Analysis of Delaminated Composite Plates

2013 ◽  
Vol 686 ◽  
pp. 104-108
Author(s):  
Ali Mahieddine ◽  
Mohammed Ouali
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Composite Beam ◽  
Composite Structures ◽  
Failure Modes ◽  
Laminated Composite ◽  
Composite Plates ◽  
Published Data ◽  
Shear Stresses ◽  
Buckling Behavior

A mathematical model for plates with partially delaminated layers is presented to investigate their behavior. In this formulation account is taken of lateral strains. The principal advantage of the element is that it allows the modeling of delamination anywhere in the structure. The region without delamination is modeled to carry constant peel and shear stresses; while the region with delamination is modeled by assuming that there is no peel and shear stress transfer between the top and bottom layers. Numerical results of the present model are presented and its performance is evaluated for static problems. Laminated beams and plates are often used as primary load-carrying structures. However, the mechanical properties of composite materials may degrade severely in the presence of damage. One of the common types of damage modes in laminated composites is delamination. The presence of delamination is one of the most prevalent life-limiting failure modes in laminated composite structures. Many researchers had been studying the effect of delamination. Wee and Boay [1] developed an analytical model to predict the critical load of a delaminated composite laminated beam. Lee et al. [2] investigated the buckling behavior of the beam plate with multiple delaminations under compression. Kapania and Wolfe [3] examined the buckling behavior of a beam plate with two delaminations of equal length. Wang et al. [4] improved the analytical solution by including the coupling between the flexural and axial vibrations of the delaminated sub-laminates. Lee et al. [5] studied a composite beam with arbitrary lateral and longitudinal multiple delamination. Finite-element methods have been developed using the layerwise theory by Kim et al. [6]. Tan and Tong [7] developed a dynamic analytical model for the identification of delamination embedded in a laminated composite beam. To investigate the effects of delamination of a plate layers, a finite-element model is developed. Both displacement continuity and force equilibrium conditions are imposed between the regions with and without delamination. The accuracy of the approach is verified by comparing results with previously published data.

Analysis of Symmetric Angle-Ply Laminated Composite Skew Plates Using Hybrid Trefftz Finite Element

2019 ◽  
Author(s):  
Subhasankar Dwibedi
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Plate Theory ◽  
Laminated Composite ◽  
Composite Plates ◽  
Point Load ◽  
Shear Stresses ◽  
Skew Angle ◽  
Distributed Load ◽  
Trefftz Finite Element

Abstract Analysis of symmetric angle-ply skew laminated composite plates has been presented in the study using a newly developed hybrid Trefftz finite element (hTFE). Mindlin’s plate theory has been used to develop the present hTFE. The forms of displacement are assumed such that governing partial differential equations are satisfied a priori inside the element domain. Particular solutions of the governing equations have been ignored and Trefftz functions are derived using the homogenous solutions only. Inter-element continuity has been established by employing another displacement field along the edges of the hTFEs. The transverse shear stresses have been ignored at the top and bottom surfaces of the laminate. The angle of inclination of the width of the plate with the y-axis has been taken as the skew angle and different forms of skew plates are obtained by varying the skew angle. Sinusoidally distributed load (SDL), uniformly distributed load (UDL), and point load (PL) have been subjected to the top surface of the laminate and the non-dimensionalized center point deflection have been evaluated to assess the performance of the present hTFE. The observation from the present study further reinforce the versatility of the hTFE method for analysis of composite structures with complex shapes or geometries.

Investigation on Interlaminar Shear Stresses in Laminated Composite Plates under Thermal and Mechanical Loading

2014 ◽  
Vol 592-594 ◽  
pp. 451-455
Author(s):  
Nagaraj Murugesan ◽  
Vasudevan Rajamohan
Keyword(s):  
Finite Element ◽  
Thermal Environment ◽  
Laminated Composite ◽  
Composite Plates ◽  
Laminated Plates ◽  
Shear Stresses ◽  
Laminated Composite Plates ◽  
Interlaminar Stresses ◽  
Composite Laminated Plates ◽  
Interlaminar Shear

In this study the combined effect of thermal environment and mechanical loadings on the interlaminar shear stresses of both moderately thin and thick composite laminated plates are numerically analyzed. The finite element modeling of laminated composite plates and analysis of interlaminar stresses are performed using the commercially available software package MSC NASTRAN/PATRAN. The validity of the present finite element analysis is demonstrated by comparing the interlaminar stresses developed due to mechanical loadings derived using the present FEM with those of available literature. Various parametric studies are also performed to investigate the effect of thermal environment on interlaminar stresses generated in asymmetric cross-ply composite laminated plates of different length to thickness ratios (L/H) and boundary conditions with identical mechanical loadings. It is observed that the elevated thermal environment under identical mechanical loading lead to higher interlaminar shear stresses varying with length to depth ratio and boundary conditions in asymmetric cross-ply laminated composite plates.

Design and Analysis of an Aircraft Composite Hinge Bracket Using Finite Element Approach

2014 ◽  
Vol 629 ◽  
pp. 158-163
Author(s):  
Wai Chee Mun ◽  
Ahmad Rivai ◽  
Omar Bapokutty
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Laminated Composite ◽  
Composite Plates ◽  
Metallic Structures ◽  
Aircraft Structures ◽  
Finite Element Approach ◽  
Heterogeneous Nature ◽  
Element Approach ◽  
Margin Of Safety

The use of composite materials in aircraft structures have been increasing for the past decade. The anisotropic and heterogeneous nature of composites remains a major challenge to the design and analysis of composite aircraft structures. Composite structures require a different design approach compared to the design of metallic structures. This paper aims to provide a step by step definitive guide to design and analyze composite structures using finite element approach. A simplified design model for the composite structural design was used to analyze an aircraft composite hinge bracket. The composite hinge bracket which is made of IM7/8552 laminated composite plates was successfully designed with a margin of safety of 0.216 and a weight savings of 43.77 percent was estimated.

scholarly journals Vibration Analysis of Carbon Fiber-Graphene-Reinforced Hybrid Polymer Composites Using Finite Element Techniques

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4225 ◽  
Author(s):  
Stelios K. Georgantzinos ◽  
Georgios I. Giannopoulos ◽  
Stylianos I. Markolefas
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Carbon Fiber ◽  
Composite Structures ◽  
Volume Fraction ◽  
Laminated Composite ◽  
Composite Plates ◽  
Computational Procedure ◽  
The Matrix ◽  
Modes Of Vibration

In this study, a computational procedure for the investigation of the vibration behavior of laminated composite structures, including graphene inclusions in the matrix, is developed. Concerning the size-dependent behavior of graphene, its mechanical properties are derived using nanoscopic empiric equations. Using the appropriate Halpin-Tsai models, the equivalent elastic constants of the graphene reinforced matrix are obtained. Then, the orthotropic mechanical properties of a composite lamina of carbon fibers and hybrid matrix can be evaluated. Considering a specific stacking sequence and various geometric configurations, carbon fiber-graphene-reinforced hybrid composite plates are modeled using conventional finite element techniques. Applying simply support or clamped boundary conditions, the vibrational behavior of the composite structures are finally extracted. Specifically, the modes of vibration for every configuration are derived, as well as the effect of graphene inclusions in the natural frequencies, is calculated. The higher the volume fraction of graphene in the matrix, the higher the natural frequency for every mode. Comparisons with other methods, where it is possible, are performed for the validation of the proposed method.

Investigation on the Effect of Resin Content on Buckling of Laminated Composite Plates

2014 ◽  
Vol 1035 ◽  
pp. 212-218
Author(s):  
Qi You Cheng ◽  
Jian Ping Huang ◽  
Ai Min Ling ◽  
Zhi Zhuang Feng
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Failure Modes ◽  
Volume Fraction ◽  
Laminated Composite ◽  
Composite Plates ◽  
Buckling Load ◽  
Laminated Composite Plates ◽  
Element Analysis ◽  
The Stability

Aerospace applications of composites involve components that are relatively thin plate or shell like structures, thus requiring the consideration of buckling as one of the many possible failure modes. To study the effect of the resin volume fraction on stability of composites, a finite element method based on micromechanics and classical lamination theory has been established to compute buckling loads of simply supported symmetric laminated composite plates subjected to the load of in-plane axial compress and shear load, respectively. The analysis procedure includes a Micromechanical finite element analysis that predicts the elastic modulus of lamina and a finite element linear buckling analysis that predicts buckling load of the composite plates. Three kinds of resin volume fraction that are equal to 44 percent, 47 percent, and 50 percent respectively are considered. The results show that the resin volume fraction has obvious influence on the stability of composite plate. The plate exhibits a relatively large increase in buckling load, about 12 percent, when the resin volume fraction increases by 3 percent. It is finds that the bending stiffness that has an obvious influence on the stability is an incremental function of elastic modulus and cubic thickness. The elastic modulus will be decreased slightly with the increase of resin volume fraction. However, the thickness of the plates is proportional to resin volume fraction.

Fracture Mechanics Approach for Analysis of Delamination in Composite Plates

2014 ◽  
Vol 969 ◽  
pp. 176-181 ◽  
Author(s):  
Milan Žmindák ◽  
Vladimir Dekýš ◽  
Pavol Novák
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Composite Structures ◽  
Ad Hoc ◽  
Failure Modes ◽  
Composite Plates ◽  
Failure Criteria ◽  
Fracture Data ◽  
Substantial Problem ◽  
Static Fracture

Delamination can be a substantial problem in designing composite structures. Modelling of delamination by finite element (FE) codes is limited. Previous efforts to model delamination and debonding failure modes using FE codes have typically relied on ad hoc failure criteria and quasi-static fracture data. Improvements to these modelling procedures can be made by using an approach based on fracture mechanics. A study of modelling delamination using the FE code ANSYS was conducted. This investigation demonstrates the modelling of composites through improved delamination modelling. Further developments to this approach may be improved.

Characterization of multilayer delaminations in composites using wavenumber analysis: numerical and experimental studies

2020 ◽  
pp. 147592172093961
Author(s):  
Hanfei Mei ◽  
Victor Giurgiutiu
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Failure Modes ◽  
Experimental Studies ◽  
Laser Doppler Vibrometer ◽  
Composite Plates ◽  
Finite Element Simulations ◽  
Successful Implementation ◽  
Out Of Plane

Delamination is one of the most common and dangerous failure modes for composites because it takes place and grows in the absence of any visible surface damage. The successful implementation of delamination detection in aerospace composite structures is always challenging due to the general anisotropic behavior of composites and multilayer delamination scenarios. This article presents a numerical and experimental investigation to detect and characterize the multilayer delaminations in carbon fiber–reinforced polymer composite plates using guided waves and wavenumber analysis. Multiphysics three-dimensional finite element simulations of the composite plate with five different delamination scenarios are conducted to provide the out-of-plane wave motion for wavenumber analysis. The out-of-plane results from finite element simulations of one delamination and two delaminations are validated by the scanning laser Doppler vibrometer measurements. It is found that the wavenumber analysis can identify the plies between which the delamination occurs and evaluate the delamination severity by comparing the new wavenumbers due to the trapped waves in the delamination regions, which is potentially related to delamination severity. Both numerical and experimental results demonstrate a good capability for the detection and characterization of multilayer delaminations in composite structures.

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