Showing papers by "Ankit Gupta published in 2020"

Processing, mechanical characterization, and micrography of 3D-printed short carbon fiber reinforced polycarbonate polymer matrix composite material

Abstract: The objective of this research is to perform the processing and mechanical characterization on 3D-printed high-temperature polymer (polycarbonate) reinforced with short carbon fiber (SCF) composite material fabricated with the help of fused filament fabrication process. For this study, different SCF volume fractions (3%, 5%, 7.5%, 10%) with varying printing speed (25, 50, 75 mm/s) are taken as the input variables. It was observed that tensile, flexural, compressive properties and micro-hardness were greatly affected by varying the input processing parameters. To find the orthotropic properties of 3D-printed specimens, tensile properties are analyzed on 0° in the X-Y plane, 90° in the X-Y plane, and 90° in Z-axis. Scanning electron microscopy (SEM) is performed to study the effect of fiber breakage, fiber distribution, fiber accumulation, and fiber length on the mechanical performance of the final part. After performing mechanical testing, investigation of microstructural behavior of tensile, flexural, and compressive samples is accomplished using SEM. From the micrograph analysis and mechanical testing, it was noticed that fiber behavior inside the composite has created a great influence in deciding the mechanical performance of the final part. Micromechanics and classical lamination theory phenomena are followed to determine the effective young’s modulus of 3D-printed samples mathematically. Printing direction and reinforcement percentage are found out to be the most influential parameters in deciding the final properties of 3D-printed specimens by using the statistical tool ANOVA. Response surface methodology is used to determine the optimum parameters to get good-quality print with SCF-reinforced PC.

Three-scale asymptotic homogenization of short fiber reinforced additively manufactured polymer composites

Abstract: In this research, prediction of mechanical properties of short fiber-reinforced composites manufactured with the help of fused filament fabrication (FFF) process is investigated. Three-scale formulation of asymptotic homogenization is employed to upscale the properties from microscale to mesoscale and from mesoscale to macroscale. Since generating microscale representative volume element (RVE) infused with short fibers requires sophisticated modeling tools, the algorithm for the microscale RVE generation is presented and discussed. Homogenization was performed for microscale RVEs with random and aligned (fibers aligned with the beads on mesoscale) fiber orientations, and for mesoscale RVEs with unidirectional and 0/90 layup formation. Tensile tests were performed for different short carbon fiber concentrations 5, 7.5 and 10% (by volume) to validate predicted homogenized properties. Moreover, to analyze the morphology of 3D printed specimens, microstructural analysis using SEM was performed on all the printed specimens. Surface morphology helped to gain more insight into the bead structure and fiber distribution. It was concluded that Young's modulus prediction using random fiber orientation has low relative errors tested in bead direction. Overall, this study has unique contribution to mechanical property prediction for FFF-made short fiber-reinforced composite parts.

Vibration of porous functionally graded plates with geometric discontinuities and partial supports

Abstract: Vibrational study of the porous functionally graded plate with geometric discontinuities and partial supports has been presented in the present paper. The kinematics of functionally graded plate is...

Mechanical and Thermal Analyses of Metal-PLA Components Fabricated by Metal Material Extrusion

Abstract: Metal additive manufacturing (AM) has gained much attention in recent years due to its advantages including geometric freedom and design complexity, appropriate for a wide range of potential industrial applications. However, conventional metal AM methods have high-cost barriers due to the initial cost of the capital equipment, support, and maintenance, etc. This study presents a low-cost metal material extrusion technology as a prospective alternative to the production of metallic parts in additive manufacturing. The filaments used consist of copper, bronze, stainless steel, high carbon iron, and aluminum powders in a polylactic acid matrix. Using the proposed fabrication technology, test specimens were built by extruding metal/polymer composite filaments, which were then sintered in an open-air furnace to produce solid metallic parts. In this research, the mechanical and thermal properties of the built parts are examined using tensile tests, thermogravimetric, thermomechanical and microstructural analysis.

Seismicity around the Mahendragarh–Dehradun basement fault in the western Ganga plain, India: a neotectonic perspective

Abstract: The NE–SW trending Mahendragarh–Dehradun Fault (MDF) is a basement fault in the western Ganga plain. The earthquake (4.7 mb) epicentered on this fault on 2nd June 2017 was focused around 10 km depth and does not show any surface rupture. Ground Penetrating Radar (GPR) survey around the epicenter detects few shallow-depth subsurface normal faults parallel to the MDF. However, it is unclear whether these normal faults are linked with the 2017 earthquake or other previous earthquakes. Seismic record (USGS) since 1975 to 2017 suggests occurrence of 22 earthquakes (~ 5 mb) around the MDF and majority (~ 63%) of these are clustered around Delhi and Rohtak. Following the 2017 earthquake, frequency of earthquakes occurence sharply increased than previously recorded instrumentation period from 1975 to 1995. Majority of the seismicity is focused around 10 km depths, shallowing to depths of 25–207 km recorded from 1975 to 2004. Earthquakes clustered along the Main Himalayan Thrust (MHT) shows similar temporal trend as near the MDF. Southward thrust movement of the Himalaya orogenic wedge predicts to impose strike-slip motion on the orthogonal-oriented steep basement faults, which is consistent with geologic and geomorphic field relations, and seismicity focal mechanisms along the MDF. The observed upper crustal deformation associated with such fault deformation pattern may be partly influenced by the MDF and partly by the foreland bulge seismicity. Potential tectono-geomorphic parameters and soil-chronosequence may suggest the surface deformation is active through the Holocene.

Influence of geometric discontinuities and geometric/microstructural defects on the temperature-dependent vibration response of functionally graded plates on elastic foundation

Abstract: In the present article, the vibrational behaviour of a functionally graded plate (FGP) resting on elastic foundations under a thermal environment with geometric discontinuities and microstructural defects (porosity) has been investigated. The structural kinematics is based on the trigonometric shear-strain function with only four unknowns. The transverse shear stress varies nonlinearly along the thickness. The FGP has geometric discontinuities in the form of a circular cut-out of different dimensions at the centre. The various geometric imperfections are modelled using a generic function, whereas the microstructural defects (porosity) have been included using modified power law. The temperature variation between the surfaces is nonlinear along the thickness direction. The FEM-based solutions are presented using C0 continuous iso-parametric element. Convergence and validation study have been carried out to demonstrate the efficacy and reliability of the presented results. The effect of porosity inclusion, circular cut-out, elastic foundation, thermal environment, geometric imperfection modes and the volume fraction index have been analysed under conventional and unconventional boundary constraints. It is observed that after a specific dimension of circular cut-out, vibrational behaviour of FGPs exhibits nonlinearity in nature.

Vibration Response of Shear Deformable Gradient Plate with Geometric Imperfection

Abstract: The vibration analysis of the geometrically imperfect functionally gradient (FGM) plate has been performed using hybrid higher order deformation theory. The present theory contains the nonlinear variation of thickness coordinate in in-plane and transverse displacement. The equation of motion for FGM plates are obtained through variational principle. The solution has been performed using a finite element method by employing C0 continuous isoparametric formulation with 72 DOF/element. The parametric study has been done to examine the influence of geometric configurations, volume fraction index and various modes of geometric imperfection on the vibration characteristics of the FGM plate.

Vibration Response of Metal-Ceramic Based Functionally Graded Plate Using Navier Solution

Abstract: In this paper, the vibrational response of the functionally graded plate has been carried out using non-polynomial based algebraic shear deformation theory. Hamilton’s variational principle has been used in deriving the governing equations. The Navier solution technique has been employed to solve the governing equation in conjunction with boundary conditions which are simply supported. In addition to these, the power-law governing equations have been considered for calculating the effective material properties of FGM and its mechanical properties are considered to be changing in the direction of thickness. The non-dimensional frequency has been evaluated for several vibrating modes of functionally graded thin and thick plates. The frequency parameter has also been evaluated for different aspect ratios and thickness ratios.