Implementation details of the assumed shear strain method in a novelfinite rotation shell theory are discussed. Careful considerations of thepertinent aspects of the Newton…
Abstract
Implementation details of the assumed shear strain method in a novel finite rotation shell theory are discussed. Careful considerations of the pertinent aspects of the Newton solution procedure are given. The latter results in a very robust performance of the presented 4–node shell element in some challenging finite rotation problems.
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ADNAN IBRAHIMBEGOVIĆ and FRANÇOIS FREY
An efficient implementation of a constitutive model for reinforced concrete plates is discussed in this work. The constitutive model is set directly in terms of stress resultants…
Abstract
An efficient implementation of a constitutive model for reinforced concrete plates is discussed in this work. The constitutive model is set directly in terms of stress resultants and their energy conjugate strain measures, relating their total values. The latter simplification is justified by our primary goal being an evaluation of the limit load of a reinforced concrete plate. A concept of the ‘rotating crack model’ is utilized in proposing the constitutive model to relate the principal values of bending moments and the corresponding values of curvatures. Efficient implementation is provided by a very robust, but inexpensive plate element. The element is based on an assumed shear strain field and a set of incompatible bending modes, which provides that the non‐linear computations, pertinent to constitutive model, can be carried out locally, i.e. independently at each numerical integration point. Set of numerical examples is presented to demonstrate a very satisfying performance of the proposed model.
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Adnan Ibrahimbegovic, Guillaume Hervé and Pierre Villon
The purpose of this paper is to provide the methodology for structural design of complex massive structures under impact by a large airplane.
Abstract
Purpose
The purpose of this paper is to provide the methodology for structural design of complex massive structures under impact by a large airplane.
Design/methodology/approach
Using case studies, the issues related to multi‐scale modelling of inelastic damage mechanisms for massive structures are discussed, as well as the issues pertaining to the time integration schemes in presence of different scales in time variation of different sub‐problems, brought by a particular nature of loading with a very short duration) and finally the issues related to model reduction seeking to provide an efficient and yet sufficiently reliable basis for parametric studies which are an indispensable part of a design procedure.
Findings
Several numerical simulations are presented in order to further illustrate the approaches proposed herein. Concluding remarks are stated regarding the current and future research in this domain.
Originality/value
Proposed design procedure for complex massive engineering structures under impact by a large airplane provides on one side a very reliable representation of inelastic damage mechanisms and external loading represented by the solution of the corresponding contact/impact problem, and on the other side a very efficient basis obtained by model reduction for performing the parametric design studies.
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ADNAN IBRAHIMBEGOVI&Cacute and EDWARD L. WILSON
This paper presents several methods for enhancing computational efficiency in both static and dynamic analysis of structural systems with localized non‐linear behaviour. A…
Abstract
This paper presents several methods for enhancing computational efficiency in both static and dynamic analysis of structural systems with localized non‐linear behaviour. A significant reduction of computational effort with respect to brute‐force non‐linear analysis is achieved in all cases at the insignificant (or no) loss of accuracy. The presented methodologies are easily incorporated into a standard computer program for linear analysis.
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Uroš Bohinc, Adnan Ibrahimbegovic and Boštjan Brank
The purpose of this paper is to address error‐controlled adaptive finite element (FE) method for thin and thick plates. A procedure is presented for determining the most suitable…
Abstract
Purpose
The purpose of this paper is to address error‐controlled adaptive finite element (FE) method for thin and thick plates. A procedure is presented for determining the most suitable plate model (among available hierarchical plate models) for each particular FE of the selected mesh, that is provided as the final output of the mesh adaptivity procedure.
Design/methodology/approach
The model adaptivity procedure can be seen as an appropriate extension to model adaptivity for linear elastic plates of so‐called equilibrated boundary traction approach error estimates, previously proposed for 2D/3D linear elasticity. Model error indicator is based on a posteriori element‐wise computation of improved (continuous) equilibrated boundary stress resultants, and on a set of hierarchical plate models. The paper illustrates the details of proposed model adaptivity procedure for choosing between two most frequently used plate models: the one of Kirchhoff and the other of Reissner‐Mindlin. The implementation details are provided for a particular case of the discrete Kirchhoff quadrilateral four‐node plate FE and the corresponding Reissner‐Mindlin quadrilateral with the same number of nodes. The key feature for those elements that they both provide the same quality of the discretization space (and thus the same discretization error) is the one which justifies uncoupling of the proposed model adaptivity from the mesh adaptivity.
Findings
Several numerical examples are presented in order to illustrate a very satisfying performance of the proposed methodology in guiding the final choice of the optimal model and mesh in analysis of complex plate structures.
Originality/value
The paper confirms that one can make an automatic selection of the most appropriate plate model for thin and thick plates on the basis of proposed model adaptivity procedure.
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Damijan Markovic, Rainer Niekamp, Adnan Ibrahimbegović, Hermann G. Matthies and Robert L. Taylor
To provide a computational strategy for highly accurate analyses of non‐linear inelastic behaviour for heterogeneous structures in civil and mechanical engineering applications
Abstract
Purpose
To provide a computational strategy for highly accurate analyses of non‐linear inelastic behaviour for heterogeneous structures in civil and mechanical engineering applications
Design/methodology/approach
Adapts recent developments on mathematical formulations of multi‐scale problems to the recently developed component technology based on C++ generic templates programming.
Findings
Provides the understanding how theoretical hypotheses, concerning essentially the multi‐scale interface conditions, affect the computational precision of the strategy.
Practical implications
The present approach allows a very precise modelling of multi‐scale aspects in structural mechanics problems and can play an essential tool in searching for an optimal structural design.
Originality/value
Provides all the ingredients for constructing an efficient multi‐scale computational framework, from the theoretical formulation to the implementation for parallel computing. It is addressed to researchers and engineers analysing composite structures under extreme loading.
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C. Kassiotis, J.‐B. Colliat, A. Ibrahimbegovic and H.G. Matthies
The purpose of this paper is to study the partitioned solution procedure for thermomechanical coupling, where each sub‐problem is solved by a separate time integration scheme.
Abstract
Purpose
The purpose of this paper is to study the partitioned solution procedure for thermomechanical coupling, where each sub‐problem is solved by a separate time integration scheme.
Design/methodology/approach
In particular, the solution which guarantees that the coupling condition will preserve the stability of computations for the coupled problem is studied. The consideration is further generalized for the case where each sub‐problem will possess its particular time scale which requires different time step to be selected for each sub‐problem.
Findings
Several numerical simulations are presented to illustrate very satisfying performance of the proposed solution procedure and confirm the theoretical speed‐up of computations which follow from the adequate choice of the time step for each sub‐problem.
Originality/value
The paper confirms that one can make the most appropriate selection of the time step and carry out the separate computations for each sub‐problem, and then enforce the coupling which will preserve the stability of computations with such an operator split procedure.
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Boštjan Brank, Said Mamouri and Adnan Ibrahimbegović
Aims to address the issues pertaining to dynamics of constrained finite rotations as a follow‐up from previous considerations in statics.
Abstract
Purpose
Aims to address the issues pertaining to dynamics of constrained finite rotations as a follow‐up from previous considerations in statics.
Design/methodology/approach
A conceptual approach is taken.
Findings
In this work the corresponding version of the Newmark time‐stepping schemes for the dynamics of smooth shells employing constrained finite rotations is developed. Different possibilities to choose the constrained rotation parameters are discussed, with the special attention given to the preferred choice of the incremental rotation vector.
Originality/value
The pertinent details of consistent linearization, rotation updates and illustrative numerical simulations are supplied.
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M. Hautefeuille, S. Melnyk, J.B. Colliat and A. Ibrahimbegovic
The purpose of this paper is to discuss the inelastic behavior of heterogeneous structures within the framework of finite element modelling, by taking into the related…
Abstract
Purpose
The purpose of this paper is to discuss the inelastic behavior of heterogeneous structures within the framework of finite element modelling, by taking into the related probabilistic aspects of heterogeneities.
Design/methodology/approach
The paper shows how to construct the structured FE mesh representation for the failure modelling for such structures, by using a building‐block of a constant stress element which can contain two different phases and phase interface. All the modifications which are needed to enforce for such an element in order to account for inelastic behavior in each phase and the corresponding inelastic failure modes at the phase interface are presented.
Findings
It is demonstrated by numerical examples that the proposed structured FE mesh approach is much more efficient from the non‐structured mesh representation. This feature is of special interest for probabilistic analysis, where a large amount of computation is needed in order to provide the corresponding statistics. One such case of probabilistic analysis is considered in this work where the geometry of the phase interface is obtained as the result of the Gibbs random process.
Originality/value
The paper confirms that one can make the most appropriate interpretation of the heterogeneous structure properties by taking into account the fine details of the internal structure, along with the related probabilistic aspects with the proper source of randomness, such as the one addressed herein in terms of porosity.