Comparison of weak and strong formulations for 3D stress predictions of composite beam structures

Accurate full field stress responses are often necessary to predict the structural performance of composite structures. The Unified Formulation (UF) is a promising approach to realise efficient and accurate 3D stress predictions of beam-like structures by using recently proposed hierarchical Serendi...

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Bibliographic Details
Published in:International journal of solids and structures 2019-12, Vol.178-179, p.145-166
Main Authors: Ojo, S.O., Patni, M., Weaver, P.M.
Format: Article
Language:English
Subjects:
3D stress
Composite beams
Composite structures
Differential quadrature method
Finite element method
Formulations
Higher order finite element
Longitude
Mathematical models
Matrix methods
Model accuracy
Multilayers
Quadratures
Serendipity Lagrange element
Stiffness matrix
Stress analysis
Symmetry
Three dimensional composites
Unified formulation
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Summary:Accurate full field stress responses are often necessary to predict the structural performance of composite structures. The Unified Formulation (UF) is a promising approach to realise efficient and accurate 3D stress predictions of beam-like structures by using recently proposed hierarchical Serendipity Lagrange Elements (SLE) for capturing the 2D response of the beam cross-section while the 1D behaviour along the beam axis is captured using the Finite Element Method (FEM). Despite the computational merits of SLE elements, the performance of UF-SLE-FEM model is strongly influenced by FEM mesh discretisation along the beam's longitudinal axis. With respect to multi-layered beam structures, a high density FEM mesh may lead to loss of efficiency of the UF-SLE-FEM model due to a significant increase in the number of degrees of freedom required to obtain convergence. This study proposes high-order refined formulations of the 1D structure based on strong-form, Differential Quadrature Method (DQM) and weak form, FEM for 3D stress analysis of composite structures. The proposed high-order strong-form DQM and weak-form FEM models, which are benchmarked against exact solutions, lead to significant computational advantages over UF-SLE-FEM models of similar accuracies. However, the symmetry and positive definiteness of the stiffness matrices of FEM models offer a numerical advantage over the strong-form DQM model with non-symmetric, non-positive definite stiffness matrices.
ISSN:0020-7683
1879-2146
DOI:10.1016/j.ijsolstr.2019.06.016