Static and dynamic nonlinear stability analyses of hybrid sandwich composite beams under variable in-plane loads

Achchhe Lal,Kanif Markad 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9

Post-buckling and dynamic nonlinear stability analyses of a sandwich functionally graded material (FGM) composite beam subject to in-plane compressive static and periodic loading are conducted by implementing a higher-order shear deformation with von Karman kinematics. The dynamic instability region is evaluated using the Mathieu-Hill-type equation in Bolotin’s method. Comparisons of the layered composite beam, FGM sandwich composite beam, shape memory polymer (SMP) composite beam, and SMP-FGM sandwich composite beam with variable in-plane loads (N ) are depicted for the first time in the current work. The unstable region ofN is lower compared with those ofN and 2 x N .

Deflection and stress behaviour of multi-walled carbon nanotube reinforced laminated composite beams

Achchhe Lal,Kanif Markad 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.6

The paper presents the thermo-mechanically induced non-linear response of multiwall carbon nanotube reinforced laminated composite beam (MWCNTRCB) supported by elastic foundation using higher order shear deformation theory and von-Karman non-linear kinematics. The elastic properties of MWCNT reinforced composites are evaluated using Halpin–Tsai model by considering MWCNT reinforced polymer matrix as new matrix by dispersing in it and then reinforced with E-glass fiber in an orthotropic manner. The laminated beam is supported by Pasternak elastic foundation with Winkler cubic nonlinearity. A generalized static analysis is formulated using finite element method (FEM) through principle of minimum potential energy approach.

Stochastic hygrothermoelectromechanical loaded post buckling analysis of piezoelectric laminated cylindrical shell panel

Achchhe Lal,Nitesh Saidane,B.N. Singh 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.6

The present work deals with second order statistics of post buckling response of piezoelectric laminated composite cylindrical shell panel subjected to hygro-thermo-electro-mechanical loading with random system properties. System parameters such as the material properties, thermal expansion coefficients and lamina plate thickness are assumed to be independent of the temperature and electric field and modeled as random variables. The piezoelectric material is used in the forms of layers surface bonded on the layers of laminated composite shell panel. The mathematical formulation is based on higher order shear deformation shell theory (HSDT) with von-Karman nonlinear kinematics. A efficient C0 nonlinear finite element method based on direct iterative procedure in conjunction with a first order perturbation approach (FOPT) is developed for the implementation of the proposed problems in random environment and is employed to evaluate the second order statistics (mean and variance) of the post buckling load of piezoelectric laminated cylindrical shell panel. Typical numerical results are presented to examine the effect of various environmental conditions, amplitude ratios, electrical voltages, panel side to thickness ratios, aspect ratios, boundary conditions, curvature to side ratios, lamination schemes and types of loadings with random system properties. It is observed that the piezoelectric effect has a significant influence on the stochastic post buckling response of composite shell panel under various loading conditions and some new results are presented to demonstrate the applications of present work. The results obtained using the present solution approach is validated with those results available in the literature and also with independent Monte Carlo Simulation (MCS).

Natural frequency of laminated composite plate resting on an elastic foundation with uncertain system properties

Lal, Achchhe,Singh, B.N.,Kumar, Rakesh Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.27 No.2

Composite laminated structures supported on elastic foundations are being increasingly used in a great variety of engineering applications. Composites exhibit larger dispersion in their material properties compared to the conventional materials due to large number of parameters associated with their manufacturing and fabrication processes. And also the dispersion in elastic foundation stiffness parameter is inherent due to inaccurate modeling and determination of elastic foundation properties in practice. For a better modeling of the material properties and foundation, these are treated as random variables. This paper deals with effects of randomness in material properties and foundation stiffness parameters on the free vibration response of laminated composite plate resting on an elastic foundation. A $C^0$ finite element method has been used for arriving at an eigen value problem. Higher order shear deformation theory has been used to model the displacement field. A mean centered first order perturbation technique has been employed to handle randomness in system properties for obtaining the stochastic characteristic of frequency response. It is observed that small amount of variations in random material properties and foundation stiffness parameters significantly affect the free vibration response of the laminated composite plate. The results have been compared with those available in the literature and an independent Monte Carlo simulation.

Stochastic hygrothermoelectromechanical loaded post buckling analysis of piezoelectric laminated cylindrical shell panel

Lal, Achchhe,Saidane, Nitesh,Singh, B.N. Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.6

The present work deals with second order statistics of post buckling response of piezoelectric laminated composite cylindrical shell panel subjected to hygro-thermo-electro-mechanical loading with random system properties. System parameters such as the material properties, thermal expansion coefficients and lamina plate thickness are assumed to be independent of the temperature and electric field and modeled as random variables. The piezoelectric material is used in the forms of layers surface bonded on the layers of laminated composite shell panel. The mathematical formulation is based on higher order shear deformation shell theory (HSDT) with von-Karman nonlinear kinematics. A efficient $C^0$ nonlinear finite element method based on direct iterative procedure in conjunction with a first order perturbation approach (FOPT) is developed for the implementation of the proposed problems in random environment and is employed to evaluate the second order statistics (mean and variance) of the post buckling load of piezoelectric laminated cylindrical shell panel. Typical numerical results are presented to examine the effect of various environmental conditions, amplitude ratios, electrical voltages, panel side to thickness ratios, aspect ratios, boundary conditions, curvature to side ratios, lamination schemes and types of loadings with random system properties. It is observed that the piezoelectric effect has a significant influence on the stochastic post buckling response of composite shell panel under various loading conditions and some new results are presented to demonstrate the applications of present work. The results obtained using the present solution approach is validated with those results available in the literature and also with independent Monte Carlo Simulation (MCS).

Thermo-mechanically induced finite element based nonlinear static response of elastically supported functionally graded plate with random system properties

Lal, Achchhe,Jagtap, Kirankumar R.,Singh, Birgu N. Techno-Press 2017 Advances in computational design Vol.2 No.3

The present work proposes the thermo mechanically induced statistics of nonlinear transverse central deflection of elastically supported functionally graded (FG) plate subjected to static loadings with random system properties. The FG plate is supported on two parameters Pasternak foundation with Winkler cubic nonlinearity. The random system properties such as material properties of FG material, external loading and foundation parameters are assumed as uncorrelated random variables. The material properties are assumed as non-uniform temperature distribution with temperature dependent (TD) material properties. The basic formulation for static is based on higher order shear deformation theory (HSDT) with von-Karman nonlinear strain kinematics through Newton-Raphson method. A second order perturbation technique (SOPT) and direct Monte Carlo simulation (MCS) are used to compute the nonlinear governing equation. The effects of load parameters, plate thickness ratios, aspect ratios, volume fraction, exponent, foundation parameters, and boundary conditions with random system properties are examined through parametric studies. The results of present approaches are compared with those results available in the literature and by employing direct Monte Carlo simulation (MCS).

Numerical Analysis of Bi-material Plate of Various Material Distributions with Crack and Other Discontinuities Under Thermo-mechanical Loadings Using XFEM

Kundan Mishra,Achchhe Lal,B. M. Sutaria 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

In this paper bi-material plate with diff erent discontinuities under mechanical and thermo-mechanical loading conditions is analyzed by utilizing the extended fi nite element method (XFEM). The main purpose of the present work is to study numerical analysis with crack growth in the bi-material plate of diff erent material distribution. The bi-material plate is used to prevent cracks to grow and penetrate in the critical region. The discontinuities in the bi-material plate are modelled by diff erent enrichment functions. The XFEM with the level set method is utilized to model the present problem. The heavy side and asymptotic functions are utilized to modelled the boundary of discontinuities and crack tip respectively. In the bimaterial diff erent combinations like two dissimilar isotropic and Isotropic-FGM are utilized for this study. In the functionally graded material (FGM) various material distributions like exponential, power-law, and moritinaka are also considered. The interaction integral method is used to evaluate the mixed-mode stress intensity factor (MMSIF), crack growth, and energy release rate (ERR) of the bi-material plate with diff erent discontinuities under mechanical and thermo-mechanical loadings.

Temperature and Salt-Dependent Dielectric Properties of Blend Solid Polymer Electrolyte Complexed with LiBOB

Anil Arya,Achchhe Lal Sharma 한국고분자학회 2019 Macromolecular Research Vol.27 No.4

In the present paper, the temperature and salt-dependent dielectric properties of poly(ethylene oxide) (PEO) and poly(vinyl pyrrolidone) (PVP) blend matrix complexed with LiBOB are investigated in the frequency range 1 Hz to 1 MHz and temperature range 40 oC to 100 oC (@10 oC). The real and imaginary part of the complex permittivity, complex conductivity have been simulated in the whole frequency window and the various fitted parameters were evaluated respectively. The estimated value of the dielectric constant and the ac conductivity increases with the increase of temperature. The lowering of relaxation time and hopping length is observed with the salt addition that is in correlation with the complex conductivity results. The modulus formalism was used to analyze the recorded dielectric data. The dc conductivity, hopping frequency, and segmental motion are strongly coupled with each other as evidenced by the Debye-Stoke-Einstein (DSE) plot. An interaction mechanism has also been proposed to explore the effect of temperature on the hopping length, relaxation time, hopping potential barrier and the segmental motion of the polymer chain

Experimental Investigation of Repair of Plate with Edge and Center Crack by Surface Bounded Composite Patch

Kundan Mishra,Achchhe Lal,B. M. Sutaria 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2

In the present study, the experimental investigation of the repair of the Al 2024 T3 plate with edge and center crack by Carbon fiber-reinforced polymer (CFRP) patch under tensile loading is carried out. The present work is carried out in two parts. In the first part, the fracture analysis of isotropic and CFRP plates with edge crack under tensile loading is carried out. Where the comparative study of Al plate and CFRP [Unidirectional (UD) and Bidirectional (BD)] is presented for the selection of proper patching material. In the second part, the repair of the cracked isotropic plate by BD CFRP patch is presented. In this present work, it is observed that CFRP (BD) patch is suitable for the crack repair of the Al plate. The crack growth does not take place from the initially generated crack in the repaired plate under tensile loading and the maximum peak load in the edge and center cracked repaired plate is increased by 26% and 16% respectively as compared to the unrepaired plate.

Geometrical nonlinear bending characteristics of SWCNTRC doubly curved shell panels

Chavan, Shivaji G.,Lal, Achchhe Techno-Press 2018 Advances in aircraft and spacecraft science Vol.5 No.1

In this paper, geometric nonlinear bending characteristics of single wall carbon nanotube reinforced composite (SWCNTRC) doubly curved shell panels subjected to uniform transversely loadings are investigated. The nonlinear mathematical model is developed for doubly curved SWCNTRC shell panel on the basis of higher-order shear deformation theory and Green- Lagrange nonlinearity. All nonlinear higher order terms are included in the mathematical model. The effective material properties of SWCNTRC are estimated by using Eshelby-Mori-Tanaka micromechanical approach. The governing equation of the shell panel is obtained using the total potential energy principle and a Newton-Raphson iterative method is employed to compute the nonlinear displacement and stresses. The present results are compared with published literature. The effect of SWCNT volume fraction, width-to-thickness ratio, radius-to-width ratio (R/a), boundary condition, linear and nonlinear deflection, stresses and different types of shell geometry on nonlinear bending response is investigated.