Applied Mechanics and Materials Vol. 924

Abstract: Certification to race in a given group requires a safe and homologated vehicle. In this context, an Audi A3 is converted to a racing car. For providing passenger safety, a T45 carbon steel roll cage is designed and assessed via FEA under different loading scenarios. In addition, a redesign of the disc brake via a heat transfer simulation followed by a thermo-mechanical stress analysis showed that at a velocity of 150 Km/h, the maximum temperatures attained by the original and modified disc brakes are 300°C and 225°C respectively. Moreover, a suspension system is designed via multi-body dynamics analysis to give solace for the driver and absorb the shock. Through trial and error, a coil over with a stiffness of 80 N/mm and a damping coefficient of 0.3 N.s/mm is selected. Finally, the engine is homologated by modifying several parameters in order to increase power such as bore, stroke, and valves. The total cost of the homologation is around 10,000 $. In conclusion, this work provides a comprehensive roadmap for those aiming to convert regular vehicles into racing cars. By outlining key processes such as structural safety upgrades, brake system optimization, suspension tuning, and engine modifications, this study serves as a detailed guide for homologation. These modifications, performed on the Audi A3, demonstrate a clear approach to achieving competitive racing standards while balancing performance, safety, and cost-effectiveness.

Abstract: Uprights are one of the most critical structural elements in vehicles suspension systems. A standard upright serves as a physical mounting for the wheel hub and brake components as well as links the axle to the control arms. Uprights are relatively bulky by design to withstand the significant loads they observe during vehicle braking, maneuvering, and driving on rough terrain. In automotive design, specifically, race car design, utilizing lightweight components and reducing fuel consumption are imperative. This weight reduction-based paradigm is being adopted by the car industry at large, particularly due to the shift towards automotive electrification. Consequently, this work investigates the potential for using topological optimization to reduce the bulkiness and weight of uprights without compromising their structural integrity and reliability. An upright designed for a racing car is selected in this study. Topological optimization is performed on the upright using the finite element software ANSYS. Results show that a considerably enhanced upright is obtained after 48 topological optimization iterations while maintaining a factor of safety of 2.5. The optimized upright exhibited less stress concentrations and 39% lesser weight than the original upright.

Abstract: Orbital welding is a relatively meticulous and precise welding technique. To achieve orbital welding, this technique is mainly used in aviation, fission fuel and other industries. For example, it can be used to join long pipes in pressure vessels. The purpose of this study is to provide an overview of the orbital welding process and equipment. The research completed to date is presented here to provide a report on orbital welding. It uses a U-shaped welding tip in a specific welding application where the arc from the tungsten electrode is rotated 360° to perform the welding.

Abstract: The increasing global demand for denim jeans necessitates sustainable practices in both production and disposal. This study investigates the mechanical properties of recycled cotton denim fabric, focusing on tensile strength, tear strength, and fabric density (GSM), in accordance with international testing standards. Results show a decrease in tensile strength but an increase in tear strength for recycled cotton denim. Specifically, there is a strong positive correlation between the tearing strength of the weft yarns in waste and recycled denim (r = 0.797, p < 0.001). Additionally, the recycled fabric has a higher GSM, indicating improved material density. These findings suggest that recycled cotton denim could be used in various durable products, such as handbags and shoes, promoting sustainability within the textile industry. Limitations include the reduced fiber length after recycling, which necessitated blending with raw cotton to achieve optimal quality. Despite equipment limitations, this research provides valuable insights into the potential of recycling cotton denim. Future work should explore advanced recycling techniques to improve quality and broaden application opportunities.

Abstract: Barges generally have an even distribution of load weight on the deck. The tendency of barges to experience hull fractures is at 0.2 ~ 0.7 L during material loading mode.The pupose of the research is to determine the ultimate strength of barge construction during loading mode. The method used is a numerical simulation. The research results show that the maximum stress value under hogging conditions for loadcase 1 and loadcase 2 with intact plate thickness is 221.204 Mpa and 223.207 MPa, the maximum stress value in hogging conditions for loadcase 1 and loadcase 2 with 20% reduction in plate thickness is 188.973 MPa and 196.303 MPa, and the maximum stress value in hogging conditions for loadcase 1 and loadcase 2 with a plate thickness reduction of 25% is 170.054 MPa and 164.861 MPa. The largest ultimate moment value was obtained in loadcase 2 hogging conditions with intact plate thickness, namely 1.92 x 10¹¹ Nmm. The thinner the construction plate, the lower its ultimate strength will be. The addition of sideboards to the barge deck can also affect the ultimate strength value he construction safety factor is rated 1.064 ~ 1.425.

Abstract: The circular saw blade is an important tool for wood processing. The controllable residual stress formed by tensioning process has a clear influence on the critical rotational speed of the circular saw blade. Due to the diversification of the circular saw blade structure and tensioning method, the influence of the residual stress field on the critical rotational speed of the circular saw blade should be further studied. In this paper, four types of circular saw blades are built using the finite element method. Circular elastic thermal expansion and annular elastic thermal expansion zones are used to produce a certain distribution of residual stress field for the circular saw blade. The critical rotational speed of circular saw blade with residual stress field is determined using the finite element method and vibration theory. The results of the theoretical analysis show that, when the tangential tensile stress with sufficient value is formed on the outer edge of the four types of circular saw blades, their critical rotational speed is increased compared with those without residual stress, and it is also increased with the increase of the tangential tensile stress.

Abstract: For conventional compression ignition (CI) engines, the phenomena of spray fuel injection are important processes. The challenge of spray simulation is to accurately capture complex physical phase changes and interactions between vaporized fuel and ambient air. The present work describes numerical simulation of spray structures in a constant vessel chamber. Large eddy simulation (LES) technique is used to simulate the complex spray structure. The prediction results from the standard Smagorinsky (LES-SML) and the dynamic structure (LES-DS) based LES turbulence model are mainly compared, while the commercial CFD software package ANSYS-Forte is employed for this purpose. The non-reacting spray case is simulated with diesel surrogate such as n-dodecane at ambient temperature of 900 K. The present research starts with an initial grid size of 2 mm, and uses a solution adaptive grid refinement (SAM) to obtain the minimum grid sizes of 0.125 mm. The existing experimental data from the database ECN are employed to validate, and the results from time averaging RANS simulations are included to compare the spray global trends. The results showed that the similar global spray characteristics results from LES-DS and LES-SML were captured. The over-predicted results were observed during the early stage when time after start of injection was less than 0.3 ms. However, the dynamic structure model (LES-DS) was able to capture gradients of vapor penetration well compared to existing experimental data, while the development was higher than those of LES-SML results during the last stage of injection. The liquid penetration length predictions from LES-DS models show good agreement with the experiments at a certain point, whereas the liquid penetration length predictions from LES-SML steadies at different levels. The global trends of mixture fraction, gas-phase temperature and gas phase velocity along the axial distance were also presented. The simulated mixture fraction performed the maximum value near nozzle exit and decreased along the axial locations. For temperature, a cooling in the central zone was observed, while the highest value of predicted gas velocity was near the tip of spray centerline. Moreover, corresponding with temperature and mixture fraction simulated contours, more large spray structures were observed with LES-DS model, and LES-DS model can provide a better local information when compared with those of LES-SML model. In conclusion, the LES-DS model was a better choice for spray simulation when compared with the standard Smarkorinsky model.

Abstract: Bridges are essential infrastructure elements vital for transportation, commerce, and societal connectivity. Ensuring their structural integrity is paramount for public safety and economic stability. However, traditional bridge inspection methods relying on periodic visual assessments may not detect subtle structural issues in real-time, potentially leading to hazardous situations. To address this challenge, we propose a Multipurpose Smart Bridge Health Monitoring System (MSBHMS) utilizing Arduino-based sensors. The MSBHMS integrates various sensors, including accelerometer, load cells, and moisture sensors, strategically placed across the bridge structure to continuously monitor its health. These sensors gather data on factors affecting bridge structural integrity, such as vibrations, strain, and environmental conditions. An Arduino microcontroller serves as the central processing unit, collecting real-time data from distributed sensors. The various data collected transmitted wireless format to a central monitoring station, where it analysis by enhancing machine learning algorithms and data visualization techniques. The MSBHMS's versatility enables early detection of structural anomalies, such as excessive vibrations or abnormal strain patterns, allowing for prompt maintenance actions to prevent potential failures or hazards. Compared to traditional inspection methods, the proposed system offers continuous real-time monitoring, early fault detection, reduced inspection costs, and enhanced safety. Moreover, it facilitates data-driven decision-making for bridge maintenance and management, ultimately improving overall infrastructure resilience and longevity.

Abstract: The quality of water stands particularly in the context of green globalization. Ensuring the safety of drinking water necessitates of water quality monitoring in real-time. The present study introduces a cost-effective solution for water quality monitoring in real-time through the advance developing of a cost less system. The system integrates multiple sensors capable of measuring both physical and chemical parameters of water, including temperature, pH, turbidity, and total dissolved solids. The data collected from these sensors are processed by a core controller, with the Arduino model identified as a suitable candidate. This system offers an affordable and efficient means of continuous water quality monitoring, thereby contributing to the provision of clean and safest drinking water resources in era of green globalization.