Conference Papers
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Item Prediction and optimization of dimensional shrinkage variations in injection molded parts using forward and reverse mapping of artificial neural networks(2012) Gowdru Chandrashekarappa, G.C.; Krishna, P.The most significant process parameters affecting dimensional shrinkage in transverse and longitudinal directions of molded parts in Plastic Injection Molding (PIM) process are injection velocity, mold temperature, melt temperature and packing pressure. In the present work, ANN model was developed for forward and reverse mapping prediction. In forward mapping PIM process parameters are expressed as the input parameters to predict dimensional shrinkage, whereas in reverse mapping, attempts were made to predict an appropriate set of process parameters required for arriving at the required dimensional shrinkage. The trained network with one thousand input-output data randomly generated from regression equations reported by earlier researchers resulted in minimum mean squared error. The performance of developed model was compared with experimental values for ten different test cases. The results show that ANN model with both forward and reverse mapping is capable of prediction with an error level of less than ten percent. © (2012) Trans Tech Publications.Item Prediction of surface finish and optimization of machining parameters in turning(2012) Prasad, D.; Krishna, P.; Rao, S.S.Surface roughness plays a crucial role in the functional capacity of machined parts. In this work, experiments were carried out on a conventional lathe for different cutting parameters namely feed, spindle speed, depth of cut and tool nose radius according to Taguchi Design of Experiments. Radial acceleration readings were taken with an accelerometer. Optimum cutting parameters and their level of significance were found using Taguchi analysis (ANOVA). Regression analysis was carried out to identify whether the experimental roughness values have fitness characteristic with the process parameters. Recurrence Plots (RP) were obtained using the sensor signals which determine surface roughness qualitatively and Recurrence Quantification Analysis (RQA) technique was used to quantify the RP obtained. Surface finish was predicted using a feed forward back propagation neural network with RQA parameters, cutting parameters and acceleration data as inputs to the network. The validity and reliability of the methods were verified experimentally. © (2012) Trans Tech Publications.Item Low cost cpm machine for knee joint(2012) Metan, S.S.; Krishna, P.; Mohan Kumar, G.C.In today's world of industrialization, no single branch of Engineering and Technology can be considered independently. In order to increase productivity and profitability, industrial products are designed with the technology involving Mechanical and Electronics principles i.e. Mechatronics. Mechatronics has a vital importance in various fields such as agricultural, aviation, automobile, medical, etc. The scope of present work is to design, manufacture and test the low cost knee Continuous Passive Motion (CPM) machine. By using motorized device of CPM machine, we can gradually move the knee joints. This is not possible actively to the patient due to pain. The knee joint motion without patient's muscular effort is called as passive motion. The machine designed and developed in present work can achieve this. Once the patient is able to use his muscular power for his active joint motion, CPM is no longer medically necessary. In the present work, design and manufacturing of the Low Cost Knee CPM machine has been successfully done and is elaborated. The machine was manufactured and tested at one of the renowned Hospitals in Sholapur-India. The patient is exercised on CPM machine for three weeks and is observed to be improved to normal condition i.e. normal Range of Motion (ROM). © (2012) Trans Tech Publications, Switzerland.Item Machinability studies of low alloy steels by face turning method: An experimental investigation(Elsevier Ltd, 2013) Lalbondre, R.; Krishna, P.; Mohan Kumar, G.C.The present study is an experimental investigation on machinability of two low alloy steels, AISI 9320 and AISI 4340, by face turning method. The face turning method makes use of cylindrical steel specimen as a test piece and a triangular P-30 insert as a cutting tool for testing the machinability. The effectiveness of this method is assessed by studying: the cutting time required for the tool to reach flank wear up to 0.3mm (tool life criterion); tool wear development and wear mechanisms involved in machining; tool life studies and machinability indices of the work-material; surface roughness investigations of the machined surfaces; and chip morphology. The machinability tests undertaken in the current investigation follows some of the guidelines indicated in the international standards, ISO 3685:1993(E) and American Foundry Society (AFS) standard machinability tests. The results presented here demonstrate the ability of the face turning method: to evaluate the tool wear development and tool life studies; to rank the work material according to their machinability, to investigate surface roughness due to tool wear; to investigate chip morphology with crater wear and to characterize the machinability of steels under consideration. The face turning method used here is simple and effective for the given tool-work material pair. © 2013 The Authors. Published by Elsevier Ltd.Item Virtual Prototyping with Rigid Body Concept for the Development of Internal Combustion Engine(SAE International, 2017) Kumar, R.R.; Krishna, P.; Kuppast, V.V.The recent surge in the demand for the virtual application has led to the need for prototype testing that control the associated problem to a great extent. Consequently, a reduction in the costs of operating the actual prototype is envisaged. However, in some cases, just by adjusting input parameters alone could increase the success rate of these prototypes. During the design process, the functional prototyping is mainly used to evaluate the appearance of product and simulate its system level functioning. Multi-body dynamics analysis involves the simulation of rigid body systems under the application of forces or motions. Virtual prototype can substitute the physical prototype to perform a system level functioning of the product. The Internal combustion engine mechanism is considered for simulating the system level working with real time dynamic responses. Virtual prototype is created with a rigid body concept for an existing four stroke, single cylinder internal combustion engine mechanism to visualize the system level functioning and to find the displacement, velocity and acceleration of the piston on account of validation of the actual functioning of the engine. Virtual engine created by modeling individual parts of the product using CAD software and is simulated by using Hyper-Works computer aided engineering (CAE) tool. Finally, the validation of the functioning of the engine is done by comparing the results obtained by mechanism response (slider-crank mechanism; idealized for an internal combustion engine) of the engine using real time operating data collected experimentally. © 2017 SAE International.Item Machinability of Hardened Alloy Steel using Cryogenic Machining(Elsevier Ltd, 2018) Arun Kumar, S.; Yoganath, V.G.; Krishna, P.Machining of hardened alloy steels demand special cutting tools such as PCBN, ceramic. However, these cutting tools are uneconomical and also demand machine tool structures, which have high stiffness and vibration dampening properties. In the current trend towards Green manufacturing it is desired to produce more with less. Green manufacturing also emphasizes on an eco-friendly process. Hence, it is postulated to improve the machinability of these materials by alternate, economical means. One such alternative is cryogenic machining. In the current research work, it is envisaged to study the machinability of hardened alloy steel using commercially available cutting tools (coated carbide) under the influence of cryogenic as the coolant. Machinability factors under influence of cryogenic machining such as tool life, surface roughness and power consumption are studied. Results show that cryogenic as an alternative to coolant during machining of hardened materials increases the process efficiency by reducing energy consumption and also showed significant improvement in tool life. The process thus demonstrates the capability of replacing the special cutting tools that are required for hard turning applications. The portability of the setup for commercial use is also considered. © 2017 Elsevier Ltd.Item Experimental study of Mode i and Mode II interlaminar fracture toughness on aerospace structural composite T300/914(American Institute of Physics Inc. subs@aip.org, 2019) Sachin, S.; Shivananda Nayaka, H.S.; Santhosh, B.; Krishna, P.Carbon epoxy composite T300/914 which has wide applications in aerospace industries, as a structural material, has been analyzed, to determine the interlaminar fracture toughness. Laminates with a thickness of 4.6 mm, consisting of 48 layers of T300/914, are considered for estimating the inter-laminar fracture toughness. These specimens have been fabricated by hand layup method followed by controlled curing in an autoclave. Tests have been conducted in accordance with ASTM standards, for Mode I by Double Cantilever Beam (DCB) test and End Notch Flexure (ENF) test for Mode II. Pulse-Echo test results and C-Scan images of the specimens were also analyzed to locate the exact position of delamination. During the preliminary tests, it was found that the interlaminar fracture toughness varied, because of bonding of release film with the sides of the laminate. By Modified Beam Theory, Mode I and Mode II fracture toughness values of the prepared specimens were found to be 0.090 kJ/m2and 0.542 kJ/m2, respectively. It was also noted that the fracture toughness of the specimens from the same laminate varied with the degree of compaction. © 2018 Author(s).Item Experimental investigation of mode I interlaminar fracture toughness in T300/914 composite(Elsevier Ltd, 2020) Sachin, S.; Nayaka, S.H.; Santhosh, B.; Krishna, P.An aerospace structural material T300/914 has been studied to understand the Mode I interlaminar fracture toughness. For experimental analysis a Double Cantilever Beam (DCB) test is conducted on the laminate to estimate the Mode I interlaminar fracture toughness of the sample. A 48-layer laminate was prepared by hand layup process and an insert included at the mid plane to produce the artificial initial crack required for the test. All the tests are conducted in accordance to the ASTM standards. Pulse-Echo test results and C-Scan images of the laminate were analyzed to find the defects in the laminate. The data from DCB test were analyzed by Modified Beam theory, Compliance calibration method and modified compliance calibration methods to find the interlaminar fracture toughness. A crack length correction method is implemented for data reduction. Numerical analysis of the data derives results in accordance with the experimental analysis. © 2019 Elsevier Ltd. All rights reserved.Item Study of elastic and frictional behaviour of fiber reinforced polymer (epoxy) matrix composite(American Institute of Physics Inc. subs@aip.org, 2020) Patil, N.; Krishna, P.This work was carried out to study the effect of graphite and bronze fillers on mechanical and frictional behaviour of short fiber reinforced epoxy composites. In this article, tensile and pin on disc wear test results are presented. The tests were carried out as per the ASTM D-3039 and ASTM G-99 standards. The results showed enhanced tensile properties of the composite for increased volume percentage of bronze filler of 5 vol% to 15 vol % (3870 MPa to 4310 MPa). Presence of bronze and graphite showed remarkable effect on friction coefficient due to formation of thin lubricating layer of worn debris. The filler bronze is found to be responsible in dissipating heat generated during rubbing. The Scanning Electronic Microscope (SEM) images clearly indicate the friction and wear mechanism of the composite. © 2020 Author(s).Item Elucidating Corrosion Behavior of Hastelloy-X Built Using Laser Directed Energy Deposition-Based Additive Manufacturing in Acidic Environments(Springer Science and Business Media Deutschland GmbH, 2021) Diljith, P.K.; Jinoop, A.N.; Paul, C.P.; Krishna, P.; Bontha, S.; Bindra, K.S.This paper reports an investigation on the electrochemical corrosion behavior of laser directed energy deposition (LDED)-based additive manufacturing built Hastelloy-X (Hast-X) bulk samples for the first time in various acidic environments (2M HNO3, 2M HCl, and 2M H2SO4). Open-circuit potential results reveal that corrosion activity is more in HCl than the other two media. The corrosion rate (CR) estimated using the Tafel extrapolation method shows that the corrosion rate (CR) is the most in HCl and least in HNO3. Potentiodynamic studies reveal active–passive behavior of Hast-X in all the media and it is seen that the material stays in passivation for a longer potential range in HCl. Further, pitting potential is observed to be comparable in all three media. The cyclic polarization curve shows no loops, which points out the absence of pitting in the samples immersed in any of the media. The estimated CR for Hast-X in all the acidic environments under investigation comes within the acceptable CR for nickel-based alloys (4 mpy). The morphology of the corroded surface is analyzed using stereo microscope and it confirms the absence of pitting in all the three samples. These observations confirm the suitability of LDED built Hast-X components for applications in investigated acidic environments. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.