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The purpose of this paper is to examine quadratic convergence of finite element analysis for hyperelastic material at finite strains via Abaqus‐UMAT as well as classification of the rates of convergence for iterative solutions in regular cases.

Different formulations for stiffness – Hessian form of the free energy functionals – are systematically given for getting the rate‐independent analytical tangent and the numerical tangent as well as rate‐dependent tangents using the objective Jaumann rate of Kirchoff stress tensor as used in Abaqus. The convergence rates for available element types in Abaqus are computed and compared for simple but significant nonlinear elastic problems, such as using the 8‐node linear brick (B‐bar) element – also with hybrid pressure formulation and with incompatible modes – further the 20‐node quadratic brick element with corresponding modifications as well as the 6‐node linear triangular prism element and 4‐node linear tetrahedral element with modifications.

By using the Jaumann rate of Kirchoff stress tensor for both, rate dependent and rate independent problems, quadratic or nearly quadratic convergence is achieved for most of the used elements using Abaqus‐UMAT interface. But in case of using rate independent analytical tangent for rate independent problems, even convergence at all is not assured for all elements and the considered problems.

First time the convergence properties of 3D finite elements available in Abaqus sre systematically treated for elastic material at finite strain via Abaqus‐UMAT.

The purpose of this paper is to investigate and to assess the capabilities of the most common finite element (FE)‐based tools to deal with global‐local analysis. Two kinds of coupling were investigated: shell to shell and shell to solid.

The issue of connecting non‐matching FE global and local models, characterized by different mesh refinements and/or different element types, was addressed by introducing appropriate kinematic constraints on the nodes at the interfaces. The coupling techniques available in the three FE‐based codes (ABAQUS^®, NASTRAN^® and ANSYS^®), were assessed by applying them on a common numerical test case (non‐linear buckling analysis of a square plate). Results of the global‐local simulations were compared to the results obtained for relevant reference solutions.

The continuity of displacements and stresses across the interface between global and local models and the influence of the presence of the local model on the global model solution were used as parameters to test the quality of the results. It was observed that the tools implemented in the different codes provide different results. The results characterized by a higher quality were found by using the Multi Point Constraint available in ABAQUS^®.

When dealing with complex structures, multi‐scale (global‐local) approaches are commonly adopted to optimize the computational cost by increasing mesh refinements and/or introducing elements with different formulations in specific region of the structures identified as “local model”. In this paper an overview of the coupling tools available in the main commercial FE code is given.

The purpose of this paper is to propose two linear solid-shell finite elements, a six-node prismatic element denoted SHB6-EXP and an eight-node hexahedral element denoted SHB8PS-EXP, for the three-dimensional modeling of thin structures in the context of explicit dynamic analysis.

These two linear solid-shell elements are formulated based on a purely three-dimensional (3D) approach, with displacements as the only degrees of freedom. To prevent various locking phenomena, a reduced-integration scheme is used along with the assumed-strain method. The resulting formulations are computationally efficient, as only a single layer of elements with an arbitrary number of through-thickness integration points is required to model 3D thin structures.

Via the VUEL user-element subroutines, the performance of these elements is assessed through a set of selective and representative dynamic elastoplastic benchmark tests, impact-type problems and deep drawing processes involving complex non-linear loading paths, anisotropic plasticity and double-sided contact. The obtained numerical results demonstrate good performance of the SHB-EXP elements in the modeling of 3D thin structures, with only a single element layer and few integration points in the thickness direction.

The extension of the SHB-EXP solid-shell formulations to large-strain anisotropic plasticity enlarges their application range to a wide variety of dynamic elastoplastic problems and sheet metal forming simulations. All simulation results reveal that the numerical strategy adopted in this paper can efficiently prevent the various locking phenomena that commonly occur in the 3D modeling of thin structural problems.

The purpose of this paper is to present a new method for determining the input parameters of the concrete damaged plasticity (CDP) model of ABAQUS standard software. The existing available methods in the literatures are case sensitive, i.e., they give different input parameters of CDP for a unique concrete class used in different finite element (FE) simulation of concrete structures. In this study, the authors attempt to introduce a new approach for the identification of the input parameters of the CDP model, which guarantees the uniqueness and precision of the model. In other words, by this method, the input parameters obtained for a specific concrete class with a unique characteristic strength can be used for FE simulation of the different concrete structures which were constructed by this concrete without the need to additional modifications raised from any new application.

For the input parameter identification of the CDP model, different standard tests of plain concrete are simulated by the ABAQUS standard software. These test simulations are performed for various set of input parameters. In the end, those set of input parameters which represents the best curve fitting with the experimental results is chosen as the optimum parameters.

By comparison of the FE simulation results obtained from the ABAQUS for two different concrete structures using the proposed input parameters for the CDP model with the experimental results, it was shown that the presented method for determining those parameters can guarantee the uniqueness and precision of the CDP model in simulation.

The method described for determining the input parameters of the CDP model of the ABAQUS standard software has not been previously presented.

The trapped geothermal heat in the infinite rock mass through which mine tunnels are excavated is a great threat to the safety of personnel and mine operating equipment in deep underground hot mines. In order to lessen the temperature inside the tunnel a considerable amount of energy is being spent by the way of using ventilation and cooling systems to dissipate the heat. However, operational costs of the system rise quite considerably, especially as the mines get deeper. Shotcrete is used both as a structural lining and as an effective insulation to reduce the heat load on the ventilation and cooling system within such tunnels. The paper aims to discuss these issues.

In order to analyse this problem of heat flow and thermal stresses and their time dependent pattern, several cylindrical models, in both analytical and numerical forms, are discussed and compared in this paper.

This study shows the validation of ABAQUS® software to predict the time dependent temperature and the thermal stresses in mine tunnels through the comparisons with the available analytical models. Further, thermal insulation effects of shotcrete are also evaluated with these theoretical models and it is found that all the models gave results in close agreements with one another.

Therefore, this study provides the theoretical proof for advantages in applying shotcrete as the thermal insulation layer in underground mines.

This study aims to propose another alternative numerical modelling tool, i.e. ABAQUS, to simulate a fully coupled seepage-deformation analysis in unsaturated slope subjected to rainfall infiltration.

The effect of rainfall infiltration on the response of pore water pressure and factor of safety has been analysed and discussed. The results of this study have also been validated based on the results of field monitoring and previous numerical modelling.

The results from ABAQUS show a better agreement with those from field monitoring compared to other numerical modelling tools.

The procedures adopted in this study can be adopted and used as a guide to model similar slope problems in ABAQUS.

The purpose of this paper is to suggest an implicit integration method for updating the constitutive relationships in the newly proposed anisotropic egg-shaped elastoplastic (AESE) model and to apply it in ABAQUS.

The implicit integration algorithm based on the Newton–Raphson method and the closest point projection scheme containing an elastic predictor and plastic corrector are implemented in the AESE model. Then, the integration code for this model is incorporated into the commercial finite element software ABAQUS through the user material subroutine (UMAT) interface to simulate undrained monotonic triaxial tests for various saturated soft clays under different consolidation conditions.

The comparison between the simulated results from ABAQUS and the experimental results demonstrates the satisfactory performance of this implicit integration algorithm in terms of effectiveness and robustness and the ability of the proposed model to predict the characteristics of soft clay.

The rotational hardening rule in the AESE model together with the implicit integration algorithm cannot be considered.

The singularity problem existing in most elastoplastic models is eliminated by the closed, smooth and flexible anisotropic egg-shaped yield surface form in the AESE model. In addition, this notion leads to an efficient implicit integration algorithm for updating the highly nonlinear constitutive equations for unsaturated soft clay.

The bodies of aircraft structures have a lot of fastener holes and under different situations these holes bear external forces, which cause a tensile stress on the surface that leads to the failure of materials. Cold expansion process is one of the widely‐used methods to improve the fatigue behavior of materials used in aerospace industry, and such improvement is due to the compressive residual stress around cold expanded hole. The induced residual stress distribution around cold expanded hole is affected by several parameters such as, diametrical interfaces, surface finish of fastener holes, temperature, mandrel speed, i.e. the speed of inserting mandrel into the hole, and so on. In previous studies, most of effective parameters were investigated, whereas, the effect of mandrel speed on the residual stress distribution has not been considered. The present study, seeks to simulate cold expansion process on aluminum alloy 2A12TA using ABAQUS finite element (FE) package and to consider the effect of different mandrel speeds on residual stress distribution around cold expanded hole. It aims to verify the results of FE simulation by experimental data.

There are two kinds of data in this paper; experimental and FE results. The experimental results for cold expansion process have been extracted from the literature and ABAQUS finite element package was employed in order to simulate the above‐mentioned process. Moreover, FE results were validated by the experiments.

The results presented here show the influence of mandrel speed on residual stress distribution around cold expanded hole using a new analytical‐numerical method. The results gained by FE simulation show relative differences between the diagrams of residual stress distribution corresponding different mandrel speeds. It is shown in the paper; the residual stress around cold expanded hole rises by the increase of mandrel speed and consequently the improvement of fatigue life will be achieved.

The present study is part of Abbas Hosseini's MSc. dissertation, an original research work.

In order to improve the robustness of bare-steel and composite structures in fire, a novel axially and rotationally ductile connection has been proposed in this paper.

The component-based models of the bare-steel ductile connection and composite ductile connection have been proposed and incorporated into the software Vulcan to facilitate global frame analysis for performance-based structural fire engineering design. These component-based models are validated against detailed Abaqus FE models and experiments. A series of 2-D bare-steel frame models and 3-D composite frame models with ductile connections, idealised rigid and pinned connections, have been created using Vulcan to compare the fire performance of ductile connection with other connection types in bare-steel and composite structures.

The comparison results show that the proposed ductile connection can provide excellent ductility to accommodate the axial deformation of connected beam under fire conditions, thus reducing the axial forces generated in the connection and potentially preventing the premature brittle failure of the connection.

Compared with conventional connection types, the proposed ductile connection exhibits considerable deformability, and can potentially enhance the robustness of structures in fire.

Pores and shrink holes are unavoidable defects in the die-casting mass production process which may significantly influence the strength, fatigue and fracture behaviour as well as the life span of structures, especially if they are subjected to high static and dynamic loads. Such defects should be considered during the design process or after production, where the defects could be detected with the help of computed tomography (CT) measurements. However, this is usually not done in today's mass production environments. This paper deals with the stress analysis of die-cast structural parts with pores found from CT measurements or that are artificially placed within a structure.

In this paper the authors illustrate two general methodologies to take into account the porosity of die-cast components in the stress analysis. The detailed geometry of a die-cast part including all discontinuities such as pores and shrink holes can be included via STL data provided by CT measurements. The first approach is a combination of the finite element method (FEM) and the finite cell method (FCM), which extends the FEM if the real geometry cuts finite elements. The FCM is only applied in regions with pores. This procedure has the advantage that all simulations with different pore distributions, real or artificial, can be calculated without changing the base finite element mesh. The second approach includes the pore information as STL data into the original CAD model and creates a new adapted finite element mesh for the simulation. Both methods are compared and evaluated for an industrial problem.

The STL data of defects which the authors received from CT measurements could not be directly applied without repairing them. Therefore, for FEM applications an appropriate repair procedure is proposed. The first approach, which combines the FEM with the FCM, the authors have realized within the commercial software tool Abaqus. This combination performs well, which is demonstrated for test examples, and is also applied for a complex industrial project. The developed in-house code still has some limitations which restrict broader application in industry. The second pure FEM-based approach works well without limitations but requires increasing computational effort if many different pore distributions are to be investigated.

A new simulation approach which combines the FEM with the FCM has been developed and implemented into the commercial Abaqus FEM software. This approach the authors have applied to simulate a real engineering die-cast structure with pores. This approach could become a preferred way to consider pores in practical applications, where the porosity can be derived either from CT measurements or are artificially adopted for design purposes. The authors have also shown how pores can be considered in the standard FEM analysis as well.