The linear buckling analysis of laminated composite cylindrical and conical shells under thermal load using the finite element method is reported here. Critical temperatures are presented for various cases of cross-ply and angle-ply laminated shells. The effects of radius/thickness ratio, number of layers, ratio of coefficients of thermal expansion, and the angle of fiber orientation have been studied. The results indicate that the buckling behavior of laminated shell under thermal load is different from that of mechanically loaded shell with respect to the angle of fiber orientation. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

R. Kari Thangaratnam

R. Palaninathan

J. Ramachandran

Equations of motion

LAMINATED PRODUCTS - THERMAL EFFECTS

MATHEMATICAL TECHNIQUES - Finite Element Method

STRESSES - Analysis

Vibrations - Analysis

ANGLE PLY SHELLS

CROSS PLY SHELLS

Laminated Composite Shells

LINEAR BUCKLING ANALYSIS

RADIUS/THICKNESS RATIO

THERMAL BUCKLING ANALYSIS

DOMES AND SHELLS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Thermal buckling of laminated composite shells

AIAA Journal

This paper presents numerical simulation studies on the vibration and acoustic response-characteristics of an isotropic cylindrical shell under a thermal environment using commercial softwares ANSYS and SYSNOISE. First, the critical buckling temperature is obtained, followed by modal and harmonic response analyses considering pre-stress due to the thermal field in the cylindrical shell, with the critical buckling temperature as a parameter. The vibration response predicted is then used to compute the sound radiation. It is found that there is a significant change in the vibration mode shapes and ring frequency towards the lowest natural frequency with an increase in temperature. There is a sudden increase in overall sound power level near the critical buckling temperature and significant changes in mode shapes with temperature does not affect the overall sound power level.

International Journal of Applied Mechanics

Vibro-acoustic response of a circular isotropic cylindrical shell under a thermal environment

Linear thermal buckling and free vibration analysis are presented for functionally graded cylindrical shells with clamped-clamped boundary condition based on temperature-dependent material properties. The material properties of functionally graded materials (FGM) shell are assumed to vary smoothly and continuously across the thickness. With high-temperature specified on the inner surface of the FGM shell and outer surface at ambient temperature, 1D heat conduction equation along the thickness of the shell is applied to determine the temperature distribution; thereby, the material properties based on temperature distribution are made available for thermal buckling and free vibration analysis. First-order shear deformation theory along with Fourier series expansion of the displacement variables in the circumferential direction are used to model the FGM shell. Numerical studies involved the understanding of the influence of the power-law index, r/h and l/r ratios on the critical buckling temperature. Free vibration studies of FGM shells under elevated temperature show that the fall in natural frequency is very drastic for the mode corresponding to the lowest natural frequency when compared to the lowest buckling temperature mode. © 2005 Elsevier Ltd. All rights reserved.

Journal of Sound and Vibration

Buckling and free vibration analysis of functionally graded cylindrical shells subjected to a temperature-specified boundary condition

A comparative study is presented on the vibratory characteristics of isotropic and orthotropic cylindrical shells with perfectly bonded piezoelectric material on the inner and outer surface of the shell lamina. The variation of free vibration natural frequencies and active damping ratios are simulated under varying magnitude of steady state axisymmetric temperatures. The objectives are explained by presenting the results of the numerical study on cylindrical shells made of mild steel and HS-graphite/epoxy bonded with PZT piezoelectric material. The vibratory characteristics under the above circumstances are interpreted from the point of view of initial stresses developed due to thermal loading. Apart from this, the changes in the vibratory characteristics due to different fiber orientations are examined. It is found from the studies that the frequency characteristic with respect to fiber orientation under thermal environment is highly dependent on the boundary condition considered for the shell laminate. © 2003 Elsevier Ltd. All rights reserved.

Studies on dynamic behavior of composite and isotropic cylindrical shells with PZT layers under axisymmetric temperature variation

Piezoelectric composite cylindrical shells operating in a steady state axisymmetric temperature are analyzed using a semi-analytical finite element method. Numerical studies are conducted on a clamped-clamped composite cylindrical shell for three typical length to radius ratios. The static thermal buckling analysis is carried out for a single layered composite cylindrical shell with different fiber orientation and hence study its influence on thermal buckling temperature. The influence of axisymmetric temperature on the natural frequencies and active damping ratio of the piezoelectric cylindrical shell is also examined. Two configurations of composite laminates: symmetric and antisymmetric with varying the number of plies is also considered to examine the effect on thermal buckling temperature. © 2002 Elsevier Science Ltd. All rights reserved.

Composite Structures

Buckling and dynamic analysis of piezothermoelastic composite cylindrical shell

A coupled fluid structure interaction problem is analyzed using semi-analytical finite element method involving composite cylindrical shells conveying hot fluid for free vibration and buckling behavior. The system under study is assumed to have a steady flow of hot fluid and the temperature variation is axi-symmetric. First order shear deformation theory is used to model the elastic shells of revolution. Geometric stiffness matrix is evaluated to consider the effects of axi-symmetric temperature variation through the shell continuum due to flow of hot fluid. The fluid domain is modeled using the wave equation. Numerical results of the studies on composite cylindrical shells made of HS-Graphite/Epoxy with two different length to radius ratios and clamped-clamped boundary condition conveying hot fluid are presented. The variation of the natural frequency of the coupled system is evaluated with the steady flow of the hot fluid. The influence of the temperature on the mean axial flow velocity through the shell is critically examined. The critical velocity of the hot fluid and cold fluid which leads to shell instability is compared thus establishing the fact that the lowest critical velocity of the hot fluid coincides with the mode corresponding to the lowest critical thermal buckling temperature. Various fibre angles are also considered in the study and its influence is also examined. © 2003 Elsevier Science Ltd. All rights reserved.

Free vibration and buckling analysis of composite cylindrical shells conveying hot fluid

Buckling analysis of composite laminates for critical temperatures under thermal loads is reported here. The formulation is based on linear theory and the finite element method using semiloof elements. The governing equation for critical temperature corresponding to the bifurcation budding is obtained by equating the second variation of total potential energy to zero. The validation checks on the program are carried out using results on homogeneous isotropic plates available in the literature. Results are presented for: 1. (1) cross-ply and angle-ply laminations with symmetry and antisymmetry stacking, 2. (2) simply supported, clamped and combination of boundary conditions, 3. (3) different aspect ratios, 4. (4) various moduli ratios, 5. (5) uniform and linearly varying temperature across thickness, 6. (6) varying ratios of coefficients of linear thermal expansion, and 7. (7) varying number of layers for given laminate thickness. Certain conclusions have been drawn based on these results. © 1989.

Computers and Structures

Thermal buckling of composite laminated plates

In this paper, Semiloof shell finite element formulation has been extended to thermal stress analysis of laminated plates and shells. The accuracy of the formulation has been verified using sample problems available in the literature. Thermal stresses in cross-ply and angle-ply laminated plates and shells subjected to thermal gradients across the thickness are presented for different boundary conditions, taking into account the temperature dependence of the material properties. The behaviour of laminates under thermal load is found to be different from that under mechanical loads in certain respects. © 1988.

Journal	AIAA Journal
ISSN	00011452
Open Access	No