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This study was on optimization of the cutting processes for corn stalks, which serve as significant sources of biomass and forage. The reduction of cutting force is crucial for enhancing energy efficiency. Cutting velocity rises, which can lead to significant power usage with minimal shear forces. Therefore, the objective is to minimize both the cutting force and power consumption. To address this multi-objective optimization problem, a modified Taguchi method was employed. Chauvenet's criterion was used to assess the validity of statistical scatter in repeated test data. The test samples had an 81 % moisture content. Through analysis of variance (ANOVA), the optimal chopping process parameters were identified as velocity of 4.4 m/s, approach angle of 30°, and feeding angle of 50°. The refined empirical relationships indicated that the cutting force ranges from 180.55 N to 393.37 N, while the cutting power ranges from 16.81 W to 44.05 W. In a single test, the output responses for the optimal parameter set were 26.32 W for power consumption and 242.60 N for cutting force, both are within the estimated range. The considerable scatter observed in repeated test data is likely due to variations in corn stalk thickness. These findings are valuable for the operation of chopping machines, ensuring minimal cutting force and power consumption when handling corn stalks residues.

This paper aims to develop models for the thermal conductivity and viscosity of hybrid nanofluids of aluminium oxide and titanium dioxide (Al2O3-TiO2). The study investigates the impact of fluid temperature (283 K–298 K) on the performance of a plate heat exchanger using Al2O3-TiO2 hybrid nanofluids with different particle volume ratios (0:5, 1:4, 2:3, 3:2, 4:1, and 5:0) prepared with a 0.1% concentration in deionised water. Experimental evaluations were conducted to assess the heat transfer rate, Nusselt number, heat transfer coefficient, Prandtl number, pressure drop, and performance index. Due to the lower thermal conductivity of TiO2 nanoparticles compared to Al2O3, a rise in the TiO2 ratio decreased the heat transfer coefficient, Nusselt number, and heat transfer rate. Inlet temperature was found to decrease pressure drop and performance index. The Al2O3 (5:0) nanofluid demonstrated the maximum enhancement of around 16.9%, 16.9%, 3.44%, and 3.41% for the heat transfer coefficient, Nusselt number, heat transfer rate, and performance index, respectively. Additionally, the TiO2 (0:5) hybrid nanofluid exhibited enhancements of 0.61% and 2.3% for pressure drop and Prandtl number, respectively. The developed hybrid nanofluids enhanced the performance of the heat exchanger when used as a cold fluid.

This study focuses on investigating the impact of various cutting parameters on surface roughness during the turning process of AZ31 magnesium alloys. The turning operation involved three key cutting parameters: depth of cut (DC), feed rate (FR) and cutting speed (CS). The experimental design followed modified Taguchi's approach and was executed using a CNC lathe. Quantitative assessment of surface roughness values was conducted through measurements obtained from the experiments. Both Taguchi and analysis of variation (ANOVA) were employed to identify the influence and contributions of the process parameters. A modified Taguchi methodology was adopted in this research to establish empirical relationships between performance characteristics (output responses) and process variables. These relationships were thoroughly validated by comparing them with the generated test data. The proposed approach recommends a limited number of tests based on an orthogonal array, offering comprehensive insights into all conceivable combinations of process variables and levels. Additionally, this approach provides an estimated range for output responses, facilitating the assessment of data scatter prior to experimentation. The optimal cutting parameter for achieving the minimum surface roughness was determined as follows: depth of cut at level 2 (2 mm), feed rate at level 1 (0.2 mm/rev) and cutting speed at level 1 (320 m/min). Empirical relations linking performance indicators to cutting process parameters were successfully formulated. The test data is within the range of expected range. [ABSTRACT FROM AUTHOR]

Purpose: This paper adopts a modified Taguchi approach to develop empirical relationships to the performance characteristics (output responses) in terms of process variables and demonstrated their validity through comparison of test data. The method suggests a few tests as per the orthogonal array and provides complete information for all combinations of levels and process variables. This method also provides the estimated range of output responses so that the scatter in the repeated tests can be assessed prior to the tests. Design/methodology/approach: In order to obtain defect-free products meeting the required specifications, researchers have conducted extensive experiments using powder bed fusion (PBF) process measuring the performance indicators (namely, relative density, surface roughness and hardness) to specify a set of printing parameters (namely, laser power, scanning speed and hatch spacing). A simple and reliable multi-objective optimization method is considered in this paper for specifying a set of optimal process parameters with SS316 L powder. It was reported that test samples printed even with optimal set of input variables revealed irregular shaped, microscopic porosities and improper melt pool formation. Findings: Finally, based on detailed analysis, it is concluded that it is impossible to express the performance indicators, explicitly in terms of equivalent energy density (E_0ˆ*), which is a combination of multiple sets of selective laser melting (SLM) process parameters, with different performance indicators. Empirical relations for the performance indicators are developed in terms of SLM process parameters. Test data are within/close to the expected range. Practical implications: Based on extensive analysis of the SS316 L data using modified Taguchi approach, the optimized process parameters are laser power = 298 W, scanning speed = 900 mm/s and hatch distance = 0.075 mm, for which the results of surface roughness = 2.77 Ra, relative density = 99.24%, hardness = 334 Hv and equivalent energy density is 4.062. The estimated data for the same are surface roughness is 3.733 Ra, relative density is 99.926%, hardness is 213.64 Hv and equivalent energy density is 3.677. Originality/value: Even though equivalent energy density represents the energy input to the process, the findings of this paper conclude that energy density should no longer be considered as a dependent process parameter, as it provides multiple results for the specified energy density. This aspect has been successfully demonstrated in this paper using test data. [ABSTRACT FROM AUTHOR]

The motive of this study is to evaluate the machinability properties of AZ31Mg alloy in the face milling operations. Depth of cut, rate of feed and speed of cut are three input variables in the face milling process, while surface roughness (Ra) and tool nose radius deviation (dR) are performance characteristics. For three input variables each with three levels, to decrease the number of experiments, an L9 orthogonal array (OA) of Taguchi was employed which enables an efficient approach for conducting a full-factorial design of experiments. Selection of optimal parameters for the face milling process to achieve the required surface quality is accomplished through the utilization of a modified Taguchi approach and a novel multi objective optimization procedure. The work establishes empirical relationships that correlate the performance characteristics (i.e. Ra and dR) with three input variables. Corrections to the empirical relations were specified to obtain the expected range of Ra and dR. Ra and dR estimates were validated with existing test data. [ABSTRACT FROM AUTHOR]

Day by day laser welding (LW) is gaining industrial importance. Good quality of weld joints can be realized through this process. Because this process yields low distortion and small weld bead. Aerospace, nuclear, automotive, and biomedical industries are opting for the lightweight and corrosion resistance titanium alloys. This paper deals with the generation of optimal weld bead profiles in the conduction mode laser beam welding (LBW) of thin Ti-6Al-4V alloy sheets. Laser beam diameter, power and welding speed are the 3 LBW parameters, whereas, bead width, depth of penetration, heat affected zone and maximum temperature are the performance indicators (PIs). 3 levels are set for each LBW parameter. Taguchi's L9 OA (orthogonal array) is selected to minimize the numerical simulations. ANSYS Fluent V16.0 with Vc++ code is used to develop a generic model. %Contribution of each process variable on the PIs is assessed performing ANOVA analysis. The range of PIs is assessed adopting the modified Taguchi approach. A set of optimal LBW parameters are identified considering a multi-objective optimization technique. For these optimal LBW parameters weld bead width is minimum, and the depth of penetration is maximum. Empirical relations for PIs are developed and validated with simulations. Utilizing the Taguchi's design of experiments, empirical relations are developed for the performance indicators in laser beam welding (LBW) simulations performing few trial runs and identified the optimal LBW process parameters. [ABSTRACT FROM AUTHOR]

The lightweight titanium alloys possess good resistance to corrosion and temperature. They are used in turbine engines and aircraft structures. The strength of weld joint is dependent on thermal history in the weld zone and the weld bead geometry. The quality of weld can be improved by specifying the optimal welding parameters. Trial-and-error experimental methods are time-consuming and expensive. This paper deals with Computational Fluid Dynamics (CFD) models to carry out three-dimensional thermo-fluid analysis. Buoyancy and Marnangoni stress are incorporated. Temperature dependent properties of Ti-6Al-4V alloy and the process conditions are specified for generating the weld bead profile. The CFD model is validated initially through comparison of existing test data. Further studies are made by conducting tests on the pulsating laser welding of Ti-6Al-4V alloy. The effects of welding speed, pulse width and pulse frequency on the weld bead geometry are examined. This study confirms the adequacy of modeling and simulations of weld bead geometry with test results. [ABSTRACT FROM AUTHOR]

Dynamic stability of elastic structures is a fascinating topic. Many researchers have examined the problem theoretically considering a cantilever column under a tip-concentrated tangential load, the so-called Beck column. Experimental verification is demanded since the critical load of Beck column is found to be approximately eight times to that of the classical Euler column. Different types of testing procedures are being adopted to create the follower force. Among them, notable Willems experimentation provides the critical load close to that of Beck column. Investigations made by other researchers indicate the controversy associated with modeling and testing of Willems on Beck column. Such an intriguing problem of structures loaded by non-conservative forces is revisited here through a simple mathematical formulation. This paper confirms the adequacy of Willems approach on Beck column and the wrong critical load assessment of others. It indicates the possibility on the practical realization of follower forces [ABSTRACT FROM AUTHOR]