Journals of Universiti Tun Hussein Onn Malaysia (UTHM)
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Progressive Methods of Finishing the Dovetail Grooves of Aircraft Engine Compressor Disc
Get PDFThe paper analyses the causes of compressor disc failures in aircraft engines. The high-pressure compressor discs were made of a nickel-based heat-resistant alloy, HN73MBTYu-VD. The complexity of the rim profile and the high level of loads create conditions for the development of fatigue cracks. Fractographic analysis of fractures has shown that the most dangerous cracks occur in the sharp corners at the base of the intergroove protrusions, which can lead to the tearing off of disc parts. The purpose of this study was to evaluate the effect of the optimal combination of finishing the groove forming surfaces on the safety factor of the rim elements of high-pressure compressor discs. Residual stresses were investigated by the layer-by-layer removal of thin metal layers using electrochemical polishing of the groove bottoms. To determine the stresses arising in the acute angle zone of the groove, the finite element method was used. The endurance limit of the specimens was determined after 2×10⁷ loading cycles. It has been established that the optimal combination for the finishing stage of disc manufacturing includes sequential treatment with polymer-abrasive brushes, hardening with steel balls in an ultrasonic field, and pneumatic blasting with glass microbeads. Finish-hardening treatment improved resistance to fatigue crack nucleation by creating a certain depth of plastic deformation in the surface layer, inducing significant compressive residual stresses, improving surface roughness, and increasing microhardness. After this treatment, the safety factor of high-pressure compressor discs increases by 1.8 to 3 times. The paper presents a model for the safety factor of compressor discs with dovetail grooves, which takes into account technological residual stresses and operating conditions
Flowability Properties of PLA/PA12 Composite with Varying Wollastonite Concentrations for 3D Printing Applications
Get PDFThis study evaluates the rheological properties and flow behaviour of PLA/PA12 composites with varying concentrations of wollastonite (WA) ceramic particles (5, 10, and 15 wt.%) to enhance their biological performance and printability in 3D printing applications. Achieving the right balance of viscosity and flow is crucial for producing high-quality filaments and reliable 3D printed structures. Comprehensive rheological analysis and material characterization were conducted, including particle size distribution, SEM, and EDX. The flow behaviour index (n) was calculated, and physical observations of extruded materials were assessed for surface quality and dimensional consistency. The 10 wt.% WA composite consistently demonstrated superior rheological properties, exhibiting optimal pseudoplastic behavior with an n value range of 0.073–0.439 and a viscosity of 5919 Pa·s at 140 °C, which was the lowest among the composites tested, ensuring smooth extrusion and structural integrity. SEM analysis showed a uniform microstructure with well-dispersed WA particles in the 10 wt.% WA composite, while the 5 wt.% WA and 15 wt.% WA composites displayed suboptimal particle distribution. Physical observations confirmed that the 10 wt.% WA composite produced a smooth, consistent extrudate, essential for high-quality filament fabrication and reliable 3D printing. These findings highlight the 10 wt.% WA composite as the most promising candidate for efficient and effective 3D printing
Effect of Scour and Seismicity on the Bridge’s Response
Get PDFBridges are critical points in rail and road networks, and their failure due to natural hazards like tsunamis, earthquakes, ground movements, or floods can cause significant losses. Identifying weaknesses and measuring bridge strength is crucial for disaster resilience. Current methods rely heavily on engineering judgment, lacking dependable quantitative evaluations. This framework offers a comprehensive approach to creating numerical simulations and assessing bridge resilience against multiple hazards. The project involves simulating a 130-metre pre-stressed concrete bridge exposed to seismic and scour depth hazards using the CSI Bridge software. The simulations consider three scour depth levels (1Df, 1.5Df, and 2Df), five earthquakes, and varying seismic intensities (0.25 to 1.5 Peak Ground Acceleration, PGA, with 0.125 increments). The foundation depth (Df) is 2.5 metres, and simulations are run under clay soil. Nonlinear Time History Analysis (NTHA) is employed for its suitability for inelastic beam-column elements under dynamic loading. Results indicate that increasing the scour depth from 1.5Df to 2Df increased pier displacement by 21.68% in clay
An Experimental Evaluation of The Effects of Relative Draft and Centre of Gravity Position on The Performance Wave Energy Converter
Get PDFPrior studies highlight that the Backward Bent Duct Buoy (BBDB) is one of the simplest and most robust wave energy converters (WECs). However, the impact of relative draft and the location of the center of gravity (COG) on the hydrodynamic performance of the BBDB remains inconsistent and underexplored in the field. Thus, this study investigates the optimal relative draft and center of gravity (COG) location for maximizing the hydrodynamic performance of the Backward Bent Duct Buoy (BBDB), a simple and robust wave energy converter. The research explores the influence of different drafts and COG locations across wave heights (0.03 m, 0.04 m, 0.05 m) and periods (1s to 2s) using the OMEY\u27s flume wave tank. A Froude scale of 1:13 was applied to the BBDB model. Verification and validation with previous studies yielded a percentage difference of 0.22%. Results show that a draft of T=0.3m (T/D=0.53) with an upright COG achieves the highest conversion efficiency of 56.7% at a wave height of 0.05 m, outperforming other configurations. Lower efficiency of 16.1% was noted for the Port COG at H=0.03m. The T=0.3m draft with the exact COG maximizes heave and pitch oscillations, enhancing internal air pressure variations and overall energy conversion. Appropriate COG positioning and draft are key to achieving resonance, reducing drag, and improving performance. This study emphasizes the significance of draft and COG location in optimizing BBDB design and operation, particularly in low wave height conditions
The Water Quality Issue: A Study of Tasik Kemajuan’s Water Quality Status
Get PDFLakes are crucial for irrigation, drinkable water, transportation, and power generation. Tasik Kemajuan, located on UTHM\u27s main campus, is used for kayaking and flood mitigation. However, pollution in the lake, through various contaminants, poses risks to human health and the aquatic environment. This study aims to monitor water quality and determine the Water Quality Index (WQI) of Tasik Kemajuan. Six water parameters were evaluated to calculate the WQI: BOD5, COD, TSS, pH, AN, and DO. These parameters contributed to determining the water quality subindex and, ultimately, the WQI based on the formula used in Malaysia. An average water quality status was determined for each parameter: AN at 0.56 mg/L (Class III), BOD5 at 9.75 mg/L (Class IV), COD at 21.93 mg/L (Class IIB), DO at 4.02 mg/L (Class III), pH at 6.45 (Class II), and TSS at 20.33 mg/L (Class I), with the water temperature recorded at 28.50°C (Class IIB). The findings reveal that the WQI for Tasik Kemajuan is on the upper edge of being polluted, with a score of 74, placing it in the Class III category. According to the NWQS, Tasik Kemajuan fails to meet the standards for recreational activities involving direct contact with water and shows that significant purification efforts are necessary to make the water suitable for such purposes
Enhancement of Cement Sand Brick Incorporating Spent Catalyst and Copper Slag as Sustainable Partial Sand Replacements
Get PDFThe use of waste materials in the manufacturing of cement sand brick constitutes a big step forward in sustainable building approaches. The partial sand replacement with waste materials, especially residual materials that can be reused in the field of construction such as spent catalyst and copper slag, has the potential to minimize environmental pollution and lead to more sustainable buildings. This study used spent catalyst and copper slag as a partial sand replacement material ranging 10% to 90% and examines the effect on the properties of cement sand bricks. Apart from that, the study used the Design Expert software approach to systematically analyzed the effect of various materials on the compressive strength and hardened density of cement sand brick. It was used to optimize the mix proportions and analyzed the correlations between four factors variables: targeted density, cement to sand ratio, proportion of sand and spent catalyst to copper slag ratio and the two responses: compressive strength and hardened density. The results show that spent catalyst and copper slag has greatly increases the compressive strength of the brick up to 26.98 MPa while hardened density reached the highest 2009.09kg/ . Hence, the replacement of 10% spent catalyst has greatly enhance the compressive strength of cement sand brick while 90% replacement of copper slag has increased the hardened density
Insect Pollinator Diversity and Significance of Pollen Resources in Urban Landscape
Get PDFInsects are the most common pollinators of flowering plants. Urban landscape often lacks of flora diversity, potentially limiting the pollinators\u27 population; thus, flowering plants would face a great decline, and this may reduce the habitat diversity of nature. Therefore, this study was conducted to determine insect pollinators in selected parks in the urban area of Penang Island and its floral source. Insect trapping using light traps and sweep nets was carried out and a total of 65 families from 10 orders were collected from three parks: Youth Park, Botanic Garden and Moon Gate in Penang. Out of that, 13 families were determined as pollinators. Insects from the order Lepidoptera, Coleoptera, Hymenoptera and Hemiptera were the principal representative orders in all study areas. Diurnal insects reported three pollen types; predominant (eight pollen species), secondary (nine pollen species) and important minor (one pollen species) while nocturnal insects recorded the Apidae family with four pollen types; predominant (13 pollen species) secondary (five pollen species), important minor (six pollen species) and minor (two pollen species). The presence of insect pollinators in urban areas suggests that such environments can play a significant role in supporting insect biodiversity that will survive in the urban landscape with nature-based
Adsorption Efficiency of UV-Irradiated Polyvinyl Alcohol-Alginate Adsorbent Beads for Chromium (VI) Removal
Get PDFDue to the risk of chromium (Cr) contamination, industrial waste emissions have become a global concern, necessitating an effective adsorption approach. Polyvinyl alcohol (PVA) alginate beads are a promising material for overcoming this problem. The present work aims to investigate the effect of ultraviolet (UV) light irradiation on the preparation of PVA-alginate beads throughout a range of UV irradiation durations, as well as its Cr (VI) removal rate. In this work, a homogeneous gel made of PVA and sodium alginate (SA) was produced and then radiated to UVA light for varying periods of time (5-20 minutes). Subsequently, the PVA-alginate adsorbent beads were made by crosslinking with 6% boric acid and 2% calcium chloride. PVA-alginate adsorbent beads were fabricated easily after UVA irradiation because the viscosity of gel PVA-alginate was reduced. The Cr (VI) adsorption experiment employed 15 g of PVA-alginate adsorbent beads, 180 minutes of adsorption time, and 50 mg/L Cr (VI) initial concentration. The size analysis revealed that the average diameter of the adsorbent beads after Cr (VI) adsorption was approximately 4.00 mm. The UV-Vis results showed that sample A prepared by exposing the PVA-alginate adsorbent beads to UV light for 5 minutes has an optimum Cr (VI) removal rate of 71.63% after in contact for 180 minutes. This study\u27s findings were critical for establishing a new knowledge of the production of PVA-alginate beads irradiated with UV light and moving forward to mitigate heavy metal pollution in waste water, therefore enhancing the quality of water and the environment
Analysis of Indentation Test Using SolidWorks Simulation
Get PDFThe finite element analysis of spherical indentation was conducted using the SolidWorks simulation software. The relationship between the load and indention was determined, and comparison with the Hertzian solution was made. In this study spherical indenters of diameter 5, 10 and 15 mm were used to assess the effect of indenter radius on indentation response at a specified load. The outcome of our study shows that the resulting load-indentation response does not closely correlate; as a result, a difference of 21.2% was observed between the hertz solution and simulated results. The increase in diameter was observed to be associated with the corresponding decrease in indentation depth and the indentation stress. The von Mises stress contour at maximum load was analysed and was observed to be highest on the indented surface beneath the indenter. The resultant displacement contour shows a uniform displacement distributio
Comparison of Landslide Disaster Risk Assessment Standards: A Study of Indonesia’s Ministry of Public Works Regulations and Malaysia’s Slope Assessment System
Get PDFSemarang City is an area prone to landslides, especially areas with hilly morphology. The landslide incident certainly brought losses in both lives and material. Seeing that there are landslides in several areas of Semarang City, an assessment is needed so that landslide disasters can be anticipated. This research is located on the slope of Building E10, Faculty of Engineering, Semarang State University. This research aims to determine the level of risk of vulnerability to landslides using the Regulation of the Minister of Public Works of the Republic of Indonesia Number 22 of 2007 and the Slope Assessment Systems Method. The results of the two methods were compared with the finite element method using the Plaxis 8.6 program. The vulnerability level value based on Minister of Public Works Republic of Indonesia Regulation Number 22 of 2007 on slope 1 is 2.44, which is included in the category of a high level of landslide vulnerability, while the value for slope 2 is 2.156, which is included in the moderate level of landslide vulnerability. The assessment results using the Slope Assessment System (Slope Management and Risk Tracking System) method for Slope 1 were 0.957, which was included in the very high level of vulnerability category, while for Slope 2, it was 0.8926, which was included in the very high level of landslide vulnerability category. The results of the finite element method with the Plaxis 8.6 program show that the value of the safety factor on the slope of Building E10, Faculty of Engineering, Semarang State University, is 0.604 and is included in unstable soil conditions