scholarly journals Analysis of Free Edge Stresses in Composite Laminates Using Higher Order Theories

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Hamidreza Yazdani Sarvestani ◽  
Ali Naghashpour
Keyword(s):  
Composite Laminates ◽  
High Efficiency ◽  
Single Layer ◽  
Free Edge ◽  
Higher Order ◽  
Design Guidelines ◽  
Computational Time ◽  
Interlaminar Stresses ◽  
Layerwise Theory ◽  
Free Edges

This paper presents the determination of the interlaminar stresses close to the free edges of general cross-ply composite laminates based on higher order equivalent single-layer theory (HESL). The laminates with finite dimensions were subjected to a bending moment, an axial force, and/or a torque for investigation. Full three-dimensional stresses in the interior and the boundary-layer regions were determined. The computed results were compared with those obtained from Reddy’s layerwise theory. It was found that HESL theory predicts precisely the interlaminar stresses near the free edges of laminates. Besides, high efficiency in terms of computational time is obtainable when HESL theory is used as compared with layerwise theory. Finally, various numerical results were presented for the cross-ply laminates. Also design guidelines were proposed to minimize the edge-effect problems in composite laminates.

scholarly journals Investigation of Through-Thickness Stresses in Composite Laminates Using Layerwise Theory

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Hamidreza Yazdani Sarvestani ◽  
Ali Naghashpour
Keyword(s):  
Composite Laminates ◽  
Stress Gradient ◽  
High Stress ◽  
Composite Plates ◽  
Reduced Form ◽  
Shear Stresses ◽  
Interlaminar Stresses ◽  
Layerwise Theory ◽  
Normal And Shear Stresses ◽  
Free Edges

In this study, an analytical method is developed to exactly obtain the interlaminar stresses near the free edges of laminated composite plates under the bending moment based on the reduced form of elasticity displacement field for a long laminate. The analytical and numerical studies were performed based on the Reddy’s layerwise theory for the boundary layer stresses within cross-ply, symmetric, angle-ply, and general composite laminates. Finally, a variety of numerical results are presented for the interlaminar normal and shear stresses along the interfaces and through thickness of laminates near the free edges. The results showed high stress gradient of interlaminar normal and shear stresses near the edges of laminates.

The Effects of Inclined Free Edges on the Thermal Stresses in a Layered Beam

1993 ◽  
Vol 115 (2) ◽  
pp. 208-213 ◽  
Author(s):  
Wan-Lee Yin
Keyword(s):  
Thermal Stresses ◽  
Stress Singularity ◽  
Approximate Solutions ◽  
Free Edge ◽  
Local Concentration ◽  
Interlaminar Stresses ◽  
Beneficial Effects ◽  
Stress Functions ◽  
Layered Beam ◽  
Free Edges

A stress-function-based variational method is used to determine the thermal stresses in a layered beam with inclined free edges at the two ends. The stress functions are expressed in terms of oblique cartesian coordinates, and polynomial expansions of the stress functions with respect to the thickness coordinate are used to obtain approximate solutions. Severe interlaminar stresses act across end segments of the layer interfaces. Local concentration of such stresses may be significantly affected by the inclination angle of the end planes. Variational solutions for a two-layer beam show generally beneficial effects of free-edge inclination in dispersing the concentration of interlaminar stresses. The significance of these effects is generally not indicated by the power of the stress singularity as computed from an elasticity analysis of a bimaterial wedge.

Progressive Damage Analyses of Composite Laminates Exhibiting Free Edge Effects Using a New Micro-Meso Approach

2011 ◽  
Vol 471-472 ◽  
pp. 263-267
Author(s):  
Hossein Hosseini-Toudeshky ◽  
Amin Farrokhabadi ◽  
Bijan Mohammadi
Keyword(s):  
Edge Effects ◽  
Composite Laminates ◽  
Free Edge ◽  
Experimental Results ◽  
Progressive Damage ◽  
Stress Strain ◽  
Laminate Thickness ◽  
Stress Variations ◽  
Angle Ply Laminates ◽  
Free Edges

In this paper, the developed new micro-meso method by the authors is used for the edge-effects analyses of various angle-ply laminates such as [10/-10]2s and [30/-30]2s. It is shown that the obtained stress-strain behaviors of laminates are in well agreement with the available experimental results. The stress variations through the laminate thickness and near the free edges are also computed and compared with the available CDM results.

GLOBAL-LOCAL PROGRESSIVE DAMAGE ANALYSIS OF COMPOSITE LAMINATES USING LAYER-WISE HIGHER-ORDER STRUCTURAL MODELSv

2021 ◽  
Author(s):  
MANISH H. NAGARAJ ◽  
ERASMO CARRERA ◽  
MARCO PETROLO
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Numerical Models ◽  
Higher Order ◽  
Computational Time ◽  
Progressive Damage ◽  
Damage Analysis ◽  
Isotropic Composite ◽  
Integration Schemes ◽  
Laminated Structures

The objective of the current work is to develop a global-local framework for the progressive damage analysis of composite laminated structures. The technique involves two sequential analyses—an initial low-fidelity 3D-FE based linear analysis of the global structure, followed by the local nonlinear analysis of critical regions where damage is likely to occur. The numerical models used for the local analysis are developed using higher-order layer-wise structural theories obtained via the Carrera Unified Formulation. Composite damage is modelled using the CODAM2 model based on continuum damage mechanics, and the nonlinear problem is solved using explicit time integration schemes. Preliminary assessments are carried out to validate the proposed global-local framework by considering open-hole tensile specimens of quasi-isotropic composite laminates. Both full-scale CUF models and the proposed global-local approach are used to predict the tensile strength of the specimen. It is shown that the obtained results are in good agreement with experiment data, thus validating the framework, and a multi-fold improvement in computational time is demonstrated.

Simple Solutions of the Free-Edge Stresses in Composite Laminates under Thermal and Mechanical Loads

1994 ◽  
Vol 28 (6) ◽  
pp. 573-586 ◽  
Author(s):  
Wan-Lee Yin
Keyword(s):  
Composite Laminates ◽  
Constitutive Relations ◽  
Free Edge ◽  
Normal Derivative ◽  
Boundary Region ◽  
Material Behavior ◽  
Interlaminar Stresses ◽  
Inelastic Material ◽  
Stress Functions ◽  
Temperature Loads

Intense and localized interlaminar stresses generally occur in a narrow boundary region near the free edge of a multilayered anisotropic laminate under mechanical and temperature loads. Quantitative measures of interlaminar action across interfaces may be readily obtained through purely algebraic operations, even if nonlinear and inelastic material behavior becomes significant in the boundary region due to severe strain concentration. These measures are the limiting values of the Lekhnitskii stress functions F and $$ (and of the normal derivative of F) along interfaces and toward the interior region of the laminate. In the present work, they are used as the basis of an exceedingly simple and efficient method of interlaminar stress analysis that is potentially applicable to free-edge problems involving nonlinear thermoelastic constitutive relations. Example solutions are obtained for symmetric, four-layer, cross-ply and angle-ply laminates under a temperature load and two different types of strain loads, and the results are found to be in reasonable agreement with the existing numerical and analytical solutions based on elaborate analysis methods.

scholarly journals Investigation of the Free Edge Interlaminar Stresses Dependence on the PLY Thickness and Orientation

2006 ◽  
Vol 15 (1) ◽  
pp. 096369350601500
Author(s):  
Dionisios T. G. Katerelos
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Laminates ◽  
Free Edge ◽  
Thermomechanical Loading ◽  
Interlaminar Stresses ◽  
Element Analysis ◽  
3 Dimensional ◽  
Out Of Plane ◽  
Dimensional Finite Element

Among the principal damage modes in composite laminates, is delamination. Design details, such as free, straight or curved, edges, induce large local out-of-plane loads, generating interlaminar stresses. In the present work, the effect of ply thickness and the angle between two adjacent layers on the interlaminar stresses developed at the vicinity of straight and curved free edges in composite laminates under thermomechanical loading is examined. The results are obtained by the application of a 3-dimensional Finite Element Analysis.

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