Department of Mechanical engineering
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Item Experimental investigation into depositing low melting point alloy utilizing fused deposition (FDM) modelling technique(Springer, 2024-10) Kala, Prateek3D printing techniques are now effectively utilized for various applications, including medical, electronics, tooling, etc. One such application is the direct printing of electronic circuitry or machine tool using low melting point alloys like solder. The most common solder material is the alloy of tin and lead. However, lead is now being replaced with other elements like copper, silver, bismuth, etc., due to its hazardous nature. The current study uses fused deposition modelling to highlight the deposition of Sn-Bi, a low melting point alloy. The customized direct-type extruder head is fitted to an existing FDM printer to achieve the required deposition. The idea behind using direct type extruder assembly instead of bourdon type is to get the necessary force for pushing the metal out of the nozzle. The process window of temperatures is identified for extruding the material and suitable print speed for depositing the same. The discontinuity is observed at a particular range of parameters and filament types. The filament combinations of 1.75 and 2.85 mm are used with subsequent modifications in the extruder assembly. The nozzle diameter is varied with two filament combinations. The results for both filament types are compared in terms of continuity and uniformity in the deposition. The microstructure of the raw material and deposited beads are also analyzed. The future scope of the current setup can be its utilization for printing electronic circuits or developing a tool for rapid tooling applications.Item 1 3D-printed smart functional prototypes as sensors and actuators for robotic applications(De Gruyter, 2024) Kala, PrateekSoft robotics, inspired by nature, is a trending research area that is based on material science and the available mechanism (pneumatic, thermal, magnetic, electrostatic, etc.) to activate them. In the recent past, polylactic acid (PLA) has shown promising material characteristics, and researchers explored the 4D printing of PLA-based functional prototypes that can be used for high-strength biomedical applications for bovines. But hitherto, little has been explored about the sensing and actuation capabilities of PLA for implantable robotic applications in bovine. In this study, PLA extracted from biomedical waste has been used to prepare the functional prototypes (implants in bovine). Further, it has been primarily recycled by varying number of shredding cycles, and finally, feedstock filaments of the same have been prepared on the single screw extruder. For analyzing the sensing and actuation capabilities of the recycled material, the prototypes were fabricated on the fused deposition modeling setup using the following process parameters: raster angle, 45°; infill pattern, grid; printing speed, 40 mm/s; and infill density, 50%. Initially, the pressure-based sensor was designed in the high-frequency structure simulator simulation software and then tested on the vector network analyzer setup to observe the dielectric properties, that is, dielectric constant (ϵr) and loss tangent (tan δ) under the effect of pressure. Further, a hydrothermal actuator for robotic application has been programmed by mechanical force, and the shape recovery of the deformed prototype has been observed under the effect of hydrothermal stimuli. The change in dielectric properties (ϵr and tan δ) of the recycled material has been observed through the insertion loss (S21) versus resonant frequency (fr), which may be used for online health monitoring of patients through a Bluetooth device by observing the electromagnetic signal in the industrial, scientific, and medical (ISM) band.Item 3D-printed conformal sensors for health monitoring of bovine post diaphragmatic hernia surgery: a review(Emerald, 2024-04) Kala, PrateekSome studies have been reported in the past on diaphragmatic hernia (DH) surgery techniques using additive manufacturing (AM) technologies, symptoms of a hernia and post-surgery complications. But hitherto little has been reported on bibliographic analysis (BA) for health monitoring of bovine post-DH surgery for long-term management. Based on BA, this study aims to explore the sensor fabrication integrated with innovative AM technologies for health monitoring assistance of bovines post-DH surgery.Item Investigating into casting LMPA (low-melting-point alloy) with 3D-printed mould and inspecting quality using 3D scanning(Emerald, 2024-07) Kala, PrateekThree-dimensional (3D) casting means using additive manufacturing (AM) techniques to print the mould for casting the cast tool. The printed mould, however, should be checked for its dimensional accuracy. 3D scanning can be used for the same. The purpose of this study is to combine the different AM techniques for 3D casting with 3D scanning to produce parts with close tolerance for preparing electrical discharge machining (EDM) electrodes.Item 3D printed hernia mesh implant: a conformability study(Open Exploration Publishing., 2024-09) Kala, PrateekThis study aims to explore the sensing capabilities of polyvinylidene fluoride-hydroxyapatite-chitosan (PVDF-HAP-CS) composite-based hernia mesh implants (of conformal/planar design), followed by in-vitro analysis for better understanding of the bio-stability in the patient’s body. Methods: For analyzing the sensing capabilities, a microstrip patch antenna (MPA)-based implantable sensor [with 17-4 precipitate hardened (PH) stainless steel (SS) (bio-compatible) and Cu alloy (non-biocompatible) materials as conducting plane/patch with PVDF-HAP-CS as dielectric material] has been considered separately in this study. Primarily, in this study, the 3D models of the hernia mesh implant have been designed in the high-frequency structure simulator (HFSS) software, and the sensing behaviour of the same has been recorded.Item In chamber calibration and performance evaluation of air quality low-cost sensors(Elsevier, 2024-12) Kala, PrateekAssessing individual exposure to PM2.5 (particulate matter of aerodynamic diameter lesser than 2.5 μm) requires precise monitoring of PM2.5 concentrations at specific geographical and temporal scales. This demand is met globally by low-cost particulate matter sensors, although calibrating them is difficult. In this study, four low-cost PM sensors, Sharp GP2Y1010AU0F, Honeywell HPMA115S0-XXX, Plantower PMSA003-A, and Sensirion SPS30, were calibrated and tested using various aerosols. The calibration method has three steps: individual (considering each sensor independently to a single aerosol type; n = 1), combined (all sensors for a specific model together for a specific aerosol type; n = 4), and generic (all sensors for a given model together to all aerosols; n = 16). Sensor responses are processed using linear, quadratic, power-law, and artificial neural network (ANN) algorithms in each calibration stage. Performance metrics, including coefficient of determination (R2), mean absolute percentage error (MAPE), root mean square error (RMSE), and percentage coefficient of variation (% CV), were utilized for assessment. Amongst all the four tested sensors, the Sensirion SPS30 sensors gave the best performance with a minimum R2 value of 0.911 when calibrated with a generic ANN calibration algorithm. Also, the MAPE was less than 10 %, and the RMSE was less than 7 % when exposed to different particles. Sensirion SPS30 showed the lowest inter-sensor variability with % CV less than 6 %. Sensors identified monodisperse polystyrene latex (PSL) particle size in the investigation. Regardless of exposure to 0.3, 0.46, 0.60, or 1.0 μm PSL, the reported number size distribution for the PMSA003 sensor remained consistent and did not align with the results from Grimm. As the PSL size rose, the SPS30 size distribution changed towards larger particle sizes, although it did not always match Grimm data. As the PSL size increased, the sensor's PM1, PM2.5, and PM10 mass proportions altered.Item Performance evaluation of developing electrical discharge machining tools through 3D-printed mould using selective laser sintering and expanding its applications in developing free-form tools(Sage, 2024-12) Kala, PrateekIn the current study, an attempt has been made to find the optimum parameters for electroplating three-dimensional (3D) casted low melting point alloys. The electroplated profile is used as a tool in an electric discharge machining setup. A selective laser sintering process is used for 3D printing the mould in two halves. The mould parts are 3D scanned to find out the dimensional deviation. The low melting point alloy (LMPA) is cast in the mould. The surface roughness of the mould and the pattern are measured. Electroplating the casted LMPA sample is carried out in three stages in search of optimum parameters for getting stable copper deposits. The thickness of copper deposits under varying conditions is measured. The microstructures of cast alloys and copper deposits are analysed using a scanning electron microscope. The casted alloy and copper composition is verified through energy dispersive spectroscopy mapping and X-ray diffraction technique. The developed electric discharge machining electrode successfully performs the machining on the workpiece, and its performance is compared with that of a solid copper tool. The information gained is transferred to prepare the free-form tool using the developed path and is tested on the implant-shaped workpiece.Item Feasibility study of fusible alloy-based copper electroplated EDM tool for biomedical applications(Springer, 2024-10) Kala, PrateekThe current study demonstrates the idea of making customised EDM tools using low melting point alloys for possible application in surface modification of biomedical implants. The mould is 3D-printed through a selective laser sintering setup and is used for casting the eutectic tin bismuth alloy. The mould is 3D scanned before and after using it as a mould for inspecting dimensional accuracy. The mould and cast pattern are measured for their surface roughness. The electroplating setup is developed, plating parameters are identified for stable copper deposits on a cast pattern, and thickness is noted with time. The scanning electron microscope analyses the microstructure of the casted and plated sample. The X-ray diffraction test and energy dispersive spectroscopy verify their composition. The plated sample is used as an electrical discharge machining tool. The planned experiments are performed, and Taguchi optimisation is carried out. The rapid cast tool performance is comparable to the solid copper tool. The valuable insights are drawn out after analysing the results, and the mechanism is explained. The previous research work done in this regard consists of the polymer base material with subsequent primary and secondary metallisation. However, the current study utilised the conductive base material, which eliminates the need for primary metallisation. The current work's application is defined in terms of creating a free-form EDM tool for surface modification of the Ti–6Al–4V femur bone implant for better cell growth.Item On the design and fabrication of polyvinylidene fluoride-based sensors to detect recurrence of diaphragmatic hernia(Sage, 2024-12) Kala, PrateekPolyvinylidene fluoride (PVDF) bio-sensors have gained potential interest in remote health monitoring of patients using Internet of Things (IoT) technologies. But hitherto, limited studies have reported on the fabrication of PVDF-hydroxyapatite (HAP)-chitosan (CS) based sensors processed through two different processing routes from a process suitability viewpoint to determine the recurrence of diaphragmatic hernia (DH). The sensors fabricated in this study comprise three layers, that is, a substrate (dielectric material), a metallic patch, and a ground plane that works on the microstrip patch antenna (MPA). Two manufacturing approaches have been followed in this study for the fabrication of the dielectric substrate: material extrusion (MEX) and gel-casting. Primarily, PVDF (90%) -HAP (8%) -CS (2%) has been selected for the sample preparation, following that different characterizations have been performed on the chosen composition to ensure its suitability for sensor fabrication. The simulated results were extracted in the form of return loss (S11) versus radiating frequency (fr), specific absorption rate (SAR) field, electric (E), and magnetic (H) field variables. Following that, the substrates were fabricated through the MEX and gel-casting approach, and Cu tape was used to make the conducting parts of the sensor. The sensor’s radio-frequency (RF) behaviour was tested on a vector network analyser (VNA) to obtain the output of S11 versus fr. The RF-characteristic of the sensors fabricated through MEX and gel-casting approaches represent that the sensors designed for dielectric constant (εr) = 9.61 resonate at 2.72 GHz for MEX and 2.67 GHz for gel-casting while possessing the S11of −14.14 and −28.40 dB respectively.Item On 3D printed polyvinylidene fluoride composite-based diaphragmatic hernia sensors(Sage, 2024-09) Kala, PrateekDiaphragmatic hernia (DH) recurrence is a commonly reported disorder among bovines. Recently, studies have been reported using wireless devices (like ultrasonic and radio-frequency (RF) based pressure sensors) to detect DH. But hitherto, little has been reported on using polyvinylidene fluoride (PVDF)-based sensors mounted on the diaphragm of bovine to detect the recurrence of the DH post-surgery. In this work, the PVDF-hydroxyapatite (HAP)- chitosan (CS) composite in the proportion of 90-8-2 (wt.%) was used as a substrate for sensor fabrication based on microstrip patch antenna (MPA). Based on the results, the parts of the sensor, that is, substrate, patch, and the ground plane, were designed in the high-frequency structural simulation (HFSS) software assigned with the material properties of PVDF-HAP-CS (as substrate) and 17-4 precipitated hardened (PH) stainless steel (SS) alloy (as patch or ground plane). Upon simulation, it was observed that some deviation in resonance frequency occurred with/ without the natural bovine diaphragm, which was verified based on experimental analysis. The parts were 3D printed for validation through material extrusion (MEX) and direct metal laser sintering (DMLS) processes. Upon testing using a vector network analyzer (VNA), it was observed that the sensor without the diaphragm resonated at 3036.57 MHz with a return loss (S11) of −12.81 dB, whereas the sensor with the diaphragm resonated at 2019.35 MHz with an S11 of −21.06 dB. This shift in frequency with/without the diaphragm is measurable in the industrial, scientific, and medical (ISM) frequency band on a Bluetooth device to detect the reoccurrence of DH.