Nonlinear Thermo-Viscoelastic Analysis of Interlaminar Stresses in Laminated Composites

1996 ◽  
Vol 63 (1) ◽  
pp. 218-224 ◽  
Author(s):  
Sung Yi ◽  
H. H. Hilton ◽  
M. F. Ahmad
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Laminated Composites ◽  
Stress Fields ◽  
Element Formulation ◽  
Present Formulation ◽  
Interlaminar Stresses ◽  
Viscoelastic Analysis ◽  
Single Integral ◽  
Stress States

A finite element formulation for analyzing interlaminar stress fields in nonlinear anisotropic viscoelastic laminated composites is presented including a hygrothermal formulation. Schapery’s single integral formulation is extended to account for viscoelastic anisotropy and multiaxial stress states. Numerical results obtained from the present formulation are compared against experimental data and excellent agreement is obtained between these results. As illustrative examples, inplane and interlaminar stresses for (45/-45)s T300/5208 laminate are also presented.

Mechanical Behavior of Laminated Composites with Circular Holes

2013 ◽  
Vol 550 ◽  
pp. 1-8 ◽  
Author(s):  
Habib Achache ◽  
Benali Boutabout ◽  
Djamel Ouinas
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Composite Structures ◽  
Laminated Composites ◽  
Three Dimensional ◽  
Laminated Composite ◽  
Element Formulation ◽  
Composites Materials ◽  
Circular Holes ◽  
Fibers Orientation

This paper presents a numerical method for the evaluation of the stress concentration factor (SCF) in three dimensional laminated composites under mechanical loads. The proposed method uses the finite element formulation. The composites materials based on the epoxy matrix and reinforcing fibers are extensively used in aircraft structures due to their high specific characteristics. However, the withstanding of composite structures can be significantly reduced by the addition of geometric singularities, such as perforations or notches. To Analyses the stress concentration around geometrical notches, several studies as analytical, numerical and experimental techniques are available. The stress distribution in a laminated composite plate with the presence of a circular hole was investigated using the finite element method. In order, the results obtained by this study are compared with those reported in literature. The aim of this analysis is to evaluate numerically the factor of stress concentration under the influence of several parameters such as fibers orientation, the mechanical characteristics of composites and the distance between notches of cross-laminated.

Modeling of the Long-Term Behavior of Glassy Polymers

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Sami Holopainen ◽  
Mathias Wallin
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Glassy Polymers ◽  
Integration Scheme ◽  
Element Formulation ◽  
Algebraic Equations ◽  
Plastic Spin ◽  
Backward Euler ◽  
Long Term Behavior

The constitutive model for glassy polymers proposed by Arruda and Boyce (BPA model) is reviewed and compared to experimental data for long-term loading. The BPA model has previously been shown to capture monotonic loading accurately, but for unloading and long-term behavior, the response of the BPA model is found to deviate from experimental data. In the present paper, we suggest an efficient extension that significantly improves the predictive capability of the BPA model during unloading and long-term recovery. The new, extended BPA model (EBPA model) is calibrated to experimental data of polycarbonate (PC) in various loading–unloading situations and deformation states. The numerical treatment of the BPA model associated with the finite element analysis is also discussed. As a consequence of the anisotropic hardening, the plastic spin enters the model. In order to handle the plastic spin in a finite element formulation, an algorithmic plastic spin is introduced. In conjunction with the backward Euler integration scheme use of the algorithmic plastic spin leads to a set of algebraic equations that provides the updated state. Numerical examples reveal that the proposed numerical algorithm is robust and well suited for finite element simulations.

Finite Element Simulation of the Upset Welding Process

1991 ◽  
Author(s):  
H. A. Nied
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Elevated Temperature ◽  
Welding Process ◽  
Element Model ◽  
Stress Fields ◽  
Element Formulation ◽  
Deformation Characteristics ◽  
Element Simulation ◽  
Major Process

A finite element model of an elevated temperature upset welding process was developed to simulate the process and to study the role and sensitivity of the major process parameters. Particular attention was focused on the deformation characteristics by studying the displacement and stress fields generated for the purpose of obtaining a better understanding of this solid-state welding process. The paper describes the finite element formulation, the experiments used to validate the modeling, and a selected application for upset welding of a titanium alloy.

Solutions of the Right Classes for Laminated Composites Satisfying Interlamina Physics

2001 ◽  
Author(s):  
K. S. Surana ◽  
H. Ngyun
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Laminated Composites ◽  
Dissimilar Materials ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Computational Framework ◽  
Mixed Formulations ◽  
The Right ◽  
Mesh Refinements

Abstract This paper presents a new theoretical and computational framework for computing solutions of right classes for laminated composites using 2D p-version least squares finite element formulation incorporating the correct physics of interlamina behavior. At the interface between two laminas of dissimilar materials we have continuity of displacements u, v, stresses σyy, τxy, and strain εxx, while the stress σxx and the strains εyy and γxy are discontinuous. Thus, a finite element formulation, incorporating the physics of laminate behavior, would require interpolation of u, v, εxx, σyy and τxy instead of u, v, σxx, σyy and τxy which is generally the case in most mixed formulations. In the p-version LSFEF presented here, we interpolate u, v and σyy, τxy (εxx = ∂u/∂x is used to eliminate εxx as a variable) using appropriate p-version interpolations which would ensure correct interlamina behavior of these components. When the mating lamina properties are different, interlamina discontinuity of σxx, εyy and γxy is automatically generated due to dissimilar material properties of the laminas. In this formulation interlamina jumps in σxx, εyy and γxy do not constitute singularities, hence mesh refinements and higher p-levels are not needed in the vicinity of inter-lamina boundaries. The major thrust of this paper is to construct interpolations for the dependant variables that are of right classes in appropriate spaces so that a sequence of converged solutions in these spaces may be computed which, when converged, would yield a numerical solution that has exactly the same characteristics (in terms of continuity and differentiability) as the analytical or theoretical (strong) solution.

Dynamic Viscoelastic Analysis of Asphalt Pavements using a Finite Element Formulation

2010 ◽  
Vol 11 (2) ◽  
pp. 409-433 ◽  
Author(s):  
Pedro Custódio de Araújo Junior ◽  
Jorge Barbosa Soares ◽  
Aurea Silva de Holanda ◽  
Evandro Parente Junior ◽  
Francisco Evangelista Junior
Keyword(s):  
Finite Element ◽  
Finite Element Formulation ◽  
Asphalt Pavements ◽  
Element Formulation ◽  
Viscoelastic Analysis

An Efficient Three Nodded Finite Element Formulation for Free Vibration Analysis of Sandwich Arches with Graded Metallic Cellular Core

2020 ◽  
Vol 12 (06) ◽  
pp. 2050069
Author(s):  
Mohammad Amir ◽  
Mohammad Talha
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Finite Element Model ◽  
Vibration Analysis ◽  
Shear Deformation Theory ◽  
Core Layer ◽  
Element Model ◽  
Element Formulation ◽  
Present Formulation ◽  
Porosity Coefficient

An efficient finite element model based on three nodded element has been developed for the vibration analysis of sandwich arches with graded metallic cellular (GMC) core. The present formulation is based on the higher-order shear deformation theory and orthogonal curvilinear coordinate axes. The arch consists of two isotropic face sheets and a GMC core layer. The internal pores in the core layer follow the different types of distributions. The material properties of the GMC core layer of the sandwich arches vary in the thickness direction as a function in terms of porosity coefficient and mass density. Three types of porosity distributions have been considered to accomplish the vibration responses of sandwich arches. The present formulation is validated with limited results available in the literature. Few new results are computed and the effects of different influencing parameters such as porosity coefficient [Formula: see text], porosity distribution type, the thickness-to-length ratio [Formula: see text], boundary conditions and opening angle [Formula: see text] on the free vibration characteristics of sandwich arches with the GMC core are observed. The present finite element model gives better convergence and more accurate results than a conventional two nodded element-based finite element model.

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