MESII - 2020
http://dl.lib.uom.lk/handle/123/17183
2024-03-28T22:28:48ZMaterials Engineering Symposium on Innovations for Industry 2020 (Pre Text)
http://dl.lib.uom.lk/handle/123/21277
Materials Engineering Symposium on Innovations for Industry 2020 (Pre Text)
Abeygunawardana, AAGA
2020-01-01T00:00:00ZInfluence of low-amplitude high-frequency pulsed current on the deformation characteristics of low and medium carbon steels
http://dl.lib.uom.lk/handle/123/17349
Influence of low-amplitude high-frequency pulsed current on the deformation characteristics of low and medium carbon steels
Hendeniya, HMND; Shiranga, WMP; Abeygunawardane, AAGA; De Silva, GIP
Abeygunawardane, AAGA
When electrical pulses are applied to a metal during deformation, the resistance to deformation is dramatically reduced while the plasticity increases significantly. This phenomenon is introduced as electroplasticity. Macroscopic observations of yield stress reduction under current pulsation due to uniaxial tension, creep and stress relaxation is in the center of attention recently.
Traditional manufacturing processes such as drawing, and rolling be contingent on the use of heat to reduce the forces associated with the fabricated parts. The high-temperature requirement is potentially leading to stress, warpage, and reduced tolerance control. Therefore, Electrically Assisted Manufacturing is introduced as an effective way of simplifying the fabrication while enhancing end- product properties.
The electroplastic deformation of low and medium carbon steels under uniaxial tensile conditions were investigated with respect to the universal uniaxial tensile testing conditions. A significant reduction of yield stress of low and medium carbon steel with different carbon content were observed due to electroplasticity effect. A qualitative and quantitative analysis of yield stress reduction was carried out. Microstructural behavior and morphological aspects of fractured and strained surfaces of low and medium carbon steel specimens were observed.
Keywords: Electro plasticity, Electron wind force, Dislocations, Uniaxial tensile test, Electrically assisted manufacturing, Low and medium carbon steel, Plasticity
2020-02-01T00:00:00ZSynthesis and morphological characterization of TiO2 nanotube arrays
http://dl.lib.uom.lk/handle/123/17348
Synthesis and morphological characterization of TiO2 nanotube arrays
Rajapakse, HD; Rathhnayaka, VWSG; Sitinamaluwa, HS; Jayasundara, DRT
Abeygunawardane, AAGA
TiO2 nanotube arrays have recently gained increased attention due to their unique properties such as high specific surface area, higher charge transport capability and excellent chemical and mechanical properties. It is an ideal candidate for advanced functional devices such as solar cells, supercapacitors, gas sensors etc. Synthesis of TiO2 can be done cost-effectively by anodization of a Ti foil in a suitable electrolyte. The morphology, and hence the functional properties of the nanotubes strongly depend on the anodization parameters, therefore, this study aims to establish a relationship between anodization parameters and nanotube morphology.
In this study, TiO2 nanotube array was successfully synthesized by anodizing a Ti foil in an electrolyte containing 99.5% Ethylene glycol, 0.5% DI water and 0.3% w/v NH4F. A range of anodization experiments were designed to vary the anodization voltage (20V-60V) and time (1h-3h) while keeping the other factors constant. Formation of crystalline nanotubes were confirmed by X-ray diffraction analysis, and scanning electron microscope was used to characterize the tube length and diameter. The diameters of synthesized nanotubes ranged from 28 nm to 90 nm while the tube lengths ranged from 2.5 μm to 15 μm.
Statistical analysis of tube dimensions showed a strong relationship between process parameters and tube dimensions. Within a 3-hour period, voltage is found to be the most significant parameter on diameter and length of the growing tubes. It was found that the tube diameter obeys the relationship D = 1.109V + 6.863t + 0.284 where D is nanotube diameter, V is anodization voltage and t is anodization time. This study thus facilitates the researchers to tailor make the structure of the TiO2 nanotube layer according to the properties required.
2020-02-01T00:00:00ZMechanical behaviour of Cu-Zr binary metallic glasses: a molecular dynamic simulation study
http://dl.lib.uom.lk/handle/123/17347
Mechanical behaviour of Cu-Zr binary metallic glasses: a molecular dynamic simulation study
Gamage, NH; Madhushan, PAC; Sitinamaluwa, HS
Abeygunawardane, AAGA
Metallic glasses (amorphous alloys) have gained increased attention in recent times due to their unique combination of mechanical properties such as high tensile strength, fatigue and wear resistance together with higher toughness values. However, the underlying deformation physics of these materials remain less firmly established as compared with crystalline alloys. One reason is the difficulty of characterization of material structure, as these materials do not have long range order in their atomic arrangements. Material modelling and simulation methods have paved new ways for the advancement of material development, modification and processing. For the study of amorphous materials, atomistic modelling and simulation techniques have proven to be very useful, as these techniques allow a closer look of local atomic environments of these materials.
In this research, molecular dynamics simulation is used to analyze mechanical behavior of Cu- Zr binary metallic glasses under tensile forces. Firstly, the relationship of toughness and strength over a range of atomic compositions of Cu-Zr metallic glasses (45 % Zr to 55 % Zr)is analyzed. In addition, the underlying deformation mechanisms of Cu-Zr metallic glasses were investigated. The MD simulations were done using Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) and OVITO software is used for visualization and analysis of the simulation results.
As this study reveals, both fracture strength and toughness of Cu-Zr alloys are increased with increasing Zr content. Also, the Young's modulus of these alloys are also increased with the increasing Zr content. In-depth analysis of atomic structures suggests that the increasing free volume with increasing Zr content is responsible for high strength and toughness observed in the alloys with higher Zr content.
2020-02-01T00:00:00Z