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Abstract: Coating blades are used in the paper industry to meter off the excess coating applied to the paper. They are essential in attaining high-quality coating films with minimum operating cost. During the coating process, the blades are worn down at the tip and are replaced when the coating quality degrades. The objectives of this study are to predict the wear rate of the blades and examine the hypothesis that the blades wear into a quasi-steady-state wear profile, despite both low- and high-angle particle impact. Experimental data and results from finite element simulations are presented for a series of blade materials and suspensions. The approach taken differs considerably from earlier studies, in that it treats blade wear as erosion from the action of the impacting slurry particles rather than abrasion, thus explaining the enhanced wear around the heel. The current approach relies on computer experiments to solve the equations for the liquid flow field, the individual particle motion, the substrate deformation and the eroded volume of the blade, rather than employing empirical relations between wear rates and average fluid velocity. The shear thinning behavior of the coating suspension was properly taken into account. To validate the calculations, blade samples from both a pilot and an off-machine coater were collected at a variety of time intervals. The blade samples aided not only in the establishment of the wear rates and the identification of the wear patterns, but also in the confirmation of the steady-state wear hypothesis that is correctly predicted by the simulations. [Copyright &y& Elsevier]

A new shell element has been proposed for geometrically non-linear, finite element analyses of axially moving paper web. Web instability problems of paper travelling in a printing system, such as wrinkling and fluttering, pose special challenges in the numerical analyses. For examples, these are finite bending stiffness (as opposed to membrane), orthotropy, and non-uniform distributions of mechanical and hygro-properties (in different length scales). The new formulation has accounted for paper transport velocity and paper bending stiffness based on a mixed Lagrangian–Eulerian description of the motion. A natural coordinate system has been employed in the analytical and finite element formulations. Benchmarking with different finite elements in various tests showed that the proposed element is indeed more stable and reliable for the chosen application than existing elements. The usability of the shell element has been successfully demonstrated by two example problems: wrinkling of stretched isotropic and orthotropic membranes, and the vibration of a web showing a speed-tensioning effect above a critical web transport velocity. [Copyright &y& Elsevier]

Thin-walled tubular deployable composite boom (DCB) has gained significant attention due to its lightweight, simple structure and high packaging efficiency. The experimental and numerical simulation methods were employed in this paper to investigate the folding behavior of the DCB. Using T700/epoxy unidirectional reinforced prepreg as raw material, DCB specimens were prepared by the vacuum bag method. To complete the folding experiments of DCB specimens, a folding mechanism was designed and manufactured. Folding experiments of DCB specimens were conducted and folding moment versus rotational displacement curves were measured. In addition, a Finite Element Model (FEM) was established to predict the folding behavior of the DCB. Different failure criteria were considered in the numerical analysis, including the Tsai‐Hill criterion and maximum stress criterion. Prediction results using the FEM were compared with experimental results, and both sets of results were in good agreement. It is shown that the DCB can achieve the folding function without failure. The research results in this paper are of great significance to the practical engineering application of the DCB. [Display omitted] • Six tubular deployable composite boom specimens and a precise folding mechanism were designed and prepared. • Folding experiments were conducted to measure the folding moment and rotational displacement curves. • A finite element model for predicting the folding behavior of the tubular deployable composite boom was established. [ABSTRACT FROM AUTHOR]

The mechanical response of three different structural core sandwich panels in out-of-plane compression and shear has been analyzed. Specific core shapes examined are arc-tangent, wavy trapezoidal and hemispherical. Unit cells consisting of representative elements of the core attached to face sheets were selected for analysis. Both face sheets and core were assumed made from paper. Finite element analysis employing large deformation and rotations and orthotropic elastic–plastic behavior was used. The results show that the arc-tangent and trapezoidal cores are prone to collapse by extensive bending and buckling, whereas the hemispherical core behaved more stably in compression and shear. Core sheets with a hemispherical shape were prepared from copy paper sheets in a specially designed forming machine. Sandwich test specimens were prepared from this core and tested in out-of-plane compression, and the load-displacement response was compared to predictions from finite element simulations. The experimental and finite element results were consistent. [ABSTRACT FROM AUTHOR]

Abstract: A finite element procedure, developed in order to account for the effect of high anisotropy at folding of coated papers, is presented. The anisotropic behaviour (with very low stiffness in the thickness direction) is modelled using stiff structural elements (trusses and beams). The numerical results indicate that high elastic anisotropy leads to lower strain levels at folding than reported in previous analyses where this effect was not accounted for. High plastic anisotropy, on the other hand, will contradict this result. [Copyright &y& Elsevier]

Folding of coated paper is examined numerically using the finite element method. Particular emphasis is put on the behaviour of field variables relevant for cracking of the coating layers. In the numerical analysis, the basepaper is modelled as an anisotropic elastic–plastic material (both elastic and plastic anisotropy is accounted for) while the constitutive behaviour of the coating layers are approximated by classical (Mises) elastoplasticity. The numerical results suggest, among other things, that particular forms of plastic anisotropy can substantially reduce the maximum strain levels in the coating. It is also shown that delamination buckling, in the present circumstances, will have a very small influence on the strain levels in the coating layer subjected to high tensile loading. [Copyright &y& Elsevier]

Abstract: Strains, computed by the finite element method, are evaluated and compared to an experimentally determined strain field. The analyzed low-density paper has been designed to ensure bond–breakage as the dominating damage mechanism and the paper material is approximately in-plane isotropic. An optical non-contact displacement measuring system has been used in fracture tests to determine the strain field in the crack-tip region of a pre-fabricated crack. Additionally, acoustic emission monitored tensile tests have been conducted to determine onset and evolution of damage processes and thereby enabling calibration of required constitutive parameters. The results suggest that the investigated paper material can tolerate significantly higher strains than what is predicted by a classic elastic–plastic J 2-flow theory. Immediately before onset of the final fracture (i.e., localization), the experimental measured normal strain in the near-tip region is around 60% higher than the computed strain when using exclusively an elastic–plastic theory for the corresponding load while the strain computed utilizing a non-local damage theory is of the same order of magnitude as the experimentally measured strain. Hence, it seems essential to include a non-local continuum theory to describe strains in the near-tip region quantitatively correct for paper materials. It is demonstrated that path independence of the well-known J-integral does not prevail for this class of material models. Only for the special situation of a homogenous damage field in the crack-tip region may the stress and strain fields be described by the well-known HRR-solutions. [Copyright &y& Elsevier]

Abstract: We present a model for the laminated composite plate problem based on the Reissner–Mindlin model and first-order lamination theory. The weak problem based on this model is solved with the finite element method using stabilized MITC (mixed interpolation of tensorial components) finite elements. Detailed a priori estimates are given for the mixed finite element formulation of the problem. Explicit bounds for the continuity and coercivity constants of the coupling terms are presented, thus refining earlier results. Furthermore, we present an application of the theory to the paper cockling problem and investigate the effect of boundary conditions on the small-scale deformation of the solution numerically. [Copyright &y& Elsevier]

Abstract: A model, using the finite element method (FEM), was developed for the analysis of the time and humidity-dependent stresses of paper webs at offset printing press conditions. The offset press was simplified to a flat thin moving web and its unit process steps were described by combinations of prescribed displacements, tractions and moisture ratios. Based on previous modelling and experimental findings, a convective hygro-viscoelastic model of the paper web was derived. The constitutive law and some of the boundary conditions were implemented as user-defined subroutines into commercial FEM software in a displacement-based framework. Some simulation examples were used to study the applicability of the proposed formulation in the analysis of web-fed offset printing at stationary conditions. The numerical stationary solutions converged rapidly and the model was robust for the investigated conditions. Incorporating effects from moisture, the numerical results show web tension profiles along the analysed model press comparable to those found by others from full-scale newsprint printing press trials. Effects of altered levels of the peripheral velocities of rollers, friction, web velocity, moisture and web properties on in-plane stresses and strains are presented. In order to exemplify the practical use of the model for runnability investigations, different analysed quantities obtained from the numerical solutions were related to web tension, web widening, misregister in multi-colour printing, sheet size analysis, conditions for web stability and traction conditions at drag rollers. [Copyright &y& Elsevier]

Abstract: The fundamentals of a new radiation model are described in this paper. The spatial and angular dependence of the radiation intensity are split in such a way that the radiation intensity is approximated by a linear combination of basis functions dependent only on the angular direction. The coefficients of the approximation are functions of the spatial coordinates. The spatial discretization is performed using the finite volume method and the angular discretization is based on the finite element method. This means that the basis functions are defined according to the criteria used in the finite element method. The step scheme was employed in the spatial discretization and bilinear basis functions were chosen for the angular discretization. The method may be applied to both grey and non-grey media, non-scattering and scattering media, simple and complex geometries. However, it is still in an early stage of development, and therefore it is applied in this paper to simple one-dimensional problems of radiative transfer in enclosures with grey, emitting-absorbing and scattering media. The results obtained show that the method gives good results for several benchmark problems with available analytical solutions, and converges to the exact solution as the grid is refined and the number of terms in the approximation increases. [Copyright &y& Elsevier]

Folding of coated papers is examined numerically using the finite element method. The analysis is focused on the influence from dynamic effects on the folding process. In particular, the behaviour of field variables relevant for cracking of the coating layers are studied in some detail. The results presented indicate that dynamic effects are of little importance as regards maximum strain levels in the coating but will influence the stress and strain distributions. Accordingly, a quasi-static analysis of the problem will be sufficient in order to describe many of the important features related to cracking. [Copyright &y& Elsevier]

In this paper, the revolutions of wafer and pad were considered the same and the force forms including the pressure exerted on the top of wafer surface and the carrier back pressure were axisymmetric distributed, a 2D axisymmetric quasi-static model for chemical mechanical polishing process (CMP) was first established. Based on the principle of minimum total potential energy, a 2D axisymmetric quasi-static finite element model with a carrier back pressure compensation for CMP was then established. In this model, the four-layer structures including wafer carrier, carrier film, wafer and pad are involved. The effect of a given carrier back pressure on the stress components and von Mises stress on wafer surface was analyzed and the effect of different carrier back pressures on the von Mises stress and nonuniformity on wafer surface was investigated. The findings indicated that the axial stress was the dominant factor to the von Mises stress distribution on wafer surface. Because that the back pressure had the maximum affect on the axial stress and it made the axial stress increased along the −z direction. Thus, while applying a back pressure, the von Mises stress distribution increased. In addition, the changes of back pressure had the trend to be proportional to the von Mises stress variation and to be inversely proportional to the nonuniformity variation. The result showed obviously that during the CMP process, it could achieve the purpose to improve the planarization of wafer surface by compensating the different carrier back pressures. [Copyright &y& Elsevier]

INCONEL® machining poses great challenges in predicting its behaviour, and exhaustive experimental evaluation of its machinability is expensive and unsustainable. Design of Experiments (DOE) can be performed without destroying components via Finite Element Analysis (FEA). However, it is paramount to establish if numerical modelling and the constitutive models can cope with an accurate predictability of INCONEL® machining. Hence, a broad review of FEA strategies will be given to systematically summarise and analyse the progress taken on INCONEL® machining predictability through FEA from 2013 to 2023 and present the most recent researchers' digital solutions, prospects, and limitations. Thanks to articles and books, this paper was conceived. The main keywords used in searching information were: "INCONEL® 718", "INCONEL® 625", "FEA", "Traditional Machining Modelling", "Johnson-Cook criteria", "ABAQUS™", "ANSYS®" and "DEFORM®". Combining these keywords was crucial to filter the current information about the evolution of INCONEL® alloy machining predictability through FEA. INCONEL® alloys FEA machining can nowadays effectively provide good quality and accurate results regarding the counterpart experiments. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents extensive test results of linear elastic mechanical properties of Nomex paper and Nomex honeycomb structures. The fundamental mechanical properties of the Nomex paper are then used in the finite element modeling and analysis of Nomex honeycomb structures. The finite element results are then compared with the experimental results and with the results using the well known theory from Gibson and Ashby [Gibson LJ, Ashby MF. Cellular solids: structures & properties. Pergamon Press; 1988]. Size effects are observed for the moduli of Nomex honeycombs. [Copyright &y& Elsevier]

Cylindrical shells with corrugation are widely used in deep sea, underground pressure structures, and other fields. It is mainly subjected to uniform and concentrated external pressure. The current research mainly includes circumferentially corrugated shells and longitudinally corrugated shells. These two kinds of corrugations improve the strength of the cylindrical shell but also have some problems such as stress concentration, buckling extension, and so on. To solve these problems, a shell with composite corrugation is proposed and it has the structural characteristics of both circumferential and longitudinal corrugations. In this paper, the numerical analysis method is used to explore the stability of the composite corrugated shell under uniform and concentrated pressures. It is analyzed by Donnell's large deflection equation. In addition, it can reduce the area of damage caused by buckling. The excellent mechanical properties of the composite corrugated shell are proven. The influence of the number of corrugations and "diameter to thickness ratio" on the buckling performance is studied by using the control variate method. It is compared with a cylindrical shell without corrugation with equal volume and weight. The concentrated pressure tests of composite corrugated shells and shells without corrugation are finished. The results show that the curve of "radial compression-reaction load" obtained by the experiment is consistent with the simulation. The ultimate load of the composite corrugated shell is 34.96% higher than the shell without corrugation. The composite corrugation can effectively enhance the compressive strength and stiffness of the cylindrical shell. Composite corrugation can make more material of the shell to be involved in resisting external deformation. This method of increasing material utilization is effective. • The advantages of the composite corrugated shell are verified from mechanical theory, finite element analysis and test. • The influence of local curvature on the buckling performance of cylindrical shell is verified. • Donnell's large deflection equation has been applied and innovated in this paper. [ABSTRACT FROM AUTHOR]

In recent years, there has been a notable increase in the utilization of multi-celled corrugated-plate CFST (MC-CFST) walls. In this paper, a connection joint between a steel beam and an MC-CFST wall was proposed. The joint consisted of MC-CFST walls, end columns, horizontal diaphragms, vertical plates, and steel beams, with each steel component being interconnected through welding. To investigate its mechanical properties, a refined finite element model was developed, and the accuracy of the modeling method was validated through existing test results. The stiffness and moment capacity of the joints were analyzed, focusing on the effects of various factors, including the insertion depth of the horizontal diaphragm, beam-to-column linear stiffness ratio, width-to-thickness ratio of the end column plate, diameter of the horizontal diaphragm opening, axial compression ratio, and concrete and steel strengths. Based on numerical and theoretical analyses, a calculation method for determining the moment capacity of the joint and establishing the lower limit value for the steel tube thickness of the end columns was proposed by using the yield line analysis. The predicted value of the moment capacity of the joint was found to deviate from the finite element result by no more than 10%, suggesting that the formula exhibited excellent accuracy and applicability. The minimum steel tube thickness of the end columns was determined by considering the yield of the beam flange section. The design method presented in this paper has the potential to offer a valuable reference for practical designs of the proposed connection joint. • A novel connection joint between a steel beam and a multi-celled corrugated-plate CFST wall was proposed. • A validated FE model was established for further investigation. • A parametric analysis was conducted to investigate the influence on the stiffness of the joints. • The effect of various parameters on the moment capacity of the joints was discussed. • Based on numerical and theoretical analyses, a formula for determining the moment capacity of the joint was proposed. [ABSTRACT FROM AUTHOR]

Processing waste tires into rubber granules for secondary use can effectively alleviate the problem of environmental pollution. Therefore, this paper prepares foam concrete by replacing cementitious materials with recycled rubber granules to recycle resources. The dry density, water absorption, cubic compression, and prismatic flexure tests are carried out with the foam admixture and rubber substitution rate as the test parameters to study the effects of foam admixture and rubber substitution rate on the performance of foam concrete. Using Monte Carlo method simulation and non-linear fitting, a numerical analysis model was developed to predict recycled rubber foam concrete's mechanical properties. The ABAQUS finite element simulation method was used to explore the changes in the stress–strain relationship and damage development of the recycled rubber foam concrete, combined with microscopic observation, SEM, and XRD tests to reveal the specimens' damage mechanism, microscopic morphology, and physical structure. The experimental results show that the foam admixture has a more significant effect on the specimens' dry density, water absorption, and strength index than the effect of the rubber replacement rate. In addition, the strength prediction model, strength conversion model, and uniaxial compression finite element model of recycled rubber foam concrete were established. [ABSTRACT FROM AUTHOR]

• Integrating innovative numerical analysis and non-invasive experimental tests. • Numerical tool to optimize the conservation conditions of Mona Lisa 's wooden panel. • Analysing the internal stress state, and its safe limits, of the panel painting. • FEM numerical modelling for the mechanical characterisation of the artwork. • Assessment of the conservation status of panel paintings. A numerical FEM (Finite Element Method) model was implemented to represent the mechanical state of the wooden panel of the Mona Lisa , as it is conserved in its exhibition case, and constrained in its auxiliary frame. The model is based on the integration of advanced numerical analysis and various experimental examinations carried out non-invasively on the artwork by the authors during over 15 years. This includes visual, microscopic and X-ray observations together with mechanical measurements and monitoring of panel deformations and constraining external forces. In addition to the development of non-invasive techniques to characterise the mechanical properties of the panel, the FEM model reliably evaluated the strains and stresses generated in the panel by the various actions it experiences. The paper consists of the following parts: (i) a short summary of the experimental measurements and other observations, (ii) a detailed description of the FEM numerical model, of the hypotheses it is based on, and of its advantages and limits, (iii) the main results obtained by running the model. This includes the identification of local strains and stresses, the location of most critical areas, an evaluation of the risk that the existing ancient crack may propagate, and an evaluation of safe ranges for the forces acting on the wooden panel, (iv) the validation criteria for such results, and (v) a discussion about the significance of the mechanical model. [ABSTRACT FROM AUTHOR]

[Display omitted] To unravel the diffusion mechanisms of percutaneous drug delivery, suitable numerical analysis of stratum corneum structure is essential. In this research paper, we accounted for the permeable envelope layer in the brick-and-mortar finite element models of human stratum corneum. Both penetration and desorption experiments for tritiated water were simulated by transient finite element analysis. Rivet-shaped corneodesmosomes were included in the brick and mortar model. Results showed that cornified lipid permeability (P env) is a determinant in desorption of the solute, while lipid transverse diffusion coefficient (D lip-trans) is prominent during penetration. These two major unknowns (P env and D lip-trans) were obtained by extensive fitting of the finite element model to the experimental water data. P env and D lip-trans were determined to be 1 × 10 − 2 cm/s and 5.7 × 10 − 10 cm 2 / s, respectively. [ABSTRACT FROM AUTHOR]

• Inclined stiffened panels of the fuselage tail were tested under shear load. • The simulation model was established to predict the buckling, post-buckling, and failure modes of inclined stiffened composite panels. • The non-linear relationship between the debonding of the stiffeners and the skin was quantitatively analyzed. • The concept of equivalent skin thickness was introduced to analyze the influence of stringer configuration on panel buckling and post-buckling. The purpose of this paper is to investigate the buckling and post-buckling behavior of inclined stiffened composite panels under shear load. Two types of stiffened composite panels were manufactured and tested. The buckling load, ultimate load and other required structural properties of the inclined stiffened composite panels were obtained. The test results show that the failure load of the two types of panels are 5.79 times and 11.2 times of the buckling load, respectively, indicating that such inclined stiffened panels have a large post-buckling capacity. The damage modes of the panel are tearing around the skin near the clamps and debonding of the stringers from the skin. The combination of Hashin failure criterion, Cohesive model and nonlinear connection of clamp was used to conduct finite element modeling, which effectively predicts the buckling, post-buckling and damage modes of the structure. The buckling and post-buckling behavior of stiffened panels with different stinger configurations were discussed based on finite element analysis. The results show that when the initial buckling occurs between the stringers, the buckling and failure load of the stiffened panel become larger as the equivalent skin thickness between the stringers become larger. The research in this paper can provide reference for aircraft structural design. [ABSTRACT FROM AUTHOR]

Shield-soil rotary friction is one of the reasons that cause asymmetrical settlements about the central axis of tunnel center line. This paper focuses on analytical analysis of the shield-soil rotary friction on tunnelling-induced ground mechanical reactions. According to the working principle of the shield machine, the way and process of the shield torque acting on the soil is proposed. Based on the calculation model of a spatial curved shield tunnel and the rewritten of the Mindlin solutions, this paper derives the analytical solutions of the effect of shield-soil rotary friction on the soil displacement field and the additional stress field, respectively. The derived theoretical solutions are verified and compared with the shield project of Beijing East Sixth Ring Road renovation project, and relevant parameters are analyzed in this paper. The numerical model analysis based on the finite element software and the field monitoring data verify the correctness of the method proposed. The theoretical study in this paper further improves the study of the construction load of shield machine. [ABSTRACT FROM AUTHOR]

In this paper, we study the parabolic Dirichlet boundary optimal control on complex connected domains. It is well known that both the complex connected domain and the Dirichlet boundary control bring great difficulties to theoretical analysis and numerical calculation. The complex connected domain is a typical non-convex domain, and it is difficult for the traditional numerical method to obtain the same convergence order as the state and adjoint state for the Dirichlet boundary control. The optimal system of the proposed control problem is first obtained by using Lagrange multiplier method. Then, based on the variational form, the Fourier finite volume element method is used to obtain the fully discrete scheme of the optimality system, that is, using Fourier expansion method in azimuthal direction and applying finite volume element method in radial direction respectively, and the Crank-Nicolson scheme in the time direction. Next, we strictly prove the error estimates of state, adjoint state and Dirichlet boundary control by using the variational discretization concept. Finally, the theoretical analysis results and the feasibility and effectiveness of the proposed method are verified by numerical experiments. • It is significant to develop the Fourier finite volume element method for optimal Dirichlet boundary control problems. • We develop and analyze the Fourier finite volume element method for an optimal Dirichlet boundary control problem. • Rigorous error estimates are provided for Dirichlet boundary control, state and adjoint state. • Numerical examples confirm the correctness of the theoretical analysis and the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Numerical simulations are used in this work to investigate aspects of microstructure and microsegregation during rapid solidification of a Ni-based superalloy in a laser powder bed fusion additive manufacturing process. Thermal modeling by finite element analysis simulates the laser melt pool, with surface temperatures in agreement with in situ thermographic measurements on Inconel 625. Geometric and thermal features of the simulated melt pools are extracted and used in subsequent mesoscale simulations. Solidification in the melt pool is simulated on two length scales. For the multicomponent alloy Inconel 625, microsegregation between dendrite arms is calculated using the Scheil-Gulliver solidification model and DICTRA software. Phase-field simulations, using Ni–Nb as a binary analogue to Inconel 625, produced microstructures with primary cellular/dendritic arm spacings in agreement with measured spacings in experimentally observed microstructures and a lesser extent of microsegregation than predicted by DICTRA simulations. The composition profiles are used to compare thermodynamic driving forces for nucleation against experimentally observed precipitates identified by electron and X-ray diffraction analyses. Our analysis lists the precipitates that may form from FCC phase of enriched interdendritic compositions and compares these against experimentally observed phases from 1 h heat treatments at two temperatures: stress relief at 1143 K (870 °C) or homogenization at 1423 K (1150 °C). [ABSTRACT FROM AUTHOR]

• FE solution of harmonic vibrations for VE layered plates with exponential complex-conjugate form and refined zig-zag theory. • Effective application of the continuation method to solve the discretised amplitude equation. • Numerous analyses of the influence of various plate and formulation parameters on the resonance behaviour of laminate plates. The paper is devoted to the numerical analysis of the harmonic vibrations of laminate plates with viscoelastic layers in the von Kàrmàn geometrically non-linear regime. The amplitude equation derived in the prequel paper Part 1 – theoretical background is discretized using the 8-noded bi-quadratic plate finite elements. The response curves are obtained using the continuation method to solve the discretised amplitude equation treated as the equation with the frequency of vibrations as a parameter. The proposed method of solution is verified by comparing the results with those from available literature. Furthermore, several numerical analyses are performed, including testing of FE mesh density, plate aspect ratio, various VE materials, support conditions and layers layout as well as the possibility of simplification of the complex-valued zig-zag function used in the description of plate kinematics. Several results of practical importance are found and discussed in the conclusions. [ABSTRACT FROM AUTHOR]

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

In this paper, a stable mixed finite element method for unsteady inductionless magnetohydrodynamics (MHD) problem coupled heat equation is devised. We first propose a mixed variational formulation based on all the variables, in which the thermal equation and Navier-Stokes equations are approximated by mini finite element method and the current density is discretized by the divergence-conforming elements. The novel feature of this scheme is that the discrete current density keeps charge conservation property. It is shown that the fully discrete first order Euler semi-implicit scheme is well-posed and unconditionally stable. The existence and uniqueness of the weak solutions for continuous problem is established by a numerical version analysis. Furthermore, under the low regularity hypothesis for the exact solutions, we prove the optimal error estimates of the velocity, current density and electric potential. Finally, some numerical experiments have been performed to validate the theoretical analysis and the law of charge conservation. [ABSTRACT FROM AUTHOR]

This paper is devoted to numerical analysis of a new class of elliptic variational–hemivariational inequalities in the study of a family of contact problems for elastic ideally locking materials. The contact is described by the Signorini unilateral contact condition and the friction is modeled by a nonmonotone multivalued subdifferential relation allowing slip dependence. The problem involves a nonlinear elasticity operator, the subdifferential of the indicator function of a convex set for the locking constraints and a nonconvex locally Lipschitz friction potential. Solution existence and uniqueness result on the inequality can be found in Migórski and Ogorzaly (2017). In this paper, we introduce and analyze a finite element method to solve the variational–hemivariational inequality. We derive a Céa type inequality that serves as a starting point of error estimation. Numerical results are reported, showing the performance of the numerical method. [ABSTRACT FROM AUTHOR]

This paper presents a quasistatic problem of an elastic body in frictional contact with a moving foundation. The model takes into account wear of the contact surface of the body caused by the friction. We recall existence and uniqueness results obtained in Sofonea et al. (2017). The main aim of this paper is to present a fully discrete scheme for numerical approximation together with an error estimation of a solution to this problem. Finally, computational simulations are performed to illustrate the mathematical model. [ABSTRACT FROM AUTHOR]

In this paper, we consider a family of simultaneous distributed-boundary optimal control problems (P α) on the internal energy and the heat flux for a system governed by a mixed elliptic variational equality with a parameter α > 0 (the heat transfer coefficient on a portion of the boundary of the domain) and a simultaneous distributed-boundary optimal control problem (P) governed also by an elliptic variational equality with a Dirichlet boundary condition on the same portion of the boundary. We formulate discrete approximations P h α and P h of the optimal control problems P α and (P) respectively, for each h > 0 and for each α > 0 , through the finite element method with Lagrange's triangles of type 1 with parameter h (the longest side of the triangles). The goal of this paper is to study the convergence of this family of discrete simultaneous distributed-boundary mixed elliptic optimal control problems P h α when the parameters α goes to infinity and the parameter h goes to zero simultaneously. We prove the convergence of the family of discrete problems P h α to the discrete problem P h when α → + ∞ , for each h > 0 , in adequate functional spaces. We study the convergence of the discrete problems P h α and P h , for each α > 0 , when h → 0 + obtaining a commutative diagram which relates the continuous and discrete simultaneous distributed-boundary mixed elliptic optimal control problems P h α , P α , P h and (P) by taking the limits h → 0 + and α → + ∞ respectively. We also study the double convergence of P h α to (P) when (h , α) → (0 + , + ∞) which represents the diagonal convergence in the above commutative diagram. [ABSTRACT FROM AUTHOR]

• A methodology for analysis of large-scale masonry structures is presented which incorporates an inelastic macroscopic framework coupled with a series of artificial neural networks. • The neural networks serve the purpose of identification of material functions embedded in anisotropic formulation as well as the specification of localization plane. • The data required for training of neural networks is generated using 'virtual experiments' that involve a mesoscale finite element analysis of masonry wallets. • Finite element analysis of a large masonry wall with multiple openings is carried out. The results are compared with those based on a detailed mesoscale model. This paper presents a methodology for analysis of large-scale masonry structures. The approach involves development of a series of artificial neural networks which enable the identification of main variables employed in the macroscopic formulation that incorporates an inelastic constitutive law with embedded discontinuity. The data required for training of neural networks is generated using 'virtual experiments', whereby the 'equivalent' anisotropic response of masonry is obtained through a mesoscale finite element analysis of masonry wallets. The paper outlines the procedure for identification of approximation coefficients describing the orientation-dependency of strength, and other relevant parameters. A numerical example is provided involving analysis of a large masonry wall with multiple openings. The results of macroscale approach are compared with those based on a detailed mesoscale model for the same geometry and boundary conditions. [ABSTRACT FROM AUTHOR]

Multi-physics are widely studied and used in numerical analysis and simulation. Physics-based splitting methods are introduced, in which different methods are applied to solve each individual aspect of a physical system in multiple steps. The implicit methods are typically used for temporal discretization and are unconditionally stable such that the time step size can be large during the computation. However, the implicit methods are more complicated to solve, especially for nonlinear problems. In contrast, the explicit methods are relatively easier to compute, while they may require a much smaller time step size. In this paper, we propose a partially explicit scheme with physics-based splitting. We take the convection diffusion equation as an example. In this scheme, the convection equation is solved using the exact solution, and then we solve the diffusion equation via finite element methods. Some degrees of freedom in the diffusion equation are treated implicitly while others are treated explicitly. We can change the large-scale implicit system into one smaller-scale implicit system and one smaller-scale explicit system, which provides saving in computation. We analyze the stability and the order of accuracy. We also present some numerical results to show the performance of our proposed scheme. [ABSTRACT FROM AUTHOR]

Liquefaction has caused severe damage to buildings and infrastructure during numerous earthquakes, leading researchers to develop constitutive models that can capture complex soil behaviour in liquefaction-induced phenomena. Constitutive models require validation against laboratory or real-world data to assess their capability. This paper first discusses the recent implementation of the stress-density (S-D) model in the OpenSees finite element platform. Subsequently, calibration and validation phases evaluate the performance of the S-D model against two previously conducted centrifuge tests. Single-element simulations of cyclic simple shear tests inform the parameter calibration for the Nevada sand, which comprises the two main layers in the centrifuge tests. The validation phase consists of eight 1-D site response analyses in OpenSees compared to the centrifuge tests in terms of accelerations, spectral accelerations, pore water pressures, and settlements. The current study shows that the model reasonably predicts the soil behaviour in terms of acceleration and pore water pressure, particularly in the liquefiable layer. • Validation analysis of stress-density model in OpenSees. • Models for single-element cyclic shear and centrifuge 1D site response. • Shear strain saturation evident in single-element calibration. • Reasonable prediction of pore pressure by S-D model in the liquefiable layer. • Underestimation of volumetric settlements by S-D and PM4Sand models. [ABSTRACT FROM AUTHOR]

Special-shaped concrete-filled square steel tube (SS-CFSST) columns are a type of prefabricated steel house structural form. They retain the characteristic high load-bearing capacity of the steel and concrete composite structures without protruding from the wall. This paper proposes a new type of connection form by improving the SS-CFSST column-steel beam outer sleeve connection. Cyclic loads were applied to nine specimens differing in terms of steel hoop width, side plate width, side plate length, and overall thickness. The failure modes, hysteresis curves, strength and rigidity degradation, and energy dissipation capacity are analysed in this study. The failure modes include side-plate fracture, beam-flange tear, and beam-plastic hinges. The hysteresis curves exhibit shuttle shapes without pinching. The equivalent viscous damping coefficients of the samples range from 0.16 to 0.26. Based on these results, a finite element model is established, and its accuracy is verified according to a comparison with the test results. A parameter analysis is also described herein. The results indicate that the key factors influencing the load-bearing capacity of these connections include (i) the thickness and height of the steel hoop and the side plate, (ii) the steel tube's width-to-thickness ratio, and (iii) the steel's yield strength. Specifically, the ratio of the height of the side plate on the beam flange's outer (h w) to inner (h n) dimension should not exceed 1.5. Moreover, the load-bearing capacity and stiffness of the connections are not affected when the axial compression ratio (n) is in the range of 0–0.6. • A novel special-shaped concrete-filled square steel tube (SS-CFSST) column to H-beam connection was proposed. • The seismic performance of the new connection was investigated based on nine specimens with different design parameters. • A parameter analysis was conducted on the factors affecting the bearing capacity of the connection. [ABSTRACT FROM AUTHOR]

This paper studies the novel vibration control of an inerter-enhanced mega sub-controlled structure system (MSCSS). The seismic response of MSCSS is investigated using a tuned viscous mass damper inerter (TVMDI) and compared with existing control methods. This novel strategy evaluates two kinds of TVMDIs on MSCSS, including the inter-story TVMDI, where the TVMDIs are installed inter-story, and the outrigger-based TVMDI, where the TVMDIs are vertically connected between the outrigger and the perimeter of the MSCSS's column to achieve significant energy dissipation. First, a finite element model of MSCSS is established and validated with the experimental model of MSCSS. The governing equation of the enhanced MSCSS is derived from the uncontrolled model. Subsequently, the MSCSS equipped with TVMDIs is thoroughly examined and compared to the existing methods. The effectiveness of the proposed strategy subject to ground motion records via the numerical analysis method is also demonstrated. Finally, the reliability analysis of the enhanced MSCSS based on the probability density function is presented. Results from the numerical investigation of the MSCSS enhanced strategies have revealed that the inter-story and outrigger TVMDI system generally improved the response effectiveness of MSCSS better than the viscous damper (VD) and middle story isolation (MSI) systems. However, the outrigger TVMDI enhanced mega frames control effectiveness more effectively than the story-based TVMDI, whereas the latter is more suitable for substructures. ● The novel vibration control of an inerter-based enhanced MSCSS is studied. ● An uncontrolled FEM of MSCS is presented and validated with the experimental model. ● The dynamic equation of MSCS equipped with TVMD is derived from uncontrolled model. ● The proposed strategies is examined and compared to the existing control methods. ● The reliability analysis of the TVMD-enhanced MSCSS based on the PDF is presented. [ABSTRACT FROM AUTHOR]

The utilization of renewable energy is an important way to solve the energy crisis, and wind power is one of the most mature new energy technologies. This paper studies the potential of applying the viscoelastic damper to mitigate vibrations of the OWT tower under wind-wave loadings. The viscoelastic damper directly converts the horizontal deformation of the tower into the shear deformation of the viscoelastic material for energy dissipation, which provides a new idea for suppressing the dynamic response of the OWT. According to OWT structural dynamic characteristics and load conditions, a new high damping wall-type viscoelastic damper (HVED) control is developed. The mechanical properties of HVED are investigated by full scale test. A numerical vibration response analysis of the controlled and uncontrolled 4 MW OWT was carried out in ANSYS. Results indicate that the HVED can significantly reduce the dynamic response of OWT and increase its fatigue life. • A new high damping viscoelastic damper (HVED) is proposed to mitigate the vibration of OWT. • Advantages of HVED are significant energy dissipation, wide-frequency control, and convenient installation. • Full scale test was conducted to verify the mechanical properties of HVED. • Interaction of soil and structure (SSI) was considered in the finite element analysis. [ABSTRACT FROM AUTHOR]

• Proper quantification of joint rotational stiffness (JRS) of a flight intersection joint (FIJ) influences the dynamic characteristics of a flight vehicle. • JRS of an FIJ is often determined experimentally due to the lack of a right predictive model. • An analytical model is proposed to evaluate the JRS of a radial-type FIJ when subjected to an external bending moment. • Numerical analyses and experiments are performed on six different FIJ configurations. • JRS and moment-rotation behavior predicted by the proposed model are correlated with both experimental and numerical analyses. • Further, the effect of joint clearances on the behavior of FIJ is investigated through the present model. Joint rotational stiffness (JRS) of a flight intersection joint (FIJ) and its accurate quantification play an essential role in studying the dynamic modal characteristics of a flight vehicle. This JRS of a FIJ is mostly determined through elaborate experiments due to the non-availability of a reliable predictive model. Therefore, in this paper, an analytical model is proposed to evaluate JRS of a radial type FIJ when subjected to external bending moment. In this model, at first, the tensile and compressive part of the FIJ section is identified by determining the neutral axis position. The respective part's contributing stiffness is then estimated by employing a spring-mass model. Later, the JRS expression is derived from the moment equilibrium condition and expressed as a function of the stiffness of the tensile and compressive part and neutral axis position. Subsequently, finite element analysis (FEA) is conducted with different numbers of screws, followed by detailed experimental investigations. The proposed analytical model is validated with the results from FEA and experiments for different screw configurations of FIJ. Further, the proposed model is extended to account for the effect of joint clearances on the JRS and the corresponding moment-rotation characteristics of the FIJ. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper examines the influence of perforations on the buckling instability and load-bearing capacity of advanced high-strength steel channel section (C-section) columns. Experimental tests were first conducted on 19 column specimens made of complex phrase steel HC700CP980 under axial compression, followed by finite element (FE) analysis. Two section types, the flat web C-section and the web-stiffened C-section, were considered, with perforations categorised as web-only or both web and flanges. Material tests and initial imperfection measurements were conducted and reported. Using test results, finite element models were established and parameter analysis was carried out. Analysis of test results and finite element data revealed that perforations had a noticeable impact on the buckling deformation of flat web C-sections but had a minor effect on load-bearing capacity. In contrast, web-stiffened C-sections exhibited intensified deformation post-perforation, significantly reducing their axial stiffness and load-bearing capacity. The Direct Strength Method (DSM) was assessed based on combined test and FE data. It revealed that the DSM resulted in a high level of inaccuracy and scatter in the load-bearing capacity predictions of high-strength steel C-sections after perforation. To address this, a modified method incorporating a perforation strength reduction factor was proposed, offering straightforward and intuitive calculations with improved design accuracy and consistency. • Tests and numerical analysis conducted on advanced high-strength steel channel section columns with perforations. • Influence of perforations on the buckling instability of columns examined. • Applicability of the Direct Strength Method (DSM) assessed. • Modified DSM with a perforation strength reduction factor proposed for improved design accuracy. [ABSTRACT FROM AUTHOR]

This paper proposes an assembled flange core-tube column connection with self-tapping bolt (AFCS), with high assembly efficiency, low pollution and high joint. Two different core tube thicknesses were set and static low circumferential reciprocation tests were performed. It was found that the core tube thickness has a small effect on the mechanical properties, and the hysteresis curves of the two members are basically the same. The two members in the tests were torn at the foot of the column, and it was concluded that the AFCS possesses good mechanical properties and can satisfy the design criteria of "strong joint, weak member". At the same time, the self-tapping bolts performed well, and the slip did not increase after 0.03 rad, which can proof that the overall safety and reliability requirements were met. The finite element model (FEM) was established by ABAQUS, and the reliability was verified by changing the gap between the core tube and the column wall, the number and diameter of the self-tapping bolts. It was also concluded that the gap should not exceed 1/100 of the column wall width and the influence of each parameter on the mechanical properties of the connection from the largest to the smallest was the number of self-tapping bolts, the diameter of self-tapping bolts, and the gap between the core tube and the column wall. Finally, a theoretical analysis was conducted to derive the strength equations of the core tube and self-tapping bolt as well as the design method of the flange plate. • An innovative assembled steel column-column connection with self-tapping bolts (AFCS) is proposed. • The new connection utilizes both inner sleeve and flange. • Detailed experimental procedures and analysis are presented. • Accurate finite element model is created. • Reasonable theoretical analysis and formula derivation of the key parts are carried out. [ABSTRACT FROM AUTHOR]

CuO particles on the surface of silicon wafers can seriously affect integrated circuits performance and service life. This paper carries out numerical calculations and experimental research on the removal of CuO particles from silicon substrates surfaces by picosecond laser. A thermal-stress coupled finite element model is established to simulate the changes in the temperature of silicon substrates and the thermal stress of CuO particles with laser action time and energy density, to predict the cleaning threshold of the particles and the damage threshold of the silicon substrates. The results show that the cleaning threshold for CuO particles with a particle size of 10 μm is 0.029 J/cm2 and the damage threshold for the silicon substrate is 0.512 J/cm2. As the laser energy density increases, the CuO particles removal rate on the silicon surface increases first and then decreases, and the silicon substrate roughness decreases first and then increases. When the laser energy density is 0.429J/cm2, the CuO particle removal rate reaches 93.42 %, the wafer surface is undamaged, and the roughness is as low as 1.33 nm. The ratio of Cu and Si elements on the cleaned silicon substrate surface is close to that on the silicon substrate surface before the sample was made. [ABSTRACT FROM AUTHOR]

Generalized/extended finite element methods (GFEM/XFEM) for an interface problem are generally enriched by a distance function to the interface to handle discontinuities across the interface. Evaluations of the distance function and its gradients are needed for assembling stiffness matrices, which requires certain computational geometry algorithms. The computational complexity grows if the number of integration points is increased. Besides, the mathematical analysis on the effect of numerical integration has not been established in the field of GFEM/XFEM yet. This study designs an improved enriched function for a stable GFEM (SGFEM, a stable version of GFEM) based on the distance function, which only requires evaluating the distance function at nodes of elements that interact the interface (the gradients of distance function are not needed). The optimal convergence order (in the energy norm) of the SGFEM with such an improved enriched function is proven. In turn, we propose a perturbed variational formula, which can be integrated exactly by simple Gaussian rules designed in this paper. We prove that the SGFEM based on the improved enriched function and the perturbed variational formula (exactly integrated by the numerical integration) achieves the optimal convergence order for the interface problem. Namely, we develop a numerical integration rule for the SGFEM such that the optimal convergence order of SGFEM is maintained for the interface problem. The theoretical achievements are verified by numerical experiments. [ABSTRACT FROM AUTHOR]

This paper focuses on the development of much-needed numerical and experimental models for understanding the mechanical behaviour, section capacity and energy absorption of the innovative fabricated columns consisting of corrugated mild-steel plates. The corrugated square columns proposed in this paper are fabricated by welding four corrugated plates which are originally produced from 3 mm thick flat mild steel plates. The experiments consist of applying a compressive axial force to the columns to determine load–displacement curves of the fabricated sections. The effects of geometric parameters such as inclination angle and corrugation height are also investigated experimentally by considering three different types of corrugated columns. Moreover, a finite element model in which the effects of material and geometric nonlinearities as well as residual stresses are taken into account is developed using ABAQUS. The experimental results are also compared with those given by the finite element (FE) model whilst a good agreement is achieved. A cost analysis is also conducted in which the cost of the innovative columns proposed in this research is compared to those of conventional welded columns currently available in the civil engineering market. [ABSTRACT FROM AUTHOR]

Abstract This paper describes a step improvement in the numerical modelling of the structural response of axially and rotationally restrained stainless steel columns at elevated temperatures. The developed finite element models form a sequentially coupled thermal stress analysis that comprises a heat transfer model, a buckling analysis, and a geometrically and materially non-linear stress analysis. The proposed finite element methodology is more sophisticated than any other reported attempts to model the fire response of structural stainless steel that take into account influence of adjoining members. A high degree of predictive accuracy is achieved, with the developed models on average predicting the failure temperatures and times of test specimens reported in the literature within 2% and 6%, respectively. A parametric study is performed that investigates the influence of axial restraint stiffness, rotational restraint stiffness, column slenderness and load level. It is shown that while increasing axial restraint stiffness reduces the failure temperature of stainless steel columns in fire, increasing rotational restraint stiffness has the opposite effect. The methodology and results of this paper will provide both a tool for practice and a suite of results that can be extended to develop the existing and currently limited codified approaches to structural stainless steel design. Highlights • Finite element modelling of axially and rotationally restrained stainless steel columns in fire. • Validation of developed finite element models against fire tests reported in the literature. • Parametric studies examining the effect of varying degrees axial and rotational stiffness. • Investigation of the structural fire response and discussion of design implications. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a new shield configuration for cryogenic current comparators (CCCs), namely the folded coaxial geometry. An analytical model describing its shielding performance is first developed, and then validated by means of finite element simulations. Thanks to this model, the fundamental properties of the new shield are highlighted. Additionally, this paper compares the volumetric performance of the folded coaxial shield to the one of a ring shield, the latter being installed in many CCCs for measuring particle beam currents in accelerator facilities. [ABSTRACT FROM AUTHOR]

Highlights • Geometrically nonlinear behavior of corrugated laminated shell is investigated. • Specimens are made by unidirectional glass/epoxy prepreg and autoclave process. • The practical challenges during curing process are discussed. • A new technical material model is also adapted to solve the problem numerically. Abstract This paper presents experimental and numerical studies on the geometrically nonlinear behavior of corrugated laminated composite shells (CLCS) under quasi-static loading along the corrugated direction. A geometrically nonlinear layer-wise shell finite element formulation is adopted to study the behavior of CLCS under large deformation by modeling of incremental different moduli in the tensile and compressive regimes through the thickness, where the spatial location of neutral axis shifts with deformation. A master curve is presented to estimate the value of compressive modulus from given tensile and flexural moduli. Using the prepreg autoclave method, the paper also describes practical challenges in the manufacturing of CLCS and reveals significant influence of thickness on the nonlinear elastic behavior of two thin and moderately thick CLCS. The proprietary layer-wise shell FE formulation is verified with solid-finite-element modeling and employing a developed user material (USERMAT) subroutine in the commercial software ANSYS. Resulting improvements in numerical modelling are assessed in both general and local behaviors. [ABSTRACT FROM AUTHOR]

Highlights • A finite-buffer vacation queue with batch Markovian arrival process has been analyzed. • The server is subjected to serve under gated-limited service discipline. • Proposed analysis is based on the successive substitution and the supplementary variable method. • The results have been matched with the corresponding infinite-buffer queue. • Numerical results are presented for different service- and vacation-time distributions. Abstract This paper analyzes the finite-buffer single server queue with vacation(s). It is assumed that the arrivals follow a batch Markovian arrival process (BMAP) and the server serves customers according to a non-exhaustive type gated-limited service discipline. It has been also considered that the service and vacation distributions possess rational Laplace-Stieltjes transformation (LST) as these types of distributions may approximate many other distributions appeared in queueing literature. Among several batch acceptance/rejection strategies, the partial batch acceptance strategy is discussed in this paper. The service limit L (1 ≤ L ≤ N) is considered to be fixed, where N is the buffer-capacity excluding the one in service. It is assumed that in each busy period the server continues to serve until either L customers out of those that were waiting at the start of the busy period are served or the queue empties, whichever occurs first. The queue-length distribution at vacation termination/service completion epochs is determined by solving a set of linear simultaneous equations. The successive substitution method is used in the steady-state equations embedded at vacation termination/service completion epochs. The distribution of the queue-length at an arbitrary epoch has been obtained using the supplementary variable technique. The queue-length distributions at pre-arrival and post-departure epoch are also obtained. The results of the corresponding infinite-buffer queueing model have been analyzed briefly and matched with the previous model. Net profit function per unit of time is derived and an optimal service limit and buffer-capacity are obtained from a maximal expected profit. Some numerical results are presented in tabular and graphical forms. [ABSTRACT FROM AUTHOR]

Abstract A Boolean Finite Synchronous Dynamical System (BFDS, for short) consists of a finite number of objects that each maintains a boolean state, where after individually receiving state assignments, the objects update their state with respect to object-specific time-independent boolean functions synchronously in discrete time steps. The present paper studies the computational complexity of determining, given a boolean finite synchronous dynamical system, a configuration, which is a boolean vector representing the states of the objects, and a positive integer t , whether there exists another configuration from which the given configuration can be reached in t steps. It was previously shown that this problem, which we call the t -Predecessor Problem, is NP-complete even for t = 1 if the update function of an object is either the conjunction of arbitrary fan-in or the disjunction of arbitrary fan-in. This paper studies the computational complexity of the t -Predecessor Problem for a variety of sets of permissible update functions as well as for polynomially bounded t. It also studies the t -Garden-Of-Eden Problem, a variant of the t -Predecessor Problem that asks whether a configuration has a t -predecessor, which itself has no predecessor. The paper obtains complexity theoretical characterizations of all but one of these problems. [ABSTRACT FROM AUTHOR]

Abstract In this paper, compressive material tests on unconfined/confined resin and steel reinforced resin were experimentally evaluated in order to validate the numerical results. The uniaxial model which combines damage mechanics and Ramberg-Osgood relationship is proposed in this paper to describe the uniaxial compressive behaviour of resin and steel reinforced resin. Numerical homogenization is conducted to predict the tensile and shear behaviour of steel reinforced resin after validated by compressive material test results. The friction angle β , the ratio of the yield stress in triaxial tension to the yield stress in triaxial compression K, and the dilation angle ψ of the linear drucker-prager plastic model are obtained based on experiments and numerical homogenization simulation. The confinement effects on resin and steel reinforced resin could be effectively simulated by combing above parameters and uniaxial compressive model. Finite element simulations on unconfined/ confined resin and steel reinforced resin material tests were conducted to validate the material parameters proposed in this paper. A good agreement is observed, indicating the model and parameters proposed in this paper could be effectively used in the finite element simulation of injected bolts. [ABSTRACT FROM AUTHOR]

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