Papers by Dr Susmita Naskar
Handbook of Probabilistic Models
Abstract This chapter quantifies the effect of uncertainty in natural frequencies of laminated co... more Abstract This chapter quantifies the effect of uncertainty in natural frequencies of laminated composite plates based on neural network–based approach coupled with finite element analysis. An exhaustive comparative investigation on the performance of artificial neural network and polynomial neural network is carried out from the viewpoint of accuracy and computational efficiency. The stochastic system parameters are modeled following a layer-wise random variable–based approach, where the random system properties are considered to be different at different layers of the laminate for a particular realization of Monte Carlo simulation (MCS). Both individual and combined variations of stochastic input parameters are considered to address the aspect of low and high dimensional input parameter spaces, respectively. The convergence of the proposed neural network–based algorithm is verified and validated with original finite element method and direct MCS.
Advanced Engineering Materials
CRC Press eBooks, Sep 2, 2022
ACS Applied Materials & Interfaces
The Journal of Strain Analysis for Engineering Design
Nanoscale beams and rods are extensively used in several nano-electro-mechanical systems (NEMS) a... more Nanoscale beams and rods are extensively used in several nano-electro-mechanical systems (NEMS) and their applications such as sensors and actuators. The surface and flexoelectricity phenomena have an extensive effect on nanosized structures and are related to their scale-dependent characteristics. This article presents the effect of different surface parameters and flexoelectricity on the electrostatic response of graphene-reinforced hybrid composite (GRHC) nanorods (NRs) using the theory of linear piezoelectricity, Euler-Bernoulli (EB), and Galerkin residual method. Based on these theories, the theoretical and finite element (FE) model is produced to investigate the static bending deflection of GRHC NRs when subjected to point and uniformly distributed load (UDL) considering different boundary conditions: cantilever (FC), fixed-fixed (FF), and simply supported (SS). This proposed FE model provides a useful tool for analyzing and investigating the outcomes of analytical models, whi...
IJCRT1893085 International Journal of Creative Research Thoughts (IJCRT) www.ijcrt.org 538 THE DE... more IJCRT1893085 International Journal of Creative Research Thoughts (IJCRT) www.ijcrt.org 538 THE DEVELOPMENT OF LANGUAGE AND COGNITIVE ABILITIES OF HEARING IMPAIRED CHILDREN Sanjoy Dutta Assistant Professor Sundarban B.Ed. College, West Bengal, India Abstract: The purpose of this paper is to analyze the nature and pattern of language development related to different aspects of cognitive abilities of hearing impaired children as well as to classify them according to test scores. A Bengali language test belonging to class VI has been applied to 20 hearing impaired children of class VI standard of Helen Keller Badhir Vidyalaya, Mukundapur, Kolkata. Different aspects of language along with cognitive abilities have been analyzed. The major findings have been found that language development of the class VI students is poor and variable also although their average age is 15.5 years, but comparatively their cognitive abilities in to some extent is not bad. They have lack of sentence construct...
Advanced Theory and Simulations, 2020
Two-dimensional (2D) materials are crucially important nanomaterials because of their exciting mu... more Two-dimensional (2D) materials are crucially important nanomaterials because of their exciting multi-functional properties. However, a single layer of 2D materials may not have a certain property adequately, or multiple application-specific properties simultaneously to the desired and optimal level. For mitigating this lacuna, a new trend has emerged recently to develop nano-scale engineered heterostructures by stacking multiple layers of different 2D materials, wherein each of the layers could also be twisted. The vast advantage of combining single layers of different 2D materials with different twisting angles has dramatically expanded this research field well beyond the scope of considering a 2D material mono-layer, leading to a set of multifunctional physical properties corresponding to each possible combination of number of layers, different 2D materials therein, stacking sequence and the twisting angle of each layer. Effective mechanical properties such as Young's moduli are generally of utmost importance for analyzing the viability of such engineered nano-heterostructures in various nanoelectromechanical applications. Efficient closed-form generic formulae are proposed for the effective Young's moduli of twisted multi-layer heterostructures. Based on this physics-based analytical approach, a wide range of insightful new results are presented for twisted heterostructures, covering mono-planar and multi-planar configurations with homogeneous and heterogeneous atomic distributions.
Materials Today Communications, 2021
Abstract The utility of carbon nanotubes as the reinforcement agents in polymer and metal matrix ... more Abstract The utility of carbon nanotubes as the reinforcement agents in polymer and metal matrix composites has opened up a new avenue in the development of novel composite materials with exceptional strength and stiffness to weight ratios. Such exploitation of superior mechanical properties of carbon nanotubes depends on their inherent irregularities and structural integration. The nanotubular structures of carbon are prone to topological defects and heteroatom dopants due to the inevitable complexities in nano-synthesis. The objective of this article is to quantify the compound influence of such inherent structural irregularities (such as single vacancy defects and nanopores) and foreign atom inclusions (such as nitrogen and boron atoms) on the mechanical characteristics (like constitutive relation, fracture strength, failure strain and Young’s moduli) of single-walled carbon nanotubes (SWCNT) under various multi-physical influences (such as temperature, strain rate, diameter and chirality) based on molecular dynamics (MD) simulations. The current investigation also includes a detailed analysis on the variation in mechanical characteristics of CNTs under different spatial distributions of defects and doping.
Advanced Theory and Simulations, 2021
A machine learning assisted efficient, yet comprehensive characterization of the dynamics of coro... more A machine learning assisted efficient, yet comprehensive characterization of the dynamics of coronaviruses, in conjunction with finite element (FE) approach, is presented. Without affecting the accuracy of prediction in low-frequency vibration analysis, an equivalent model for the FE analysis is proposed, based on which the natural frequencies corresponding to first three non-rigid modes are analyzed. To quantify the inherent system-uncertainty efficiently, Monte Carlo simulation is proposed in conjunction with the machine learning based FE computational framework for obtaining complete probabilistic descriptions considering both individual and compound effect of stochasticity. A variance based sensitivity analysis is carried out to enumerate the relative significance of different material parameters corresponding to various constituting parts of the coronavirus structure. Using the modal characteristics like natural frequencies and mode shapes of the virus structure including their stochastic bounds, it is possible to readily identify coronaviruses by comparing the experimentally measured dynamic responses in terms of the peaks of frequency response function. Results from this first of its kind study on coronaviruses along with the proposed generic machine learning based approach will accelerate the detection of viruses and create efficient pathways toward future inventions leading to cure and containment in the field of virology.
Due to its electromechanical applications in the form of nanodevices such as distributors, actuat... more Due to its electromechanical applications in the form of nanodevices such as distributors, actuators, and sensors, the electromechanical behavior of piezocomposite structures becomes a new avenue for research. This article presents the derivation of an exact analytical solution of the composite plate based on theory of Kirchhoff’s plate and extended theory of piezoelectricity. The electromechanical behavior of piezocomposite structures accounting the influence of size-dependent properties such as piezoelectric and surface effect is investigated. In addition to this, the parametric analysis is carried out using the different parameters such as aspect ratio and thickness on the electromechanical response of composite structures. The consequences of the present study explore that the influence of size-dependent properties on the electromechanical behavior of composite structures is noteworthy with respect to the size of structures and can be ignored at bulk sizes. The electromechanical...
Archives of Computational Methods in Engineering, 2020
Due to the absence of adequate control at different stages of complex manufacturing process, mate... more Due to the absence of adequate control at different stages of complex manufacturing process, material and geometric properties of composite structures are often uncertain. For a secure and safe design, tracking the impact of these uncertainties on the structural responses is of utmost significance. Composite materials, commonly adopted in various modern aerospace, marine, automobile and civil structures, are often susceptible to low-velocity impact caused by various external agents. Here, along with a critical review, we present machine learning based probabilistic and non-probabilistic (fuzzy) low-velocity impact analyses of composite laminates including a detailed deterministic characterization to systematically investigate the consequences of source-uncertainty. While probabilistic analysis can be performed only when complete statistical description about the input variables are available, the non-probabilistic analysis can be executed even in the presence of incomplete statistical input descriptions with sparse data. In this study, the stochastic effects of stacking sequence, twist angle, oblique impact, plate thickness, velocity of impactor and density of impactor are investigated on the crucial impact response parameters such as contact force, plate displacement, and impactor displacement. For efficient and accurate computation, a hybrid polynomial chaos based Kriging (PC-Kriging) approach is coupled with in-house finite element codes for uncertainty propagation in both the probabilistic and non-probabilistic analyses. The essence of this paper is a critical review on the hybrid machine learning algorithms followed by detailed numerical investigation in the probabilistic and non-probabilistic regimes to access the performance of such hybrid algorithms in comparison to individual algorithms from the viewpoint of accuracy and computational efficiency.
Thin-Walled Structures, 2019
Abstract This paper quantifies the influence of uncertainty in the low-velocity impact responses ... more Abstract This paper quantifies the influence of uncertainty in the low-velocity impact responses of sandwich plates with composite face sheets considering the effects of obliqueness in impact angle and twist in the plate geometry. The stochastic impact analysis is conducted by using finite element (FE) modelling based on an eight nodded isoparametric quadratic plate bending element coupled with multivariate adaptive regression spline (MARS) in order to achieve computational efficiency. The modified Hertzian contact law is employed to model contact force and other impact parameters. Newmark's time integration scheme is used to solve the time-dependent equations. Comprehensive deterministic as well as probabilistic results are presented by considering the effects of location of impact, ply orientation angle, impactor velocity, impact angle, face-sheet material property, twist angle, plate thickness and mass of impactor. The relative importance of various input parameters is determined by conducting a sensitivity analysis. The results presented in this paper reveal that the impact responses of sandwich plates are significantly affected by the effect of source-uncertainty that in turn establishes the importance of adopting an inclusive stochastic design approach for impact modelling in sandwich plates.
Composites Part B: Engineering, 2019
This paper deals with the stochastic sensitivity analysis of functionally graded material (FGM) p... more This paper deals with the stochastic sensitivity analysis of functionally graded material (FGM) plates subjected to free vibration and low-velocity impact to identify the most influential parameters in the respective analyses. A hybrid moment-independent sensitivity analysis is proposed coupled with the least angle regression based adaptive sparse polynomial chaos expansion. Here the surrogate model is integrated in the sensitivity analysis framework to achieve computational efficiency. The current paper is concentrated on the relative sensitivity of material properties in the free vibration (first three natural frequencies) and low-velocity impact responses of FGM plates. Typical functionally graded materials are made of two different components, where a continuous and inhomogeneous mixture of these materials is distributed across the thickness of the plate based on certain distribution laws. Thus, besides the overall sensitivity analysis of the material properties, a unique spatial sensitivity analysis is also presented here along the thickness of the plate to provide a comprehensive view. The results presented in this paper would help to identify the most important material properties along with their depth-wise spatial sensitivity for low-frequency vibration and low-velocity impact analysis of FGM plates. This is the first attempt to carry out an efficient adaptive sparse PCE based moment-independent sensitivity analysis (depth-wise and collectively) of FGM plates under the simultaneous susceptibility of vibration and impact. Such simultaneous multiobjective sensitivity analysis can identify the important system parameters and their relative degree of importance in advanced multi-functional structural systems.
Practice Periodical on Structural Design and Construction, 2019
This article presents a concise overview on condition monitoring and retrofitting/ strengthening ... more This article presents a concise overview on condition monitoring and retrofitting/ strengthening of structures including a practical case study of strengthening for an existing historical building. Condition assessment of an existing structure is required mainly to check serviceability and safety requirements of the structure after short term events like earthquake or long term degradation of the structure with time. It is carried out to assess the ability of a structure to perform its intended operations under changed loading conditions with time or modification in its structural system as per newly imposed requirements. The condition assessment and strengthening may also be required for integrated extension of an existing structure. After assessing the condition of the structure, either it is retrofitted (or strengthened) or it is demolished according to the severity of the damage. In this article, such a critical condition assessment for an existing historical masonry building is presented and appropriate strengthening schemes are suggested by following two separate measures (concrete jacketing and fiber reinforced polymer strengthening). Subsequently, the relative advantages and disadvantages of the strengthening measures are discussed from a practical engineering perspective. Aim of this article is not to propose any new method for condition assessment and strengthening of structures, rather we take a systematic approach to demonstrate our experience. Critical case studies on condition assessment and strengthening of historical buildings with adequate technical insights are very scarce to find in scientific literature. This article would serve as a valuable reference for the practicing engineers and the concerned scientific community.
Composites Part B: Engineering, 2018
The coupled effect of manufacturing uncertainty and a critical service-life damage condition (del... more The coupled effect of manufacturing uncertainty and a critical service-life damage condition (delamination) is investigated on the natural frequencies of laminated composite plates. In general, delamination is an unavoidable phenomenon in composite materials encountered often in real-life operating conditions. We have focused on the characterization of dynamic responses of composite plates considering source-uncertainty in the material and geometric properties along with various single and multiple delamination scenarios. A hybrid high dimensional model representation based uncertainty propagation algorithm coupled with layer-wise stochastic finite element model of composites is developed to achieve computational efficiency. The finite element formulation is based on Mindlin's theory considering transverse shear deformation. Numerical results are presented for the stochastic natural frequencies of delaminated composites along with a comprehensive deterministic analysis. Further, an inevitable effect of noise is induced in the surrogate based analysis to explore the effect of various errors and epistemic uncertainties involved with the system.
Composite Structures, 2019
This article presents a non-probabilistic fuzzy based multi-scale uncertainty propagation framewo... more This article presents a non-probabilistic fuzzy based multi-scale uncertainty propagation framework for studying the dynamic and stability characteristics of composite laminates with spatially varying system properties. Most of the studies concerning the uncertainty quantification of composites rely on probabilistic analyses, where the prerequisite is to have the statistical distribution of stochastic input parameters. In many engineering problems, these statistical distributions remain unavailable due to the restriction of performing large number of experiments. In such situations, a fuzzy-based approach could be appropriate to characterize the effect of uncertainty. A novel concept of fuzzy representative volume element (FRVE) is developed here for accounting the spatially varying non-probabilistic source-uncertainties at the input level. Such approach of uncertainty modelling is physically more relevant than the prevalent way of modelling non-probabilistic uncertainty without considering the ply-level spatial variability. An efficient radial basis function based stochastic algorithm coupled with the fuzzy finite element model of composites is developed for the multi-scale uncertainty propagation involving multi-synchronous triggering parameters. The concept of a fuzzy factor of safety (FFoS) is discussed in this paper for evaluation of safety factor in the non-probabilistic regime. The results reveal that the present physically relevant approach of modelling fuzzy uncertainty considering plylevel spatial variability obtains significantly lower fuzzy bounds of the global responses compared to the conventional approach of non-probabilistic modelling neglecting the spatially varying attributes.
Composites Part B: Engineering, 2018
This article presents a probabilistic framework to characterize the dynamic and stability paramet... more This article presents a probabilistic framework to characterize the dynamic and stability parameters of composite laminates with spatially varying micro and macro-mechanical system properties. A novel approach of stochastic representative volume element (SRVE) is developed in the context of two dimensional plate-like structures for accounting the correlated spatially varying properties. The physically relevant random field based uncertainty modelling approach with spatial correlation is adopted in this paper on the basis of Karhunen-Loève expansion. An efficient coupled HDMR and DMORPH based stochastic algorithm is developed for composite laminates to quantify the probabilistic characteristics in global responses. Convergence of the algorithm for probabilistic dynamics and stability analysis of the structure is verified and validated with respect to direct Monte Carlo simulation (MCS) based on finite element method. The significance of considering higher buckling modes in a stochastic analysis is highlighted. Sensitivity analysis is performed to ascertain the relative importance of different macromechanical and micromechanical properties. The importance of incorporating source-uncertainty in spatially varying micromechanical material properties is demonstrated numerically. The results reveal that stochasticity (/ system irregularity) in material and structural attributes influences the system performance significantly depending on the type of analysis and the adopted uncertainty modelling approach, affirming the necessity to consider different forms of source-uncertainties during the analysis to ensure adequate safety, sustainability and robustness of the structure.
Composite Structures, 2016
This paper presents the quantification of uncertain natural frequency for laminated composite pla... more This paper presents the quantification of uncertain natural frequency for laminated composite plates by using a novel surrogate model. A group method of data handling in conjunction to polynomial neural network (PNN) is employed as surrogate for numerical model and is trained by using Latin hypercube sampling. Subsequently the effect of noise on a PNN based uncertainty quantification algorithm is explored in this study. The convergence of the proposed algorithm for stochastic natural frequency analysis of composite plates is verified and validated with original finite element method (FEM). Both individual and combined variation of stochastic input parameters are considered to address the influence on the output of interest. The sample size and computational cost are reduced by employing the present approach compared to direct Monte Carlo simulation (MCS).
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Papers by Dr Susmita Naskar