A Study on Nonlinear Stress and Strain Fields in Two-Dimensional Panels of Elastic Composite Materials (original) (raw)
Related papers
International Journal of Solids and Structures
A theory is developed for evaluation of nonlinear elastic moduli of composite materials with nonlinear inclusions dispersed in another nonlinear material (matrix). We elaborate a method aimed for determination of elastic parameters of a composite: its linear elastic moduli (second-order elastic constants) and nonlinear elastic moduli, which are known as the Murnaghan moduli (third-order elastic constants). We find an analytical form for the effective Murnaghan moduli of a composite with spherical inclusions. The effective moduli depend linearly on Murnaghan moduli of constituents. The results obtained have been verified through numerical modeling using the finite element method.
2019
In this paper, the distribution of stresses in an open circular cylindrical thin-shell panel having a central square hole and various shell curvatures and is subject to uniform axial tension loading is investigated. Analysis is carried out using both linear and geometrically nonlinear behaviors using the finite element analysis computer program ABAQUS. Shell panels are assumed to consist of four symmetrical laminas [θ/-θ]s that are made of a fibrous Graphite/Epoxy (AS/3501) composite. Fiber-orientation angles varied from θ= 00 to 900 in steps of 150. Three types of shell curvatures are considered; namely, shallow shell (SS), moderately-deep shell (MDS) and deep shell (DS) with all edges being clamped. The presence of a central hole resulted in the redistribution of stresses along the hole perimeter. Accordingly, this changed the general trend of stresses from tension to compression in the hole zone and caused stress concentration at hole corners. Also, the peak stresses are increase...
Nonlinear elasticity of composite materials
The European Physical Journal B, 2009
We investigate the elastic properties of model composites, consisting in a dispersion of nonlinear (spherical or cylindrical) inhomogeneities into a linear solid matrix. Both phases are considered isotropic. Under the simplifying hypotheses of small deformation for the material body and of small volume fraction of the embedded phase, we develop a homogenization procedure based on the Eshelby theory, aimed at describing nonlinear features. We obtain the bulk and shear moduli and Landau coefficients of the overall material in terms of the elastic behavior of the constituents and of their volume fractions. The mixing laws for the nonlinear properties describe a complex scenario where possible strong amplifications of the nonlinearities may arise in some given conditions.
Non-linear finite element analysis of composite panels
Composites Part B: Engineering, 1999
In order to promote the efficient use of composite materials in civil engineering infrastructure, effort is being directed at the development of design criteria for composite structures. Insofar as design with regard to buckling of composite shells is concerned, it is well known that a key step is to investigate the influence of initial geometric imperfection on the non-linear behaviour of the composite shells. One possible approach is to use the validated numerical model based on the non-linear finite element analysis. Thus, the objective of this article is to present the formulation used in developing a composite shell element and to validate the element from the composite panels. The finite element used in the current study is an eight-noded shell element with six degrees of freedom per node. The non-linear formulation of the shell element is based on the updated Lagrangian method. The shell element is capable of small strain and large displacement analysis with finite rotations. In order to remove the rigid body rotation, a co-rotational method is used. The transverse shear deformation effects using the Reissner-Mindlin theory are included in formulating the linear and geometric stiffness matrix. Thus, the present composite shell element allows modeling of relatively thick composite plates and shells for both the linear and non-linear analyses. The validation of the composite shell element shows that the present results have very good agreement with existing references. Subsequently the postbuckling analyses for the modeling of the curved panel with initial imperfections are performed in order to investigate the effect of the initial geometric imperfection shape and amplitude. The results are used to estimate imperfection sensitivity for such panels. ᭧
Stress fields in a composite material by means of a non-classical approach
International Journal of Engineering Science, 1989
For a two dimensional, bimaterial composite body under elastic deformation, a method is developed to determine separate stress field expressions for each material in the body. Far-field strain components, measured or calculated by classical methods, are considered as known inputs. By considering the long-range effects, caused by the inhomogeneity on a micro-structural scale, the interactions between the point of consideration and the other material regions are expressed. Combining the local stresses and the stresses caused by the long-range interactions, separate expressions for the stresses in the different materials of the body are obtained. Two solutions for a plane strain, bimaterial, laminated composite are obtained through the methods of classical elasticity for the purposes of comparison with the present method.
Applied Sciences, 2021
In this study, the geometrically nonlinear behaviour caused by large displacements and rotations in the cross sections of thin-walled composite beams subjected to axial loading is investigated. Newton–Raphson scheme and an arc length method are used in the solution of nonlinear equations by finite element method to determine the mechanical effect. The Carrera-Unified formulation (CUF) is used to solve nonlinear, low or high order kinematic refined structure theories for finite beam elements. In the study, displacement area and stress distributions of composite structures with different angles and functionally graded (FG) structures are presented for Lagrange polynomial expansions. The results show the accuracy and computational efficiency of the method used and give confidence for new research.
Deformation Characteristics of Composite Structures
Applied and Computational Mechanics, 2016
The composites provide design flexibility because many of them can be moulded into complex shapes. The carbon fibre-reinforced epoxy composites exhibit excellent fatigue tolerance and high specific strength and stiffness which have led to numerous advanced applications ranging from the military and civil aircraft structures to the consumer products. However, the modelling of the beams undergoing the arbitrarily large displacements and rotations, but small strains, is a common problem in the application of these engineering composite systems. This paper presents a nonlinear finite element model which is able to estimate the deformations of the fibre-reinforced epoxy composite beams. The governing equations are based on the Euler-Bernoulli beam theory (EBBT) with a von Karman type of kinematic nonlinearity. The anisotropic elasticity is employed for the material model of the composite material. Moreover, the characterization of the mechanical properties of the composite material is ac...