scholarly journals Thermal buckling analysis of cross-ply plates based on new displacement field

2021 ◽  
Vol 9 (3B) ◽  
Author(s):  
Widad Ibraheem Majeed ◽  
Keyword(s):  
Elasticity Theory ◽  
Displacement Field ◽  
Equations Of Motion ◽  
Composite Plates ◽  
Thermal Buckling ◽  
Thin Plates ◽  
Aspect Ratios ◽  
Number Of Layers ◽  
3D Elasticity ◽  
Transverse Shear Strains

A higher-order displacement field is used for the analysis of the thermal buckling of composite plates subjected to thermal load; it is based on a constant ‘‘m’’, which is optimized to get results relatively close to those given by 3D elasticity theory. Adequate transverse shear strains distribution through the thickness and free stress surfaces of the plate is satisfied using this theory. Hamilton’s principle is used to derive equations of motion, which are solved using Navier-type series for simply supported plates. Thermal buckling of cross-ply laminates with various (α2 / α1) ratios, number of layers, aspect ratios, E1/E2 ratios, and stacking sequence for thick and thin plates is studied in detail. It is concluded that the obtained results using this displacement field are close to those calculated by 3D elasticity theory and other shear deformation plate theories when m=0.05.

scholarly journals Thermal Buckling of Angle-Ply Laminated Plates Using New Displacement Function

2019 ◽  
Vol 25 (12) ◽  
pp. 96-113
Author(s):  
Ibtehal Abbas Sadiq ◽  
Widad Majeed
Keyword(s):  
Displacement Field ◽  
Equations Of Motion ◽  
Order Theory ◽  
Higher Order ◽  
Displacement Function ◽  
Thermal Buckling ◽  
Laminated Plates ◽  
Three Dimensions ◽  
Thin Plates ◽  
Aspect Ratios

ABSTRACT Critical buckling temperature of angle-ply laminated plate is developed using a higher-order displacement field. This displacement field used by Mantari et al based on a constant ‘‘m’’, which is determined to give results closest to the three dimensions elasticity (3-D) theory. Equations of motion based on higher-order theory angle ply plates are derived through Hamilton, s principle, and solved using Navier-type solution to obtain critical buckling temperature for simply supported laminated plates. Changing (α2/ α1) ratios, number of layers, aspect ratios, E1/E2 ratios for thick and thin plates and their effect on thermal buckling of angle-ply laminates are studied in detail. It is concluded that, this displacement field produces numerical results close to 3-D elasticity theory with maximum discrepancy (7.4 %).

scholarly journals Thermal Buckling of Laminated Composite Plates Using a Simple Four Variable Plate Theory

2021 ◽  
Vol 27 (9) ◽  
pp. 1-19
Author(s):  
Hussein Tawfeeq Yahea ◽  
Wedad Ibraheem Majeed
Keyword(s):  
Plate Theory ◽  
Equations Of Motion ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Composite Plates ◽  
Thermal Buckling ◽  
Design Parameters ◽  
Laminated Composite Plates ◽  
Buckling Behavior ◽  
Uniform Temperature Field

In this study, the thermal buckling behavior of composite laminate plates cross-ply and angle-ply all edged simply supported subjected to a uniform temperature field is investigated, using a simple trigonometric shear deformation theory. Four unknown variables are involved in the theory, and satisfied the zero traction boundary condition on the surface without using shear correction factors, Hamilton's principle is used to derive equations of  motion depending on a Simple Four Variable Plate Theory for cross-ply and angle-ply, and then solved through Navier's double trigonometric sequence, to obtain critical buckling temperature for laminated composite plates. Effect of changing some design parameters such as, orthotropy ratio (E1/E2), aspect ratio (a/b),  thickness ratio (a/h), thermal expansion coefficient ratio (α2/α1), are investigated, which have the same behavior and good agreement when compared with previously published results with maximum discrepancy (0.5%).

Thermal buckling load optimization of laminated general quadrilateral and trapezoidal thin plates

2013 ◽  
Vol 20 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Umut Topal
Keyword(s):  
Plate Theory ◽  
Mathematical Formulation ◽  
Thermal Buckling ◽  
Laminated Plates ◽  
Buckling Load ◽  
Thin Plates ◽  
Load Optimization ◽  
Aspect Ratios ◽  
Feasible Direction Method ◽  
Optimization Routine

AbstractThis paper deals with thermal buckling load optimization of symmetrically laminated angle-ply general quadrilateral and trapezoidal thin plates. The objective function is to maximize the critical temperature capacity of the quadrilateral and trapezoidal laminated plates and the fiber orientation is considered as a design variable. The mathematical formulation is based on the classical laminated plate theory for the frequency analysis. The modified feasible direction method is used as the optimization routine. Therefore, a program based on FORTRAN is used. Finally, the significant effects of aspect ratios, boundary conditions, taper ratios and unsymmetric trapezoidal plates on the optimal results are investigated and the results are compared.

Finite Element Large-Amplitude Free and Forced Vibrations of Rectangular Thin Composite Plates

1991 ◽  
Vol 113 (3) ◽  
pp. 309-315 ◽  
Author(s):  
C. K. Chiang ◽  
C. Mei ◽  
C. E. Gray
Keyword(s):  
Finite Element ◽  
Forced Vibration ◽  
Large Amplitude ◽  
Laminated Composite ◽  
Composite Plates ◽  
Thin Plates ◽  
Element Formulation ◽  
Aspect Ratios ◽  
Mode Method ◽  
Vibration Responses

A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration responses of arbitrarily laminated anisotropic composite rectangular thin plates. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite rectangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The finite element results are compared with available approximate continuum solutions. The amplitude-frequency relations for convergence with gridwork refinement, different boundary conditions, aspect ratios, lamination angles, number of plies, and uniform versus concentrated loads are presented.

Vibration of functionally graded carbon nanotube-reinforced composite plates under a moving load

2015 ◽  
Vol 22 (1) ◽  
pp. 37-55 ◽  
Author(s):  
Parviz Malekzadeh ◽  
Mojtaba Dehbozorgi ◽  
Seyyed Majid Monajjemzadeh
Keyword(s):  
Carbon Nanotube ◽  
Moving Load ◽  
Equations Of Motion ◽  
Micromechanical Model ◽  
Shear Deformation Theory ◽  
Composite Plates ◽  
Functionally Graded ◽  
Integration Scheme ◽  
Aspect Ratios ◽  
Reinforced Composite

AbstractThe vibration behavior of functionally graded carbon nanotube (CNT)-reinforced composite (FG-CNTRC) plates under a moving load is investigated based on the first-order shear deformation theory of plates using the finite element method. An embedded single-walled CNT (SWCNT) in the polymer matrix and its surrounding interphase is replaced with an equivalent fiber to obtain the effective mechanical properties of the CNT/polymer composite plates using the Eshelby-Mori-Tanaka micromechanical model. The equations of motion of plate elements are derived by utilizing Hamilton’s principle. Newmark’s time integration scheme is employed to discretize the equations of motion in the temporal domain. The convergence of the method is numerically demonstrated and its accuracy is shown by performing comparison studies with existing solutions for the free vibration and static analysis of FG-CNTRC plates and also the exact solution of isotropic plates under a moving load. Then, the numerical results are presented to study the effects of various profiles of the CNT distribution, which includes both symmetric and asymmetric distributions, the velocity of the moving load, and thickness-to-length and aspect ratios together with boundary conditions on the dynamic characteristic of the FG-CNTRC plate under a moving load.

Acoustic characterization of silica nanoparticle-impregnated Kevlar fabric

2021 ◽  
pp. 004051752110238
Author(s):  
Oluwafemi P Akinmolayan ◽  
James M Manimala
Keyword(s):  
Transmission Loss ◽  
Silica Nanoparticle ◽  
Air Gap ◽  
Thin Plates ◽  
Residual Porosity ◽  
Ballistic Performance ◽  
Number Of Layers ◽  
Structural Applications ◽  
Acoustic Characterization

Silica nanoparticle-impregnated Kevlar (SNK) fabric has better specific ballistic performance in comparison to its neat counterparts. For multifunctional structural applications using lightweight composites, combining this improved ballistic functionality with an acoustic functionality is desirable. In this study, acoustic characterization of neat and SNK samples is conducted using the normal-incidence impedance tube method. Both the absorption coefficient and transmission loss (TL) are measured in the 60–6000 Hz frequency range. The influence of parameters such as number of layers of neat or treated fabric, percentage by weight of nanoparticle addition, spacing between fabric layers, and residual porosity is examined. It is found that while absorption decreases with an increase in nanoparticle addition for frequencies above about 2500 Hz, increasing the number of layers shifts peak absorption to lower frequencies. By introducing an air-gap behind the fabric layer, dominant low-frequency (1000–3000 Hz) absorption peaks are obtained that correlate well with natural modes of mass-equivalent thin plates. Examining the influence of residual porosity by laminating the SNK samples reveals that it contributes to about 30–50% of the total absorption. Above about 1500 Hz, 3–5 dB of TL increase is obtained for SNK samples vis-à-vis the neat samples. TL is found to increase beyond that of the neat sample above a threshold frequency when an air-gap is introduced between two SNK layers. With an increase in the weight of nanoparticle addition, measured TL tends to be closer to mass law predictions. This study demonstrates that SNK fabric could provide improved acoustic performance in addition to its ballistic capabilities, making it suitable for multifunctional applications and could form the basis for the development of simplified models to predict the structural acoustic response of such nanoparticle–fabric composites.

Improved Bilinear Degenerated Shell Element

2015 ◽  
Vol 12 (02) ◽  
pp. 1550004 ◽  
Author(s):  
N. V. Swamy Naidu ◽  
B. Sateesh
Keyword(s):  
Shell Element ◽  
Shell Structures ◽  
Thin Plates ◽  
Element Formulation ◽  
Rigid Body Modes ◽  
Test Requirements ◽  
Degenerated Shell Element ◽  
Deformation Modes ◽  
Torsional Rotation ◽  
Transverse Shear Strains

The development of a new four node 24 degree of freedom bilinear degenerated shell element is presented for the analysis of shell structures. The present finite element formulation considers the assumed covariant transverse shear strains to avoid the shear locking problem and the assumed covariant membrane strains, which are separated from covariant in-plane strains, to overcome the membrane locking problem. The formulation also includes the deviation of the normal torsional rotation of the mid surface in the governing equation. This element is free from serious shear and membrane locking problems and undesirable spurious kinematic deformation modes. The element is tested for rigid body modes and distorted edges to meet the patch test requirements. The versatility and accuracy of this new degenerated shell element is demonstrated by solving several numerical examples for thick and thin plates.

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