Nov'2022
Focus
The ultimate goal of any manufacturer is to produce high quality products at affordable cost and in less time. Materials like Acrylonitrile Butadiene Styrene (ABS) polymers, that can easily be injected, molded and processed, have gained utmost importance, owing to the huge demand and dependency of the industry on lightweight and superior mechanical products as well as components. ABS is a common thermoplastic polymer typically used for injection molding applications, and is popular due to its low production cost and the ease with which the material can be machined by manufacturers. The mechanical properties of ABS can further be enhanced with the addition of filler materials such as carbon fibers, silica dioxide and polycarbonates for better strength properties. That said, failure diagnosis invariably involves both creep and fatigue phenomena involving a spectrum of loading conditions-ranging from pure steady to cyclic conditions-that play an important role in assessing the mechanical behavior of ABS polymers. Between these two, creep is the tendency of materials to deform when subjected to long-term stress, whereas fatigue life of a material is determined by the number of cyclic loading till its failure. Fatigue load is the most major type of load acting on the structural components. A majority of the structural components (about 80% to 90%) fail due to fatigue. Hence, determining the fatigue life of a component is an important aspect of engineering applications. In the next paper, "Fatigue Life of Rapid Processed Polymer Specimen: An Experimental Investigation", Venkatesh K Havanur has carried out tests on a dog-bone shaped ABS polymer specimen. A rotating bending fatigue test machine was used in the experimental investigations, while ANSYS Software was used in the simulation results. The bending moment applied in either case varied from 40 kgf-cm to 70 kgf-cm. The corresponding bending stress and the number of cycles to failure are determined and compared. The experimental results are in close agreement with the simulation results. The results show that as the bending stress increases, the fatigue life-number of cycles to failure-decreases. The results are in agreement with the general notion that an increase in the bending stress decreases the fatigue life.
Energy demand is on the rise globally, and is expected to increase by more than 40% in the coming decades, due to the ever increasing demand and industrial activity. Rapid depletion of the fossil fuel has prompted the development and use of ecofriendly and sustainable energy sources. Renewable energy sources, in particular sustainable biofuels, find direct application as an alternative resource. The last paper, "A Review of Biogas Production and Its Applications" by Vishal Dabra, presents a brief review of the potential usage of biogas an energy source. The review describes several renewable energy resources that are available and explains various aspects regarding the use of biogas. It also describes the effect of feedstock on producing biogas for different applications and throws light on the proper utilization of feedstock, how to enhance the performance of biogas using different upgrading/purification processes, and the barriers to the development of biogas among nations. The review could help promote further research on biogas as the best alternative fuel for the future.
Entransy Dissipation Analysis of the Data of Halkarni et al. on the Effect of Random Packing Inside Heat Exchangers
Entransy dissipation analysis has been applied to the published results of Halkarni et al. (2018) by considering the flow rates and temperatures of hot and cold fluids to determine whether it leads to improved performance of the heat exchanger. Rates of entransy dissipation, entransy dissipation-based thermal resistances and entransy dissipation numbers have been determined at unchanged conditions. Based on the analysis, the significance of entransy concept has been discussed, which can be implemented for thermal performance investigation of various heat exchangers. The entransy dissipation analysis suggests that utmost effectiveness (0.38) for heat exchanger is at the lowest rate of entransy dissipation (73.5 kJ-K/s) with least thermal resistance (9.585 K-s/kJ) and with smallest dissipation number (0.67). It is well known that for a heat exchanger, the effectiveness should be highest (0.38) but rate of entransy dissipation (73.5 kW-K) should be as low as achievable like exergy destruction rate (0.23 kW) with the conditions of low flow rates of fluids and smaller ball diameter. Same results have been received with different parameters in the previously published paper as the glass ball of 4 mm diameter showed excellent performance. Hence, a comparative analyses shows that the entransy concept can safely be recommended to evaluate the thermal performance of various heat exchangers.
Fatigue Life of Rapid Processed Polymer Specimen: An Experimental Investigation
In materials science, fatigue load is the most major type of load acting on structural components. About 90% of the components fail due to fatigue. Hence, determining the fatigue life of a material is an important aspect in engineering applications. The fatigue life is estimated as number of cycles to failure. In this paper, fatigue life of rapid processed ABS polymer material is determined using rotating bending fatigue test machine. The specimen is prepared in 3D printing machine. This ABS material specimen is shaped like a dog bone, and specimens are tested on the machine. Experimental and simulation tests are carried out, and the results obtained are within acceptable limits. The bending moment applied on the specimen varied from 40 kgf-cm to 70 kgf-cm. The experimental results are compared with the simulation results. The maximum stress or bending stress obtained by manual calculation for 70 kgf-cm bending moment is 136.58 MPa, and by simulation, it is 122.43 MPa with an error of 10.36%. The number of cycles to failure for 70 kgf-cm bending moment obtained by experiment is 9,801 cycles, and by simulation, it is 10,031 cycles with an error of 2.3%. The range of values obtained by experiment and simulation is plotted as stress (S) v/s number of cycles to failure (N) graph.
A Review of Biogas Production and Its Applications
The paper reviews the potential of biogas as an alternative energy source and discusses its entire production aspects. It explains the composition of feedstock, different upgrading/purification processes, and the effect of the parameters of anaerobic digestion on the performance of biogas. The paper further highlights the barriers to the large-scale adoption of biogas as a source of energy and offers solutions to overcome them.
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