Browsing by Author "Yurdakul, Mustafa"

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Analysis of the effect of the number of criteria and alternatives on the ranking results in applications of the multi criteria decision making approaches in machining center selection problems
(2020) Ic, Yusuf Tansel; Yurdakul, Mustafa
Multi criteria machining center selection models are widely used in the literature. In the applications of multi-criteria decision making models, machining center selection criteria are directly taken from catalogues. It is known that to have a ranking model sensitive to the weights of the selection criteria, it is especially important to limit the number of selection criteria to 7 +/- 2. A similar proposal can be put forward for the number of machining centers. In this study, whether or not reducing the number of criteria and alternative machining centers make the ranking results more sensitive to the changes in the criteria weights is studied using Spearman's rank correlation test. The study results show that the ranking results become more sensitive with a reduced number of criteria and alternative machining centers.
Analysis of the manufacturing flexibility parameters with effective performance metrics: a new interactive approach based on modified TOPSIS-Taguchi method
(2022) Ic, Yusuf Tansel; Sasmaz, Turgut; Yurdakul, Mustafa; Dengiz, Berna; 0000-0001-9274-7467; AGE-3003-2022
Flexibility is one of the most important strategy parameters to achieve a long-term successful performance for a manufacturing company. Studies in the literature aim to operate a manufacturing system at optimum levels of flexibility parameters under its own manufacturing environment. This study aims to present an interactive analysis framework based on TOPSIS and Taguchi parameter design principles for investigating the effects of different levels of flexibility parameters on the performance of a flexible manufacturing cell (FMC). The main performance metric used in this study is manufacturing lead time. Other important metrics to evaluate quality control and inspection policies are also investigated in this study. To conclude, a combined model of an interactive approach based on TOPSIS and Taguchi methods are used to assess the effectiveness of the flexibility parameters for a FMC.
Analysis of the Robustness of the Operational Performance Using a Combined Model of the Design of Experiment and Goal Programming Approaches for a Flexible Manufacturing Cell
(2023) Ic, Yusuf Tansel; Yurdakul, Mustafa; Dengiz, Berna; Sasmaz, Turgut
A combined model of a 2(k) design of experiment (DOE) and goal programming (GP) approaches is presented to determine optimum levels of input variables and analyze their robustness for a multiobjective performance of a flexible manufacturing cell (FMC) in this study. Two main performance metrics, namely, manufacturing lead time (MLT) and surface roughness (SR), are considered performance outputs for the FMC. Machine sequence, robot speed, tool type, and material type are selected as the four input variables on the input side of the proposed model. The study shows that even with a limited number of experiments, one can determine optimum input levels for the multiobjective performance of the FMC and determine their robustness.
Application of Cellular Manufacturing and Simulation Approaches for Performance Improvement in an Aerospace Company's Manufacturing Activities
(2019) Ic, Yusuf Tansel; Yurdakul, Mustafa; Gulsen, Mehmet; Dalcan, Gizem; Kirdar, Didem; Kale, Meric; Altinkaya, Zeynep; Aktas, Dogukan; https://orcid.org/0000-0001-9274-7467; AGE-3003-2022
This paper presents performance improvement studies performed in manufacturing activities of an aerospace company. Cellular Manufacturing (CM) and simulation approaches are used to improve performance in the factory of the company. In the application of CM, reorganization of machines in the machining section as manufacturing cells is performed by using Rank Order Clustering (ROC) algorithm and Hollier method. The performance improvement provided by CM application is measured in terms of the total material handling distances travelled by the parts. On the other hand, a simulation model in SIMAN is developed for panel production section of the factory. Based on the performance outputs of the simulation model, various recommendations are proposed in the operation rules and numbers of resources in the panel production section. The results show that both approaches provide considerable performance improvement in the manufacturing activities of the factory.
Comparison of Fuzzy and Crisp Versions of an AHP and TOPSIS Model for Nontraditional Manufacturing Process Ranking Decision
(2019) Yurdakul, Mustafa; Ic, Yusuf Tansel; AAI-1081-2020
Nontraditional manufacturing processes (NTMPs) are especially preferred when it is necessary to machine very small and delicate parts, obtain complex shapes or process very hard and high strength materials. New NTMPs are developed continually and the total number of NTMPs being used in the machining industry is increasing so that ranking and selection of the most proper NTMP requires multi-level and systematic models. [M. Yurdakul and C. Cogun, Development of a multi-attribute selection procedure for non-traditional machining processes, Proc. Inst. Mech. Eng. J. Eng. Manuf. 217 (2003) 993-1009] developed such an NTMP ranking model. The developed NTMP ranking model in [M. Yurdakul and C. Cogan, Development of a multi-attribute selection procedure for non-traditional machining processes, Proc. Inst. Mech. Eng. J. Eng. Manuf. 217 (2003) 993-1009] had a two-level structure and used crisp Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) together to rank feasible NTMPs. This study aims to replace crisp (nonfuzzy) versions of the AHP and TOPSIS with the fuzzy ones. Application of the fuzzy NTMP ranking model is illustrated and its results are compared with the ones obtained in [M. Yurdakul and C. Cogan, Development of a multi-attribute selection procedure for non-traditional machining processes, Proc. Inst. Mech. Eng. J. Eng. Manuf. 217 (2003) 993-1009] to evaluate the significance of the differences in ranking results. The comparisons show that using fuzzy AHP and TOPSIS approaches instead of the crisp ones in the ranking model provided considerable ranking differences. The fuzzy NTMP ranking model is studied furthermore in the paper by updating the NTMP list and fine-tuning fuzzy weights of the pertinent attributes.
A Component Based Model Developed for Machine Tool Selection Decisions
(2020) Ic, Yusuf Tansel; Yurdakul, Mustafa; AAI-1081-2020
Machine tools are widely used in manufacturing sectors; such as automotive industry, metal cutting industry, aerospace industry etc. Purchase of a machine tool is a long-term capital investment decision and requires a high initial investment cost. Machine tool producers offer a wide-ranging types and models of machine tools. On the other hand, expectations and requirements of the manufacturing companies differ depending on the parts produced and their strategic objectives. High stiffness, rigidity, metal cutting performance, surface finish and low tolerance range are common expectations from machine tools. This paper aims to develop a technical evaluation model to help manufacturing companies in their machine tool purchasing decisions. In the proposed model, first components used in machine tools are analyzed and based on this analysis a technical evaluation model is developed. The application of the developed model is illustrated by making a selection among nine different machine tool alternatives.
A Decision Support System for Selection of Net-Shape Primary Manufacturing Processes
(2014) Yurdakul, Mustafa; Arslan, Emre; Ic, Yusuf Tansel; Turkbas, O. Selim; https://orcid.org/0000-0001-9274-7467; AGE-3003-2022
Developments in the capabilities of the manufacturing processes increased the number of processes that can produce a part within the requirements determined by its design and market research. The increased number of processes and unfamiliarity of manufacturing engineers to many new manufacturing processes forces the researchers to develop systematic process selection tools instead of depending on the accumulated human expertise only. In this paper, a net-shape primary manufacturing process selection decision support system (DSS), which is named PROSEL (PROcess SELection), is developed. The developed selection programme eliminates the unsuitable processes step by step by checking a part's material, annual production quantity, specified shape, thickness and presents the most economical process as the most appropriate net-shape primary process after a final cost analysis. The developed DSS is written in Visual Studio and tested with a great deal of real-life examples. It can be concluded from the tests that the programme provides the same or better primary manufacturing process selection decisions than the practical usage, and it is a very useful support tool for net-shape primary process selections.
Determination of periodic inspection time in pressurized equipment exposed to fatigue by estimating the probability of fracture
(2021) Sozen, Levent; Yurdakul, Mustafa; Ic, Yusuf Tansel; 0000-0001-9274-7467; AGE-3003-2022
It is essential to inspect the pressurized equipment such as vessels, pipes, heat exchangers, boilers, etc., which are under the influence of variable load periodically to minimize the possibility of damage occurring or early disclosure of existing damage. These inspections may be carried out at fixed time intervals or can be carried out at determined intervals depending on a risk assessment that considers settlement of the equipment, operating conditions, and the potential danger of the equipment's chemical contained. Within the scope of this study, we evaluate the thin-walled pressurized equipment under variable internal pressure load. Special attention is crucial to the hot points where the stress is relatively high for inspection of fatigue-related damage on the equipment. We know that stress concentration factors are critical in welded zones in thin-walled pressure vessels. Therefore, the fatigue crack formation in the welded joints is more likely than the equipment's base metal. As a result of the study, we present the probability of time-dependent damage under the effect of fatigue caused by variable internal pressure for butt welded joints. Also, we propose a new approach for periodic control planning. As a case study, damage probabilities of the fuel or gas pipelines operating under variable pressure are calculated based on the diversity of the mentioned parameters, and a new approach is provided to determine the most suitable periodic inspection interval.
Development and comparison of airplane fuselage panel assembly system alternatives using axiomatic design principles and simulation methodology
(2022) Celek, Osman Emre; Yurdakul, Mustafa; Ic, Yusuf Tansel; 0000-0001-9274-7467; AGE-3003-2022
This paper presents a combined usage of axiomatic design principles and simulation in developing and comparison of alternative assembly systems for airplane fuselage panels. In the application, four assembly system alternatives are obtained with axiomatic design methodology; and their performance results are obtained using simulation. The simulation results are made available for system designers to see each alternative's capabilities and make a comparison among the alternatives. The application of the proposed combined application of axiomatic design principles and simulation provides a reference guide for system designers to apply in designing other assembly systems' design.
Development of A Decision Support System for Robot Selection
(2013) Ic, Yusuf Tansel; Yurdakul, Mustafa; Dengiz, Berna; 0000-0001-9274-7467; 0000-0002-1562-5738; AGE-3003-2022; AAA-6966-2021
With the availability of more different robot types and models along with their separate specifications, selecting the most appropriate robot is becoming more difficult and complicated for companies. Furthermore, a common set of robot selection criteria is not available for the decision makers. In this study, a two-phase robot selection decision support system, namely ROBSEL, is developed to help the decision makers in their robot selection decisions. In development of ROBSEL, an independent set of criteria is obtained first and arranged in the Fuzzy Analytical Hierarchy Process (FAHP) decision hierarchy. In the first elimination phase of the decision support system, the user obtains the feasible set of robots by providing limited values for the 15 requirements. ROBSEL, then, uses FAHP decision hierarchy to rank the feasible robots in the second phase. ROBSEL is illustrated and tested and several critical issues in its practical usage are explored in the paper. The applications of ROBSEL show that ROBSEL is a useful, practical and easy to use robot selection tool and improves robot selection decisions in the companies. (C) 2012 Elsevier Ltd. All rights reserved.
Development of a decision support system to select materials for pressure vessels
(2018) Ic, Yusuf Tansel; Balci, Arif; Yurdakul, Mustafa; AAI-1081-2020
Improvements in technologies applied in material field and continual increase in the number of material types force to develop and use new approaches in material selection. In this paper, a multi-criteria decision support system, called MATSEL, is developed to make material selection decisions for pressure vessel components more thorough and inclusive. MATSEL consists of two separate stages. In the first elimination stage of the MATSEL, it obtains a feasible set of materials for a specified pressure vessel component. MATSEL, then, uses three different multi criteria approaches namely ELECTRE, TOPSIS and VIKOR in the second stage to rank the feasible materials. An overall total score is obtained by summing the rankings of every feasible material and MATSEL proposes the material with the lowest total score as the most suitable one for the specified component. In this study, the statistical similarities between the rankings are also calculated to analyze the differences between rankings if there are any. Instead of inputting the materials every time MATSEL is used, a material data base is formed with the usage of ASME (American Society of Mechanical Engineers) and Ashby material selection diagrams for selection of alternative materials for the specified application.
Development of a Goal Programming Model Based on Response Surface and Analytic Hierarchy Process Approaches for Laser Cutting Process Optimization of St-52 Steel Plates
(2022) Yurdakul, Mustafa; Tukel, Taha; Ic, Yusuf Tansel
This paper presents an integrated model for optimization of laser cutting process of St-52 steel plates with multiple performance characteristics using Goal Programming (GP), Analytic Hierarchy Process (AHP), and Response Surface Methodology (RSM) approaches. In this study, optimum levels of the laser cutting process input parameters namely, material thickness, cutting speed, laser power, and assist gas pressure are obtained. For optimization purposes, four different surface roughness types of a cut surface, surface hardness, cutting time, and heat-affected zone (HAZ) of the cut surface are considered as performance outputs (responses) in this study. Optimization of multiple performance objectives (responses) requires obtaining regression functions with RSM first, and then weighting the regression functions using the AHP and finally combining the multiple functions into a single overall goal within a GP model and solving the model to optimize the laser cutting process. The study clearly shows that the presented optimization model is flexible enough to optimize the laser cutting process for various scenarios and conflicting priorities.
Development of a multi-criteria decision making model for the selection of appropriate robots for the aerospace industry
(2021) Celek, Osman Emre; Yurdakul, Mustafa; İç, Yusuf Tansel
Industrial robots have different capabilities and features according to their application areas and requirements. In a sector with highly specialized processes such as aerospace industry, accurate selection of an industrial robot to meet the requirements is a very complex and difficult process. The main challenge is that there are many appropriate robots for the aircraft manufacturing and assembly processes. In addition many technical criteria should be evaluated for determining the most appropriate robot among the industrial robots. In this study the MOORA and TOPSIS method, which are multi-criteria decision making methods are presented for the selection of appropriate industrial robots in the aerospace industry. A real case study related to the application of the methods is also included in the paper content.
Development of A Multi-Level Performance Measurement Model for Manufacturing Companies Using A Modified Version of the Fuzzy TOPSIS Approach
(2018) Yurdakul, Mustafa; Ic, Yusuf Tansel; 0000-0002-1562-5738; 0000-0001-9274-7467; AAA-6966-2021; AGE-3003-2022
This paper aims to develop a comprehensive hierarchical performance measurement model. The proposed model not only determines a manufacturing company's overall performance within its industry but also obtains its strengths and weaknesses in critical activities. It lets one to combine a company's performance scores in seventeen critical activities with important industry-specific objectives to obtain a single overall performance score by using a 4-Point Fuzzy Scale and a modified fuzzy version of the Technique for Order Preference by Similarity to Ideal Solution approach. The calculated overall performance scores provide a ranking order among manufacturing companies within their industry. In addition, it also enables each company to compare its performance in critical activities with respect to other companies in its industry. Furthermore, the performance measurement model has the capability to determine what a company should do to improve its performance in critical activities. This paper provides an example to illustrate the application of the proposed model.
Development of a New Support Mechanism to Calculate Feed-in Tariffs for Electricity Generation from Renewable Energy Sources in Turkey
(2019) Yurdakul, Mustafa; Ic, Yusuf Tansel; 0000-0001-9274-7467; AGE-3003-2022
Turkish government agencies support capital investments in electricity generation from renewable energy sources. When making support decisions related with renewable electrical energy sources, the government agencies should consider various issues such as renewability, cleanliness, origin of the source, supply security, cost per kilowatt hour (kWh), and total electricity generation capacity. The tariff mechanism being used in Turkey provides constant rates per kWh of electricity generated from renewable energy sources. The levels of the rates are determined to stimulate renewable energy sources' usage. In this paper, instead of a constant rate, a feed-in tariff is calculated for each individual electricity generation project using renewable energy source and its level is increased according to the source's desirability with respect to other renewable energy sources. Various criteria are taken into account in determination of electrical energy sources' desirability. Furthermore, a combination of two multi-criteria decision-making (MCDM) approaches (the fuzzy versions of the analytic hierarchy process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)) is used in obtaining a ranking among alternative renewable electrical energy sources. The developed support model's applicability is illustrated in this paper. The new model developed in this paper has many key benefits. For example, for an individual renewable electrical energy project, final cost per kWh can be calculated and multiplied by new Support Constant to calculate feed-in tariff purchase price per kWh. In another key benefit of the developed model, only local instead of state-wide renewable electrical energy projects can be compared within the AHP-TOPSIS decision hierarchy.
Development of a new trapezoidal fuzzy AHP-TOPSIS hybrid approach for manufacturing firm performance measurement
(2021) Ic, Yusuf Tansel; Yurdakul, Mustafa; 0000-0001-9274-7467; AGE-3003-2022
This study develops a multi-level hierarchical performance measurement model to measure a manufacturing firm's overall performance score by grading its success levels in critical operations and combining them. Linking overall performance score to local grades of a manufacturing firm in critical operations requires placement of manufacturing goals in the performance measurement model. The relative importance scores of the components at any level in the multi-level performance measurement model with respect to each component belonging to the immediately above level are determined using the fuzzy analytic hierarchy process (FAHP) method. The relative importance scores of the components are combined with success grades in seventeen pre-determined critical operations to obtain overall performance scores for manufacturing firms using the technique for order preference by similarity to ideal solution (TOPSIS) approach. In this study, scorecards are developed to guide scoring in each critical operation by checking levels of success in terms of practices, infrastructures, investments and actions. The developed performance measurement approach provides a structured decision-making environment with the scorecards and fixed hierarchy. Furthermore, the developed approach is more comprehensive in representing important issues necessary for obtaining realistic overall performance scores. For example, fuzzy numbers take into account vagueness (uncertainties) in the assignment of scores. Another advantage identified by the users is that the developed decision hierarchy can be adapted to new sectors or decision environments by adding new components or removing existing ones using the same overall structure and calculation steps.
Development of an Innovative Product Using Axiomatic Design Methodology
(2020) Uluturk, Ibrahim; Yurdakul, Mustafa; Ic, Yusuf Tansel
In this study, axiomatic design methodology is applied to design an innovative rifle butt. The developed rifle butt model is sized to fit into common rifle types and ANSYS Workbench program is used for its structural analysis. So that, this study presents in detail a new product design and engineering process to develop a completely new product that satisfies customer requirements without copying any existing products designs.
Development of an intuitionistic fuzzy ranking model for nontraditional machining processes
(2020) Yurdakul, Mustafa; Ic, Yusuf Tansel; Atalay, Kumru Didem
Nontraditional machining processes (NTMPs) are capable of processing very small parts, producing intricate geometries, operating on very narrow machining areas and machining high strength materials. These capabilities lead to a very diverse and large application area for NTMPs. Such a diverse and large application area along with more than one hundred NTMPs requires development of systematic and comprehensive models to help manufacturing engineers in their NTMP selection decisions. Furthermore, fuzzy models instead of crisp ones are being used in the literature in recent years to represent preferences of decision makers more realistically. This study proposes intuitionistic and triangular fuzzy NTMP ranking models and compares their ranking results with the crisp ranking model. The comparisons show that there are statistically significant differences among all three ranking models' NTMP ranking results.
Improvement of the Surface Quality in the Honing Process Using Taguchi Method
(2016) Yurdakul, Mustafa; Gunes, Serkan; Ic, Yusuf Tansel; 0000-0001-9274-7467; 0000-0002-1562-5738; AGQ-5008-2022; AAA-6966-2021
Steel cylinders are critical components of hydraulic systems and they are available in various diameters and thicknesses. Defects and discontinuities that remain on the inner body surfaces of the cylinders after turning operation can harm components that move inside the cylinders such as pistons and piston seals. Honing operation is commonly performed after turning operation as a finishing operation to improve inner surface quality of cylinders. Honing operation reduces surface roughness values to acceptable levels. The most critical parameters that are important in the honing operation are honing tool head forward speed, rotational speed of the tool and honing stone grain size. Optimizing these parameters will increase honing operation productivity and provide the best surface roughness values. This study aims to obtain the values of the most critical parameters that provide the best surface quality in the honing operation using Taguchi method.
A knowledge-based material selection system for interactive pressure vessel design
(2020) Yurdakul, Mustafa; Balci, Arif; Ic, Yusuf Tansel; AAI-1081-2020
Continual introduction of new materials and improvements in existing materials increase the variety of materials that can be used for pressure vessel components. Among wide variety of materials, the most suitable one must be selected for a component by matching its functional requirements with various available materials' specifications. This study proposes an interactive knowledge-based decision support system for selecting the most suitable material for a given pressure vessel component and its working environment. The developed decision support system, namely Pressure Vessel SELection (PVSEL), consists of two separate phases. In the first elimination phase of PVSEL, the user obtains a feasible set of alternative materials by answering various questions and providing lower-limit values at materials' critical specifications. PVSEL, then, uses a ranking phase which uses ELECTRE, TOPSIS and VIKOR methods to rank the feasible materials. In the second phase, each alternative material's ranking is determined by combining its performance values at weighted critical specifications (selection criteria), which are considered as important in meeting the functional requirements of the component. Usage of PVSEL is illustrated in the paper and the results show that the proposed PVSEL is an effective selection tool and provides meaningful results for the designers.