PSI - Issue 60

Rakesh Bhadra et al. / Procedia Structural Integrity 60 (2024) 149–164 Bhadra et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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The literature indicates that there are currently no available studies on the indentation contact analysis of CNT FGM nanocomposites, as per the author's best knowledge. For this research, a square CNT-FGM nanocomposite block is utilized, and the indentation process is carried out using a rigid indenter. The FEMis employed in the ANSYS platform using APDL code to develop the model. The study focuses on extracting various contact parameters, such as contact force, contact area, contact pressure distribution, von Mises stress distribution, and deformation behavior, from the developed models. These parameters are analyzed with respect to variations in CNTs thickness and gradation parameters of elastic-graded material (EGM). To ensure the accuracy and reliability of the developed model, the model is validated by comparing its results with suitable published literature on similar topics before proceeding to extract the contact properties. 2. Finite element modelling The focus of this study is on the loading-unloading indentation contact analysis of a nanocomposite consisting of CNTs and FGM. For the sake of simplicity and accelerated computations, a 2D model is employed instead of a 3D model. The dimensions of the 2D nanocomposite block are illustrated as 10x10 nm, as depicted in Fig.1. In this representation, the radius of the carbon nanotubes (CNTs) is 0.5 nm, and the CNTs are positioned 0.5 nm below the surface of contact. Several assumptions are made during the model development process. These assumptions include considering the CNTs to be defect-free and perfectly bonded with the matrix material, ensuring no slippage or detachment of CNTs from the matrix, considering the indenter as rigid, assuming all CNTs are parallel to each other, and considering the contact between the indenter and the nanocomposite to be frictionless.

(a) (b) Fig.1. Schematic representation of the Indentation model with coordinate axes and boundary conditions (a) for the FGM alone and (b) for the CNT-FGM nanocomposite. The current model is implemented using APDL code in the ANSYS platform, where a square block of nanocomposite material is simulated with the Berkovich indenter. The contact edge of the indenter is represented by a straight line, forming an angle of 65.3 o with the vertical line or the line of action of the applied load [Shi et al. (2010), Hallad et al. (2016)], as illustrated in Fig.1.