Prof. Dineshkumar Harursampath - Academia.edu (original) (raw)

Papers by Prof. Dineshkumar Harursampath

IOP Publishing eBooks, Dec 1, 2022

Journal of Composite Materials, 2016

Low-velocity impact response of glass/epoxy composite plates and fiber metal laminates with and w... more Low-velocity impact response of glass/epoxy composite plates and fiber metal laminates with and without holes is investigated. The critical parameters that affect the delamination characteristics of laminates are impact energy, holes separation distance, type and directionality of fibers. An experimental investigation has been conducted to evaluate the effect of the presence of holes and the incorporation of aluminum layers in the extent of delamination. The extent of damage introduced during the impact event was observed on images obtained from C-scan non-destructive ultrasonic technique. Results indicate that fiber metal laminate made with aluminum layers exhibits an improved dynamic response in comparison with that of conventional laminates. The beneficial effect of using aluminum layers to reduce the extent of delamination produced by impact loading especially on laminates with holes is demonstrated. Furthermore, fiber metal laminates show better load carrying capability than co...

Composite materials are used instead of metals in many weight-sensitive applications because of t... more Composite materials are used instead of metals in many weight-sensitive applications because of their superior performance embodied in their higher specific stiffnesses and strengths. They are now exclusively used in various primary load-bearing parts of aircraft and helicopters, for example. It has been observed [2] that with the addition of a secondary reinforcement in the form of Carbon nano particles (CNP), the strengths of fibre reinforced polymer composites increase. The current work deals with a comparison of the one-dimensional stiffness matrix of a tapered composite flex beam, with and without CNP reinforcements. The beam without the CNP reinforcement is shown to have lower strengths. As a result, it is demonstrated that the crack tends to initiate at a quicker rate when the beam is cyclically bent in time. The full paper intends to qualify the delay in the onset of the crack due to the addition of the CNP to the composite beam. Modeling will be focussed around a matrix-ric...

Mechanics of Advanced Materials and Structures

The European Physical Journal Plus

Journal of Natural Fibers, 2022

Sandwich Composites, 2021

High Altitude Airships (HAA) are lighter-than-air platforms deployed at around 20km altitude abov... more High Altitude Airships (HAA) are lighter-than-air platforms deployed at around 20km altitude above sea level, currently gaining widespread attention for their potential as cheap substitutes for satellites. Non-rigid airships are the only choice for HAA due to their low-density requirement. They are characterized by the lack of metal frames, which in turn restricts payload capacity as well as rigidity of the airship envelope [2]. Variational Asymptotic Method (VAM) is a computational tool used to develop asymptotic models for composite structures like beams and shells [1]. This has advantages such as elimination of ad hoc assumptions as well as dimensional reduction in the models without compromising on accuracy. Hence, according to the nature of the problem, a theory can be derived with the desired orders of accuracy. This work is an attempt to propose a system of stiffeners to the airship envelope using inflatable membranous toroids, the advantages being prevention of kinks on the ...

Journal of Composite Materials, 2021

We characterize the material properties of a woven, multi-layered, hyperelastic composite that is... more We characterize the material properties of a woven, multi-layered, hyperelastic composite that is useful as an envelope material for high-altitude stratospheric airships and in the design of other large structures. The composite was fabricated by sandwiching a polyaramid Nomex® core, with good tensile strength, between polyimide Kapton® films with high dielectric constant, and cured with epoxy using a vacuum bagging technique. Uniaxial mechanical tests were used to stretch the individual materials and the composite to failure in the longitudinal and transverse directions respectively. The experimental data for Kapton® were fit to a five-parameter Yeoh form of nonlinear, hyperelastic and isotropic constitutive model. Image analysis of the Nomex® sheets, obtained using scanning electron microscopy, demonstrate two families of symmetrically oriented fibers at 69.3°± 7.4° and 129°± 5.3°. Stress-strain results for Nomex® were fit to a nonlinear and orthotropic Holzapfel-Gasser-Ogden (HGO...

The scope of the work is to deal with the asymptotically correct modeling of delamination initiat... more The scope of the work is to deal with the asymptotically correct modeling of delamination initiation and calculate the delamination initiation life. Concept of interface elements is chosen so that they can easily be incorporated with in the Variational Asymptotic Frame work and damage initiation is captured in one single coherent simulation. Furthermore, a relative displacement-based fatigue damage model was integrated with the cohesive zone model to simulate the deleterious influence of the fatigue loading at the interfaces. The usage of the interface based analysis requires the calculation of the relative displacements. The work uses the Variational Asymptotic method (VAM) as a platform to generate the relative displacements, which is considered as a parameter for the damage variable. The evolution of the damage variable is expressed as a function of the fatigue cycles. The formulation is applied to the short beam shear test and the number of cycles for the delamination initiation...

Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, 2021

The present study aims at investigating the ballistic impact response of jute, natural rubber and... more The present study aims at investigating the ballistic impact response of jute, natural rubber and aluminium based tri-layer composites with two different configurations, namely Aluminium-Jute-Rubber-Jute and Jute-Rubber-Jute-Aluminium. The proposed composites were fabricated using the compression moulding technique and subjected to ballistic impact testing at impact velocities of 75 m/s, 105 m/s, 154 m/s and 183 m/s. The energy absorption and damage mitigation characteristics of the proposed fibre metal elastomer tri-layer composites were assessed. Results showed that among the two proposed composites, the composite with rubber facing the impact side exhibits better energy absorption and also helps in damage mitigation compared to the composite having aluminium on the impact side. In addition, a parametric study was carried out by varying the thickness of the rubber layer. It was observed that the impact response of the proposed tri-layer composites improved with increasing thicknes...

3D and 4D Printing of Polymer Nanocomposite Materials, 2020

Abstract Tailored multifunctional capabilities, demanded in domains ranging from aerospace to bio... more Abstract Tailored multifunctional capabilities, demanded in domains ranging from aerospace to biomedical fields, are achieved through judicious combinations of structural/nonstructural fibers, matrices, and coatings. Multifunctional composite structures are thus designed to perform a variety of secondary functions (sensing, actuation, energy storage/harvesting, etc.) apart from their primary structural functions (strengthening, stiffening, and stabilizing). In realizing such multifunctional capabilities, complex stress-prone assemblies of low-length-scale components/coatings of materials with distinct properties are essential. Fortunately, additive manufacturing has demonstrated the potential to efficiently and effectively enable such robust assemblages. Apart from such three-dimensional (3D)-printed spatial nonuniformity, four-dimensional (4D) printing renders time-dependent properties to be triggered by various stimuli; 3D/4D printing of multifunctional composites possesses advantages over conventional manufacturing (where even feasible!) in term of time, mass, volume, overall cost, and efficiency. This chapter reviews various printing methods, candidate materials, and characterization of multifunctional printed components. The emphasis is on structural members integrated with electronic components, photovoltaic solar cells, piezoelectric materials, and battery fiber composites. A short review of 4D structures due to various stimuli is also carried out. Such 3D/4D printed flexible/wearable electronics, smart devices, and adaptive structures could find applications all the way from household appliances to satellites.

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020

This work presents a higher order finite element (FE) model to gauge the static behaviour of hygr... more This work presents a higher order finite element (FE) model to gauge the static behaviour of hygrothermo-magneto-electro-elastic (HTMEE) plates with different electro-magnetic circuits. The FE model is composed of eight-noded isoparametric elements. The displacement equations are presumed to obey the higher order shear deformation theory (HSDT) and the governing equations of motion are obtained with the support of the virtual energy principle. The correctness of the FE model is verified against previously published results. The influence of electro-magnetic boundary conditions associated with hygrothermal loads, stacking sequences, empirical constants and different loading profiles have been studied in detail. The results of this article are the first of its kind in literature. Hence, it is believed to set benchmark for future investigations on multifunctional structures.

The Journal of Physical Chemistry B, 2021

Key Engineering Materials, 2019

One of the most important features of a material to know before using it is the maximum limit of ... more One of the most important features of a material to know before using it is the maximum limit of the load at which it fails. This paper presents a micromechanical strength theory to estimate the tensile strength of the unidirectional fiber reinforced composite. The fibers used can be considered transversely isotropic and elastic till failure, but the matrix material is considered to be Elastic-plastic. The mathematical formulation used is the Variational-Asymptotic Method (VAM), which is used to construct the asymptotically-correct a reduced-dimensional model that is free of a priori assumption regarding the kinematics. The 3-D strain generated in each constituent material is explicitly expressed in 1-D strains and initial curvatures. The advantage of using VAM is that the stress state correlation of constituent materials is taken care of while applying warping constraints. Prandtl-Reuss plasticity theory has been implemented for the plastic region constitutive relationship. The oth...

Introduction of smart materials as actuators in flapping wing micro aerial vehicles (MAVs) elimin... more Introduction of smart materials as actuators in flapping wing micro aerial vehicles (MAVs) eliminates the need for the traditional rotary power delivery mechanisms, allowing for lighter, smaller and more energy efficient designs. General kinematics of insect flight is investigated to relate the independent variable wing length to two dependent variables wingbeat frequency and stroke amplitude, to establish a benchmark of characteristics the smart material must possess. Dielectric Elastomers due to their high actuation strain, high actuation speed, low density, compliant nature and silent operation were evaluated to be suitable for flapping wing actuation. Through an experimental reference design study, corresponding finite element validation and extrapolation of the model to a unimorph bender actuator representative of an insect wing, a path is laid to achieving the kinematic parameters required for flight. Further modelling and analysis of the high voltage custom waveform generator...