investigated. [ABSTRACT FROM AUTHOR]

This paper studied the axial compression behavior of the steel tube reinforced concrete (STRC) column, which consisted of inner CFST and outer RC components. Ten specimens, including seven STRC columns, two RC columns, and one CFST column were tested. The test parameters included the CFST area ratio (inner CFST to the whole section), longitudinal rebar ratio and stirrup space. The test results showed that the compressive behavior of STRC column with a CFST area ratio of 0.04 was close to that of the RC column, and the compressive behavior of the STRC column with a CFST area ratio of 0.13 was between that of the RC column and CFST column. The finite element (FE) models were developed and verified by test results to investigate the effects of longitudinal rebar ratio and stirrup space on the axial compression behavior of STRC column with various CFST area ratios. The load distribution between inner CFST and outer RC components was analyzed. The FE results showed that the effects of the longitudinal rebar ratio on the ultimate load of STRC column were related to the CFST area ratio. The accuracy and applicability of the five methods suggested by codes for predicting the ultimate load of STRC column were discussed based on the test and FE results. • The compression test of steel tube reinforced concrete (STRC) column with low CFST area ratio was firstly carried out. • The influences of both CFST area ratio and longitudinal rebar ratio on ultimate strength of STRC column were discussed. • The refined finite element model of STRC column for parameter analysis is established. • The five methods of codes for ultimate strength of STRC column was calculated and discussed. [ABSTRACT FROM AUTHOR]

Metamaterial structures that exhibit negative stiffness (MSNS) behavior have shown the potential to be used as energy dissipation systems in different applications. Negative stiffness honeycomb structures consist of multiple pre-buckled beams that snapping through from one pre-buckled mode to another buckled mode, when subjected to transverse loads, displaying negative stiffness, and dissipating a significant portion of the input energy. This paper presents finite element models (FEMs) developed to investigate the performance of negative stiffness pre-buckled beams and honeycombs. The FEMs were validated using experimental results of single pre-buckled beams and honeycomb structures. The experimental testing of the pre-buckled beams was presented in the current study while the results of the honeycomb were available in the literature. The FEMs have the ability to capture the transition of the elements from one mode of buckling to another mode as well as the force thresholds, energy dissipation values, and residual displacements. The FEMs were extended to investigate the effect of different parameters such as boundary condition, apex height-to-beam thickness ratio, and constraining the second mode of buckling on the behavior of negative stiffness honeycombs. • Metamaterial structures that exhibit negative stiffness (MSNS) have potential for use in energy dissipation systems. • Finite element models (FEMs) are presented to study the performance of MSNS beams and honeycombs. • FEMs are validated using experimental results from single pre-buckled beams and honeycomb structures. • FEMs can accurately predict transitions between different modes of buckling, force thresholds, and energy dissipation. [ABSTRACT FROM AUTHOR]

[Display omitted] This paper is devoted to the investigation of the density sorting of grains using water jigging. Experiments achieved in a laboratory scale water jig for two initial binary bed configurations are studied and compared to numerical results. The vertical composition of the deposit is estimated after different number of water pulses to represent the sorting evolution in time. Simulations are based on a multiscale model in which the fluid is solved at a larger scale than the grain diameter using the finite element method, while the grains are considered as rigid bodies and solved using the nonsmooth contact dynamics. Key parameters are numerically varied and observed to determine the sensitivity of the process. • Collective phenomena increase sorting rate in binary mixtures. • Density difference between the materials influences the sorting rate. • Water jigging depends on the friction between densest grains and walls. • Numerically unresolved fluid slip drives the sorting dynamics. [ABSTRACT FROM AUTHOR]

Highlights • Beam finite element with eccentric, variable neutral axis. • Non-linear materials and material softening considered. • Computationally efficient finite element formulation. • Case studies considering large deflections and material nonlinearity considered. • Applicable to composite beams, bridge decks and other similar structures. Abstract This paper presents a beam finite element and analysis methodology for structures with neutral axes (NA) that are eccentric to the positions about which they are modelled, and that change position during the process of an analysis. This NA shift occurs due to non-linear material behaviour (softening, cracking, etc.). The proposed formulation is based upon a modified corotational approach. It has been developed specifically for structures subjected to severe fires, although it is also applicable to the non-linear analysis of structures such as wind towers and bridge decks where the position of the neutral axis in a beam section changes due to material nonlinearity. The analysis formulation results in lower computational effort relative to contemporary analysis methods employing shell or volume elements, while providing comparable results. Four case studies that include material nonlinearity, large deflections and geometric nonlinearity are included to validate the proposed formulation, and results are compared to shell element models analysed using Abaqus. The contributions of this paper are: (a) the application of standard Euler beam theory in a novel manner to allow for adjusted position of neutral axes in beams, (b) the presentation of simple case studies that can be used for validating finite element methods, but which incorporate material, geometric and cross-sectional non-linearity, and (c) illustrating the influence of cross-sectional discontinuity and how it may influence results when using beam elements. [ABSTRACT FROM AUTHOR]

Abstract Increasing awareness of environmental concerns is leading a drive towards more sustainable structural materials for the built environment. Natural fibres such as flax and jute have increasingly been considered for fibre-resin composites, with a major motivation for their implementation being their notable sustainability attributes. This paper is part of an ongoing effort by the author to demonstrate the structural properties of primary structural elements and members fabricated from natural fibre composites of flax and jute. Previously the structural properties of flat plates, plain channel sections and channel sections with complex stiffeners were investigated under pure compression. This paper presents investigations of channel sections with complex stiffeners under pure bending. A series of sixteen channels with varying geometries, complex stiffener arrangements and composite thicknesses were tested in pure flexure. Material tests indicated that the mean tensile elastic stiffness and strength values were 6386 MPa and 55.1 MPa for flax, and 6941 MPa and 62.1 MPa for jute. The experimental results indicated that flexural failure of the channel sections was governed by tensile fracturing. The ultimate moment capacities varied from 1.043 to 1.501 kNm for four-layered composites, and 2.184 to 2.511 kNm for six-layered composites. The analytical models predicted the experimental ultimate moment capacities well, with a mean and coefficient of variation of the test to predicted ratio of 0.97 and 0.06, respectively. Finite element models used progressive damage analysis via stress-based damage initiation models and damage evolution laws, to replicate the tension fracture failure mode of the channels. The numerical models predicted the experimental ultimate moment capacities well, with a mean and coefficient of variation of the test to predicted ratio of 0.99 and 0.06, respectively. [ABSTRACT FROM AUTHOR]

Abstract This paper presents in a unified and comparative manner, the formulation of two triangular plate bending composite elements, i.e. DKMT and MITC3 which are published in 1993 and 2004. Both elements have 3 nodes and 5 dof per node (three displacements and two rotations), taking into account transverse shear effects. There are valid for thin to thick composite plates, and give good results in classical benchmark and patch tests. The numerical results using DKMT element show the optimal and uniform convergence for thin and thick plates with an advantage for DKMT compare to MITC3 due to semi quadratic interpolation for the rotation variables The present paper contains new convergence analysis based on the s -norm tests for sandwich plates considering uniform and distorted meshes, and for symmetric and non symmetric composite plates with 3 and 9 layers. As the novelty and main contribution of this article, we propose the shear projection method in the element formulations to show the asymptotic equivalence of DKMT and the MITC3 for thick to thin composite plates. [ABSTRACT FROM AUTHOR]

Abstract A common form of coastal protection in New South Wales, Australia, is the rubble mound breakwater. This consists of quarried rock or unreinforced concrete armour units. However, increased impact forces on these structures due to greater storm surge levels that are predicted by global warming models, suggest that they will require strengthening. Traditionally steel bar reinforcement is used to strengthen concrete; however, as steel is particularly susceptible to corrosion in aggressive coastal environments, it is not a robust solution. This paper reports on the potential of using macro-synthetic fibre reinforcement in reinforcing of breakwater armour units, in lieu of traditional steel reinforcing bars. To this end, a programme to ascertain the tensile capacity of 0.6 percent and 1.0 percent by volume of concrete reinforced with macro-synthetic fibres was implemented. The behaviour of this synthetic fibre reinforced concrete in Dolos type breakwater armour units was then examined using the finite element analysis software ATENA. The results of the numerical analysis indicate that the addition of synthetic fibres at these volume percentages into concrete armour units improves the post peak response under impact loading by a factor of two to three, compared with unreinforced units. Furthermore, the addition of fibres significantly reduced the maximum crack width for the same number of impact loadings and allows the units to withstand larger crack widths before failure. Highlights • This paper assesses the effectiveness of Dolosse concrete armour units reinforced with 0.6 percent and 1.0 percent of macro-synthetic fibres. • An experimental programme was developed to investigate the post crack capacity of the synthetic FRC. • The experimental results were used to simulate the properties of synthetic FRC in Dolosse breakwater armour units. • The addition of fibres significantly improves the breakwater armour unit's capacity to withstand higher and more numerous impact loads. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for explicit modeling of the time-dependent behavior or creep of structural steel in the Abaqus finite element (FE) models under transient temperature conditions representative of building fires. In this methodology, available creep models based on conventional creep tests under constant or steady-state temperature conditions were used to predict the time-dependent or creep behavior of steel under variable or transient-state temperature conditions. Specifically, user-defined CREEP subroutines were created in Abaqus to define time-dependent or viscoplastic deformation of structural steel under changing temperatures. To demonstrate the robustness of the proposed methodology, the time-dependent behavior of structural steel at elevated temperatures was modeled under three distinct conditions. These were: steady-state temperature conditions, stepwise steady-state temperature conditions, and transient-state temperature conditions. This paper further presents and discusses the application of the methodology in studying the creep behavior of a shear tab connection assembly under the transient temperature conditions of a fire. Through this application, the importance of explicit consideration of creep in predicting the response of connection assemblies at different stages in the evolution of a structural-fire is also emphasized. [ABSTRACT FROM AUTHOR]

This paper presents a new nanoforce sensor based on a suspended carbon nanotube gate field-effect transistor. To do so, a numerical investigation of Suspended Gate Silicon-on-Insulator MOSFET (SG-SOIMOSFET) is carried out using ATLAS 2D simulator. Based on the relationship between the nanotube’s deflection and the applied force, a comprehensive study of the proposed nanoforce sensor behavior is performed. Moreover, we describe the evolution of the drain current characteristics as a function of the applied force while examining the influence of capacity variation of the insulating gate on the drain current in the saturation region. It is found that the sensor has a good sensitivity of 230.68 ln(A)/pN. Our second contribution in this paper is to develop a model based on artificial neural networks (ANNs). We successfully integrate our neural model of nanoforce sensor as a new component in the ORCAD-PSPICE electric simulator library; this component must accurately express the behavior of the sensor. A second model based on neural networks, which deals with correction and linearization of the sensor output signal, is designed and implemented into the same simulator. The proposed device can be considered as a potential alternative for CMOS-based nanoforce sensing. [ABSTRACT FROM AUTHOR]

In this paper, we are interested in the displacement of two incompressible phases in a Darcy–Brinkman flow in a porous media. The equations are obtained by the conservation of the mass and by considering the Brinkman regularization velocity of each phase. This model is treated in its general form with the whole nonlinear terms. This paper deals with construction and convergence analysis of a combined finite volume–nonconforming finite element scheme together with a phase-by-phase upstream according to the total velocity. [ABSTRACT FROM AUTHOR]

This paper provides means for obtaining the first three significant vibration modes for rectangular plates based on mass participation ratios. A non-dimensional frequency parameter is presented which results into the vibration frequency of rectangular plates at each of these three significant modes. Various aspect ratios and four combinations of boundary conditions at the plate edges are studied. A correlation between the nonlinear load-deformation behavior of the plate and its vibrational behavior is also presented accordingly. It is demonstrated that the vibration frequency of the studied rectangular plates increases significantly upon increasing the applied lateral pressure if the large deformation effects are considered in the analysis. The easy-to-follow method of frequency calculation presented in this paper is useful for assessing the dynamic characteristics of rectangular plates with or without lateral pressure that are subject to vibration. [ABSTRACT FROM AUTHOR]

• Micro-piling implemented as minimally disruptive trackbed stabilisation technique at a soft subgrade rail site. • Computer vision-based monitoring system measures track deflection under train passage to quantify trackbed quality. • Stabilisation improved trackbed quality by up to 30% and 50% improvement is achievable with clean ballast and longer piles. • Finite element analysis identifies triangular pile layout as an optimum configuration for cost vs improvement %. Excessive deflection of a rail in response to axle loading can lead to discomfort for passengers and increased wear of both railway structures and trains. These oscillations are often caused by poor trackbed stiffness which may be due to either soft subgrade and/or contaminated ballast. A variety of trackbed stabilisation (TBS) techniques are available to remediate soft subgrades and increase the safety of tracks within the railway network. Traditional TBS methods require track removal, which is expensive, disruptive and often inefficient maintenance works. Micro-piling, using screw piles installed between sleepers, is an innovative low disruption TBS technique. This paper investigates the performance of a soft subgrade and contaminated ballast section of rail line in the UK, before and after screw pile TBS. Pre and post remediation, a computer vision-based system was used to measure rail vertical deflections during train passages and then analysed to quantify the trackbed stiffness. Additionally, 3D finite element models are created and validated by the site measurements. The finite element models are used to simulate a range of different scenarios exploring how changes to the TBS piling layout and/or further works, such as ballast improvement could add further improvements or design efficiencies. Site measurements show TBS reduced rail deflection by 20–30%, indicating that micro-piling is an effective technique for soft subgrades. The finite element analysis revealed the efficiency of micro-piling is highly dependent on the conditions of ballast, strength of the ground at the pile toe, and the pile arrangement. When the aforementioned are optimised the rail deflection could be reduced to approximately 50% of the pre TBS condition. [ABSTRACT FROM AUTHOR]

This paper made pilot studies on behaviours of concrete-filled stub square stainless-steel tubes (CFSSSTs) subjected to low-temperature compression. Firstly, 16 CFSSSTs were tested under low-temperature axial compression. This testing program studied the effects of testing temperature (T) and SS-tube wall thickness (t). The tests showed that local buckling, corner-region splitting fracture, and concrete crushing occurred to CFSSSTs. The compressive load-shortening curves behaved a four-stage manner, which behaved differently from those hollow stainless-steel tubes (HSSTs). Compared with the common concrete-filled steel tube columns, the CFSSSTs exhibit a higher ductility. Studies showed that reducing T improved the compression capacity (P u) but compromised the ductility of CFSSSTs; increasing the t of HSSTs improved the compression behaviour of CFSSSTs; filling concrete to the HSSSTs significantly improved the compression behaviour of CFSSSTs. This study also developed 3D finite element models (FEM) for the CFSSSTs using the low-temperature mechanical properties of both HSSTs and concrete, which accurately predicted compression behaviours of CFSSSTs at low temperatures. Moreover, the prediction equations in different codes were also adopted to predict the low-temperature P u of CFSSSTs. Validations showed that these code equations provided about 15% underestimations on P u , and they were recommended to predict P u of CFSSSTs at low temperatures. • Arctic low temperatures improve compressive behaviours of concrete-filled square stainless-steel tubes (CFSSSTs). • Low temperatures have limited effects on failure modes of CFSSSTs. • Low temperatures improve compression capacity, but reduce the ductility of CFSSSTs. • Developed FEM predict well low-temperature compressive behaviours of CFSSSTs. [ABSTRACT FROM AUTHOR]

In the context of the theory of elasticity, the stress state at a sharp notch is singular, and the degree of stress singularity depends on the notch opening angle. Most existing analytical approaches for evaluating asymptotic linear elastic stress fields ahead of V-notches rely on notch stress intensity factors (N-SIFs). This paper presents an alternative analytical approach for evaluating notch stress fields by taking advantage of traction-based structural stress and Williams' eigenfunction methods. To better represent notch stress fields, the first order and higher order terms of eigenfunction are included in the present study. The analytical solutions are then compared to the stress fields resulting from finite element analysis for validation purposes. The stress contours evaluated by the analytical approach are nearly identical to the numerical results corresponding to three distinguishing notch opening angles under pure Mode I loading, which signifies the effectiveness and robustness of the analytical solution methodology developed in the present study. Subsequently, the approach is extended to accommodate Mode II loading by introducing a skew-symmetric term in the stress function. The generalized method is then applied on a welded cruciform joint, which precisely captures the notch fields compared to FEA results. • Developed a robust evaluation approach of linear elastic stress fields around a sharp V-notch under Mode I loading conditions. • Extended the analytical approach to accommodate the presence of Mode II loading. • Validated the analytical approach by FEA under Mode I and combined Mode I and II loading conditions. [ABSTRACT FROM AUTHOR]

For estimation of the durability of recycled aggregate concrete (RAC) in chloride-rich environment, it is valuable to investigate the chloride diffusivity in RAC. Because RAC is highly heterogenous, an ideal five-phase model was designated as the representative research object of RAC in this paper. To investigate the effect of micro-scale randomness on the meso -scale chloride diffusivity in RAC, this paper developed a multiscale digital-image driven stochastic method, in which the digital-image covariance kernel was used in the Karhunen-Loeve expansion to generate basis functions for the model. The proposed method was at the first time used to analyze chloride ion diffusion in RAC. Through a couple of numerical experiments, it is indicated that the effects of aggregate shape, aggregate size and the thickness of interfacial transition zones (ITZs) are considerable on the coefficient of variation of chloride diffusivity in RAC. It is also found that the digital image kernel is more sensitive about noise than other standard covariance kernels. [ABSTRACT FROM AUTHOR]

Helmholtz resonator is one of the most basic acoustic models in acoustic theoretical research and engineering applications. It is simple and effective to directly apply the theoretical formula for its resonant frequency calculation, but sometimes the calculation error is too large or even wrong. In this paper, the characteristics of Helmholtz resonators are studied based on the finite element numerical analysis. The influence of structural parameters and boundary conditions of the Helmholtz resonator on the resonant frequency is given, several related problems of the theoretical formula are supplemented and the relevant conclusions are obtained. The explanations employed in this paper could be used as a supplement to the theoretical formula for theoretical study and engineering applications of Helmholtz resonators. [ABSTRACT FROM AUTHOR]

A numerical investigation on cold-formed high strength steel (HSS) tubular beams is presented in this paper. The nominal 0.2% proof stresses of the HSS sections ranged from 700 MPa to 1100 MPa. In the complementary study [1], experimental investigation on the beam specimens have been performed. In the present study, numerical modelling methodology for beams was first validated and parametric study on the cold-formed HSS tubular beams was conducted. A total of 423 numerical data was obtained to investigate the structural performance of HSS tubular beams. The experimental and numerical results were then compared with the codified design guidelines from ANSI/AISC 360-10 [2], EN 1993-1-1 [3], AS 4100 [4] and AISI S100 [5] in addition to the predictions from Direct Strength Method (DSM) for square hollow sections (SHS), rectangular hollow sections (RHS) and circular hollow sections (CHS). The codified slenderness limits for sections subjected to bending were examined. Improvements on the design guidelines are proposed in this paper. [ABSTRACT FROM AUTHOR]

This paper presents the results of a combined experimental and numerical investigation on the mechanical behaviour of annealed glass–Glass Fibre Reinforced Polymer (GFRP) hybrid beams. The experimental results showed that an adhesively-bonded GFRP interlayer significantly improved the strength and ductility of annealed glass beams. The paper also presents the post-breakage behaviour and the response of damaged beams in unloading. The paper numerically investigates the degree to which the strength and stiffness of the hybrid beams can be modelled by using finite element (FE) analyses. The novelty of work also includes numerical modelling and validating the through-thickness stress profiles in the hybrid beams. [ABSTRACT FROM AUTHOR]

This paper concerns the short-term behaviour of innovative steel-timber composite (STC) floors comprising of cross-laminated timber panels connected to steel girders by various mechanical fasteners and/or glue. The results of four-point bending tests performed on full-scale STC beams are reported and the structural behaviour (the load-deflection response, short-term stiffness, peak load capacity, and failure modes) of the proposed STC system is studied. In addition, extensive non-linear 1D and 2D finite element (FE) analyses of STC beams are carried out and the numerical results are verified against the test results. It is shown that 1D and 2D FE models are adequate in capturing the structural response of the STC beams. Using the FE and experimental results, the composite efficiency of STC beams that can significantly influence their structural behaviour beams is determined and reported in the paper. [ABSTRACT FROM AUTHOR]

Surface roughening is essential for the design of new nanostructures. In this paper, a continuum model based on phase field theory is developed to study the surface roughening in heteroepitaxial structures. A long-range order parameter is introduced to represent a diffusional free surface profile. By minimizing the system total free energy under constraints, the coupled field equations of quasi-static mechanical equilibrium and diffusion-controlled surface evolution are obtained. In contrast to the existing phase field models of free surface which are mostly based on the analytical Green’s function, the Galerkin finite element formulation is derived in this paper to solve the weak form of the coupled field equations. The advantage is that it is very convenient to deal with the elastic inhomogeneities and complex boundary conditions without additional complications. The proposed model is applied to study the nonlinear surface morphology evolution of heteroepitaxial thin films. The simulation shows that the heteroepitaxial film with an initial random fluctuation develops to form islands and coarsens during annealing. The kinetics of coarsening and the calculated average wavelength are consistent with the existing experimental results. It also shows that the initial island array formed during annealing consists of islands with similar size, shape and spacing. The influences of film thickness and misfit strain on the formation of initial island array are studied. [ABSTRACT FROM AUTHOR]

A Finite element analysis (FEA) modeling method for grinding wheel and long fiber reinforced ceramic matrix woven composites (LFRCWCs) specimen was integrated and proposed in this paper. This method was adopted to analyze the grinding process of a 2.5D woven quartz fiber reinforced silicon dioxide ceramic matrix (SiO 2 /SiO 2) composite. Relevant grinding experiments were conducted, whose results verified the accuracy of the FEA method. Based on the FEA and experimental investigation, material removal mechanism in the grinding process of this material was discussed and the following conclusions can be drawn: 1) the modeling method that sets the interface of fibers and matrix with the same mechanical configuration as the matrix can obtain a pretty high simulation precision; 2) ceramic matrix can be easily broken and removed by fiber squeezing caused by grinding forces thus reducing the surface quality. To alleviate this damage, grinding directions should be selected as along with the fiber orientation which generates shear stress on fibers; 3) fiber debonds are caused by the inconsistent deformations of the warp and weft fiber bundles. Grinding across the axis of the wefts is a better choice to alleviate this damage. [ABSTRACT FROM AUTHOR]

The ITER vacuum vessel (VV) is a torus-shaped, double-wall structure with shielding and cooling water between the shells. Low distortion welding techniques are chosen in order to manufacture the 4 poloidal segments composing each sector and to weld them together. Control of the distortions during the welding process is the main technological challenge. Finite element analysis (FEA) tools have been developed in order to predict the mechanical behavior of the assembly during welding. These tools allowed on one side to optimize the welding process and on the other side to design ad-hoc supporting structure (Jigs) needed to control the distortion and to react to the huge forces generated during the process. The jigs are the key components during the manufacturing since their failure could jeopardize the whole process. In this paper a novel approach is proposed to design and assess the mechanical behavior of the Jigs and to mitigate the risk related to their failure in controlling distortions by implementing in-process control strategies based on the coupling between finite element analysis and metrology surveys/direct measurements. This approach has been applied on the ITER VV PS1 Jig. Experimental test have been carried out in order to validate the FE model feeding the computational tool by metrology measurements. Finally an optimize configuration of direct measurements devices (instrumented washers, strain gauges, displacement sensors) has been proposed in order to live control the behavior of the Jig during the manufacturing process by directly computing via FEA (feeding the analysis with the measurements) all the relevant mechanical variables needed to assess the structural integrity of the supporting structure. [ABSTRACT FROM AUTHOR]

• Natural convection of Bingham fluids was studied numerically in horizontal annuli. • The yield number has a significant impact on the heat transfer performance. • At the same yield number, the plug regions can increase with increasing Ra. • The unyielded plugs tend to accumulate at the bottom of the annulus. • Increasing in the annular gap width causes a faster growing of plug region. This paper aims to investigate the laminar natural convection of Bingham fluids between horizontal concentric cylinders. The governing equations are solved numerically by using the Galerkin's weighted residuals scheme of finite element method with a non-uniform unstructured triangular grid. The effects of various parameters such as the Rayleigh number (10 3 ≤ R a ≤ 10 6) , yield number (0 ≤ Y ≤ Y max) , ratio of gap width to inner cylinder radius (0.5 ≤ L / R i ≤ 5) and fixed Prandtl number (Pr = 100 since results are not sensitive to Pr in the tested range) on the flow and temperature profiles as well as on the heat transfer and morphology of yielded/unyielded regions are presented and discussed. The heat transfer rate shows a positive dependence on the Rayleigh number and L / R i , however, there is an optimum value for L / R i which maximizes the heat transfer rate. The results also show that the yield number has a significant impact on the flow and temperature fields and the heat transfer performance. In fact, the heat transfer rate decreases with the rise of the yield number and above a certain value of Y , the convection does not occur, and heat transfer is only due to conduction. It is found that while the enhancement of the Rayleigh number augments the heat transfer, it is not necessarily associated with a decrease in the size of the unyielded zones. [ABSTRACT FROM AUTHOR]

• Dynamic relaxation method for static buckling of compressed rods in cylinders. • The effects of damping, element size, contact stiffness and penetration on post-buckling. • Six post-buckling modes as axial compression load increases. • Transition section includes only two non-contact sections in the helical buckling mode. Buckling of rods with cylindrical constraints is an essential problem in engineering and medical fields. Completely different to the buckling of classical Euler rods, the post-buckling modes for rods with cylindrical constraints involve highly complicated deformations and geometric configurations. In this paper, the rods are discretized into beam elements by finite element method, and the constraint relation between the rods and cylinders is described by gap element. A dynamic relaxation method for static buckling of compressed rods in cylinders is introduced. Numerical simulations have been carried out to investigate the effects of damping, element length, initial contact stiffness and penetration on post-buckling, etc. The characteristic buckling modes include deflection curves with single point, two points, three points and point-line-point contact. For the helical buckling, it is found that the transition section consists of two noncontact sections only, while the perturbed-helix section does not exist. Except the critical load and shear force of helical buckling, numerical simulation results are in good agreement with the analytical solution. By using the dynamic relaxation method, stable helical buckling modes can be obtained directly without undergoing sinusoidal buckling deformation under given compressive loads. [ABSTRACT FROM AUTHOR]

Multi-well pressure data from the Magnolia Field, located on a flank of the salt-bounded Titan passive mini-basin in the Garden Banks area of the continental slope of the Gulf of Mexico, indicate remarkably high overpressures that vary, at similar depths, by up to 10 MPa between sand bodies 1 km apart. In the present paper, we integrate geological and geophysical analysis with 2D forward hydro-mechanical evolutionary modelling to assess the contribution of both disequilibrium compaction and diapir-related tectonic loading to the observed overpressure and to understand controls on pressure compartmentalisation. The 2D finite element evolutionary model captured the sedimentation of isolated sand channels bounded by mud-dominated sediments close to a rising salt wall which led to tectonic loading on sediments. Comparison of results from the 2D and 1D models shows that disequilibrium compaction can explain most of the overpressure as a result of very rapid deposition of mainly mud-rich, low permeability sediments; tectonic loading contributes around 7% of the observed overpressure. The models also show that linked to the high sedimentation rates, small variations in the permeability and connectivity of the mud-rich sections that bound the channel sands result in highly compartmentalised pressure distributions in adjacent sand bodies. • Evolutionary hydromechanical simulation of a GoM mini-basin. • Prediction of structure, strain, stress, and overpressure histories. • Quantification of disequilibrium compaction vs tectonically induced overpressure. • Modelling of overpressure compartmentalisation in isolated sand channels. [ABSTRACT FROM AUTHOR]

This paper presents an artificial neural network (NN) modelling approach to represent a connector model in large-scale finite element explicit crash simulations. The NN model was established to describe the local force–deformation response of point connectors in automotive applications, namely self-piercing rivets and flow-drill-screws. The study is limited to two-sheet connections and to the use of feedforward NNs. Successive loading and unloading of the joints is not studied. Various architectures and complexities of the feedforward NNs were evaluated and trained based on data generated from a constraint model found in the literature. This forms a proof of concept for implementing a modelling technique not based on physics-motivated constitutive equations. The impact of the network complexity and training data diversity was investigated. The NN model was implemented as a cohesive zone model for incremental force prediction in an explicit finite element code. In order to have a wide selection of joint types, five different joint configurations including self-piercing rivets (SPR) and flow-drill screws (FDS) were investigated. Numerical results from the NN model were compared to physical tests from all joint configurations. It was shown that a rather basic machine learning technique like a feedforward NN was able to reproduce path-dependent force–deformation behaviour for the application in explicit FE solvers. • A novel approach for artificial neural network modelling of joints in crash analysis. • In-situ ANN predictions of the joints mechanical response in an explicit FEM-solver. • Effects of neural network complexity and dataset quality analysed. • Validation with large-scale FEM simulations of components versus physical tests. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanical behaviour of lap steel-timber composite connections using a 3-D continuum-based finite element (FE) model. In the FE models developed, the non-linear behaviour and failure of the timber is captured by a stress-based failure criterion formulated in the framework of continuum-damage mechanics. Yielding of the steel plates and fasteners ( i.e. coach screws and bolts) is captured by an elastic-hardening plastic constitutive law. These FE models are validated by experimental (push-out) tests conducted on laminated veneer lumber (LVL)-steel and cross-laminated timber (CLT)-steel composite lap connections. It is shown that the FE models developed in the paper can replicate adequately the load-slip response and failure mode of the hybrid steel-timber composite connections tested. The validated FE model is used to undertake a parametric study that elucidates the influence of the yield strength and the length of the fasteners and the post-tensioning force in the bolts on the stiffness, load carrying capacity and load-slip behaviour of hybrid steel-timber composite connections. [ABSTRACT FROM AUTHOR]

In this paper, supermode characteristics of a dual-core fiber and a four-core fiber are analyzed by a simple couple-mode theory. The effective refractive index and corresponding relative error of each supermode are investigated in detail with different gapsize, relative refractive index and core radius using numerical method and finite element method. Both adjacent coupling and non-adjacent coupling are taken into consideration when keeping single mode condition of each core. The magnitude of relative error can achieve 10 −5 and 10 −4 for a dual-core structure and a four-core structure, respectively. The obtained results clearly show the validation of numerical method compared with finite element method. One is going to benefit from the succinct equation expressions in this paper when designing and analyzing supermode supporting fiber structure. [ABSTRACT FROM AUTHOR]