Journal of Engineering & Technological Advances

EXPERIMENTAL INVESTIGATION ON THE INFLUENCE OF LATERAL EARTH PRESSURES ON RETAINING WALLS

2024-07-05T23:29:51+08:00

Despite continual advancement in retaining wall technology, failures of these structures still frequently make national news. In tropical countries like Malaysia, rainfall-induced landslides are a primary cause of these failures. Bridging the gaps in the Sustainable Development Goals (SDGs) of Sustainable Cities and Communities (SDG11), this study offers valuable insights to the importance of lateral earth pressure and its effects on retaining walls, therefore fostering the development of resilient infrastructure for the future. By focusing on prototype development and software simulations, this study investigates the failure mechanisms of an L-shaped cantilever retaining wall influenced by different groundwater table profiles, with a constant surcharge atop the backfill soil. The results indicate that the higher water tables correlate with lower factor of safety (FOS) and increased wall deformation. The results obtained using both software and prototype modelling shows FOS of sliding, overturning, and bearing capacity failure did not satisfy the requirement set by authorities due to the overloading and insufficient design of the geometry of the wall. These findings provide practical implications and are consistent with existing literature. Thus, this study provides an easy yet solid methodology to research on lateral earth pressures for future endeavours.

METALLURGICAL FAILURE ANALYSIS OF A TRICYCLE FRONT WHEEL AXLE

2024-09-09T11:39:22+08:00

Due to the rampant failure of the tricycle front wheel axle in Nigeria, the failure analysis of a tricycle front wheel axle was conducted in this work. The failed front wheel axle of the tricycle part was obtained. Chemical composition, microhardness and microstructures through metallography and SEM were performed. The results show the carbon content of the failed axle wheel (0.354 wt% C) is below standard. The hardness results showed that the failed material probably had not undergone proper hardenability heat treatment to produce a hardened surface and a toughened core as the microhardness at the surface and the core were found to be in the range 254-294 HV. In addition, the metallography shows ferrite and pearlite microstructures at both the surface and the core of the failed axle. The SEM analysis of the fractured surface reveals the presence of burnished and crystalline surfaces. This shows that the failed axle does not meet the standard for the axle in terms of chemical, microstructure and hardness properties. The failure of the axle is typical of a fatigue failure.

THE EFFECT OF WELDING METHODS ON THE MECHANICAL AND MICROSTRUCTURE OF HIGH-CARBON STEEL

2025-02-19T11:29:23+08:00

High-carbon steel, with a carbon content of 0.6% to 1.5%, is widely used in critical applications like cutting tools, springs, and high-performance bearings due to its strength, hardness and wear resistance. However, joining high carbon steel is challenging due to its susceptibility to cracking, brittleness, microstructural alteration in the heat affected zone. The impact of welding parameters, particularly current levels, on the mechanical and microstructural properties of high-carbon steel remains underexplored. This research explores the mechanical properties and microstructure of high-carbon steel welded using Shielded Metal Arc Welding (SMAW) and Gas Metal Arc Welding (GMAW) at varying current levels. SMAW was found to produce superior mechanical properties, with SMAW 140A achieving the highest ultimate tensile strength (495 MPa) and elongation (15%). In contrast, GMAW 120A had lower tensile strength (424 MPa) and elongation (10.5%). Higher current levels in GMAW, particularly GMAW 140A, resulted in coarser grain structures and reduced mechanical performance, with a UTS of 317 MPa and elongation of 7.5%. Hardness testing revealed increased hardness in the weld zones of all samples, attributed to the formation of martensite and other hard phases such as pearlite and bainitic ferrite. Microstructural analysis via optical microscopy and SEM showed ferrite, pearlite, martensite, and bainitic ferrite, with SMAW samples displaying a lath martensitic structure and GMAW samples showing bainitic ferrite. These findings suggest that SMAW produces better mechanical properties and microstructural stability, making it more suitable for high-carbon steel applications requiring strength and durability.

OIL SORPTION CAPABILITY OF TREATED HUMAN HAIR SORBENT FOR OIL SEA-WATER CLEANUP

2024-12-23T11:26:43+08:00

This study explored the use of modified human hair as a biosorbent for oil spill clean-up, with a focus on enhancing its oil sorption capacity. Human hair was modified using Sodium Hydroxide (NaOH) and Potassium Hydroxide (KOH) through two methods: hot water treatment at 80°C and mercerization with 5% NaOH and KOH. Structural analysis was conducted, including elemental composition, surface roughness (via Field Emission Scanning Electron Microscopy or FESEM), and hydrophobicity (via wettability tests). The oil sorption capacity was tested using an oil-seawater mixture at different adsorption times (60-100 minutes). Results showed that hair treated with hot water at 100°C achieved the highest oil sorption capacity (2.592 g/g), followed by hair treated with 5% NaOH (2.471 g/g). The optimal adsorption time was found to be 80 minutes, with all samples showing increased oil sorption. The study concluded that hot water treatment significantly improved the surface roughness and hydrophobic properties of the hair, leading to enhanced oil sorption. In comparison, mercerization with NaOH and KOH was less effective in improving the sorption capacity. Raw human hair showed high oil sorption initially, but its effectiveness decreased over extended adsorption times. These findings suggest that modified human hair, especially when treated with hot water, has strong potential for use in oil spill clean-up due to its improved structural and hydrophobic properties.