Ramesh Raghavendra

Ramesh Raghavendra
Waterford Institute of Technology | WIT · School of Engineering

M.Sc., M.S., Ph.D., MBA

About

85
Publications
18,478
Reads
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1,419
Citations
Citations since 2016
43 Research Items
726 Citations
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140

Publications

Publications (85)
Article
Full-text available
Additively manufactured (AM) metal parts are usually post-processed by mechanical surface finishing to attain desired surface roughness. Simulation of AM chain provides means to effectively optimize the final product's quality characteristics in the design stage. The present study developed theoretical models for simulation of surface topography an...
Article
The use of additive manufacturing (AM) has grown exponentially in recent years and has many advantages, including feasibility, over other conventional processes in many current applications. The use of a second process, for example, machining, improves the surface finish and in this case, the use of two processes is known as hybrid manufacturing. H...
Article
Full-text available
Metal additive manufacturing (AM) processes, viz laser powder bed fusion (L-PBF), are becoming an increasingly popular manufacturing tool for a range of industries. The powder material used in L-PBF is costly, and it is rare for a single batch of powder to be used in a single L-PBF build. The un-melted powder material can be sieved and recycled for...
Article
Laser-based powder bed fusion (L-PBF) of AlSi10Mg is used to fabricate complex, light-weight structures with high thermal conductivity. Much effort has gone into investigating the mechanical behavior of L-PBF components; however few studies investigated their thermal properties. This investigation characterizes the effect of process parameters on t...
Article
Full-text available
In this study, the effect of as-built and heat-treated additively manufactured 316L stainless steel at different temperatures was examined on the electrochemical corrosion performance. The corrosion was investigated by Tafel polarization and electrochemical impedance spectroscopy methods in a 3.5% NaCl solution. For this purpose, the as-built and h...
Conference Paper
Full-text available
Metal Additive Manufacturing (AM), viz, laser powder bed fusion (L-PBF), processes are becoming an increasingly popular manufacturing tool for a range of industries. L-PBF allows for the manufacture of complex and often critical components in the medical device, medical implants, aerospace, and automotive industries, to name a few. The powder mater...
Conference Paper
Full-text available
With the proliferation of metal additive manufacturing (AM) as a production technique in industry, the need to effectively and efficiently inspect components with free-form shapes and internal geometries is constantly increasing. X-ray micro-computed tomography is a natural inspection partner for this production technology; however, metallic sample...
Conference Paper
Full-text available
This paper presents a methodology for the embedding of a sensor in a 316L stainless steel component during the laser powder bed fusion process. The aim of this study is to overcome the drawbacks of traditional sensor attachment to the surface of a component via placing sensors into a part during the manufacturing process. A methodology for the embe...
Article
This paper presents the embedding of a temperature Surface Acoustic Wave (SAW) sensor in an additively manufactured 316L stainless steel part during the Laser Powder Bed Fusion (L-PBF) process. The embedding of sensors and integrated circuits in additively manufactured (AM) parts is an important step towards the development of smart components; how...
Article
This paper presents a comparative study on the effect of multi-machine laser powder bed fusion manufacturing on the quality of 316L stainless steel parts. Within industry, often the same additive manufacturing machines are used for research and development of components as are used for production. However, there is a challenge in terms of determini...
Article
Despite the recent progress in additive manufacturing (AM) process and technology, challenges in the repeatability and reproducibility of AM parts still hinders the adoption of this technique in many industries. This is particularly difficult when a part is qualified on a particular part on a certain machine using optimised parameters. If a manufac...
Article
Full-text available
Post-processing is one of the main ways to improve mechanical and microstructural characteristics of stainless steel 316L fabricated by the laser-based powder bed fusion (LPBF) process. In this study, optimized LPBF parameters were used to manufacture SS316L bars. For the post-processing, two main heat treatment strategies have been used, quenching...
Article
Full-text available
Laser-Powder Bed Fusion (L-PBF) of metallic parts is a highly multivariate process. An understanding of powder feedstock properties is critical to ensure part quality. In this paper, a detailed examination of two commercial stainless steel 316L powders produced using the gas atomization process is presented. In particular, the effects of the powder...
Conference Paper
With the increasing popularity of metal additive manufacturing, in particular the powder bed fusion (PBF) process for the production of end-use components in a wide range of industries, the ability to recycle un-melted powder increases the attraction of PBF. Previous research has characterised the effects of recycling the powder on both the powder...
Poster
Full-text available
Lipoyl-apocynin and lipoyl-sesamol are bio-active conjugates of thioctic acid (also known as alpha-lipoic acid), synthesized by benign chemical approach by the combination of thioctic acid and powerful bio-phytonutrients, apocynin and sesamol respectively. Encapsulation is done for chemically modified thioctic acid conjugates within liposome struct...
Article
Full-text available
In this study, selective laser melting (SLM) was investigated for the manufacturing of 316L stainless steel press-fit joints. The accuracy of selective laser melting technique in fabrication of texture profile in shape, pitch and height of microsurface texturing was examined. The resulting insertion and removal forces achieved from the produced tex...
Article
Full-text available
Manufacturing-induced defects are a key source of crack initiation and component failure under high temperature cyclic loading. In this work, 3D X-ray micro-computed tomography and microstructural analysis of manufacturing-induced defects is presented for forged and cast MarBN martensitic-ferritic steel, along with high temperature, low cycle fatig...
Article
Full-text available
free access to the paper: https://rdcu.be/b32vL The objectives of this study are: 1) to verify whether using linear heat input alone is sufficient to predict the resulting microstructure. 2) to demonstrate the potential of single-step process of functionally graded material using powder bed fusion. In laser powder bed fusion, linear heat input is...
Article
Recycling metallic powders used in the additive manufacturing (AM) process is essential for reducing the process cost, manufacturing time, energy consumption, and metallic waste. In this paper, the focus is on pore formation in recycled powder particles of stainless steel 316L during the selective laser melting process. We have introduced the conce...
Article
Full-text available
Lipoyl-apocynin and lipoyl-sesamol are bio-active conjugates of thioctic acid (also known as alpha-lipoic acid), synthesized using a benign chemical approach via the combination of thioctic acid and the powerful bio-phytonutrients, apocynin and sesamol, respectively. Encapsulation was performed for chemically modified thioctic acid conjugates withi...
Conference Paper
Direct metal laser sintering (DMLS) is a powder bed fusion (PBF) additive manufacturing process commonly used within the medical device and aerospace industries where regulations drive the requirement for stringent quality control. Using in-situ monitoring, the identification of defects, as well as the geometric and dimensional measurement of the l...
Article
Additive manufacturing, viz. powder bed fusion (PBF), processes are becoming increasingly more applicable to a range of industries. Direct metal laser sintering (DMLS) is a PBF process commonly used within the medical and aerospace industries to produce complex and often critical components. Powder material used in the DMLS process can be costly an...
Article
The tensile mechanical properties and anisotropy levels of identical test-coupons, fabricated from maraging steel 300 (MS300) using two alternative EOS EOSINT M280 Additive Manufacturing (AM) systems, have been examined. The mechanical performance variations resulting from process differences between the two suppliers and the part's build volume or...
Article
This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0, 45, and 90deg) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) system. The alloy's microstructure, har...
Article
Full-text available
The research presented here compares the weight and structural strength of several lightweight 3D metal printed fractal antennas to the equivalent metal-coated polymer 3D printed antenna. Lattice structures are recognized for their advantages in providing lightweight, stiff and shock-resistant structures. In this work, they are used to create a str...
Conference Paper
Direct metal laser sintering (DMLS) is a powder bed fusion (PBF) process commonly used within the medical device and aerospace industries to fabricate high value, complex components. Powder material used in the DMLS process can be costly and it is rare for a single build to require a full batch of powder. The un-melted powder, which differs in part...
Conference Paper
Additive manufacturing, viz. powder bed fusion (PBF), processes are becoming increasingly more applicable to a range of industries. Direct metal laser sintering (DMLS) is a PBF process commonly used within the medical and aerospace industries to produce complex and often critical components. Powder material used in the DMLS process can be costly an...
Article
Cold working of austenitic stainless steel results in the formation of α⁰-martensite (ferromagnetic) within the host material (paramagnetic). The role of α⁰-martensite and carbide precipitation in the reverse transformation mechanism during the heat treatment of AISI 304 is presented. A magnetic Barkhausen noise (MBN) measurement technique was empl...
Article
This research relates to the design, modelling and fabrication of 3D metal printed heat sinks. The heat sinks presented in the research are the commonly used longitudinal fin solid heat sink (LFSHS) and three LFSHS lattice structure designs, differing only in their lattice sizes, fabricated using the Direct Metal Laser Sintering (DMLS) technique, o...
Conference Paper
This research presents the impact on surface roughness of build orientation in the fabrication of a 3D metal printed X-band horn antenna (8.2-12.4 GHz). Build orientation is investigated by printing the antenna at three different orientations of 45,̊ 90̊ and 180̊, with respect to the building platform. The results indicate that the build orientatio...
Conference Paper
An overview of literature and the work carried out by the authors in 3D metal printed microwave components is presented. Components produced include a conventional horn antenna, Sierpinski gasket antenna, waveguide antenna array, a monocone antenna with an integrated feed and horn antenna with inbuilt periodic structures. In addition, antenna with...
Conference Paper
Full-text available
The research presents a 3D metal printed X-band (8.2-12.4 GHz) horn antenna with side-lobe reduction, achieved by printing pyramidal periodic structures on the inner faces of the antenna’s E-plane. The 3D pyramidal periodic structures result in the suppression of the surface current and hence reduce the side-lobes of the horn antenna. The placement...
Conference Paper
Full-text available
In this work, a 3D monocone antenna for wideband applications, with an integrated N-type feed, is created via Additive Manufacturing (AM). AM permits the production of complex RF components with ease, in this case in realizing both the monocone structure and the integrated feed. Integrating the feed as part of the antenna reduces the assembly requi...
Conference Paper
In this research, the design, simulation, and fabrication of the first ever 3D metal printed Sierpinski gasket antenna, with multiple resonance characteristics is reported. The antenna is fabricated from Titanium alloy Ti-6Al-4V, using the Direct Metal Laser Sintering (DMLS) technique. Mechanical considerations like Rumsey’s principle and the suppo...
Conference Paper
The research presents the performance evaluation of a 3D metal printed antenna, as the inherent surface roughness is gradually reduced using different surface treatment techniques. In this work, surface treatment is performed on a complex shaped, 3D metal printed Sierpinski gasket antenna, fabricated from Ti-6Al-4V using a Direct Metal Laser Sinter...
Conference Paper
Full-text available
In this research, the post-processing steps and their importance is highlighted for 3D printed microwave components. The components created so far include various antennae and a waveguide fabricated with Titanium alloy (Ti-6Al-4V), using the Direct Metal Laser Sintering (DMLS) technique. The variations in performance after each post-processing step...
Article
Full-text available
For many years there has been considerable research from both an academic and industrial perspective into the monitoring and control of CNC machining processes, and progress has been well documented. It is widely acknowledged within the CIRP community that collection of information into the performance of material cutting processes is a worthwhile...
Article
Full-text available
Etoricoxib (ECB) is a large, lipophilic molecule that is practically insoluble in water and exhibit an exceedingly slow dissolution rate making it a Class II compound in Bio pharmaceutics Classification System. In the present article, the higher solubility advantage of ECB in solid dispersion is explored. More specifically, solid dispersion of ECB...
Article
Full-text available
The aim of present study was to develop conventional and PEGylated (long circulating), liposomes containing anastrozole (ANS) for effective treatment of breast cancer. ANS is a third-generation non-steroidal aromatase inhibitor of the triazole class used for the treatment of advanced and late-stage breast cancer in post-menopausal women. Under such...
Article
Full-text available
The properties of porous silicon make it a promising material for a host of applications including drug delivery, molecular and cell-based biosensing, and tissue engineering. Porous silicon has previously shown its potential for the controlled release of pharmacological agents and in assisting bone healing. Hydroxyapatite, the principle constituent...
Article
In precision engineering, tool wear affects the dimensional accuracy and surface finish of machined components. Currently, errors associated with tool wear remain uncompensated for and are usually only detected at the end of the machine cycle, by which time the product may be scrap. If real-time, accurate monitoring were available, machine paramete...
Article
Full-text available
ZnO based varistors are widely used for overvoltage protection in many electrical and electronic circuits, at voltages ranging from a few to over a million volts. By careful control of the microstructure, through nano-structuring by chemical routes, it should be possible to produce varistors with high breakdown voltage (Vc), as this is proportional...
Article
Microwave sintering of multilayer capacitor/varistor-based integrated passive devices (IPDs) has been investigated for the first time. The sintered samples were characterized for density, microstructure, composition, and electrical performance. It was found that IPDs with varistor/capacitor formulations could be microwave sintered to fully dense de...
Chapter
This paper was published in Ceramic Engineering and Science Proceedings [© The American Ceramic Society] and details of the definitive version are available from: http://ceramics.org/acers-bookstore/cesp-ceramic-engineering-and-science-proceedings/ The feasibility of employing the microwave methodology for the processing of integrated passive devic...
Article
Full-text available
The co-firing characteristics of ZnO varistor and NiZn ferrite thick films were investigated, the objective being to create an integrated passive device. Bismuth oxide additions were used to increase the shrinkage of the ferrite during sintering. Dilatometry analysis proved that well-matched shrinkage characteristics could be obtained for bismuth o...
Article
Full-text available
An industrially viable solution-based processing route using minimal amounts of solvent has been used to prepare bulk quantity nanopowders (average particle size 15 +/- 3 nm) for the fabrication of ZnO varistors. The xerogels, calcined powders and sintered materials were fully characterised. The preparation of varistors from nanopowders has been op...
Article
Full-text available
ZnO varistor materials were prepared by a sol gel route with subsequent drying and calcination. Varistor discs fabricated from these materials were subjected to a two step sintering schedule. Therefore in a typical experiment, the samples were heated to 1000 degrees C, then allowed to cool for over 30 min to 900 degrees C and held there for 6 h. Th...
Article
In this paper design, modeling and characterization of single and double coils, which consist of conductive layer embedded in the soft ferrite material, are described. These surface-mount components, comprising of a cofired multilayered ferrite and coil, have been developed in the ceramic coprocessing technology. A simple analytical model of propos...
Article
Full-text available
This paper describes the design, modeling, simulation and fabrication of zig-zag and meander inductors embedded in low- or high-permeability soft ferrite material. These microinductors have been developed with ceramic coprocessing technology. We compare the electrical properties of zig-zag and meander inductors structures installed as surface-mount...
Article
Thirteen glasses of the general formula (M1, M2)9.33Si14Al5.33O41.5N5.67 where M1=La or Nd and M2=Y or Er have been prepared with M1/(M1+M2) fractions of 1, 0.75, 0.5, 0.25, and 0. Data for molar volume (MV), glass compactness (C), Young's modulus (E), microhardness (H), glass transition temperatures (Tg), and dilatometric softening temperatures (T...
Article
Nucleation and crystallization studies were conducted on a YSiAlON glass that contained 17 equiv.% nitrogen (7.5 at.%) by using a two-stage nucleation-and-growth treatment. Classical and differential thermal analysis (DTA) techniques were both used to study the crystallization process, to ensure that the optimum heat-treatment schedule that yielded...
Article
This letter describes the design, modeling, simulation, and fabrication of novel integrated passive devices (IPDs). These IPDs, comprising of a cofired multilayered varistor and inductor, have been developed in the ceramic coprocessing technology. The equivalent model of the new structures is presented, suitable for design and circuit simulations....
Article
Full-text available
ZnO nanoparticles were prepared by a solid state pyrolysis reaction of zinc acetate dihydrate and oxalic acid dihydrate at 500degreesC. The course of reaction at various temperatures was followed by XRD. Subsequently varistors were fabricated from this nano-ZnO material by solid state mixing with various oxide additives and sintering to 1050degrees...