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1

Effect of novel grain refiner and Ni alloying additions on microstructure and mechanical properties of Al-Si9.8-Cu3.4 HPDC castings – optimization using Multi Criteria Decision making approach

Apparao K. Ch., Bannaravuri Praveen Kumar, Pulisheru Kumar Swamy, Francis E. D., Sunny Kalakanda Alfred, Babu Rao Gadudasu, Daniel P. Freedon, Kumar Birru Anil

Materials Science Poland

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2022

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Vol. 40, No. 1

9--24

EN

Studies dealing with process improvement of aluminum alloys and their grain structure refinement are the current area of interest in casting companies and foundries, the aim being to enhance the properties of the base metal. In this study, the microstructural and mechanical properties of commercial Al-Si9.8-Cu3.4 alloy die castings influenced by different additions of Al-3.5FeNb-1.5C master alloy (viz. 0 wt.%, 0.1 wt.%, and 1.0 wt.%) as a new grain refiner and Al-6Ni master alloy (viz. 0 wt.%, 0.5 wt.%, and 5.0 wt.%) as an alloying element have been investigated. A multi-criteria decision-making approach for the improvement of the die casting process was performed using grey relational analysis (GRA) and TOPSIS analytical techniques. It was observed that the primary aluminum α-grains were significantly refined, particularly at the lower addition level 0.1 wt.% of Al-3.5FeNb-1.5C, and conversely, poor grain refining efficiency was observed at a higher addition level 1.0 wt.% of Al-3.5FeNb-1.5C. Due to the refinement by Al-3.5FeNb-1.5C grain refiner and the effect of Ni alloying element additions, the ultimate tensile strength (UTS) and hardness (Brinell and micro) of the Al-Si9.8-Cu3.4alloy are improved, particularly at 0.1 wt.% of Al-3.5FeNb-1.5C and 0.5 wt.% of Al-6Ni master alloys. Quantitatively, UTS, Brinell hardness, and microhardness values have been increased by 12.3%, 7.0%, and 20%, respectively.

2

The technique to precisely design the product in a house of quality considering current customers' requirements

Siwiec Dominika, Pacana Andrzej

Quality Production Improvement - QPI

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2021

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Vol. 3, Iss. 1

9--16

EN

The competitive and turbulent environment generates the need to use various techniques to determine the level of product quality. In this aim, it is necessary to determine the direction of improvement attributes and function of the product based on customer requirements, which are usually uncertain. Therefore, the aim of the article is to propose the technique to improve the product quality by precisely determine the customers' requirements and the importance of the quality parameters for the current attributes of the product. This technique is a combination of methods i.e.: the QFD method (Quality Function Deployment) with the GRA method (Grey Relational Analysis). Using the QFD method, customer requirements were translated into technical features of the product. In turn, using the GRA method the imprecise customers' requirements were reduced and the importance of quality parameters was determined in a more accurate way. A test of a combination of the QFD and GRA methods for the household vacuum cleaner was made. The originality of the article is ensuring a precise study of the current attributes of the product from the point of customer satisfaction.

3

Comparison of Electrochemical Micromachining Performance using TOPSIS, VIKOR and GRA for Magnetic field and UV rays heated Electrolyte

Saravanan K. G., Thanigaivelan R., Soundarrajan M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e138816

EN

The application of micro components in various fields such as biomedical, medical, automobile, electronics, automobile and aviation significantly improved. To manufacture the micro components, different techniques exist in the non-traditional machining process. In those techniques, electrochemical micromachining (ECMM) exhibits a unique machining nature, such as no tool wear, non-contact machining process, residual stress, and heat-affected zone. Hence, in this study, micro holes were fabricated on the copper work material. The sodium nitrate (NaNO₃) electrolyte is considered for the experiments. During the experiments, magnetic fields strength along with UV rays are applied to the electrolyte. The L₁₈ orthogonal array (OA) experimental design is planned with electrolyte concentration (EC), machining voltage (MV), duty cycle (DC) and electrolyte temperature (ET). The optimization techniques such as similarity to ideal solution (TOPSIS), VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) and grey relational analysis (GRA) were employed to find the optimal parameter combinations. The entropy weight method is used to assess the weight of responses such as MR and OC. The optimal combination using TOPSIS, VIKOR and GRA methods shows the same results for the experimental runs 8, 9 and 7, and the best optimal parameter combination is 28 g/l EC, 11 V MV, 85 % DC and 37°C ET. Based on the analysis of variance (ANOVA) results, electrolyte concentration plays a significant role by contributing 86 % to machining performance. The second and least contributions are DC (3.86 %) and ET (1.74 %) respectively on the performance. Furthermore, scanning electron microscope (SEM) images analyses are carried out to understand the effect of magnetic field and heated electrolyte on the work material.

4

Optimization of Output Responses during EDM of AZ91 Magnesium Alloy using Grey Relational Analysis and TOPSIS

Tajdeen A., Megalingam A.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 4

1105--1113

EN

Unconventional machining of magnesium alloys through die sinking and Wire Electrical Discharge Machining (WEDM) processes are preferred over conventional machining processes to overcome the rapid loss in strength and affinity that occurs with tool materials at high temperatures. in the present study, AZ91 magnesium alloy is machined in EDM using a prepared alloy tool (copper alloyed with titanium diboride). Based on Taguchi’s L27 orthogonal array, a total of 27 experiments have been conducted by varying the process parameters such as pulse on time (Ton), gap voltage (Vg) and current (Ip) with three different levels. Techniques for Order Preference by Similarity to Ideal Solution (TOPSIS) and Grey Relational Analysis (GRA) have been applied to optimize the response parameters of EDM to obtain maximum Material Removal Rate (MRR) and minimum Tool Wear Rate (TWR) and Surface Roughness (SR). Analysis of variance (ANOVA) is carried out based on F-test at a confidence interval of 95% to confirm the significant influence of individual parameters. From the above two optimization techniques, the obtained optimal values are current 15 A, gap voltage 55 V, pulse on time 30 μs and an error of less than 5% is observed from the confirmation experiments. Scanning Electron Microscope (SEM) images revealed that there is no formation of cracks but micro pits and holes are observed.

5

Influence of Taguchi-Grey Relational Analysis of Gating System Design on Mechanical Properties of Casting

Ingle P. D., Narkhede B. E.

Archives of Foundry Engineering

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2019

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iss. 3

72--77

EN

Throughout the casting process, mold filling plays a very significant role in the casting quality control. It is important to study the effect of gating system design on ingate velocity of the metal which affects the mechanical properties of casting. The effect of varying the design of four gating system elements namely pouring cup, sprue height, runner and ingate design on the multiple responses like tensile strength and percentage elongation is studied using a Taguchi’s L9 OA. The Taguchi technique was coupled with a Grey Relational Analysis (GRA) to obtain a Grey Relational Grade (GRG) for evaluating multiple responses. ANOVA has been applied to identify the significance of different parameters and it was found that the pouring cup design and the runner cross-section along its length collectively contributed above 76% of the total GRG value. Finally, the confirmation tests were performed to validate the predicted optimized results and it established an improvement of 9.90% from the initial design.

6

Assessment of the track condition using the Gray Relational Analysis method

Tabaszewski M., Firlik B.

Eksploatacja i Niezawodność

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2018

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Vol. 20, no. 1

147--152

EN

The article concerns the developed methodology for assessing the technical condition of a tramway track. Thanks to the data collected from multiple tram journeys equipped with an on-board vibration recording system, it was possible to create profiles of crossings through track sections in different technical condition. In order to identify the track condition, an algorithm based on the gray-scale modeling was proposed, and a similarity comparison between the obtained track profiles. A new measure of similarity has been proposed that has not been used so far in gray-scale modeling. The obtained results confirm the applicability of the proposed methodology.

PL

Praca dotyczy opracowanej metodyki do oceny stanu technicznego toru tramwajowego. Dzięki zgromadzonym danym z wielokrotnych przejazdów tramwaju wyposażonego w pokładowy system rejestracji drgań, udało się stworzyć profile przejazdów przez odcinki torów w różnym stanie technicznym. W celu identyfikacji stanu toru zaproponowano algorytm oparty na metodzie modelowania szarych systemów oraz badanie podobieństwa pomiędzy uzyskanymi profilami przejazdów. Zaproponowano także nową miarę podobieństwa nie stosowaną do tej pory w zagadnieniach modelowania szarych systemów. Uzyskane wyniki potwierdzają aplikacyjność zaproponowanej metodyki.

7

Performance Analysis of Vertical Handoff Metrics using Variance Based Algorithms

Bijwe A., Dethe C. G.

Journal of Applied Computer Science Methods

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2015

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Vol. 7 No. 1

33--42

EN

Vertical handover is the evolving concept in 4G for seamless communication between heterogeneous networks. In this paper, our main objective is to analyze handover between two WLAN, two Wimax, two UMTS networks. The vertical handover decision is taken based on the variance based algorithm, which calculates the variance of parameters such as delay, jitter, bandwidth and packet loss for various above mentioned networks and the network with most of the parameters with minimum variance is selected. This algorithm is also compared with other algorithms such as MEW (Multiplicative experiment weighting), SAW (Simple Additive Weighting), TOPOSIS (Technique for order preference by similarity to ideal solution) and GRA (Grey Relational Analysis). These algorithms are appropriate for different traffic classes. Simulation results for proposed variance based algorithm in Matlab is discussed and compared with other Multiple attribute decision making algorithm basis of bandwidth; jitter, delay etc. are discussed in the paper. It can be seen that the proposed variance algorithm gives less packet delay than all the algorithms, Jitter is also is least than all the other algorithms.