Advanced Engineering Forum Vol. 39

Abstract: In this study both natural ageing (NA) and artificial ageing (AA) behaviour of Al-Mg-Si aluminium alloy having trace addition of 0.04 wt.% Sn (Tin) was studied at different solution heat treatment (SHT) temperature and time, ageing time and temperatures. Microstructural analysis was performed to identify the intermetallic phases. It was observed that peak NA hardness strongly depends on the SHT temperature and time. SHT at 530 for 0.5 hour, slows down the peak NA hardness attaining time of the alloy to a maximum of 5 days. But as the SHT time increases to 3.5 hours, the peak NA hardness attaining time reduced to 1 day. Alloy SHT at 530 for 1 hour attain a maximum peak hardness of HRB 24 during 3 days of NA. Artificial ageing improved the hardness of the NA alloy to a maximum of HRB 41 during 12 hours of ageing at 190 . The overall hardness of Al-Mg-Si-Sn as-cast alloy increases by 32 % during ageing process.

Abstract: Ultrasonic inspection is a well-known method in non-destructive testing. Based on the changes in the ultrasonic sound speed, tested materials are evaluated in terms of internal defects. In addition to flaw detection, ultrasonic testing is used in the material characterization of ductile cast iron. Graphite shape detection has been widely investigated by ultrasonic inspection in literature. However, most of the measurements has been conducted at single frequencies. In this work, three different nodulizer included casting operations were carried out to produce ductile cast irons having various graphite morphologies. A wide frequency range of 1.25-10 MHz was selected in the ultrasonic inspection. In addition to graphite morphology analyses, the relationship between ultrasonic sound speed and mechanical properties was studied. In the mechanical analyses, hardness and tensile testing properties were investigated for the specimens. From the results, ultrasonic sound speed exhibits a considerable dependency to the graphite morphology. In addition to a good graphite detection capability, ultrasonic inspection exhibits promising results for predicting the mechanical properties such as hardness, elastic modulus, yield strength and tensile strength. It is also found that there is a slight increase in the ultrasonic sound speed by increasing the frequency, although sound speed is independent from this parameter.

Abstract: Additive Manufacturing (AM) has shown great potential for efficient realization of complicated microdevices fabricated with higher freedom of design and made from a wide variety of materials suiting to their specific target functionalities. Capability of generation of components with reduced weights, higher part consolidation, greater customization offered along with minimal waste generation are its advantages over conventional manufacturing processes. The AM built parts, however, need to undergo relevant post processing techniques to render them fit for their end product application. The paper attempts to classify the post processing techniques and emphasize their applicability to specific AM methods, generalized procedure as well as the recent improvements undergone. The post processing techniques have been categorised as methods for support material removal, surface texture improvements, thermal and non-thermal post processing and aesthetic improvements. The main challenges to the expansion of additive manufacturing have been discussed which highlight the future, scope of improvement and research required in the area of appropriate tool path development and product quality with regards to surface roughness, resolution and porosity levels in the built part.

Abstract: The influence of oxygen flow rate is examined on structural, optical and tribological properties of molybdenum oxide films deposited by reactive magnetron sputtering. The films were characterized by X-ray diffraction, scanning electron microscope (SEM), and contact angle measurement system. The optical properties of the films were measured by UV-Vis-NIR spectrophotometer and transmittance of ∼73% in the visible region of the spectrum was achieved. The band gap increases with increases in oxygen gas flow rate. AFM figure illustrates that the roughness of surface increases as oxygen flow rate increases. As oxygen increases wear rate and COF decreases while at the 18 sccm the lowest wear rate found.

Abstract: A stability loss of varistor is subjected to any of variety extreme conditions such different stresses AC or DC, temperature, pulse, pressure, humidity, etc. This causes degradation phenomenon and leads to thermal runaway or failure of varistor. The investigation of degradation phenomena is an important subject for prolonging their lives. In this study, we investigate the degradation process of ZnO_1-x-CoO_2.0-SLS_x varistor ceramics where x= 0.5, 1.0, 1.5, and 2.0 mol % by using conventional solid state method at sintering temperature of 1100 °C for 2 hour. The stability of their nonlinear properties was investigated under prolonged application of DC electric field at different SLS glass concentration. The degradation process was speeded up by applying direct current (DC) 85 % of electric field for 12 hours at temperature of 85 °C. A concentration of 2 mol % SLS glass doped ZnO varistor shows the best degradation properties as its nonlinear coefficient has increased by 3.56 %, the breakdown field has increased by 3.85 %, and the leakage current density (J_L ) increased by 2.40 % in comparison to its initial value.

Abstract: Among all the solar cell system dye sensitized solar cell is the third-generation solar cell that contains working electrode coating with semiconducting material, dye sensitizer, counter electrode and the efficiency of dye sensitized solar cell is reliant on the material which is absorbing light and converting it as energy. In this respect, dye sensitizer is the most substantial component in dye sensitized solar cell. Though organic and natural dye has been used in solar cell but due to the deleterious effect of organic dye, its application has been suppressed by the natural dye which is environment friendly and accessible. Ample of natural dyes has been applied in solar cell as sensitizer, while their way of application is different especially in case of dye extraction process. In this theoretical analysis, various research work related to dye sensitized solar has been included and explained the working principle of dye sensitized solar cell (DSSC), also summarized the extraction process of natural dye from different along with their photovoltaic parameters of various natural dye sensitized solar cell. Moreover, this study also compares the performance of natural dye sensitized solar cell according to presence of chromophore group in natural pigment.

Abstract: Sugarcane bagasse pyrolysis in a fixed-bed reactor has been studied. The Pyrolytic oil and char obtained were characterized to determine their feasibility as fuels and chemical reagent in other processes. The runs were performed under the following conditions: temperature from 350°C–600°C, sample size of 0.5–1 mm, and an inert gas flow rate of 200 cm³/min. The study aimed to characterize the obtained oil and char to determine their feasibility as source of energy and chemical product. The product has been characterized by different techniques including gas chromatography–mass spectrometry (GC–MS), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). The obtained bio-oil exhibited a molecular formula of CH_1.03O_0.28 N_0.012 and a higher heating value (HHV) of 27.68 MJ/kg. These results indicated that it could be used after refining as a source of fuel and produced a chemical product. In addition, the obtained biochar (HHV = 31.53 MJ/kg) can be used as a solid fuel.

Abstract: This investigation was carried out to identify the engineering properties of compressed interlock earth blocks manufactured from locally available lateritic soil and introduce to use the manufactured soil blocks to minimize the material and finishing cost for the low cost housing projects. The soil samples used in this study were well-graded lateritic sandy soil which has the composition of 1.9% gravel, 94% sand and 4.1% silt / clay. These soil samples were passed through the 100-mesh sieve and mixed with ordinary Portland cement to prepare the admixture. While compressing through a hydraulics jack by varying the compositions and the volume of soil-cement admixtures, compaction soil blocks were manufactured in a locally fabricated 250 mm x125 mm x100 mm standard steel mould. The manufactured soil blocks allowed to cure while spraying small quantity of water and covering with polythene for 28 days. Average compressive strengths of soil blocks made with 5% cement with 1.6:1 and 1.8:1 volume compactions were 1.3 Mpa and 1.9 Mpa, respectively. However, both compressive strength values were less than the standard limits of 2.8 MPa stated in SLS 1382:2009, local standards for soil blocks used for construction industry. However, soil blocks made with 10% cement under same compaction ratios attained compressive strengths of 3.0 MPa and 3.6 MPa respectively and it is above the required standards limits. However, 15% and 20% cement containing earth blocks have much higher compressive strengths but increase the cost of production. Regression analysis results confirmed the strong correlation between cement content and the compressive strength of the soil bricks. The soil bricks manufactured with more than 12.06% cement soil mix by maintaining compaction ratio into 1.6:1 or Soil bricks manufactured with more than 5.16% cement mix by maintaining compaction ratio into 1.8:1 will produce standards soil bricks for construction industry and these results further confirmed that wet and dry compressive strength of soil bricks will increase with increasing the compaction ratio and the cement content. However, when considering the compressive strength, water absorption level and cost effectiveness, soil bricks manufactured by maintaining compaction ratio into 1.8:1 with more than 5.16% cement mix will produce required standards cost effective soil bricks for construction industry.

Abstract: The current study presents vulnerability and a reliability-mechanical approach which focuses on evaluating the seismic performance of reinforced concrete structures to determine the probability of failure. In this case, the performance function reflecting the non-linear behavior of the structure is modeled by a response surface to establish an analytical relationship between the random variables (strength of concrete and yield strength of steel) and mechanical responses of the structure (inter-floor displacement) obtained by the pushover results of finite element simulations. The push over analysis is executed by software SAP2000. The results acquired prove that properly designed frames will perform well under seismic loads. It is a comparative study of the behavior of the existing structure before and after reinforcement using the pushover method. The coupling indirect mechanical reliability by response surface avoids prohibitive calculation times. Finally, results of the proposed approach are compared with Monte Carlo Simulation. The comparative study shows that the structure is more reliable after the introduction of new shear walls.

Abstract: This research was focused on evaluating the influence of the different variables that affectsplitting in prestressed concrete members, particularly prestressed concrete ties. These include the thickness of concrete cover, release strength of concrete, and the type of wire indentation. Different combinations of these variables can affect splitting. This research was focused on finding the best possible material characteristics to avoid potential failures in the field. The objective of this research was to set the minimum value of the thickness of concrete cover, for different wire types used in manufacturing having given types of aggregate for concrete mixture. The importance of this research was to identify the best materials and the best system (concrete, wire, cover) designs before the production of prestressed concrete ties. Splitting test results presented in this research were focusedon three different thicknesses of concrete cover, three different concrete mixes, a 4500psi concrete release strength, and seven different indented wire types.