Ayan Haldar

Bio: Ayan Haldar is an academic researcher from Cardiff University. The author has contributed to research in topics: Morphing & Bistability. The author has an hindex of 5, co-authored 16 publications receiving 95 citations. Previous affiliations of Ayan Haldar include Leibniz University of Hanover.

Design optimization of multistable variable-stiffness laminates

Abstract: Exploiting the anisotropic nature of composite laminates is a driving factor to improve the design regime of multistable structures. The concept of laminate tailoring is being taken a step ahead by...

Analysis of Novel Morphing Trailing Edge Flap Actuated by Multistable Laminates

Abstract: This paper presents an analysis of a novel morphing trailing edge flap design for a wind turbine rotor blade with embedded multistable composite plates. Morphing trailing edge devices are promising...

Bistable morphing composite structures: A review

Abstract: Bistable structures, a class of highly geometrically nonlinear morphing structures, have two stable configurations that remain in their respective equilibrium positions without the continuous application of an external force. This paper aims to summarise, review, and assess the literature about the theoretical studies, driving methods, numerical simulations, experimental investigations, and fields of application of the structures. The theoretical models are separated into anisotropic and isotropic composites based on the properties of the material. The generalised methods to study the bistability of structures with various properties are presented. The driving methods used to trigger the snap of one equilibrium structure to the other include mechanical force, piezoelectric actuation, shape memory alloy actuation, thermal actuation, and magnetic actuation. Numerical simulations of the curing process during manufacture and of the morphing process, which includes the snap-through and snap-back of the bistable structure, are reviewed. Moreover, the experimental investigations of structures with unsymmetric and antisymmetric layups are also presented. Bistable composite laminates and their structures have been used in aerospace, bionics, energy harvesting, and other fields due to their unusual behaviour and morphing potential. This paper also highlights the remaining challenges and possible future work on bistable composite transition, from phenomenon to potential applications.

Bistable Morphing Composites for Energy-Harvesting Applications

Abstract: Bistable morphing composites have shown promising applications in energy harvesting due to their capabilities to change their shape and maintain two different states without any external loading. In this review article, the application of these composites in energy harvesting is discussed. Actuating techniques used to change the shape of a composite structure from one state to another is discussed. Mathematical modeling of the dynamic behavior of these composite structures is explained. Finally, the applications of artificial-intelligence techniques to optimize the design of bistable structures and to predict their response under different actuating schemes are discussed.

Stability and vibration analysis of CNT-Reinforced functionally graded laminated composite cylindrical shell panels using semi-analytical approach

Abstract: The present paper examined the buckling, postbuckling and vibration characteristics of pre-buckled and post-buckled laminated CNT reinforced composite (CNTRC) cylindrical shell panel made up of single walled carbon nanotubes (SWCNTs) and isotropic matrix. The effective material properties of CNTRC panel are computed using extended rule-of mixture (ROM) method. Higher order shear deformation theory (HSDT) with von Karman type of nonlinearity is adopted to model the CNTRC cylindrical shell panel. Four different boundary conditions are considered. Besides uniform loading, different types of non-uniform in-plane load distribution such as triangular, trapezoidal, parabolic and partial edge loadings are considered. The internal stress distribution within the shell panel due to applied non-uniform loadings is evaluated by prebuckling analysis. Subsequently, via Hamilton's principle the governing partial differential equations of CNTRC laminated cylindrical shell panel are derived. Employing Galerkin's method and by neglecting the inertia terms the partial differential equations are reduced to a set of non-linear algebraic equation for the static problem. However, for dynamic problem the partial differential equations are converted to a set of ordinary differential equations. Beside parametric study the obtained numerical results from the present semi-analytical study illustrates the effects of CNT volume fraction, CNT dispersion profile, non-uniform load distribution and boundary conditions on the stability and vibration characteristics of CNTRC cylindrical panel.

Thermal buckling behaviour of variable stiffness laminated composite plates

Abstract: Here, the thermal buckling behaviour of variable stiffness laminated composite plates subjected to thermal loads is numerically studied employing finite element approach based on first-order shear deformation theory. In the composite laminate considered here, the fibre orientation varies continuously within the layer leading to spatial variation of stiffness in the laminate. Different types of thermal loadings such as uniform and non-uniform temperature distributions are assumed in the analysis. The governing equations developed, applying the principle of minimization of total potential energy, are solved through an eigenvalue approach. The displacement field of pre-buckling of the laminate is evaluated before proceeding for the thermal buckling analysis depending on the type of temperature distributions. The formulation is tested against problems for which the solutions are available. A detailed study considering various design parameters such as curvilinear fibre angles at the centre and edge of the lamina, lay-up, thickness ratio, coefficients of thermal expansion, and modular ratio is made on the critical buckling temperature. The present analysis shows the significant change in the critical thermal buckling parameter while varying the curvilinear fibre angles and lay-up of the laminate.

Design optimization of multistable variable-stiffness laminates

Abstract: Exploiting the anisotropic nature of composite laminates is a driving factor to improve the design regime of multistable structures. The concept of laminate tailoring is being taken a step ahead by...