Advanced Engineering Forum Vol. 53

Abstract: In the case of hardfacing the usage of high-strength steels is more and more influential. Several applications can be found in the construction and demolition fields where the dynamic loading occurs beside the abrasive loading. Additionally, the applied steel strength is increased, and S690QL and S960QL base materials are used as base materials for hardfacing. These materials are quenched and tempered which means that the heat cycle of the welding / hardfacing can cause significant changes in the heat-affected zone. The heat cycles of hardfacing have a different effect on the heat-affected zone, than the welding. Additionally, there are sub-zones where 2 or 3 heat cycles cause softening or hardening due to microstructural changes. The properties of the heat-affected subzones basically depend on the heat input, the number of heat cycles, and the base material. In this research, the hardness of heat-affected zones was investigated in the case of S690QL and S960QL base material. Hardfacing was made by different heat inputs in the case of both materials and after comparison, differences are written. One butter layer and 3 hardfacing layers were made in each case by robotic MIG/MAG welding. Several heat-affected subzones are determined, so for exact results hardness maps were made in all cases by hundreds of hardness tests. These maps show perfectly the differences between the hardness of the zones and the differences between the dimensions of heat-affected zones. There are significant differences in the multiple times heated subzones according to heat input. In the case of S690QL, the hardening is more significant than the softening in the heat-affected zone, the S960QL shows the opposite reaction to the heat cycles of hardfacing. On the hardness maps, the differences between the hardfacing layers are almost visible, and it shows big drops in the hardness of these layers in all cases.

Abstract: The tool steel materials are expensive this is the reason why the lifetime increase is a goal of the production technology. The tool life is determined by the various complex mechanical, thermal, chemical, and tribological properties. Tools properties depend on the chemical composition and their microstructure. The microstructure depends on the chemical composition, the production process, the heat treatment and surface treatment technologies. The goal of this research was to increase the service lifetime of the casting mould tool. It was prepared and investigated four kinds of test specimens. The first kind of specimen was made from conventional steel (W302). It was made an austenitization (1020°C) and was cooled with 9 bar nitrogen gas to 40°C and kept for 6 minutes. The quenching was followed with three times tempering processes (570°C, 580°C, 560°C) in 2 bar N₂ gas. The second kind of test specimen was made from Unimax electro-slag remelted steel (ESR). It was made an austenitization (1020°C) and was cooled with 9 bar nitrogen gas to 40°C and kept for 6 minutes. After quenching the process continues with three times tempering (610°C, 620°C, 600°C). The third kind of test specimen Unimax a electro-slag remelted steel (ESR), to which firstly an austenitization (1020°C) was made, quenched in nitrogen gas with 9bar and then cooled in liquid nitrogen till minus 150°C. After cryogenic treatment, the process continues with three times tempering (610°C, 620°C, 600°C). The fourth kind of specimen was made by the same process as the second and after it a PVD coating process was made to coat the surface by a TiBN layer. It investigated the hardness and wear resistance of all heat-treated and surface-coated steel specimens. The comparative wear resistance testing was investigated by a ball cratering tester. The rank of the tested specimen was the next: the lowest wear resistance measured in the case of the heat-treated W302, the middle in the case of cryogenic heat-treated Unimax and the highest wear resistance earned in the case of the PVD-coated Unimax. The results of the investigations proved that the Unimax tool steel service lifetime can increase better than the conventional tool steel by heat treatment and surface treatment. The practice certified that the surface-treated Unimax tools' service lifetime is much longer than the conventional ones.

Abstract: Environmentally friendly building materials known as geopolymers are made by combining high-alkalinity solutions with powder components rich in silica and alumina. It has long been known that adding fibers to the matrix phase can improve the mechanical characteristics of composite materials made for various uses. Among these are SIFCON composites, which are made by first inserting the fibers into the mold and then packing the gaps between the fibers with an extremely fluid matrix phase. The present study looked over the mechanical properties and efficiency of cement-based and geopolymer-based slurry infiltrated fiber concrete SIFCON and G-SIFCON. In the current study, for the production of both SIFCON and G-SIFCON composites, 7.5% steel fiber by volume fraction was utilized for this purpose. Therefore, sets of concrete specimens including cylinders and prisms were prepared and tested in accordance with standard specifications. The results obtained from the conducted tests prove that the 7.5% of steel fiber ratio can be used effectively to improve the mechanical performance of G-SIFCON and SIFCON composites. Furthermore, the cement-based SIFCON can be effectively replaced by fly ash-based geopolymers. Also, for composites made with fly ash-based geopolymers (G-SIFCON), high compressive strength slurries may exhibit more enhancement in mechanical properties than normal strength slurries.

Abstract: Fires can affect both civil and industrial buildings. Following a fire affecting a building or industrial structure, inspections are normally carried out to assess how the materials used in the construction have deteriorated and the severity of this phenomena. Emphasis is put on assessing the material damage, which involves understanding the mode of degradation, the mechanical and physical characteristics of these building materials and their behaviour in the presence of a thermal source. Understanding how heat affects building materials is very useful in assessing the extent of damage to various building components. Paper presents the results of an in-depth investigation of the effect of fire on an industrial building that has suffered a fire. Conclusions are drawn on the degree of material degradation of various elements of the hall structure.

Abstract: This paper presents a case study of an in-service failure occurred in a pressurized gas supply pipeline, which has been recurring in recent years, particularly during the winter season. The investigation focused on two pipe coupons extracted from a DN 300 pipeline, which had sustained damage while in operation as part of a natural gas pipeline. Through the implementation of mechanical and non-destructive testing methods on the pipe couplings and their welds, multiple non-conformities were identified. These non-conformities were found to be the root causes of failures that occurred after welding and during operation. The findings of this investigation have led to several valuable comments and recommendations, which are beneficial for manufacturing companies and clients alike. Implementing these suggestions can contribute to enhanced safety and operational efficiency in gas pipeline systems.

Abstract: As urban populations burgeon and available surface space becomes scarce, the concept of underground cities gains traction as a viable technological solution. The movement of people, purchases, and recreational trips using vehicles has also become more intensive and requires new concepts to operate in a safe environment, especially in modern underground cities. However, a major challenge faced in subterranean environments is the limited access to natural daylight. This research explores the pivotal role of engineering technology in enhancing the quality of natural daylight within underground urban spaces. Through an interdisciplinary approach, the study investigates advanced lighting utilizing, architectural design strategies with sustainable transportation, and innovative materials to mitigate the inherent constraints of subterranean living. The research assesses the effectiveness of technological interventions to provide comfortable living and safe, sustainable transportation. It therefore addresses the design of light wells, utilize of smart materials, and the incorporation of cutting-edge lighting systems to optimize the distribution of natural light. Additionally, the study evaluates the psychological and physiological impacts of enhanced daylight exposure on residents, emphasizing the importance of human-centric design in subterranean environments. Key findings highlight the significance of daylight simulations in the planning phase, emphasizing the need for architects and urban planners to utilize state-of-the-art engineering utilizing to predict sunlight patterns to achieve great benefit in providing conceptual solutions to provide a suitable environment for vehicle operation. The research also emphasizes the importance of incorporating modern technology systems as atriums, light wells, and reflective surfaces to maximize natural light penetration. Furthermore, the research investigates the energy implications of relying on artificial lighting in conjunction with natural daylight. It explores sustainable energy conceptualized technological solutions, such as solar technology and vehicle transportation according to implementation considerations, to minimize the environmental impact of energy consumption in modern underground cities.

Abstract: Auto-rickshaws serve as one of the public transport modes for many Ghanaians. However, there is growing concern regarding their safety when used for commercial transport. Therefore, this study assessed the safety of Auto-rickshaw used for commercial public transport in Ghana through Delphi and safety matrix techniques. The study focused on major safety factors such as operational, active, passive and operational safety perspectives, as well as accident, injury, and death prevention. Data was collected through questionnaire surveys to assess the identified safety factors, which were quantitatively evaluated in terms of their occurrence likelihood and consequence safety index. This study extends safety analysis from vehicle safety standards (VSS) to assess the operational safety of Auto-rickshaw. First, a Delphi survey and safety matrix approach were used to identify the major safety factors. Further endurance behaviour of Auto-Rickshaw was examined using commercial code ANSYS 19.2 workbench. Findings indicate that installation and usage of seatbelts in Auto-rickshaw are the most convenient and adaptable safety features perceived to protect occupants from injuries and death. Simulation results further showed that Auto-rickshaw with seatbelts offer 80.3% protection to occupants, compared with Auto-rickshaw without seatbelts, which offer 58.6% protection. Efforts must be made to enact and enforce policies that ensure seatbelts are incorporated into commercial auto-rickshaws.

Abstract: Climate change resulting from the burning of fossil fuels has led to severe consequences like global warming, flooding, and melting of ice sheets. One of the significant contributors to this problem is the ever-increasing production and consumption of energy, which is still primarily fossil-based and emits billions of tons of hazardous GHG. The transportation industry is one of the biggest contributors to carbon dioxide emissions, and the rail transportation sector has a significant opportunity to reduce its carbon footprint by adopting renewable energy sources like solar power. This research aims to assess the potential of solar photovoltaic systems in powering railway transportation and to evaluate the economic viability of such a system. The study focuses on the light rail transit system in Addis Ababa, Ethiopia, and aims to determine the energy-generating capacity and economic benefits of installing solar panels on various structures like train rooftops, railway depots, passenger stations, and DC traction substations. Subsequently, the research tried to address the question of how much energy could be generated by a solar photovoltaic system installed on various structures in the railway transportation system and to what extent these energies could support the railway traction supply system. The study also aimed to determine the economic feasibility of adopting solar power in railway transportation. Therefore, the research employs a quantitative research methodology and uses a Google Earth system with Helioscopes software to evaluate the potential of PV systems along rail lines and on rooftops. The study uses a case study approach and analyses the data collected through simulations to determine the energy-generating capacity and potential economic benefits. Consequently, the research finds that the solar PV system can generate 72.6 MWh per day, with an annual power output of 10.6 GWh, which can reduce CO2 emissions by 180,000 tons while generating a total profit of 892 million Ethiopian birrs. The PV-AA-LRTS has a return on investment of 200%, with a payback time of less than 13 years, and the price of solar-generated electricity is less than $0.08/kWh. Finally, the research concludes that solar power has tremendous potential in the railway transportation sector, particularly in reducing carbon emissions and generating economic benefits. In addition, the research findings support the adoption of solar power in railway transportation systems and provide a framework for assessing the potential of renewable energy sources in powering transportation systems.

Abstract: This study addressed an identified issue of representative daily load curves and parameters of Nigerian higher academic institutions and communities to eliminate prevailing application of assumed models that are representative of other climes with reliable power supply. Normal probabilistic distribution statistic, relative frequency statistic and per unit maximum load concept algorithms were composed and applied to meter-logged experiential daily load data sets with apparent inconsistent patterns and chaotic cluster. This made it impossible for local power operators to determine a representative daily load pattern for local generation planning and load management. The relative statistic-based model was used for comparison purpose. With a root mean square error of 5.6%, the probabilistic statistical algorithm was able to produce desired standard representative curve and parameters for a typical and relevant academic institution of technology in the Nigerian space, indicating a peak load at about 13:00 hour and a load factor of 0.54. The composed and applied methodology can be used for characterizing other load points of interest and categories in the region.

Abstract: The paper presents an experimental investigation of the influence of thread length and tightening torque of the M8 and M12 bolts on the vibration fixture response. To perform the tests electromagnetic vibration exciter with amplifier (LDS V8900), controller (M+P), single-axis control and measurement accelerometer (PCB), and calibrated dynamometric key (Hazet) were used. As vibration profile was used sinusoidal on a linear scale amplitude (g²) versus time (Hertz) according to the IEC 60068-2-6 standard. To investigate the length and diameter of the bolts aluminum 7075 T6 fixtures with dimensions of 40 mm ´ 40 mm width and different lengths were used as part of the samples. It was found that the investigated parameters have a major influence on the vibration fixture response.