Elastic buckling of rectangular fiber-metal laminated plates under uniaxial compression

2019 ◽  
Vol 33 (12) ◽  
pp. 1629-1651 ◽  
Author(s):  
George SE Bikakis ◽  
Costas D Kalfountzos ◽  
Efstathios E Theotokoglou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aspect Ratio ◽  
Mode Shapes ◽  
Elastic Buckling ◽  
Simple Method ◽  
Buckling Stress ◽  
Buckling Coefficient ◽  
Fiber Metal ◽  
Element Method

In this article, the elastic buckling response of rectangular simply supported and clamped fiber-metal laminates (FMLs) subjected to uniaxial compressive loading is investigated using the finite element method and eigenvalue buckling analysis. Using validated finite element method (FEM) models, the buckling coefficient-aspect ratio diagrams and the mode shapes of nine GLARE grades are obtained and studied along with the diagrams and the mode shapes of three unidirectional glass-epoxy composites and monolithic 2024-T3 aluminum. It is found that the critical average buckling stress and the buckling load of the materials increases for increasing metal volume fraction, when the plate aspect ratio is greater than 1.5. The rule of mixtures is evaluated and found to be a simple method to estimate approximately the average critical buckling stress of the GLARE plates. An approximate formula is derived for the estimation of the critical buckling coefficient of the GLARE plates using the buckling coefficients of their constituents. The applicability of the results to thermoplastic-based FMLs is discussed.

scholarly journals Parametric Earthquake Analysis of Thick Plates Using Mindlin’s Theory

2010 ◽  
Vol 17 (6) ◽  
pp. 771-785
Author(s):  
Y.I. Özdemir ◽  
Y. Ayvaz
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aspect Ratio ◽  
Time Integration ◽  
Mode Shapes ◽  
Spatial Integration ◽  
Thick Plates ◽  
Simply Supported ◽  
Mindlin’S Theory ◽  
Element Method

The purpose of this paper is to study parametric earthquake analysis of thick plates using Mindlin's theory, to determine the effects of the thickness/span ratio, the aspect ratio and the boundary conditions on the linear responses of thick plates subjected to earthquake excitations and to present the frequency parameters and the mode shapes of the same plates. In the analysis, finite element method is used for spatial integration and the Newmark-βmethod is used for time integration. A computer program using finite element method is coded in C++ to analyze the plates clamped or simply supported along all four edges. In the analysis, 8-noded finite element is used. Graphs and tables are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio. It is also concluded that the effects of the change in the thickness/span ratio on the frequency parameter of the thick plates are always larger than those of the change in the aspect ratio.

scholarly journals Dynamics Characteristics of Blast Furnace Shell

2011 ◽  
Vol 2-3 ◽  
pp. 1018-1020
Author(s):  
De Chen Zhang ◽  
Yan Ping Sun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Blast Furnace ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Theoretical Foundation ◽  
Structural Mechanics ◽  
Mode Shapes ◽  
The Future ◽  
Element Method

Finite element method and structural mechanics method are used to study the blast furnace shell modal analysis and the natural frequencies and mode shapes have been calculated. The two methods were compared and validated , and the results provide a theoretical foundation for the anti-vibration capabilities design of blast furnace shell in the future .

Mechanical Behavior of SiC Fiber Reinforced Al Matrix Composites: A Study Based on Finite Element Method

2011 ◽  
Vol 239-242 ◽  
pp. 2785-2789
Author(s):  
Chao Sun ◽  
Min Song ◽  
Ru Juan Shen ◽  
Yong Du
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aspect Ratio ◽  
Plastic Region ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Sic Fiber ◽  
Al Matrix Composites ◽  
Al Matrix ◽  
Element Method

The effects of SiC fiber shape, aspect ratio and loading direction on the deformation behavior of SiC fiber reinforced Al matrix composites were studied by finite element method using axisymmetric unit cell model. The results showed that the addition of reinforcements will cause constraint on the plastic flow of ductile matrix, and thus result in no-uniform stress distribution. The reinforcement shape has a pronounced effect on the overall plastic deformation of the metal matrix composites. The loading condition will cause different failure mechanisms of composites. Under tensile loading, the stress-bearing ability in the plastic region is increased with the fiber aspect ratio due to the increase in the interface between the reinforcement and matrix and the decrease in the inter-particle space.

scholarly journals The Application Research of Inverse Finite Element Method for Frame Deformation Estimation

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yong Zhao ◽  
Hong Bao ◽  
Xuechao Duan ◽  
Hongmei Fang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Optical Measurement ◽  
Estimation Algorithm ◽  
Mode Shapes ◽  
Real Time Control ◽  
Applied Loading ◽  
Percentage Difference ◽  
Inverse Finite Element Method ◽  
Element Method

A frame deformation estimation algorithm is investigated for the purpose of real-time control and health monitoring of flexible lightweight aerospace structures. The inverse finite element method (iFEM) for beam deformation estimation was recently proposed by Gherlone and his collaborators. The methodology uses a least squares principle involving section strains of Timoshenko theory for stretching, torsion, bending, and transverse shearing. The proposed methodology is based on stain-displacement relations only, without invoking force equilibrium. Thus, the displacement fields can be reconstructed without the knowledge of structural mode shapes, material properties, and applied loading. In this paper, the number of the locations where the section strains are evaluated in the iFEM is discussed firstly, and the algorithm is subsequently investigated through a simple supplied beam and an experimental aluminum wing-like frame model in the loading case of end-node force. The estimation results from the iFEM are compared with reference displacements from optical measurement and computational analysis, and the accuracy of the algorithm estimation is quantified by the root-mean-square error and percentage difference error.

Influence of Defects on Elastic Buckling Properties of Single-Layered Graphene Sheets

2014 ◽  
Vol 636 ◽  
pp. 11-14 ◽  
Author(s):  
Bao Long Li ◽  
Li Jun Zhou ◽  
Jian Gao Guo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Vacancy Defect ◽  
Elastic Buckling ◽  
Graphene Sheets ◽  
Effect Factors ◽  
Vacancy Defects ◽  
Size Dependent ◽  
Buckling Stress ◽  
Geometrical Dimensions

Molecular structural mechanics based finite element method has been applied to study the effects of two types of Stone-Wales (SW) defects and vacancy defect on elastic buckling properties of single-layered graphene sheets (SLGSs). The defect effect factors of critical buckling stresses are calculated for the defective SLGSs with different chirality and geometrical dimensions. It is proved that defect effect factors are size-dependent and chirality-dependent. The results show that the vacancy defects will always weaken the SLGSs’ stability, and two types of SW defects have different effects on zigzag and armchair SLGSs. What’s more, the positions of defects also have remarkable influence on the critical buckling stress of SLGSs.

Free Vibration Characteristics of Sandwich Conical Shells With FGM Face Sheets: A Finite Element Approach

2019 ◽  
Author(s):  
Tripuresh Deb Singha ◽  
Apurba Das ◽  
Gopal Agarwal ◽  
Tanmoy Bandyopadhyay ◽  
Amit Karmakar
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Vibration ◽  
Conical Shell ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Iteration Algorithm ◽  
Operational Life ◽  
Sandwich Type ◽  
Element Method

Abstract This paper presents an analytical investigation on the free vibration characteristics of symmetric sandwich conical shell with functionally graded material (FGM) face sheets using finite element method. Sandwich-type structures offer higher stiffness to weight ratio with excellent thermal barrier in high temperature application extending the operational life of the component. The sandwich-type conical structure used in the advanced supersonic and hypersonic space vehicles. The material properties of FGM face sheets are considered to be varied in thickness direction as per simple power law distribution in terms of the volume fractions of the FGM constituents. The core layer is considered as homogeneous and made of an isotropic material (Titanium alloy-Ti–6Al–4V). A finite element method is used to reduce the governing equations of vibration problem. The QR iteration algorithm used to solve the standard eigen value problem for determine the natural frequencies. Convergence studies are performed in respect of mesh sizes to substantiate the accuracy of the proposed method. Computer codes developed to obtain the numerical results for the combined effects of twist angle and rotational speed on the free vibration characteristics of symmetric sandwich conical shell with FGM face sheets. A detailed numerical study is carried out to examine the influence of the sandwich plate type, volume fraction index on the free vibration characteristics. The typical mode shapes are also illustrated for different cases.

Eigenvector and eigenvalue analysis of thick plates resting on elastic foundation with first order finite element

2018 ◽  
Vol 4 (2) ◽  
pp. 61
Author(s):  
Yaprak Itır Özdemir
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aspect Ratio ◽  
Free Vibration ◽  
Vibration Analysis ◽  
Free Vibration Analysis ◽  
Winkler Foundation ◽  
Thick Plates ◽  
First Order ◽  
Element Method

The purpose of this paper is to study free vibration analysis of thick plates resting on Winkler foundation using Mindlin’s theory with first order finite element, to determine the effects of the thickness/span ratio, the aspect ratio, subgrade reaction modulus and the boundary conditions on the frequency parameters of thick plates subjected to free vibration. In the analysis, finite element method is used for spatial integration. Finite element formulation of the equations of the thick plate theory is derived by using first order displacement shape functions. A computer program using finite element method is coded in C++ to analyze the plates free, clamped or simply supported along all four edges. In the analysis, 4-noded finite element is used. Graphs are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that 4-noded finite element can be effectively used in the free vibration analysis of thick plates. It is also concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio.

A Finite Element Method Study of Combined Hydraulic and Thermal Autofrettage Process

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Rajkumar Shufen ◽  
Uday S. Dixit
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Residual Stresses ◽  
Surface Temperature ◽  
Hydraulic Pressure ◽  
Simple Method ◽  
Inner Surface ◽  
Set Up ◽  
Element Method ◽  
Autofrettage Pressure

Autofrettage is a metal working process of inducing compressive residual stresses in the vicinity of the inner surface of a thick-walled cylindrical or spherical pressure vessel for increasing its pressure capacity, fatigue life, and stress-corrosion resistance. The hydraulic autofrettage is a class of autofrettage processes, in which the vessel is pressurized using high hydraulic pressure to cause the partial plastic deformation followed by unloading. Despite its popularity, the requirement of high pressure makes this process costly. On the other hand, the thermal autofrettage is a simple method, in which the residual stresses are set up by first maintaining a temperature difference across the thickness of the vessel and then cooling it to uniform temperature. However, the increase in the pressure carrying capacity in thermal autofrettage process is lesser than that in the hydraulic autofrettage. In the present work, a combined hydraulic and thermal autofrettage process of a thick-walled cylinder is studied using finite element method package ABAQUS® for aluminum and SS304 steel. The strain-hardening and Bauschinger effects are considered and found to play significant roles. The results show that the combined autofrettage can achieve desired increase in the pressure capacity of thick-walled cylinders with relatively small autofrettage pressure. For example, in a SS304 cylinder of wall-thickness ratio of 3, an autofrettage pressure of 150 MPa enhances the pressure capacity by 41%, but the same pressure with a 36 °C higher inner surface temperature than outer surface temperature can enhance the pressure capacity by 60%.

Finite Element Method and Analytical Studies on Fiber-Metal Laminates under Multiaxial Loadings

2017 ◽  
Vol 23 ◽  
pp. 63-71
Author(s):  
David J. Kvam ◽  
Yi Yu Duan ◽  
Erica Donnelly ◽  
Alicia Restrepo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Strength ◽  
Finite Element Method Simulation ◽  
Fiber Metal Laminates ◽  
Composites Materials ◽  
Laminate Theory ◽  
Fiber Metal ◽  
High Strength Fiber ◽  
Element Method

Fiber-metal laminates (FMLs) are composites materials that are commonly used in areas such as aircraft industry. They are composed of ductile metal layers with high strength fiber reinforced polymer layers. So far, however, only uniaxial tests have been used to characterize the quasistatic mechanical properties, which cannot reflect the real loading situation of the FML applications. In this work biaxial tensile behavior of FMLs with glass and Kevlar fibers based on aluminum alloy is studied with finite element method simulation. The simulation is run to find the stress-strain relationship for FMLs at the off-axis angles of 0˚ and 45˚ for glass and Kevlar fibers. The “composites layups” are constructed for the 3D FML part. Two different elements C3D8R (8-node linear) and C3D20R (20-node quadratic) are used to carry out the simulation. The results show that C3D20R shows major advantages. Analytical solutions based on the classical laminate theory are obtained to compare with the finite element method (FEM) solutions. The results show good consistency.

The Theoretical Investigation on Critical Buckling Stress of Graphene Nanosheets

2016 ◽  
Vol 859 ◽  
pp. 79-84
Author(s):  
Li Jun Zhou ◽  
Jian Gao Guo ◽  
Bao Long Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Graphene Nanosheets ◽  
Structural Mechanics ◽  
Elastic Buckling ◽  
Boundary Constraints ◽  
Buckling Stress ◽  
Good Consistency ◽  
Analytical Expressions ◽  
Geometrical Dimensions

The elastic buckling behaviors of graphene nanosheets are investigated via molecular structural mechanics based finite element method. The size-and chirality-dependent critical buckling stresses of monolayer and bilayer graphene nanosheets are calculated for different geometrical dimensions and boundary constraints, respectively. By analogy with classical buckling theory of elastic plate, the analytical expressions of critical buckling stress are derived for the graphene nanosheets with different boundary constraints, and the comparisons of analytical results with the counterparts obtained by molecular structural mechanics simulation show a good consistency.

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