http://103.99.128.19:8080/xmlui/handle/123456789/46 Thesis published in Dept. of M.E. 2026-04-09T19:30:12Z http://103.99.128.19:8080/xmlui/handle/123456789/524 Title: Study on the Effect of Process Parameters of Laser Powder Bed Fusion on the Microstructure and Mechanical Properties of SAF 2507 Super Duplex Stainless Steel Authors: SUVA, ANISUL ISLAM Abstract: Laser-powder bed fusion (L-PBF) is a type of additive manufacturing (AM) that involves the addition of metal powders in a sequential layer-by-layer manner to create near-net-shape components. An outstanding characteristic of this technology is its ability to achieve high cooling rates, reaching up to 107 K/s. This unique characteristic has benefits in the production of high-strength stainless steel alloys, as it helps to reduce unwanted phase formation. SAF 2507 super duplex stainless steel (SAF 2507 SDSS), a type of stainless-steel alloy, contains around 25% chromium and 7% nickel, has a unique phase composition with an equal distribution of about 50% ferrite and 50% austenite and characterized by its higher mechanical strength and resistance to corrosion, which are attributed to its high levels of chromium and nickel content along with its low level of carbon. Producing intricate geometry with SAF 2507 using traditional methods with a specific phase composition is challenging and requires post-processing. LPBF is an alternative technology capable of manufacturing near-net-shape components with complicated geometry. It is important to conduct a comprehensive investigation to retain the desired phase composition while fabricating components using L-PBF. Although several studies have investigated the microstructure and mechanical properties of SAF 2507 using L-PBF. However, the influence of different L-PBF process parameters as well as energy density on microstructure and mechanical properties has yet to be investigated. This study examines the influence of L-PBF process parameters (laser power, scan speed, hatch distance) on the microstructure and mechanical properties of SAF 2507 SDSS. Additionally, the corrosion properties are investigated using the established optimum parameters. A design of experiment (DoE) was performed using the central composite design over a wide range of process parameters: laser power (100–300 W), scan speed (250–1000 mm/s), and hatch distance (50–180 μm) to investigate their effect on the microstructural and mechanical properties of SAF 2507. By implementing the selected parameter set, the as-built SAF 2507 SDSS sample had porosity less than 1%, a Vicker hardness ranging from 288 to 357 HV, a yield strength of 824 to 1220 MPa, an ultimate tensile strength of 965 to 1304 MPa, elongation of 6% to 18.1%, and a corrosion rate of 127.65 μm/y was determined. The findings derived from this investigation have the potential to facilitate the customization of component quality by meeting design specifications and minimizing as-built defects, thereby decreasing the need for post-processing. Description: An M.Sc. Thesis from the department of Mechanical Engineering. 2024-08-14T00:00:00Z http://103.99.128.19:8080/xmlui/handle/123456789/523 Title: Synthesis and Electrochemical Cycling of Nanostructured Ti2C Mxene as Anode Materials for Lithium-ion Batteries Authors: Chy, Mohammad Nezam Uddin Abstract: By offering a high energy density, long cycle life, and relatively low self-discharge rates, LIBs have become the preferred choice for powering everything from smartphones to electric vehicles. Their ability to be rapidly charged and discharged while maintaining a compact and lightweight form has also made them essential in renewable energy systems, where they facilitate the storage of solar and wind energy. The electrochemical performance of a LIB greatly depends upon the anode material. The essential requirements for excellent anode material of Lithium-ion batteries (LIBs) are high safety, minimal volume expansion during the lithiation/de-lithiation process, high cyclic stability, and high Li+ storage capability. However, most of the anode materials for LIBs, such as graphite, SnO2, Si, Al, Li4Ti5O12, etc., have at least one issue. Hence, creating novel anode materials continues to be difficult. Broad adoption has already been started of MXenes materials in various energy storage technologies such as super-capacitors and batteries due to the increasing versatility of the preparation methods as well as the ongoing discovery of new members. Few MXenes have been investigated experimentally as anode of LIBs till date due to their distinct active voltage windows, large power capabilities, and longer cyclic life. Here, Ti2C MXene was synthesized by using an efficient NaOH etching technique. The surface appearance, structural composition, and crystalline structure were assessed using X-ray diffraction, SEM, and EDX analysis. The as-synthesized MXene were used as negative electrode in LIB and electrochemical performance were evaluated. First cycle charge-discharge capacities are found 658.02 mAhg-1 and 419.11 mAhg-1 respectively with an initial columbic efficiency of 63.6% and excellent capacity retention of 259.1 mAhg-1 is obtained after 100 cycles at a current density of 50 mAg-1. The excellent cyclic performance and stability of this cell are attributed to the unique properties of MXene structure such as high electronic conductivity, low operating voltage, large surface area and fast Li ion diffusion characteristics Description: An M.Sc. Thesis from the Department of Mechanical Engineering. 2024-08-18T00:00:00Z http://103.99.128.19:8080/xmlui/handle/123456789/506 Title: Experimental Investigation of Cycling Characteristics of Anatase TiO2 Nanotubes as Negative Electrode of Lithium-ion Batteries Authors: Das, Simul Abstract: Lithium-ion batteries (LIBs) have emerged as a ground-breaking technology that has revolutionized modern portable devices and facilitated the electrification of numerous industries, such as transportation and grid energy storage, as a result of the pursuit of sustainable and efficient energy storage solutions. Due to their superior qualities, such as their high energy density, prolonged cycle life, and lightweight nature, which facilitates greater portability, lithium-ion batteries have been embraced as a replacement for conventional energy storage systems. A consistent effort has been made to investigate developments in the field of lithium-ion batteries in response to the growing need for energy storage systems that exhibit improved performance metrics, including increased energy density, faster charging capabilities, enhanced safety, and longer lifespan. The current issues with current LIB technology must be resolved in order to use lithium-ion batteries (LIBs) as a viable energy storage solution with increased capacity. This requires the creation of new electrolyte formulations, cell structures, and production methods. Nanotubes Anatase TiO2 (NT-TiO2) have been brought forth via electrochemical anodization of 99.9% pure titanium foils in a fluorine containing and four different percentages (10%, 20%, 30% & 50%) of Ethylene Glycol (EG) electrolyte. After that calcination process is done at 5500C for 2h. Different types of structure is observed in SEM images for four different electrolyte type samples. Among them in 10% of EG electrolyte type, the nanotubes NT-TiO2 is observed and by using this as anode the battery is assembled and tested the electrochemical analysis. In the first cycle, the chargedischarge capacities are 550 mAhg-1 and 400 mAhg-1, respectively, with columbic efficiency 75.75%. At 40th cycle, charge-discharge capacities are found to be 375 mAhg-1 and 325 mAhg-1, respectively, and at this cycle, the columbic efficiency is 80%. The superior electrochemical performances of this type of battery were viii originated from its high specific surface area and highly nanotubes structure. These advanced features of the nanotubes provide higher contact between electrode and electrolytes, shorten the diffusion pathways for conductive ions and electrons and ensure fast kinetics. Description: An M.Sc. Thesis from the Department of Mechanical Engineering 2023-10-04T00:00:00Z http://103.99.128.19:8080/xmlui/handle/123456789/502 Title: Analytical and Experimental Analysis of Wheel Alignment System for Light Vehicle Authors: Das, Riton Kumer Abstract: Wheel alignment is an important factor that influences the performance of automotive vehicles. This study experimentally investigated the effects of wheel alignment, especially front wheel toe angle, tire pressure, vehicle load, and brake application, on fuel consumption and tire travel life for two different models of light vehicles. According to the analysis, the vehicle's wheel started to become out of alignment when its travel distance increased over time. It is observed that vehicle wheels became out of alignment due to changes in different factors, including vehicle load, road condition, brake application, tire pressure, suspension condition, etc. The experimental findings also demonstrate that a number of variables, including engine rpm, rolling resistance, energy consumption, fuel consumption, and tire wear of the vehicles, are strongly correlated with front wheel toe angles, tire pressure, vehicle load, and brake application. The test result shows that the increase in rolling resistance and energy consumption led to an increase in fuel consumption, tire wear rates, and travel costs. It is found that due to the misalignment of the front wheel toe angle, the car travels about 4.77 km (for left toe-in, 2.53°), 5.12 km (for left toe-out, -2.53°), 7.37 km (for total toe-in, 5.06°), and 7.63 km (for total toe-out, -5.06°) less for the same amount of fuel, and the KPL reduction rate is up to 38.22%, 42.24%, 73.99%, and 79.31%, respectively. In comparison to the front wheel's left toe-in angle, the fuel consumption rate is 4.02% higher at the front wheel's left toe-out angle. Additionally, it is found that when both wheels are at a toe angle, fuel consumption is a little bit higher. In the second experiment, the effect of tire inflation pressure on the fuel performance of a light vehicle at a front wheel total toe angle of 0.00°, 1.44° (toe-in), and -1.44° (toe-out) is investigated. The experimental finding shows that when tire pressure changes from over-inflated to under-inflated while maintaining a constant front wheel toe angle, the vehicle's engine rpm, rolling resistance, energy consumption, fuel consumption, and travel cost rates increase. In comparison to a total toe angle of 0.00°, a front wheel total toe-in angle of 1.44° results in a 3.62% increase in fuel consumption, while a front wheel total toe-out angle of -1.44° results in a 4.63% increase. In the third experiment, a Toyota Echo Plus-2ZZ-GE-02 light-duty vehicle is used to investigate the effect of vehicle load on fuel performance. It is revealed that when the vehicle load rose from low to high while x maintaining a constant front wheel toe angle, the engine rpm, rolling resistance, energy consumption, fuel consumption, and travel cost rates increased. The analysis results also reveal that the rolling resistance varies non-linearly with the vehicle load under steady-state conditions, while the fuel consumption varies almost linearly. Interestingly, energy consumption also increases almost non-linearly with vehicle load. In the fourth case, the same vehicle is used to investigate the effect of brake application on fuel performance. According to the test results, increasing the number of brakes applied (0 to 100 times) results in increased rolling resistance and fuel consumption. The rates of rolling resistance coefficient and rolling resistance increased to 198.79% and 198.79%, respectively, and the rates of energy consumption and fuel consumption increased to 198.79% and 81.74%, respectively. In the fifth case, the effect of wheel toe angle on tire wear is investigated experimentally. It is shown that when the vehicle's front wheel total toe-in angle is changed from 0.00° to 4.80° for the Toyota Corolla-2E-86, the engine rpm, rolling resistance, energy consumption, tire wear, and tire traveling life reduction rate are increased. It is observed that the rate of loss in tire travel life with regard to a condition without misalignment is up to 99.08% when the front wheel total toe-in angle is out of alignment (from 0.00° to 4.80°). The rate of increase in rolling resistance is found to be about 167.84%, and the rate of carbon dioxide emissions is nearly 40% higher for the car as the front wheel total toe-in angle increased (from 0.00° to 4.80°). It is also seen that tire outside lateral groove wear, tire inside lateral groove wear, and tire circumferential groove wear change (from 0.03 mm to 3.01 mm, 0.03 mm to 0.29 mm, and 0.04 mm to 4.35 mm) with the changes in the front wheel total toe-in angle (from 0.00° to 4.80°) after the vehicle's traveling distance and tire travel life are recorded to be 3,500 km and 1537.50 km, respectively. Finally, a regression model is proposed using the test data. Such a model might be useful to explain the relationship between the related factors and determine the rate of fuel consumption, tire wear, and travel costs. The light automotive vehicle is expected to benefit from these findings in the form of improved fuel economy, less tire wear, lower energy usage, and prolonging the tire's useful life if the front wheel toe alignment, tire pressure, vehicle load, and brake application are maintained properly. Description: A PhD Thesis from the Department of Mechanical Engineering 2023-09-26T00:00:00Z