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Abstract: This paper investigates the skiving and cutting stock problem (SCSP) encountered in the paper and plastic film industries, in which a set of nonstandard reels generated from previous cutting processes are used to produce finished rolls through the skiving and cutting process. First, reels are skived together lengthwise to form a reel‐pyramid (a polygon), and then the reel‐pyramid is cut into finished rolls of small widths. Depending on if a reel can be divided lengthwise into subreels to form the reel‐pyramid, the problem can be classified into divisible SCSP (DSCSP) and indivisible SCSP (ISCSP). In this paper, two integer programming (IP) models are proposed for DSCSP and ISCSP, respectively. A sequential value correction procedure combined with the two IP models (SVCTIP) is developed to solve the two SCSPs. The effectiveness of the SVCTIP is demonstrated through extensive computational tests. [ABSTRACT FROM AUTHOR]

The focus of this paper is on the solution of Maxwell's equations for time-harmonic fields on triangular, possibly non-orthogonal meshes. The method described was first introduced in References 1 and 2 for eigenvalue problems arising in the design of accelerator components and dielectric loaded waveguides. It is based on the well-known Finite Integration Technique (FIT) which is a proven consistent discretization method for the computation of electromagnetic fields. The FIT-discretization on non-orthogonal 2D grids has close relations to the Nédélec elements or edge elements in the Finite Element Method. Revisiting FIT on triangular grids this paper intends to stimulate thorough studies of the latter subject which is well worth further investigations. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This work is part of the European RFCS "FISHWALL" project entitled "Fire and Seismic performances of hybrid fire walls in case of single‐storey industrial and commercial steel buildings". The aim of the project is to design a hybrid firewall solution using sandwich panels for single‐storey buildings connected with the unprotected steel structure by means of fusible links, made of aluminium bolts. In this respect, the paper shows the results of preliminary numerical analyses performed on existing case studies of single‐storey steel buildings located in low and moderate seismicity zones and they were used: i) to estimate the seismic forces acting on the fusible links and ii) to subsequently design the specimens to be tested in the laboratory. In this respect, several finite elements models were developed in order to consider the widest range of configurations of the firewall with respect to the direction of the portal frame composing the steel buildings, i.e. firewall parallel and orthogonal to the portal frames. Based on the estimated forces, the design of the six different specimens was performed and it is thoroughly shown in the paper. [ABSTRACT FROM AUTHOR]

Assessment of the structural behaviour of steel and steel‐concrete composite plate girders exposed to web shear buckling is essential when it comes to their implementation involving heavy loads and/or long spans. In this paper, numerical model of a benchmark steel‐concrete composite girder capable of capturing this phenomenon has been developed using the ABAQUS software. The developed finite element model, based on a series of large‐scale girders planned to be tested in the future, has been evaluated and elaborated on. That includes the implementation of appropriate analysis procedures, element types and contact behaviour in the study of the post‐critical buckling behaviour of steel and steel‐concrete composite plate girders. The advantages and disadvantages as well as recommendations for the future use of the investigated modelling strategies have been scrutinized. In the end, this study demonstrates the parameters with the most significant influence on the structural behaviour of composite girders exposed to shear loading. [ABSTRACT FROM AUTHOR]

This paper focuses on the Y type perfobond shear connectors of steel‐concrete composite beams with the aim to investigate the influence of the structural parameter of the connection to the resistance and ductility of the structures. The Y shaped shear connections are a new shape developed with the benefits of resisting a higher shear force by the transversal bars and a bigger area of the concrete dowels surrounded by the Y shaped plate. This type of shear connection has significant resistance against vertical separation. In this paper, an advanced finite element model for a push‐out test with a Y type perfobond shear connector has been developed and validated by the experimental test. The aim of this research is to investigate different parameters such as the concrete strength, perfobond yield stress, the existence of the transversal bars on the structural behavior. The results showed that the concrete strength has a major effect as using a higher concrete resistance gave a higher ultimate resistance with a higher ductility. The existence of the transverse bars shows a major effect on the ductility load level. On the contrary, the effect of changing the diameter of the bars on the ductility load level was slightly noticeable. While using deferent steel grades for the perfobond plate significantly affected the ultimate resistance, but not the ductility load level. In further studies more parameters will be checked, and a formula and a guideline could be developed for a design purpose. [ABSTRACT FROM AUTHOR]

It is difficult to separate Luer lock adapters during the external ventricular drainage (EVD) since they are often connected by a threaded connection, and the infusion needle put into the patient's body gets pulled out when extubation occurs unexpectedly. The paper described a new magnetic connection assembly made up of ring magnetic permanents and a Hall sensor that could be used to replace Luer lock adapters for quicker disconnection and reconnection of the drainage catheter. For the design and analysis of the device, the finite element method magnetics (FEMM) was used to estimate the size of magnetic permanents and the best detection site of the Hall sensor for detecting whether the magnetic permanents were closely attracted and/or pulled apart. Then an experiment was conducted to confirm our findings. Both simulation and experiment revealed that a pair of hollow cylindrical magnetic permanents, each with height 10 mm, outer diameter 8 mm, and inner diameter 4 mm, could achieve the same force as the Luer lock adapters held, and that the best Hall sensor detection position was in the middle of the permanent magnets, with a radial distance of about 2 mm. [ABSTRACT FROM AUTHOR]

For the simulation of acoustic-structure interaction problems, the coupled field equations must be solved. The structure is commonly discretized using finite elements, whereas for the acoustic field the boundary element method (BEM) is favorable. A mortar BEM-FEM coupling algorithm is developed that allows the combination of non-conforming meshes. The high flexibility for the choice of discretizations offers a high efficiency, since specialized shape functions and adaptive mesh refinement can be used in the subdomains. The mortar coupling algorithm yields a saddle point problem that is solved using a preconditioned inexact Uzawa algorithm. The iterative solver enables the use of the fast multipole BEM and thus coupled simulations on large boundary element models. [ABSTRACT FROM AUTHOR]

Highlights This paper presents the experimental, analytical, and numerical extensive investigation into the flexural creep performance of pultruded glass fiber reinforced polymer (pGFRP) composites at elevated service temperatures. The experimental phase involved a physical testing program on pGFRP coupons in a four‐point bending setup covering a wide range of loads (12%, 24%, and 37% stress levels) and temperature conditions (20, 40, and 60°C) over a long test duration of 720 h. The analytical Burgers model was employed to provide theoretical insights into the time‐dependent deformation behaviors, while the finite element analysis (FEA) simulations using derived reduction factor validated the accuracy of the proposed procedure. Burgers model was able to capture the experimental data very well and reached the ultimate strain failure limit within about 1.4–50 years depending on the case. The proposed simple FEA procedure yielded a pattern closely resembling the one observed from Burgers model in which they resulted in estimated endurance times with a roughly 15% difference between them. The higher stress and/or temperature, the longer the primary creep stage is. Burgers model is able to capture the experimental data very well in all conditions. Burgers general equation is able to predict failure within about 1.4–50 years. A proposed reduction factor based on Burgers model is utilized in FEA The FEA procedure shows a roughly 15% difference compared to Burgers model. [ABSTRACT FROM AUTHOR]

In recent years, the propagation of ultrasonic guided waves (UGW) along the structure to inspect has amply proven to be an excellent strategy for the health monitoring of isotropic and composite structures (SHM—structural health monitoring). For the proper development of the SHM system, the finite element method (FEM) must be mentioned, since the possibility to study the UGW in very complex structures, even characterized by different materials. Successfully locating any possible damage and identifying its severity are key factors in SHM, thus allowing to reduce the design costs. Numerically, the damage can be modeled with several approaches but it is still not clear which is the best solution to accurately reproduce the UGW mechanisms in a faulty structure. The objective of this paper is to study the various effects that different severities of damage can have on UGW propagation. For the scope, various numerical approaches are considered and the results are compared. [ABSTRACT FROM AUTHOR]

The application of design by finite element analysis (FEA) is becoming increasingly prevalent in applied engineering; however, codified provisions remain scarce. The vision of CEN/TC 250/SC 3 was to develop a new comprehensive document based on the existing provisions currently distributed throughout the different Eurocode 3 parts, and with extension where necessary to cover all fields of structural steel design. Within the development process, two documents are being prepared: (i) the code, prEN 1993‐1‐14 and (ii) a Technical Report. The new code aims to provide rules on the use of finite element analysis and other numerical methods for verifying ultimate limit states, serviceability limit states and fatigue. In parallel, the Technical Report will provide background information and explanations of all aspects of the code, as well as benchmark cases and design examples to support the correct application of the prEN1993‐1‐14 design rules and the necessary benchmarking required for model validation. The assumed stakeholders are mainly designers who can find direct guidance for design by finite element analysis in daily engineering practice. This current paper gives an overview of the new code and accompanying Technical Report, as well as the development process and harmonisation within the current Eurocode 3 framework. [ABSTRACT FROM AUTHOR]

In this research the effect of prebuckling in‐plane deflections on the critical moment to lateral‐torsional buckling of beams is investigated. Though this topic is already discussed in the literature, the relevant papers show that there are some discrepancies in the proposals and results from the various authors. In this paper a numerical parametric study is reported, conducted on doubly symmetric simple supported I‐shaped beams. The critical moment values were calculated with and without considering the effect of prebuckling deflections. Various methods were considered, including analytical formulae, thin‐walled beam finite element, and shell finite element calculations. The results justify that the in‐plane deflection has a positive effect on the critical moments, and that the effect is essentially determined by the ratio of in‐plane and lateral rigidities. However, the results highlight that the moment‐increasing effect of the prebuckling deformations can be much smaller compared to the prediction of the analytical formulae, if a shell finite element model is employed. [ABSTRACT FROM AUTHOR]

During the last decade there is an increasing awareness towards sustainable construction solutions. The reason of this shift is that the construction sector contributes to approximately 40 % of the global output of CO2 emissions, thus making it essential to act in lowering this high amount. A key aspect in the successful implementation of sustainable construction solutions is the use of construction materials that can be 100% recycled, such as steel, and that come from renewable sources, such as timber. Therefore, the interest in using steel‐timber composite (STC) elements and connections has grown since they can provide a robust alternative construction technique to traditional ones. The aim of this paper is to investigate the structural performance of a bolted STC shear connection using finite element analysis. The connection under study consists of two dahurian larch glulam elements that are bolted to the flanges of an H‐profile steel element by means of four M6 bolts for each timber component. The numerical model has been validated using the results of an experimental study where a pull‐out test of the same connection is performed [1]. Overall, the numerical results have shown good accuracy. The bolt failure has occurred when 47.5 kN of force had been applied. This amount of load is about 12% less than the failure load found in the experiment. The slip of the numerical model has been found equal to 5.4 mm whereas the slip measured in the experiment has been measured equal to 7.5 mm. In addition, the failure mode that has developed in the numerical model is governed by the formation of two hinges on the bolts which coincides to the experimental one. To sum up, the numerical model has managed to capture to a great extent the structural performance of the composite connection as presented in the experimental findings. [ABSTRACT FROM AUTHOR]

This paper is focused on the behavior of bolted 3D beam‐to‐column joints, when the secondary beams are attached to the weak axis of the column by two additional plates welded between the column flanges. In this joint configuration the component column web in tension is modifying by the presence of the additional plates that must be considered in the stiffness evaluation. Moreover, the stiffness of this component is different in case of double‐sided and single‐sided joints. Therefore, based on the result of a parametric study with finite element models, two different mechanical models for the stiffness of the component column web in tension are proposed for double‐sided and single‐sided joints. [ABSTRACT FROM AUTHOR]

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As one kind of jacketed vessels, half‐pipe jacketed vessels are widely used in engineering owing to the structural and heat transfer advantages. But for the design of half‐pipe jacketed vessels, there are limitations in codes ASME VIII‐1 and ASME VIII‐2. In this paper, a new design method based on numerical limit‐load analysis is proposed to design half‐pipe jacketed vessels. The scheme and advantages of the method are presented through a design of half‐pipe jacketed vessel. It is found that by performing limit‐load analysis, problems of the codes ASME VIII‐1 and ASME VIII‐2 about the structural limitation of the half‐pipe jacketed vessels and loading limitation are solved. In addition, by performing limit‐load and parametric analysis, the strength weakness areas on the vessels can be found, and the rational strength design of a structure can be achieved. [ABSTRACT FROM AUTHOR]

In this paper, we propose and analyze the numerical algorithms for fast solution of periodic elliptic problems in random media in ℝd$$ {\mathbb{R}}^d $$, d=2,3$$ d=2,3 $$. Both the two‐dimensional (2D) and three‐dimensional (3D) elliptic problems are considered for the jumping equation coefficients built as a checkerboard type configuration of bumps randomly distributed on a large L×L$$ L\times L $$, or L×L×L$$ L\times L\times L $$ lattice, respectively. The finite element method discretization procedure on a 3D n×n×n$$ n\times n\times n $$ uniform tensor grid is described in detail, and the Kronecker tensor product approach is proposed for fast generation of the stiffness matrix. We introduce tensor techniques for the construction of the low Kronecker rank spectrally equivalent preconditioner in a periodic setting to be used in the framework of the preconditioned conjugate gradient iteration. The discrete 3D periodic Laplacian pseudo‐inverse is first diagonalized in the Fourier basis, and then the diagonal matrix is reshaped into a fully populated third‐order tensor of size n×n×n$$ n\times n\times n $$. The latter is approximated by a low‐rank canonical tensor by using the multigrid Tucker‐to‐canonical tensor transform. As an example, we apply the presented solver in numerical analysis of stochastic homogenization method where the 3D elliptic equation should be solved many hundred times, and where for every random sampling of the equation coefficient one has to construct the new stiffness matrix and the right‐hand side. The computational characteristics of the presented solver in terms of a lattice parameter L$$ L $$ and the grid‐size, nd$$ {n}^d $$, in both 2D and 3D cases are illustrated in numerical tests. Our solver can be used in various applications where the elliptic problem should be solved for a number of different coefficients for example, in many‐particle dynamics, protein docking problems or stochastic modeling. [ABSTRACT FROM AUTHOR]

Intrinsic localized mode (ILM) can be generated in multiple mass‐spring systems using nonlinear springs, and ILM has attracted a lot of attention due to its special vibration modes that are not found in linear systems. However, the difficulty of creating nonlinearity remains a barrier to ILM research. In this paper, we propose a rotating magnetic spring based on magnetic nonlinearity. The nonlinear restoring properties of the proposed magnetic spring are confirmed by finite element method (FEA). Finally, using the restoring properties obtained from FEA, it is shown that ILM can be excited by MATLAB numerical analysis. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Ring flange connections with preloaded high strength bolts are most commonly used to connect two segments of steel tubular towers. Behaviour and durability of ring flange connections is influenced by various factors, including stiffness of ring flanges, fabrication and execution imperfections, welding technology and welding details of the ring flange/segment connection, type of bolts, pretension technique and control of accomplished pretension force in bolts. This paper focuses on ring flange connections with defined contacts compared to the "full ring flange connection". No imperfections are considered. Behaviour of the ring flange connections is investigated by advanced finite element analysis (FEA). The realistic geometry of bolted connection, ductile damage material model and element removal are used in the advanced FE model with explicit numerical solver. In addition, the influence of two types of high strength bolts, fully‐threaded and partial‐threaded bolts, on the mechanical behaviour of connections is considered. The failure modes and tensile stiffness are compared using different analytical models. Finally, recommendations for calculation of the tensile resistance of the connection and the bolt force with defined surface area are provided. [ABSTRACT FROM AUTHOR]

In this paper, we adopt the discontinuous Galerkin finite element method and the enriched Crouzeix‐Raviart finite element method to study the magnetohydrodynamic (MHD) Stokes eigenvalue problem describing the flow of a viscous and electrically conducting fluid in a duct under the influence of a uniform magnetic field. We give the convergence and error analysis for the approximations, and the theoretical analysis and numerical experiments show that the methods are effective and can be applied to general domains. We also explore the influence of the Hartmann number on the eigenpairs and the consequential variation of the eigenstructure with the magnetic field by numerical experiments. [ABSTRACT FROM AUTHOR]

The effect of openings left in reinforced concrete shear walls due to functional requirements or architectural reasons is an important issue that should not be underestimated mainly since shear walls are considered as one of the most critical load‐carrying members in a structure owing to playing an active role against seismic forces. In this paper, a parametric study was carried out by creating a nonlinear finite element model to determine the effects of openings in reinforced concrete shear walls on the maximum shear force bearing capacities, initial stiffness, displacement ductility ratios, and energy dissipation capacities of the shear walls. The variables examined in the study were the size of the openings left in the reinforced concrete shear walls, opening location, the number of openings, and the concrete compressive strength used in the production of the shear walls. In the first part of the study, nonlinear finite element models of three experimental shear wall test elements: one with no opening (solid), and two with openings: were created using ABAQUS finite element software package, then verified by comparing the numerical analysis results with the experimental results. In the second part of the study, a nonlinear finite element model of 44 reinforced concrete shear walls, including the parameters planned to be investigated, was created by using the verified model, and finite element model (FEM) analyses were performed. As a result of numerical analyses, a capacity reduction coefficient proposal has been developed to calculate the shear force capacities of reinforced concrete shear walls with openings. [ABSTRACT FROM AUTHOR]

Summary: This paper concentrates on strong delay‐independent stability of neutral linear time‐invariant delay systems with multiple commensurate time delays. The stability analysis of linear neutral systems is complicated by the need to locate the roots of a transcendental characteristic equation and to take into account the global hyperbolicity of an associated difference system. In this paper, we propose a convex necessary and sufficient condition for testing strong delay‐independent stability. This result mainly follows from Kronecker sum properties and the Kalman‐Yakubovich‐Popov lemma, which allows us to present the main result in terms of a single linear matrix inequality feasibility test. The paper is closed by showing numerical examples that illustrate the applicability and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents the findings of a large‐scale experimental study that focus on assessing structural behavior of reinforced concrete (RC) cantilever slabs with carbon/epoxy fiber‐reinforced polymer (CFRP) composite strips using a near‐surface‐mounted (NSM) approach. The NSM/CFRP system evaluated in this study was implemented in strengthening the shoulders of the Slide Canyon Bridge in California, USA. The experimental phase is divided into two main parts: (i) determining the design parameters for NSM, including the bondline strength through pull‐out tests, and (ii) conducting a practical evaluation of the bending behavior of original and retrofitted RC cantilever slabs, each with varying NSM reinforcement and three different development lengths. Results of this study indicated that the use of NSM‐CFRP has a considerable benefit in that it significantly improves ductility and changes the failure mode of the unstrengthened RC slab from the typical brittle shear‐based failure mode to a more ductile flexural‐based failure mode. The large‐scale slab specimens' performances, which had different development lengths, showed little variance, except for the slab specimen with a development length of 457.0 mm that exhibited an appreciable flexural stiffness as compared to other specimens evaluated in this study. In order to simulate the serviceability and ultimate behavior of the RC slab specimens, linear and nonlinear finite element analyses were performed. A satisfactory agreement between numerical and experimental results was achieved especially at load level prior the initiation of large‐size cracks. [ABSTRACT FROM AUTHOR]

Liquid sodium hybrid bearing is mechanical pump shaft bottom key support components, that play a balanced radial force of the impeller by fluid effect, in order to improve the bearing performance, based on the calculation model, simulation analysis, structure improvement and other aspects of analysis, this paper based on the theory of fluid mechanics of bearing finite element model for numerical calculation and analysis of flow field. Under different eccentricities and vibration velocities, the influence of structure improvement on bearing capacity is analysed. The results show that the bearing capacity of the liquid sodium hybrid bearing is mainly the hydrostatic bearing capacity, and the hydrodynamic pressure only plays an auxiliary role. After the improvement of the load‐bearing structure, the load‐bearing capacity is increased by 4%–7.3%. And the leakage is reduced by 27%–38% when the depth of the annular groove is 0.6 mm. [ABSTRACT FROM AUTHOR]

This paper presents the design and commissioning of a novel pseudo‐static test apparatus for underground structures that accounts for soil‐structure interaction by simulating the soil with suitably designed springs. The developed apparatus was employed to conduct 1:10 large scale tests on a two‐story three‐span prefabricated subway station structure. Two comparative cyclic load tests were conducted: one involved the developed springs‐structure system; and one involved the structure alone (no springs). The test results demonstrated important differences in the damage location, damage degree, bearing capacity, and deformation capacity of the prefabricated subway station structure under the two loading conditions (i.e., with and without springs). The presence of springs (i.e., soil‐structure interaction) enhanced the lateral collapse resistance of the underground structure and affected the inter‐story displacement ratio (IDR) between the upper and lower layers of the two‐story prefabricated subway station structure. However, it did not affect the deformation coordination of the walls and columns of each layer. A finite element model of the prototype station was also established to conduct dynamic time history analysis simulating the soil‐structure interaction. The results from the dynamic analysis validated the effectiveness of the pseudo‐static test method employing the spring‐structure system. The excellent agreement between the calculated dynamic responses and the responses obtained from the pseudo static tests confirmed the ability of the developed apparatus to conduct seismic tests on complex large‐scale underground structures such as prefabricated subway stations. Thus, this test methodology might be utilized to attain valuable insights into the seismic performance of prefabricated subway stations at a relatively low cost and effort. [ABSTRACT FROM AUTHOR]

Unlocking the biomechanical effects of cervical spine positioning rotation manipulation in the treatment of patients with neck pain. In this paper, the safety of the cervical positioning rotation manipulation is analyzed by experimentally obtaining head kinematic data, importing them into a finite element model that has been developed and validated, and calculating and analyzing the angular displacements, disc pressures, and articular surface contact forces in the normal and pathological models. The results show that the cervical spine positioning rotation technique is more effective in adjusting the position and applying force to the cervical spine C5–C6 "tendon out of the groove and bone misalignment" pathological model. Also, the cervical positioning rotation manipulation is applied with less variation in disc nucleus pulposus pressure than in the non‐positioning situation. Thus, in patients with disc degeneration, cervical positioning rotational manipulation has a more direct mechanical effect and is safer than non‐positioning rotational manipulation. The cervical spine positioning rotation manipulation is a safe method that can effectively treat patients with neck pain. It has been well demonstrated in the computational analysis of the pathological model. [ABSTRACT FROM AUTHOR]

This paper analyses the performance of the experimental setups to assess the punching strength of slab‐column connections in continuous flat slabs under vertical and horizontal loading. In the last years, several experimental campaigns have been performed to investigate the punching strength of slab‐column connections, but most of the experimental tests concerned isolated slab‐column connections. Among the few setups aimed at reproducing the eccentric punching failure in continuous flat slabs, the setup developed at the NOVA School of Science and Technology in Lisbon is considered in this paper. The performance of the Lisbon setup is assessed through nonlinear finite element analyses, calibrated on experimental data, by comparison with numerical results of a theoretical continuous setup. Then, the performance of the isolated setups, used in many researches and at the base of some international codes, is also evaluated through the same finite element model. Numerical analyses highlight that the setup developed in Lisbon could provide reliable ultimate rotations of continuous flat slab connections, but it underestimates the punching strength. Despite isolated setups lead to similar results when compared with the Lisbon setup, the latter seems to provide a better representation of a continuous slab‐column connection. The numerical analyses presented in this paper have been performed assuming monotonic lateral loading. [ABSTRACT FROM AUTHOR]

The purpose of this article is to report on improvements on the interpretation and insights emerging from dynamic decomposition weight analysis (DDWA). These improvements emerged from efforts to further automate and expand the eigenvalue elasticity analysis methods and resolve inconsistencies in assumptions made in published reports of DDWA usage. In addition to making available to the broad system dynamics community an improved toolset to perform eigenvalue elasticity analysis, in this paper we clarify the set of assumptions needed to obtain reliable results and develop a new framework to assess the impact of model parameters on the projections of behavior modes on stock behavior. We illustrate the use of these developments by updating a previously published model analysis. The paper concludes by summarizing our findings and their implications for the further development of structural dominance analysis. © 2018 System Dynamics Society [ABSTRACT FROM AUTHOR]

The linear elasticity problem has important applications in structural analysis and engineering design. It is shown that the classical Crouzeix–Raviart finite element method is unstable to solve the linear elasticity eigenvalue problem with the pure traction boundary condition. In this paper, first we propose a new scheme with the stabilization terms. Then we prove the a priori error estimates for approximate eigenpairs. Finally, we carry out numerical experiments using the stabilized scheme. Theoretical analysis and numerical results show that this scheme is locking free and efficient. [ABSTRACT FROM AUTHOR]

This paper describes a 2D‐3D hybrid model for tsunami simulations that uses an overlapping method based on an arbitrary grid. A 2D model is used to simulate wave propagation from the source area to the offshore area, and a 3D model is then used to simulate the free surface flow around structures in coastal areas. An overlapping method that satisfies the conservation and compatibility conditions is developed to couple the two models. The shallow water equations are applied for the 2D model, and the Navier‐Stokes equations and continuity equations are applied for the flow field of the 3D model. The Allen‐Cahn equation is applied for the interface‐capturing method of the 3D model. The stabilized finite element method is applied for the spatial discretization and the Crank‐Nicolson method is used for the temporal discretization of the governing equations. The model is verified and validated through several numerical analysis examples. [ABSTRACT FROM AUTHOR]

This paper describes a novel method for mapping between basis representation of a field variable over a domain in the context of numerical modelling and inverse problems. In the numerical solution of inverse problems, a continuous scalar or vector field over a domain may be represented in different finite-dimensional basis approximations, such as an unstructured mesh basis for the numerical solution of the forward problem, and a regular grid basis for the representation of the solution of the inverse problem. Mapping between the basis representations is generally lossy, and the objective of the mapping procedure is to minimise the errors incurred. We present in this paper a novel mapping mechanism that is based on a minimisation of the L2 or H1 norm of the difference between the two basis representations. We provide examples of mapping in 2D and 3D problems, between an unstructured mesh basis representative of an FEM approximation, and different types of structured basis including piecewise constant and linear pixel basis, and blob basis as a representation of the inverse basis. A comparison with results from a simple sampling-based mapping algorithm shows the superior performance of the method proposed here. © 2016 The Authors. International Journal for Numerical Methods in Engineering Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

The paper presents the tridimensional numeric model of an inner slab‐column connection of reinforced concrete, which was previously tested against the punching shear in the lab of the University of Brasília. The numerical analysis has been carried out by the finite element method, using the software ABAQUS. To evaluate the sensitivity of the main factors that influence the responses of the model, a parametric investigation was conducted as per the finite element mesh, mechanical properties of the concrete and plastic parameters of the assumed model for the concrete, named by concrete damaged plasticity model (CDPM). The results of the resistance capacity, displacements, strains, cracking pattern, and failure mode were compared with those obtained experimentally. From this comparison, it was concluded that the numerical model was able to reproduce the punching shear phenomenon with a high level of precision. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a finite‐time stability results of linear delay fractional‐order systems is investigated based on the generalized Gronwall inequality and the Caputo fractional derivative. Sufficient conditions are proposed to the finite‐time stability of the system with the fractional order. Numerical results are given and compared with other published data in the literature to demonstrate the validity of the proposed theoretical results. [ABSTRACT FROM AUTHOR]

In current practice, a relatively wide range of different interconnections and assembly systems is being used for the design of modular buildings made of volumetric prefabricated frames. The integration strategies and design criteria for providing structural robustness or prevention of disproportionate collapse for such buildings are completely different with those with conventional systems. This is mainly because of their fundamentally different configuration of joints and the redundancy they provide for the structure. This paper studies the robustness of multistory modular structures, made of prefabricated volumetric steel frames, against progressive collapse, which can be triggered by various column or module loss scenarios. In this study, the flexibility of modules and propagation of the damage inside the individual modules are taken into account, and the buckling of columns, as well as the effects of material nonlinearity on the responses and capacity of the entire system, are also considered. Load redistribution patterns and possible gravity-induced collapse mechanisms are inspected in various collapse scenarios for a typical mid-rise modular steel frame. In the numerical model, each individual prefabricated volumetric module is composed of discrete beam and column frame elements, connected through conventional rigid beam-column connections. The volumetric modular steel frames are connected via corner vertical and horizontal intermodule joints; each one is modeled utilizing one axial and two shear springs with predefined nonlinear force-displacement behavior in a 3D finite element analysis. The local damage scenarios are assumed to be due to instantaneous loss of columns or entire modules, for which the interactions between the modular units, overall structural robustness, load redistribution, possible collapse mechanisms, and progressive collapse response of the frames are investigated. The results indicate that the additional redundancy may help the modular steel frames survive from some corner column or single module removals but will not be able to maintain their robustness under combined module removal scenarios. [ABSTRACT FROM AUTHOR]

Dynamic two-phase interaction of soil can be modelled by a displacement-based, two-phase formulation. The finite element method together with a semi-implicit Euler-Cromer time-stepping scheme renders a discrete equation that can be solved by recursion. By experience, it is found that the CFL stability condition for undrained wave propagation is not sufficient for the considered two-phase formulation to be numerically stable at low values of permeability. Because the stability analysis of the two-phase formulation is onerous, an analysis is performed on a simplified two-phase formulation that is derived by assuming an incompressible pore fluid. The deformation of saturated porous media is now captured in a single, second-order partial differential equation, where the energy dissipation associated with the flow of the fluid relative to the soil skeleton is represented by a damping term. The paper focuses on the different options to discretize the damping term and its effect on the stability criterion. Based on the eigenvalue analyses of a single element, it is observed that in addition to the CFL stability condition, the influence of the permeability must be included. This paper introduces a permeability-dependent stability criterion. The findings are illustrated and validated with an example for the dynamic response of a sand deposit. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the field patterns of the TE modes in antipodal ridge waveguide (ARW) and double antipodal ridge waveguide (DARW) are presented by finite element method. The figures in this paper are useful in the design of antipodal waveguide components for wideband microwave transmission. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 79–82, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10679 [ABSTRACT FROM AUTHOR]

This paper presents the buckling response and vibration characteristic of the cylindrical steel liquid storage tanks filled with water when subjected to strong earthquake excitations. Finite element analysis (FEA) is performed by using ABAQUS software. The geometrically perfect tanks with different R/t and H/R ratios are considered for modal and linear seismic analysis. The modeling method, appropriate element type, and the necessary number of elements for numerical analysis are recommended. Field observations during past earthquakes and published experimental results are used to substantiate the accuracy of employed FEA. The accuracy of the current design guidelines is assessed based on the extensive parametric study. According to the results of the parametric study of the perfect tanks, the buckling strength decreases significantly as the radius‐to‐thickness ratio (R/t) increases. Furthermore, it decreases slightly as the height‐to‐diameter ratio (H/R) increases. [ABSTRACT FROM AUTHOR]

This paper provides an efficient and robust numerical solution for the linear buckling analysis of tubular members, such as the supporting tower structures of wind turbines. The method uses Fourier‐series approximations for the displacement functions. Longitudinal discretization can optionally be applied, i.e., the member can be divided into segments. The strain‐displacement relationship directly considers the curved geometry. The implementation allows for arbitrary support conditions. Four pure loading situations are considered, uniform – in each segment – along the length: normal force, bending moment, torque, and shear force; however, they can arbitrarily be combined, as is commonly occurring in wind turbine towers. The applied methodology results in a computational advantage compared to the shell finite element method, while still maintaining much more generality and applicability compared with common analytical solutions. Furthermore, the method is supplemented with features, as spectral analysis and buckling length calculation. [ABSTRACT FROM AUTHOR]

Inclusion is one of the main causes for unqualified wire. However, the forming mechanism of drawing fracture due to inclusions is still unclear. Therefore, it is significant to figure out the forming mechanism of wire drawing fracture with inclusions for designing and manufacturing high‐quality wires. In this paper, a physical model of wire with inclusion is established based on experimental observations. Multipass drawing is simulated by using finite element method (FEM) with the developed numerical damage modeling. Numerical results demonstrate that the damage increases with the development of drawing progress, and the damage caused by high elastic modulus of inclusion is greater than that of low elastic modulus. Pen‐tip shaped fracture of wire with inclusions is mainly caused by the superposition of core and external V‐shaped damage. Furthermore, the core V‐shaped crack will propagate along the external V‐shaped damage area. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we present a set of complete solutions for a nonconvex variational problem with double‐well potentials in higher dimensions. Based on the canonical duality theory, the corresponding nonlinear Euler‐Lagrange equation with Neumann boundary condition can be converted into an algebraic equation, which can be solved analytically to obtain the solutions of the dual problem. Correspondingly, local extrema of the primal problem can be identified by the pure complementary energy principle. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the saturated delayed stabilization of a chain of integrators with higher‐order nonlinear terms. With the aid of a recent state transformation, the system is transformed into a canonical form in which time delay appears in both input and states. As a result, natural cancellations can be fully used in the saturation reduction analysis, and fewer terms need to be estimated in the asymptotical stability analysis of the reduced system. In addition, a single tuneable parameter is introduced to the special state transformation, which facilitates compensating an arbitrarily large input‐delay. As an example, a simplified inertia wheel pendulum system is provided with an explicit controller and numerical simulations are given to demonstrate the effectiveness of the suggested controller. [ABSTRACT FROM AUTHOR]

In this paper, the cell-based smoothed finite element method (CS-FEM) with the semi-implicit characteristic-based split (CBS) scheme (CBS/CS-FEM) is proposed for computational fluid dynamics. The 3-node triangular (T3) element and 4-node quadrilateral (Q4) element are used for present CBS/CS-FEM for two-dimensional flows. The 8-node hexahedral element (H8) is used for three-dimensional flows. Two types of CS-FEM are implemented in this paper. One is standard CS-FEM with quadrilateral gradient smoothing cells for Q4 element and hexahedron cells for H8 element. Another is called as n-sided CS-FEM (nCS-FEM) whose gradient smoothing cells are triangles for Q4 element and pyramids for H8 element. To verify the proposed methods, benchmarking problems are tested for two-dimensional and three-dimensional flows. The benchmarks show that CBS/CS-FEM and CBS/nCS-FEM are capable to solve incompressible laminar flow and can produce reliable results for both steady and unsteady flows. The proposed CBS/CS-FEM method has merits on better robustness against distorted mesh with only slight more computation time and without losing accuracy, which is important for problems with heavy mesh distortion. The blood flow in carotid bifurcation is also simulated to show capabilities of proposed methods for realistic and complicated flow problems. [ABSTRACT FROM AUTHOR]

This paper develops a method to analyze the piled raft foundation under vertical harmonic load. This method takes into account the interactions among the piles, soil, and raft. The responses of the piles and raft are formulated as a series of equations in a suitable way and that of layered soils is simulated with the use of the analytical layer-element method. Then, according to the equilibrium and continuity conditions at the piles-soil-raft interface, solutions for the piled raft systems are obtained and further demonstrated to be correct through comparing with the existing results. Finally, some examples are given to investigate the influence of the raft, pile length-diameter ratio, and layering on the response of the piled raft foundations. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A major challenge for crash failure analysis of laminated composites is to find a modelling approach, which is both sufficiently accurate, for example, able to capture delaminations, and computationally efficient to allow full-scale vehicle crash simulations. Addressing this challenge, we propose a methodology based on an equivalent single-layer shell formulation which is adaptively through-the-thickness refined to capture initiating and propagating delaminations. To be specific, single shell elements through the laminate thickness are locally and adaptively enriched using the extended finite element method such that delaminations can be explicitly modelled without having to be represented by separate elements. Furthermore, the shell formulation is combined with a stress recovery technique which increases the accuracy of predicting delamination initiations. The paper focuses on the parameters associated with identifying, introducing and extending the enrichment areas; especially on the impact of these parameters on the resulting structural deformation behaviour. We conclude that the delamination enrichment must be large enough to allow the fracture process to be accurately resolved, and we propose a suitable approach to achieve this. The proposed methodology for adaptive delamination modelling shows potential for being computationally efficient, and thereby, it has the potential to enable efficient and accurate full vehicle crash simulations of laminated composites. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Heat transfer of a power-law non-Newtonian incompressible fluid in channels with porous walls has not been carefully studied using a proper numerical method despite a few constructions of approximate analytic solutions through the similarity transformation and perturbation method for Newtonian fluids (i.e. power-law index being one). In this paper, we propose a finite element method for the thermal incompressible flow equations. The incompressible condition is treated by a penalty formulation. Numerical solutions are validated by comparing them with an approximate analytic solution of the Navier-Stokes equation in the Newtonian fluid case. Then, the method is used to simulate the heat transfer of various power-law fluids. Additionally, unlike previous studies, we allow the thermal diffusivity to be a function of temperature gradient. The effect of different values of the parameters on the temperature and velocity is also discussed in this paper. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we propose a Galerkin finite element method for the Cahn‐Hilliard‐Cook equation involving the Caputo‐type fractional derivative, which can be used to describe the interface phenomena for modeling the phase transitions with the random effects and the properties of shape memory. The regularity properties of mild solution to the given problem are presented, and a result concerning the convergence error estimate of the corresponding semidiscrete scheme is established. Finally, we construct the fully discrete scheme based on the approximations of the Mittag‐Leffler function, and the strong convergence error estimate of the proposed scheme is also studied. [ABSTRACT FROM AUTHOR]

In this paper, numerical limit analysis is applied to evaluate the bearing capacity of a single rigid pile embedded in a ponderable homogeneous cohesive‐frictionless soil subjected to vertical, horizontal, and moment (VHM) loading combinations. All loads act in the same plane. Accurate lower and upper bounds are calculated using finite element limit analysis code OPTUMG3. As the gap between the bounds hardly exceeds 5%, the average limit load provides a good estimate of the exact ultimate load and can be used with confidence for design purposes. By adopting typical values for the dimensionless pile length‐to‐diameter ratio, most cases of practical interest are treated. The numerical results are compared against failure surfaces predicted by theories from the literature. Comparison shows that previously developed methods can be conservative or slightly overestimates the limit loads. New design charts are provided. The safe loads domain is constructed in the VHM space using the average limit load. Closed‐form expressions are proposed to describe the native and the normalized VMH failure envelope as a function of the pile length‐to‐diameter ratio. In the VH plane, the failure surface is described by an eccentric superellipse, whereas in the MH plane, the limit curve is an inclined ellipse. [ABSTRACT FROM AUTHOR]

In this paper, we introduce numerical schemes and their analysis based on weak Galerkin finite element framework for solving 2‐D reaction–diffusion systems. Weak Galerkin finite element method (WGFEM) for partial differential equations relies on the concept of weak functions and weak gradients, in which differential operators are approximated by weak forms through the Green's theorem. This method allows the use of totally discontinuous functions in the approximation space. In the current work, the WGFEM solves reaction–diffusion systems to find unknown concentrations (u, v) in element interiors and boundaries in the weak Galerkin finite element space WG(P0, P0, RT0). The WGFEM is used to approximate the spatial variables and the time discretization is made by the backward Euler method. For reaction–diffusion systems, stability analysis and error bounds for semi‐discrete and fully discrete schemes are proved. Accuracy and efficiency of the proposed method successfully tested on several numerical examples and obtained results satisfy the well‐known result that for small values of diffusion coefficient, the steady state solution converges to equilibrium point. Acquired numerical results asserted the efficiency of the proposed scheme. [ABSTRACT FROM AUTHOR]

In this paper we provide key estimates used in the stability and error analysis of discontinuous Galerkin finite element methods (DGFEMs) on domains with curved boundaries. In particular, we review trace estimates, inverse estimates, discrete Poincaré–Friedrichs' inequalities, and optimal interpolation estimates in noninteger Hilbert–Sobolev norms, that are well known in the case of polytopal domains. We also prove curvature bounds for curved simplices, which does not seem to be present in the existing literature, even in the polytopal setting, since polytopal domains have piecewise zero curvature. We demonstrate the value of these estimates, by analyzing the IPDG method for the Poisson problem, introduced by Douglas and Dupont, and by analyzing a variant of the hp‐DGFEM for the biharmonic problem introduced by Mozolevski and Süli. In both cases we prove stability estimates and optimal a priori error estimates. Numerical results are provided, validating the proven error estimates. [ABSTRACT FROM AUTHOR]

In this paper, we consider the effect of adding a coarse mesh correction to the two‐grid algorithm for the mixed Navier–Stokes/Darcy model. The method yields both L2 and H1 optimal velocity and piezometric head approximations and an L2 optimal pressure approximation. The method involves solving one small, coupled, nonlinear coarse mesh problem, two independent subproblems (linear Navier–Stokes equation and Darcy equation) on the fine mesh, and a correction problem on the coarse mesh. Theoretical analysis and numerical tests are done to indicate the significance of this method. [ABSTRACT FROM AUTHOR]

In this paper, the seismic behavior of wind turbines sitting on a finite flexible soil layer is investigated in three-dimensional space. A numerical algorithm formulated in frequency domain is proposed in order to simulate the dynamic soil-structure interaction (SSI). The wind turbine is discretized using finite element method (FEM) while, the underlying soil is represented by complex dynamic stiffness functions based on cone models. A parametric study consisting of 24 ground motions and three soil profiles is carried out, and different response quantities of the wind tower model are calculated and presented in the paper. The free-field ground motions are estimated based on an equivalent linear approach using SHAKE2000 computer software. Transfer functions for total acceleration of the wind tower are obtained under the considered soil profiles and the modal frequencies of the coupled wind turbine-soil foundation are estimated. It is shown that the response quantities such as displacement, rotation, acceleration, base shear and moment are significantly affected by SSI, although the effect of SSI on the fundamental frequencies of the wind tower is insignificant. The moment and shear force distribution along the height of the tower is highly influenced as the soil stiffness decreases. The change in seismic demand distribution along the tower height because of SSI is not addressed by simplified design approached and should be carefully considered in seismic design of wind towers. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]