Delamination Buckling of Composite Cylindrical Panels Under Axial Compressive Load

Volume 1 ◽  
2004 ◽  
Author(s):  
Tim Leigh ◽  
Azam Tafreshi
Keyword(s):  
Finite Element ◽  
Service Use ◽  
Computing Time ◽  
Compressive Load ◽  
Shear Deformation Theory ◽  
Local Mode ◽  
Global Mode ◽  
Local Modes ◽  
Cylindrical Panels ◽  
Delamination Buckling

Composite cylindrical shells and panels are widely used in aerospace structures. Delaminations within the composite structure reduce the compressive strength of laminates, and often result because of damage incurred during manufacturing and in-service use. This paper investigates the buckling behaviour of laminated cylindrical panels loaded in axial compression using the finite element method. The use of three-dimensional finite elements for predicting the delamination buckling of these structures is computationally expensive. Here the analysis has been carried out using a layerwise shell finite element based on the first-order, shear deformation theory. Contact elements were placed between the delaminated regions to avoid physical interpenetration of the elements. It is shown that through-the-thickness delamination can be modelled and analysed effectively without requiring a great deal of computing time and memory. Delamination shapes considered in this study were square and rectangular — extended longitudinally over the entire length or extended along the entire circumference of the panel. Some of the results were compared with the corresponding analytical results which were in good agreement. The most influential parameters for a given laminated panel were the size of the delamination and its through-the-thickness position. The effect of the curvature on the global buckling strength of a delaminated panel was also studied. Depending on the size and through the thickness position of delaminations, three different modes of buckling behaviour occur. The local mode occurs when the delamination is near the free surface of the laminate and the area of the delamination is large. The global mode occurs when the delamination is deeper within the laminate and has a small area. The mixed mode is a combination of global and local modes.

CLASSIFICATION OF BUCKLING MODES IN STIFFENED FUNCTIONALLY GRADED COMPOSITE TUBES SUBJECT TO BENDING

2021 ◽  
Author(s):  
LUAN TRINH ◽  
PAUL WEAVER
Keyword(s):  
Wall Thickness ◽  
Functionally Graded ◽  
Geometric Parameters ◽  
Mode Shapes ◽  
Local Mode ◽  
Buckling Mode ◽  
Global Mode ◽  
Local Modes ◽  
Linear Discriminant ◽  
Finite Element Software

Bamboo poles, and other one-dimensional thin-walled structures are usually loaded under compression, which may also be subject to bending arising from eccentric loading. Many of these structures contain diaphragms or circumferential stiffeners to prevent cross-sectional distortions and so enhance overall load-carrying response. Such hierarchical structures can compartmentalize buckling to local regions in addition to withstanding global buckling phenomena. Predicting the buckling mode shapes of such structures for a range of geometric parameters is challenging due to the interaction of these global and local modes. Abaqus finite element software is used to model thousands of circular hollow tubes with random geometric parameters such that the ratios of radius to periodic length range from 1/3-1/7, the ratio of wall thickness to radius varies from 1/4-1/10. The material used in this study is a type of bamboo, where the Young’s and shear moduli are point-wise orthotropic and gradually increase in magnitude in the radial direction. Under eccentric loads with varying eccentricity, the structures can buckle into a global mode or local modes within an internode, i.e. periodic unit. Moreover, the local modes may contain only one wave or multiple waves in the circumferential direction. As expected, numerical results show that the global mode is more likely to occur in small and thick tubes, whereas the local modes are observed in larger tubes with a smaller number of circumferential waves present in thicker walls. Also, greater eccentricity pushes the local mode domains towards smaller tubes. An efficient classification method is developed herein to identify the domains of each mode shape in terms of radius, wall thickness and eccentricity. Based on linear discriminant analysis, explicit boundary surfaces for the three domains are defined for the obtained data, which can help designers in predicting the mode shapes of tubular structures under axial bending.

scholarly journals Free Vibration Exploration of Rotating FGM Porosity Beams under Axial Load considering the Initial Geometrical Imperfection

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Nguyen Thi Giang
Keyword(s):  
Finite Element ◽  
Compressive Load ◽  
Shear Deformation Theory ◽  
Parameter Study ◽  
Compression Load ◽  
Large Structures ◽  
Geometrical Imperfection ◽  
Compressive Loads ◽  
Vibration Responses ◽  
Sine Functions

In practice, some components in large structures such as the connecting rods between the rotating parts in the engines, turbines, and so on, can model as beam structures rotating around the fixed axis and subject to the axial compression load; therefore, the study of mechanical behavior to these structures has a significant meaning in practice. This paper analyzes the vibration responses of rotating FGM beams subjected to axial compressive loads, in which the beam is resting on the two-parameter elastic foundation, taking into account the initial geometrical imperfection. Finite element formulations are established by using the new shear deformation theory type of hyperbolic sine functions and the finite element method. The materials are assumed to be varied smoothly in the thickness direction of the beam based on the power-law function with the porosity. Verification problems are conducted to evaluate the accuracy of the theory, proposed mechanical structures, and the calculation programs coded in the MATLAB environment. Then, a parameter study is carried to explore the effects of geometrical and material properties on the vibration behavior of FGM beams, especially the influences of the rotational speed and axial compressive load.

A Numerical Investigation on Delamination Buckling Behavior in Laminated Composites under Compressive Load

2012 ◽  
Vol 598 ◽  
pp. 484-487
Author(s):  
Zhong Hai Xu ◽  
Rong Guo Wang ◽  
Wen Bo Liu ◽  
Cheng Qin Dai ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Investigation ◽  
Laminated Composites ◽  
Compressive Load ◽  
Laminated Composite ◽  
The Finite Element Method ◽  
Buckling Behavior ◽  
Depth Position ◽  
Delamination Buckling

In this paper, we predict the delamination buckling behavior in slender laminated composite with embedded delamination under compressive load by using the finite element method (FEM). For the different delamination size and depth position, we illustrate the various parameters effects on buckling behavior.

Solar sail structural analysis via improved finite element modeling

2016 ◽  
Vol 231 (2) ◽  
pp. 306-318 ◽  
Author(s):  
Luisa Boni ◽  
Giovanni Mengali ◽  
Alessandro A Quarta
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Solar Sail ◽  
Mode Shapes ◽  
Solar Sails ◽  
Element Analysis ◽  
Global Mode ◽  
Local Modes ◽  
Global Buckling ◽  
Stabilization Technique

Despite the existence of many studies about the structural analysis of a square solar sail, the need for obtaining reliable numerical results still poses a number of practical issues to be solved. The aim of this paper is to propose a new method that improves the existing analysis techniques. In this sense, the solar sail is modeled using distributed sail-boom connections, and its structural behavior in free flight is studied, using the inertia relief method, at different incidence angles of the incoming solar radiation. The proposed approach is able to circumvent the onset of numerical convergence problems by means of suitable strategies. A nonlinear analysis is carried out starting from an initial geometrical configuration in which the whole solar sail is perturbed using a linear combination of the first global buckling modes, obtained with a static eigenvalue analysis. Key points of the procedure are the application of a correct sail pre-stress, a clever choice of the type of elements to be used in the finite element analysis and the use of a suitable mesh refinement. The performance of the new approach have been successfully tested on square solar sails with side length varying from relatively small to medium-to-large sizes, in the range of 10–100 m. A detailed analysis is presented for a reference 20 m × 20 m square solar sail, where the paper shows that the suggested procedure is able to guarantee accurate results without the need of additional stabilization technique. In particular, the vibration global mode shapes and frequencies of the solar sail are correctly described even in presence of unsymmetrical loading conditions. In other terms, the numerical analysis is completed without any convergence problem and any disturbing local modes.

Finite element bending analysis of symmetric and non-symmetric functionally graded sandwich beams using a novel parabolic shear deformation theory

2021 ◽  
pp. 146442072110050
Author(s):  
Mohamed-Ouejdi Belarbi ◽  
Abdelhak Khechai ◽  
Aicha Bessaim ◽  
Mohammed-Sid-Ahmed Houari ◽  
Aman Garg ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Shear Deformation ◽  
Transverse Shear ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
Element Model ◽  
Beam Element ◽  
Functionally Graded ◽  
Sandwich Beams

In this paper, the bending behavior of functionally graded single-layered, symmetric and non-symmetric sandwich beams is investigated according to a new higher order shear deformation theory. Based on this theory, a novel parabolic shear deformation function is developed and applied to investigate the bending response of sandwich beams with homogeneous hardcore and softcore. The present theory provides an accurate parabolic distribution of transverse shear stress across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the functionally graded sandwich beam without using any shear correction factors. The governing equations derived herein are solved by employing the finite element method using a two-node beam element, developed for this purpose. The material properties of functionally graded sandwich beams are graded through the thickness according to the power-law distribution. The predictive capability of the proposed finite element model is demonstrated through illustrative examples. Four types of beam support, i.e. simply-simply, clamped-free, clamped–clamped, and clamped-simply, are used to study how the beam deflection and both axial and transverse shear stresses are affected by the variation of volume fraction index and beam length-to-height ratio. Results of the numerical analysis have been reported and compared with those available in the open literature to evaluate the accuracy and robustness of the proposed finite element model. The comparisons with other higher order shear deformation theories verify that the proposed beam element is accurate, presents fast rate of convergence to the reference results and it is also valid for both thin and thick functionally graded sandwich beams. Further, some new results are reported in the current study, which will serve as a benchmark for future research.

Nonlocal finite element model for the bending and buckling analysis of functionally graded nanobeams using a novel shear deformation theory

2021 ◽  
Vol 264 ◽  
pp. 113712 ◽  
Author(s):  
Mohamed-Ouejdi Belarbi ◽  
Mohammed-Sid-Ahmed Houari ◽  
Ahmed Amine Daikh ◽  
Aman Garg ◽  
Tarek Merzouki ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Shear Deformation ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
Element Model ◽  
Buckling Analysis ◽  
Functionally Graded

scholarly journals Forced Vibration Analysis of Laminated Composite Shells Reinforced with Graphene Nanoplatelets Using Finite Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Trung Thanh Tran ◽  
Van Ke Tran ◽  
Pham Binh Le ◽  
Van Minh Phung ◽  
Van Thom Do ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Thermal Environments ◽  
Forced Vibration Analysis ◽  
Laminated Composite Shells ◽  
Element Method

This paper carries out forced vibration analysis of graphene nanoplatelet-reinforced composite laminated shells in thermal environments by employing the finite element method (FEM). Material properties including elastic modulus, specific gravity, and Poisson’s ratio are determined according to the Halpin–Tsai model. The first-order shear deformation theory (FSDT), which is based on the 8-node isoparametric element to establish the oscillation equation of shell structure, is employed in this work. We then code the computing program in the MATLAB application and examine the verification of convergence rate and reliability of the program by comparing the data of present work with those of other exact solutions. The effects of both geometric parameters and mechanical properties of materials on the forced vibration of the structure are investigated.

Energy method for modelling delamination buckling in geometrically constrained systems

2003 ◽  
Vol 217 (9) ◽  
pp. 1015-1026 ◽  
Author(s):  
B J Hicks ◽  
G Mullineux ◽  
C Berry ◽  
C J McPherson ◽  
A J Medland
Keyword(s):  
Finite Element ◽  
Full Range ◽  
Constrained Systems ◽  
Third Party ◽  
Constrained System ◽  
Finite Element Approach ◽  
Delamination Buckling ◽  
Element Approach ◽  
Geometrically Constrained ◽  
Energy Formulation

Delamination buckling analysis of laminates is of considerable interest to the mechanical and materials engineering sectors, as well as having wider applications in geology and civil engineering. With advances in computing power, the ability to model ever increasingly complex problems at more detailed levels becomes more of a reality. However, many of the common finite element packages, with the exception of all but the most specialized, do not perform particularly well where complex non-linear problems are dealt with. In many cases, these packages can fail to determine the full range of solutions or accurately predict the properties and geometry of the final state. This is particularly the case where large deformations and buckling of laminates are considered. Because of this, many researchers prefer to use what they perceive to be more reliable techniques, such as the symbolic computation of the underlying differential equations, rather than finite element approaches. The use of finite element packages is further frustrated by the steep learning curve and implicit restrictions imposed by using third-party software. In this paper, a finite element approach and an energy formulation method are considered and used to model the delamination buckling in a geometrically constrained system. These methods are compared with experimental results and their relative merits are discussed. In particular, the accuracy and the ability to represent the geometry of the buckled system are discussed. Both the finite element approach and the energy formulation are described in detail and the numerical results are compared.

A Study on the Design Curves for Pultruded Composite Columns

2007 ◽  
Vol 26-28 ◽  
pp. 337-340 ◽  
Author(s):  
Seung Sik Lee ◽  
Soo Ha Chae ◽  
Soon Jong Yoon ◽  
Sun Kyu Cho
Keyword(s):  
Local Mode ◽  
Design Equation ◽  
Global Mode ◽  
Buckling Loads ◽  
Steel Columns ◽  
Short Columns ◽  
Theoretical Approaches ◽  
Interaction Mode ◽  
Column Design ◽  
Thin Walled

The strengths of PFRP thin-walled columns are determined according to the modes of buckling which consist of local mode for short columns, global mode for long columns, and interaction mode between local and global modes for intermediate columns. Unlike the local and global buckling, the buckling strength of interaction mode is not theoretically predictable. Refined theoretical approaches which can account for different elastic properties of each plate component consisting of a PFRP thin-walled member are used. Based on both the analytical buckling loads and the experimentally measured buckling loads from literatures, the accuracies of Ylinen’s equation and modified AISC/LRFD column design equation for isotropic steel columns were compared. From the comparison, it was found that the modified AISC/LRFD column design equation is more suitable for the prediction of the buckling loads of PFRP thin-walled members than Ylinen’s equations.

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