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A new cable-damper stopper equipped for Coal-Fired Thermal Power Plants (CFTPPs) was proposed in our previous paper, where a series of shaking table tests were carried out to investigate its seismic performance, so this paper aims to reveal the working mechanism of the stopper from the theoretical and numerical simulation aspects. The stopper is composed of three main components, i.e. a steel cable, a steel block and a viscous damper. First, the nonlinear restraint stiffness of the steel cable to the boiler was derived; second, the critical damping of the stopper, which makes the vibration of the boiler decay exponentially with no oscillation, was derived; third, an iterative method was proposed to globally tune the CFTPP structure, which makes it possible to obtain the optimal parameters of the cable-damper stopper, including the diameter of the steel cable and damping coefficient of the damper. Finally, finite element models were built and time history analyses were conducted to verify the proposed optimization approach. Firstly, the finite element models were proved valid through the comparison between the results of the simulations and the experiments. Then, based on the results of the simulations, the theoretical procedure was validated. The results revealed that the proposed cable-damper stopper reduced the seismic responses of displacements of the top floor and the boiler significantly, about 30.18% and 60.01% respectively compared with their counterparts of CFTPPs without stoppers. [ABSTRACT FROM AUTHOR]

The seismic analysis of historical and monumental masonry buildings, especially churches and cathedrals, is challenging and expensive. These difficulties are mainly related to complex geometry and the mechanical modelling of historic masonry structures. This paper aims to show the methodological approach to evaluate the seismic vulnerability of Masonry Cathedrals by modelling seismic analysis. The numerical finite element model, modelled with solid elements, was optimised based on identifying the primary dynamic properties performed in ambient and seismic excitations recorded by a continuous dynamic monitoring system in operation since 2015. We carried out linear dynamic analyses for the optimised model of the entire structure. We also carried out non-linear dynamic analyses for the vaults, where damage concentrations were detected after various seismic events. The linear dynamic analysis of the optimised entire structural model aimed to estimate the time histories of acceleration at the connection areas between the vaults to the vertical structures. The numerical analysis results were consistent with the damage maps identified for the actual structure. Furthermore, the numerical model and the analysis procedure showed an excellent ability to reproduce the accurate structural response. [ABSTRACT FROM AUTHOR]

This paper comparatively addresses the numerical modeling techniques for simulating the nonlinear behavior of unreinforced masonry (URM) walls. An experimental test program including two specimens with and without opening was conducted to document the behavior of the specimens. Both specimens were subjected to constant axial load and monotonically increasing in-plane lateral load during the tests. Two different modeling approaches, macro and detailed micro modeling, were considered to develop the finite element models (FEMs) of URM walls. The numerical simulation was performed using ABAQUS finite element software. The results of both modeling strategies were compared with experimental results in terms of the lateral load–displacement response and crack pattern of URM walls. Based on the comparison, the approaches implemented for numerical analyses are found reasonably applicable for simulating the in-plane response of URM walls with and without opening under lateral load. [ABSTRACT FROM AUTHOR]

In order to understand the distribution of streaming potentials in cartilage pores, this paper established finite element model to analyze. The results showed that the streaming potential in cartilage micro-pores increased along the axis. The electric potential in 5 μm straight micro-pore was about 50 μV, and the electric potential of curved bifurcation model was about 30 μV. The pressure and Zeta potential had a linear growth relationship with the streaming potential. The streaming potential decreased with the increase of ion concentration until ion concentration was saturated. These results could provide a theoretical basis for cartilage research. [ABSTRACT FROM AUTHOR]

Repeated wet–dry cycle exposure to seawater during ballasting processes hastens the surface corrosion rate. Moreover, the larger volumetric changes of corroded ballast tanks generate lower pitting severity. This paper models the pitting severity of corroded ballast tanks of varying roughness and volumes. Seven rectangular finite elements models with Gaussian rough surfaces are examined. The surface roughness modelling is analyzed with correlation among corrosion-statistical parameters at various corroded specimen volume changes. Additionally, the paper elaborates the severity of pitting corrosion characteristics using the pitting factor and the relationship between the maximum and average pit depth. The pitting severity – volumetric changes scenario investigates the model's stress distribution, showing that the greater change in volume and lower pitting severity tend to have a lower stress distribution, which is randomly concentrated on the larger area. Comparison of the theoretical results with physical test data using 3D laser scans indicates a close match. [ABSTRACT FROM AUTHOR]

Thin-walled structures have been widely adopted in engineering projects because of the advantages of good load-bearing capacity, light weight and low cost. In this paper, a refined finite element method (FEM) based on the Carrera Unified Formula (CUF) is performed to analyze the free vibration of thin-walled beams with the variables cross-section, length and boundary. The low-dimensional FEM method could improve the efficiency of numerical analysis and reduce the time consumption. The one-dimensional (1D) CUF is employed in which the models are assumed to be a beam-like axis-oriented structures. In this case, the geometry of the thin-walled beam can be discretized as a limited number of 1D beam elements along the axis, while the Lagrange polynomial expansion may be used to approximate the displacement field on the cross-beam surface. Thus, FEM matrices and vectors can be written in terms of fundamental nuclei whose forms are independent of beam theories. The validity and capabilities of the method presented are examined in some numerical examples, and a comparative study is carried out between the method proposed and the three-dimensional element method with and without warping solutions. The results obtained by CUF 1D models are in close agreement with the reference solutions. In addition, it has been argued that the innovative approach presented in this paper can be used as a precise tool for structural analysis for complex cross-section thin-walled beams to reduce computational costs. [ABSTRACT FROM AUTHOR]

In the present study, the fracture analysis of functionally graded materials (FGMs) of various material distributions with discontinuities (crack and inclusion) under localized loadings is carried out by the extended finite element method (XFEM). In the present work, the effect of discontinuities and material distributions like exponential, power law, Mori–Tanaka, and sigmoidal in FGMs is also presented, where the different material distributions are compared for the fracture analysis of FGM plates and beams. This present work will be helpful for the researchers to understand the effect of different material distributions on FGMs under localized ladings. The XFEM-based numerical analysis is carried out to find stress intensity factors (SIFs) and stress distributions. The MATLAB code is developed for this analysis and is validated with a previously published research paper. [ABSTRACT FROM AUTHOR]

Conservation of the European-built heritage is nowadays closely related to interventions in masonry construction. Since a significant part of these structures are located in earthquake prone zones, designing protective measures that ensure their preservation requires the assessment of the associated seismic vulnerability and the understanding of their degradation mechanisms. However, due to the presence of discontinuities between its constituent elements, the numerical simulation of the non-linear response of masonry structures subjected to strong earthquakes is a cumbersome task, especially when performed using the traditional finite element method. As an alternative, the discrete element method is particularly suitable for the numerical analysis of such structures under large, damaging loads. By allowing discrete displacements/rotations of individual bodies, and by automatically recognising new contacts between bodies, while eliminating obsolete ones, this numerical approach can simulate the complete detachment of discrete bodies initially in contact. The present paper illustrates the use of the discrete element method to assess the seismic vulnerability of stone arches. A probabilistic approach allows to consider the variability of the seismic action and the uncertainties in the definition of the material properties. First, an un-reinforced masonry arch is considered. Based on non-linear multi-directional incremental dynamic analyses, five damage states are proposed and the respective fragility curves are elaborated. To improve the arch's seismic performance, two reinforcing solutions using steel elements are considered and analysed comparatively. [ABSTRACT FROM AUTHOR]

In this paper, the crashworthiness characteristics of tapered structures with the uniform cells in cross-section subjected to oblique impacts are theoretically and numerically investigated. Benefiting from tapered structure simplifications into the corner, crisscross and T-shape parts in non-tapered structures, an engineering formula is proposed to estimate the mean crush load during structure deformations. In order to represent the behavior of the structures subjected to oblique impacts with regard to energy absorption, an oblique impact coefficient extracted from a comprehensive parametric study on the responses of the structures is considered in the formulation. In order to conduct the parametric study, a finite element model for the crumpling processes of different tapered and non-tapered structures with the uniform cells in the cross-section under axial and oblique impacts is prepared. The contributions of cell-number in the cross-section, taper angle, wall thickness, aspect ratio and impact angel on the peak crush load, mean crush load, specific energy absorption, crush force efficiency, transition thickness and transition impact angle in the crushing processes of the tapered structures with uniform cells in cross-section subjected to oblique impacts are presented and discussed. In particular case, the predicted structural energy absorption by the numerical model is compared with those experimental results that are available in the literature, indicating a good agreement. [ABSTRACT FROM AUTHOR]

This paper proposes four novel designs of steel-concrete interface connections in fully encased composite (FEC) columns ((i) C1 Bars welded to the steel's flange, (ii) C2 Bars welded to the steel's web, (iii) C3 Bars welded to the steel's flange with the stirrup, and (iv) C4 Bars welded to the steel's flange side with the stirrup) to connect the concrete reinforcement bars to the steel section to be used as shear connectors and stirrups at the same time. Using regular reinforcing bars in these designs make them easier to design, fabricate, and install on structural steel. The finite element models were built using ANSYS software and calibrated with previously published experimental results (load-displacement curve, load capacity and failure mode). The results show that using the proposed designs have increased the strength capacity by 0.46%-8.37%, the ductility improved by 12.73%-25.18% and the stiffness increased 0.21%-17.72% compared to the FEC column without any connectors and the FEC column with stud connector. [ABSTRACT FROM AUTHOR]

A type of tube with corrugated patterns, aiming at inducing extension deformation, was proposed in this paper. Fifteen patterned tubes and one conventional square tube were simulated using the finite element model which was validated by an axial quasi-static compression experiment. The numerical results show that four deformation modes generated, which are closely related to the patterns number and the pattern angle. Tubes deform in D mode has the highest energy absorption. The influence of geometric parameters and wall thickness on energy absorption performance was also investigated. A geometric optimization was carried out as well. Deformation mechanism of two of the four modes, EF mode and E mode, were established and theoretical predictions of mean force were derived. The energy absorptions of different deformation forms were analyzed, and the results show that half of the energy is dissipated by extension deformation in E mode but little in EF mode. [ABSTRACT FROM AUTHOR]

The swimming pool on large passenger ships creates challenges for structural designers. Designers have to take into account the effect of the large opening and its reinforcement on the strength of deck structures. In this paper, experimental and finite element analyses are presented on the ultimate compressive strength of two double-deck structures with a large opening on the upper deck. Buckling collapse behaviour of the upper and lower decks are investigated during the progressive collapse of double-deck structures. Comparison of the experimental results shows that the structural reinforcement for deck opening increases about 29% the ultimate compressive strength and changes the overall buckling and collapse behaviour of double-deck structures. The finite element analysis quantifies the effect of reinforcing large openings to improve the structural strength of perforated structures. A design methodology is put forwards for reinforcements based on equivalent buckling and ultimate strength concept. [ABSTRACT FROM AUTHOR]

The dynamic behaviour of dry stone monuments is highly nonlinear as it involves rocking and slippage of numerous blocks, and occasionally cracking of blocks and plastic deformation of metal connectors. This is why the assessment of the efficiency of structural interventions (for restoration purposes) on such monuments located in seismic areas is a very complicated task. One way to address this issue is nonlinear dynamic numerical analysis in which material nonlinearity is taken into account for each component of the structure (blocks, connectors). This paper advocates that this is the way by which the most accurate results are to be expected, provided that all models are sufficiently validated. With this aim, such a holistic numerical approach is presented, regarding the assessment of the seismic performance of new titanium connectors designed for the architrave of an ancient-Greek temple, currently under restoration. The monument is the temple of Apollo Epikourios at Bassai, Peloponnese, which is included in the UNESCO World Heritage List since 1986. The numerical analyses, in overall, showed a way of using a sophisticated FE software for the design or the evaluation of one of the most common structural interventions on dry stone monuments (the replacement of the ancient connectors of the stone blocks with new elements made of titanium), as well as they demonstrated the key benefits of this use (global overview, detailed analysis, and easiness in conducting parametric investigations). Furthermore, they yielded quantitative information concerning the efficiency of a major intervention on an important ancient temple. [ABSTRACT FROM AUTHOR]

The flow of water in mining waste may cause serious environmental impacts associated with acid-rock drainage. In relatively dry climates, dry soil covers have been considered as feasible alternatives to minimise such effects. The objective of this paper is to evaluate the influence of the hydrological cycle and soil type on the performance of dry cover systems, considering the tropical conditions found in Brazil's central-west region. Numerical analyzes of four different cover systems composed of tropical soils were performed using the Finite Element Method. Among the proposed arrangements, three use a soil that presents a bimodal soil-water characteristic curve and the fourth system employs a unimodal soil. The thicknesses of intermediate materials were varied and different representative precipitation parameters were considered for a period of one year. The results obtained were compared in terms of the internal flow and the capacity of the cover to store water. The results indicate that bimodal soils may not be ideal materials and require specific compaction conditions to reduce the volume of macropores. Unimodal tropical soils presented adequate response as store-and-release materials. The use of an intermediate layer acting as a capillary barrier did not offer significant improvement to the cover systems evaluated. [ABSTRACT FROM AUTHOR]

Imperfect geometry beams with functionally graded carbon nano tubes (CNT) have recently been used in many structural applications, and many numerical analyses have been performed to assess the stiffness property in beams and structures. Where the stiffness enhancement of a beam greatly contributes to its stability by augmenting the geometrically defective beam's deformation withstanding capabilities under loading. However, the stiffness enhancement in terms of imperfect geometrical design characteristics has not been considered in previous research. Hence in this paper, a novel Persuaded Resilient Design is introduced in which the geometric imperfection is induced in the design in the form of a hollow trapezoidal laminate in such a way that the designed imperfect layered laminate enhances the flexural rigidity of the beam. Additionally, by employing a Parametric Stability Analysis, the act of the curved beam is structured by meshing the design with FEA applying UDL, and three-point bending. The peak and trough sustainability of the unique designed geometrically flawed beam incorporating functionally graded CNTs is determined via a finite element model. Thus, the FG-CNT reinforced curved beam behavior of the novel design is efficiently analyzed. [ABSTRACT FROM AUTHOR]

This paper presents the numerical damage analysis of concrete structures using higher-order beam theories based on Carrera Unified Formulation (CUF). The concrete constitutive relation is modeled using continuum damage mechanics based on a modified Mazars concrete damage model, in which both the tensile and compressive softening behaviors are regularized with classical fracture energy methodology. An expression is proposed to estimate the characteristic length in higher-order beam theories, to prevent mesh dependency. Both softening constitutive laws and fracture energy calculations are obtained according to Model Code 2010. To assess the efficiency of the proposed model, three classical benchmark quasi-static experiments are taken for validation. From the comparison between numerical and experimental results, the proposed CUF model using continuum damage mechanics can present 3D accuracy with low computational costs and reduce the mesh dependency. [ABSTRACT FROM AUTHOR]

The paper aims to develop a finite element methodology to deal with vibrations and buckling of laminated thin plates subjected to thermal and hygroscopic effects, once a second-order strain gradient theory is included to overcome the limitations of conventional elasticity and to capture nonlocal phenomena. The numerical scheme takes advantage of Hermite approximation for both membrane and bending primary variables, since the strain gradient introduces higher-order derivatives of the nodal displacements. Its versatility is proven by dealing with general lamination schemes and arbitrary boundary conditions. The analyzed configurations cannot be solved analytically. [ABSTRACT FROM AUTHOR]

The present study examines the efficacy of the thickness of recycled construction and demolition waste (RCDW) layer (0.4D, 0.6D, 0.8D, 1D and 1.2D; D: diameter of footing) prepared at different relative densities (30%, 50% and 70%) overlaying on loose sand. Two sizes of RCDW, 5 mm named RCDW-I and 10.6 mm named RCDW-II, were used in this investigation. The plate load test and finite element analysis using ABAQUS were carried out on different combinations. Moreover, a large box direct shear test was conducted to determine the angle of internal friction (α) of RCDW-I and RCDW-II at relative densities (ID) of 30%, 50% and 70%. With the usage of RCDW layer over sand, the ultimate bearing capacity increases by 640% for RCDW-I and 597% for RCDW-II, and the corresponding decrement in the settlement was 36.86% and 33.54% (at ID = 70% and u = 1.2B), respectively. The conjoined analysis shows that RCDW-II performs better than RCDW-I at lower ID. Whereas the opposite trend is witnessed at higher ID. The experimental results were compared to the numerical model created in ABAQUS 3D. In addition, regression analysis was performed using SPSS software to build empirical expressions of the given results. [ABSTRACT FROM AUTHOR]

The elastic wave propagation and vibration attenuation zones for periodically scattering piles in unsaturated ground were investigated using Finite-Element Method (FEM) and Bloch periodic theory. The unsaturated ground was modelled by unsaturated poroviscoelastic medium with the weak form governing equations derived from the mass and momentum conservative equations using Galerkin method and Fourier transform. The quadratic polynomial eigenvalue equations for the unsaturated medium were obtained using the Bloch periodic theory, and solved by FEM for the complex eigenvalues to evaluate the band gaps of the pile-soil system. The eigenvalue bands combined with the frequency response function were used to analyse the mitigation effects of piles in unsaturated ground with different soil properties and piles parameters. This research found that the pile-soil system has three propagational waves, in which the shear wave and the slow longitudinal wave carry low-frequency vibrations that undermine the attenuation effects of the piles barrier. The increasing soil saturation degree affects the attenuation effects by reducing the soil modulus and increasing the fluid content. And both of those two mechanisms reduce the frequency of the attenuation zones (AZ), which improves the low-frequency vibration attenuation, and reduces the width of AZ that could reduce the vibration mitigation effects. [ABSTRACT FROM AUTHOR]

Miniaturized and head-mountable scanning nonlinear fibre-optic microscopy offers an exciting opportunity for the visualization of brain activity on freely walking mice. One challenge in the creation of such miniaturized microscopes is the design of optical fibres capable of delivering ultrashort pulses without distortion and collecting fluorescence simultaneously and efficiently. A double-clad photonic crystal fibre (DCPCF) with 37-cell air holes arranged in hexagonal lattice in core is proposed. The full vector finite element method (FEM) is used for numerical analysis. Nearly zero dispersion of −0.34 ps/nm/km at 920 nm wavelength is finally achieved. The single-mode core with an NA of 0.53 at 920 nm wavelength is used to deliver the femtosecond excitation beam and the inner cladding with an NA of 0.54 at 532 nm is used to collect the two-photon fluorescence signal. The nearly zero dispersion, high NA and low nonlinearity will be beneficial to promote its application in two-photon microscopy. [ABSTRACT FROM AUTHOR]

Topologically interlocked materials (TIMs) are an emerging class of architectured materials that each of block is supported by their neighboring blocks without any connector, which is inspired by microstructures observed in nature. Therefore, they showed alluring attributes such as resistance to impact, toughness, high flexibility even when using brittle materials, and high crack propagation resistance. In these structures, the presence of lateral compressive force, applied on peripheral blocks, ensures the integrity and identified properties. Lateral load, however, can adversely affect TIM plates and cause instability, and initiate buckling. In the present study, to focus on the buckling behavior of TIM plates due to the lateral force, a finite element model of TIM plates, made of tetrahedral blocks, was first validated using numerical results available in the literature and then analyzed. In this regard, an appropriate procedure has been presented to simulate the possible instability of these structures. Unlike monolithic plates, geometric parameters of TIM plates are dependent and this makes their parametric study more challenging. Therefore, some case studies have been accomplished to illustrate the effect of diverse parameters. The current study indicates that increasing the assembly plate length and decreasing its thickness causes a reduction of buckling load; nevertheless, it is necessary to mention that the thickness variation is a more impressive factor. [ABSTRACT FROM AUTHOR]

The Finite Strip Method (FSM) was employed to study the buckling behavior of laminated glass fiber-reinforced polymer (GFRP) stiffened plates with different boundary conditions under axial compression. The theoretical formulation was established based on the first-order shear deformation theory (FSDT) for the thin plate and the stiffener. In this formulation, the stiffeners are not required to be placed on the nodal lines. This feature is considered useful in modeling the stiffened plates in which the stiffener elements are placed arbitrarily in complex planforms. Experimental, numerical and analytical studies were conducted to investigate the effects of the plate width-to-thickness ratio, the stiffener thickness-to-width ratio, dimensions, angle, eccentricity, torsional stiffness and geometric configuration of stiffeners on axial buckling capacity. Furthermore, the obtained results of the analytical method were compared with experimental results and ANSYS code to show its accuracy and convergence. The advantages of the present are that number of elements is much less and the mesh refinement process is much more convenient than commercial finite element software and traditional finite element method (FEM). Therefore, time consumed for analysis is less than the codes which work based on the finite element method. [ABSTRACT FROM AUTHOR]

In order to identify the liquefaction potential, soil is considered as homogeneous horizontal layers in all previous studies. However, in reality, soil is composed of layers with some irregularities. Therefore, in the present research, the liquefaction potential of two layers of saturated sand is evaluated considering the irregular topography of layers. The effect of different topographies including crown and valley shapes of one, two, and four sine waves has been considered using two-dimensional models subjected to earthquakes. The results indicate that the irregularly embedded topographies play a role in assessing liquefaction, which can be useful in geotechnical earthquake engineering. [ABSTRACT FROM AUTHOR]

We propose and study a scheme combining the finite element method and machine learning techniques for the numerical approximations of coupled nonlinear forward–backward stochastic partial differential equations (FBSPDEs) with homogeneous Dirichlet boundary conditions. Precisely, we generalize the pioneering work of Dunst and Prohl [SIAM J. Sci. Comp., 38(2017), 2725–2755] by considering general nonlinear and nonlocal FBSPDEs with more inclusive coupling; self-contained proofs are provided and different numerical techniques for the resulting finite dimensional equations are adopted. For such FBSPDEs allowing for non-Lipschitz nonlinearity on unknown variables, we prove the existence and uniqueness of the strong solution as well as of the weak solution. Then, the finite element method in the spatial domain leads to approximations of FBSPDEs by finite-dimensional forward–backward stochastic differential equations which are numerically computed by using some deep learning-based schemes. A strong convergence analysis is addressed for the spatial discretization of coupled FBSPDEs under an additional Lipschitz assumption, and the numerical examples, including both decoupled and coupled cases, indicate that our methods are quite efficient. [ABSTRACT FROM AUTHOR]

The effects of screw diameter, pilot hole, and material type on withdrawal load resistance (WLR) of screw driven in medium density fibreboard (MDF) and particleboard (PB) were investigated through using experimental and numerical methods. Meanwhile, the results of experimental tests and numerical analysis were compared with the empirical equations. The results showed that (1) the material type and the diameter of screw had significant effects on the WLR, but the pilot hole was not; (2) the equations proposed in Eurocode 5 had better performance in predicting WLRs of screw in both MDF and PB than the other equations; (3) density distributions of wood-based materials affected the mechanical behaviours of WLR of screw; (4) finite element model (FE-model) established could be used to simulate the WLR of screw in wood-based samples; (5) the complex FE-model considering threads of screw can reflect the stress distributions on threads in detail, which contributes to optimal design of threads geometry of screws. And the simplified FE-model without considering threads of screw had advantages in predicting the WLR with higher accuracy. [ABSTRACT FROM AUTHOR]

In this study, an experimental and numerical analysis of the bond-slip model is made on timber-to-timber bonding connections. The variables examined in this study are the types of adhesives used for bonding, the length of adhesion, and the types of reinforcement used to increase the adherence to the adhesion surface. Two different types of adhesives were used namely polyurethane and epoxy. Three different bonding lengths of 180, 250, and 350 mm were chosen as the bonding length. For each variable, four different test specimens were produced and tested under axial tensile force as a nonreinforced reference test specimen and aluminum, fiber, and steel net type as a reinforced bonding strength. In the experimental study, a total of 24 test specimens were tested and the bond-slip behavior of the timber connections and changes in the axial strain values along the timber adhesion zone were measured. By interpreting the experimental results, a bond-slip model is proposed for the timber bonding connections. In this proposed bond-slip model, the effects of the variables examined in the experimental study are interpreted. In this study, the most successful bond-slip behavior and load-carrying capacity have shown in the test specimen, which is reinforced with steel material reinforcement mesh, using epoxy adhesive, and 350 mm adhesion length. By using the experimental results, the bond-slip behavior is verified by numerical modeling with ANSYS software, and a finite element model was formed. [ABSTRACT FROM AUTHOR]

Using plate load test to evaluate the scale effects of shallow foundation bearing capacity on geogrid-reinforced sand is expensive because large boxes need to be built, and the devices to apply the loads to the reinforced soil are complex. Consequently, the finite element method is an alternative to investigate this phenomenon. In this study, a series of 3D axi-symmetry finite element models were developed to study the scale effect on the bearing capacity of circular footings resting on geogrid-reinforced sand. First, a 100 mm-diameter circular foundation supported by geogrid-reinforced sand was simulated in order to validate the finite element model with laboratory tests. Subsequently, different models were made by increasing the diameter of the foundation and the diameter of the geogrid in the same proportion. Modelling results indicated that as the foundation diameter increased, the bearing capacity of unreinforced and reinforced soil decreased. Likewise, the benefit obtained from the reinforcement was less when the model size was increased. [ABSTRACT FROM AUTHOR]

In nodal-based finite element method (FEM), degrees of freedom are associated with the nodes of the element whereas, for edge FEM, degrees of freedom are assigned to the edges of the element. Edge element is constructed based on Whitney spaces. Nodal elements impose both tangential and normal continuity of vector or scalar fields across interface boundaries. But in edge elements, only tangential continuity is imposed across interface boundaries, which is consistent with electromagnetic field problems. Therefore the required continuities in the electromagnetic analysis are directly obtained with edge elements whereas in nodal elements they are attained through potential formulations. Hence, while using edge elements, field variables are directly calculated but with nodal elements, post-processing is required to obtain the field variables from the potentials. Here, we present the finite element formulations with the edge element as well as with nodal elements. Thereafter, we have demonstrated the relative performances of different nodal and edge elements through a series of examples. All possible complexities like curved boundaries, non-convex domains, sharp corners, non-homogeneous domains have been addressed in those examples. The robustness of edge elements in predicting the singular eigen values for the domains with sharp edges and corners is evident in the analysis. A better coarse mesh accuracy has been observed for all the edge elements as compared to the respective nodal elements. Edge elements are also not susceptible to mesh distortion. [ABSTRACT FROM AUTHOR]

Ring foundations are used for circular industrial structures and often placed over a rock mass. However, the bearing capacity factors for ring foundation are not available in the literature. Hence upper and lower bound finite element limit analysis (FELA) was performed to evaluate the bearing capacity factors for the ring foundation resting over a rock mass. The Hoek-Brown constitutive model was adopted to study variations in the geometry of ring foundation, Geological Strength Index (GSI), intact rock constant (mi), and unit weight of rock mass (γ) on the bearing capacity of the ring foundation. The bearing capacity factors Nσ are presented for the different values of GSI, mi, and γ. The failure patterns under varying ring geometry and the rock mass unit weight are presented and discussed. The results show an increase in the bearing capacity with an increase in Hoek-Brown parameters for a rock mass. The bearing capacity is observed to be decreasing with an increase in the ratio (Ri/Ro) of the inner radius (Ri) to the outer radius (Ro) of the ring foundation. Design tables are provided as a ready reference for practitioners to evaluate the bearing capacity of the ring foundations resting over a rock mass. [ABSTRACT FROM AUTHOR]

Research on carbon-fiber-reinforced polyetheretherketone (CF-PEEK/CFR-PEEK) as a bone tumor joint prosthesis remains limited. Herein we numerically determine the feasibility of CF-PEEK material containing 30% Wt carbon fiber (CF30-PEEK) as a material for the dual-action tumor-type distal femoral prosthesis. Use CT scan method to build a complete finite element model of the knee joint. Simulate the resection of the distal femoral tumor, and then reconstruct it with the dual-action tumor-type distal femoral prosthesis. The femoral condyle and extension rod components were simulated with cobalt chromium molybdenum (CoCrMo), PEEK and CF30-PEEK materials respectively. When simulating the standing state, a vertical stress of 700 N is applied to the femoral head. When simulating the squatting state, a vertical stress of 2800 N is applied to the femoral head. The displacement and rotation angle of each node of the distal tibia are fully restrained in three directions (X-axis, Y-axis, Z-axis). We examined the stress magnitude, stress distribution, and stability of the prosthesis and each of its components by means of finite element analysis (FE analysis). The FE analysis results show: after replacing the distal femur and the extension rod with CF30-PEEK material, the stress is still evenly distributed, and the average stress is significantly reduced. In addition, the stability is similar to CoCrMo material. Therefore, CF30-PEEK is an appropriate material for this type of prosthesis. [ABSTRACT FROM AUTHOR]

For efficient use of adhesive joints, reliable prediction techniques should be made available to the designer. Simulation of these joints' behaviour is usually performed using the Finite Element Method (FEM). However, it is known that, in adhesive joints, the adhesive thickness (tA) is much smaller than the adherend thickness (tP), thus requiring a highly refined mesh to produce good results. Linked to this, the adhesive has to withstand high strains, causing mesh distortion and hindering the resolution. In these cases, meshless methods can be a good alternative. This work aims to implement the von Mises (vM) and Exponent Drucker-Prager (EDP) criteria combined with a meshless formulation based on the Radial Point Interpolation Method (RPIM), for the strength prediction of adhesively-bonded single-lap joints (SLJ). Validation with experiments is undertaken for joints with brittle to ductile adhesives, with varying overlap lengths (LO). Stress and strain distributions were plotted in the adhesive layer, and the failure load (Pm) was assessed by strength of materials failure criteria. Significant adhesive and LO effects were found on Pm. The RPIM proved to be a promising tool to predict the behaviour of bonded joints, although some limitations were found by using strength of materials criteria. [ABSTRACT FROM AUTHOR]

In deep sea engineering, strain gauges set outside of structure would be subjected to external hydrostatic pressure. The pressure effect in electric-resistance strain measurement would be derived in theory. A simplified model of strain gauges in finite element analysis (FEA) had been proposed and also verified by theoretical and real beam model results. After pressure effect analysis of metal based on presented FEA and theoretical methods, two block specimens of PMMA material had been designed and accomplished high pressure test. The presented FEA had agreed well with the experimental results. Compared with theoretical data and series of multi- parameter model calculation, the presented FEA exposed that the pressure effect should not be neglected in electric-resistance strain measurement to PMMA material, and the measured strain would have difference with that real strain appearing on flat surface of structure, especially for high pressure loading. [ABSTRACT FROM AUTHOR]

In this article, a fully discrete numerical method is studied to solve the system of singularly perturbed parabolic convection–diffusion problem. The full discretization incorporates the backward-Euler method and the streamline-diffusion finite element method (SDFEM) for the temporal and spatial discretization, respectively. In each equation, the highest ordered spatial derivatives are multiplied by distinct parameters, hence the overlapping boundary layers phenomena displayed in the solution. To capture the singularity of the solution, a layer-adapted mesh has been used for the spatial domain discretization. The stability of the numerical method has been addressed by considering an appropriate stabilization parameter. A complete error analysis has shown the first order of accuracy of the fully discrete method in the discrete L 2 (0 , T ; S D) -norm. Lastly, few numerical experiments have been addressed to justify the theoretical estimates. [ABSTRACT FROM AUTHOR]

Square-circle hybrid section (SCHS) tubes under axial loading which combine the advantage of square tubes and circular tubes are investigated. Firstly, effective finite element models of SCHS tubes are established to study the crashworthiness characteristics. Through a series of finite element models, the influence of the geometry on the behaviour of crashworthiness is studied, including relative size of square and circular sections in SCHS tubes and the position of connecting plates. The results show that compared with corresponding traditional multi-cell tubes, SCHS tubes improve the performance in energy absorption, with a maximum increase of 40.49%, while reducing peak force and improving crushing load efficiency. Moreover, the deformation of elements constituting the SCHS tube is analysed, and deformation of arc-plate elements could be classified into three typical modes. According to the observed deformation modes, the theoretical model is proposed to predict the mean crushing force of SCHS tubes. The theoretical results show that it is in good agreement with the numerical results. [ABSTRACT FROM AUTHOR]

Friction stir welding induces a relatively low level of deflection, and residual stresses and recent advances in the welding technology has shown that friction stir welding may now be broadly used in steel welding leading to significant improvement of the welding quality for new constructions and repairs. In the present study experimental and numerical analyses of friction stir welding in thick steel plates are performed. A finite element model is developed, based on a new heat input source mathematical formulation, accounting for the welding transient thermo-mechanical process of the friction stir welding-induced residual stresses. The welding-induced residual stresses, estimated by the new developed finite element model, are compared with the experiment. The present study shows that the newly developed heat source finite element model demonstrates an acceptable agreement between the numerical and experimental results. A sensitivity analysis concerning the essential governing parameters predicting the friction stir welding – induced residual stresses is also addressed. [ABSTRACT FROM AUTHOR]

The performances of a piled raft system in terms of serviceability and load-carrying capacity have been reviewed. The settlement behaviour of a square-piled raft in a layered soil is investigated using numerical analysis. The emphasis is given on quantifying the reduction of the average and the differential settlements of the raft in layered soil. A 3D finite element analysis using a commercial software called PLAXIS 3D (Version 2) is performed for various pile positions, pile numbers and pile lengths under the raft subjected to a uniform vertical loading. The settlement aspects for an efficient design of a piled raft subjected to vertical loadings have been addressed. It is found that the required piled group-raft area ratio (Bg/Br) for minimising the differential settlement of a raft in a layered soil should be within a range of 0.4 to 0.6. [ABSTRACT FROM AUTHOR]

Skirted spudcan foundations can effectively provide a considerable bearing capacity and moment fixity to withstand the complex combined vertical, horizontal, and moment loadings encountered in offshore engineering practices. The failure envelope is a general solution that characterizes the bearing capacities of offshore foundations under combined loading conditions. In this study, a series of probe tests were carried out using finite element analysis to investigate the undrained failure envelope of skirted spudcan foundations in soft clay. Particular attention was paid to exploring the influences of the soil strength heterogeneity, the footing–soil interface roughness, and the embedment depth ratio. The analysis results indicate that the envelope's size is influenced by these conditions to varying degrees, while the envelope's shape is only slightly influenced. The failure envelope associated with smooth interface conditions provides conservative results, particularly for the deeply embedded scenarios. A closed-form algebraic expression was derived to describe the failure envelope of skirted spudcan foundations, which takes proper account of the soil strength heterogeneity, footing–soil interface roughness, and embedment depth ratio. [ABSTRACT FROM AUTHOR]

This study is concerned with evaluating the response of single pile subjected to cyclic horizontal uniaxial loading. Combination of lateral cyclic loading and constant vertical or lateral load in two-orthogonal directions is also studied. Moreover, the influence of one- and two-way loading, number of cycles and the intensity of constant load in conjunction with the cyclic lateral load is presented. The study is further continued by comparing the performance of long and short single pile embedded in clayey soil. A series of three-dimensional finite element models using ANSYS code are conducted to model three-dimensional transient analysis as well as the complicated soil pile interaction. In order to verify the validity numerical model, the numerical response is compared with reported results obtained by experimental cyclic load test performed on single pile penetrated in soft clay. Results show strong coupling between the two-orthogonal direction of lateral loading that decreases the lateral pile capacity. The interaction relation of biaxial loading with the factor b = 1.2 and 1.15 for one- and two-way loading respectively may well approximate the analysis results. The results of study are presented in terms of lateral cyclic capacities, pile head deflection, displacement profile and bending moment over the pile length. [ABSTRACT FROM AUTHOR]