Department of Modeling and Design Engineering Systems

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http://hdl.handle.net/20.500.11905/1220

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EXPERIMENTAL EVALUATION AND CFD STUDY OF THERMAL COMFORT, IAQ INDICES, AND THERMAL ENERGY STORAGE FOR THE IMPROVEMENT OF THE ENERGY PERFORMANCE OF OVERCROWDED AREA
(2022-12-11) AL-MALAKI, Fadhil Asaad Mohammed Kadhim; JAFARI, Rahim
In recent years, buildings, including prison halls, have contributed significantly to the world's rising energy use, with 34 % of the energy used by these buildings being attributed to cooling and heating. This study examines the use new combination of phase change materials (PCMs) for energy conservation in buildings through thermal storage, including the use of double layers of PCMs paraffin waxes with different properties. The study evaluates the indoor air quality characteristics of two protocols for cooling and heating in four different scenarios that are classified according to the seasons in a location, with a high daily temperature range, similar to that of Iraq. An experimental facility for the study was designed, constructed, and tested at Technology University in Baghdad. The experimental measurements were taken in a small-scale model 1:4 of a prison quarry, with dimensions of 1.2 by 0.6 by 0.8 meters and a side inlet grill. This prototype model was used to investigate the impact of integrating double layers of panels on the roof of the space and their ability to minimize fluctuations, energy usage, and shift peak load. The computational work involved solving the partial differential equation for the conservation of mass, momentum, and energy and its rate of dissipation using the finite volume technique. Modifications to the algorithm were made to simulate the space with and without PCMs in the roof for all scenarios. The majority of the computed data were presented as temperature contours and other thermal contours, and when compared to the experimental results, a reasonable level of agreement was observed. The use of PCMs as latent heat thermal energy storage (LHTES) in the room envelope for passive cooling has gained significant attention due to their ability to store large amounts of energy. The results of this study show that the use of TES can reduce the energy required for the space by 47.2 % in the summer and in varying proportions during other seasons, also when PCMs are used in hot weather, in door temperature drops by 7 °C at average, compared to when they are not used.
LOAD DEMAND FORECASTING USING ARTIFICIAL NEURAL NETWORKS AND FUZZY LOGIC METHODS
(2022-05-12) AL-ANI, BARQ RAAD KHASHEI; ERKAN, Turan Erman
This study proposes using artificial neural networks (ANNs) and fuzzy logic (FL) to estimate load demand data to forecast hourly electricity loads in Turkey or 2017 and 2018. We used Real Time Consumption as hourly electric load based on EPİAŞ data for 2017 to 2018. The load forecast was actualized using two machine learning techniques: ANN and fuzzy logic FL. The predicted data was compared to the actual data by plotting on a graph. This study used the ANN and FL methods to optimise the demand for load forecast in Turkey's power systems. The first and last 200 hours were plotted on ANN to get a better visualisation pattern, and the overall estimated hourly load for Turkey was calculated by adding the hourly estimations from each area. The minimum and maximum readings for the year 2017 are 18851.35 MWh and 47062.40 MWh whereas the mean and standard deviation readings are 33102.19 Mwh and 4968.67 MWh. As a result, the comparison of these models was used to forecast the load, all of which have different load patterns and origins. The series are stationary across the year and it peaks during the month of August. The MAPE values for FL for 2017 and 2018 are 3.7986094 and 5.28635983 respectively which is very good and falls in high accurate forecasting results. It can be concluded that the FL gives a better prediction than the ANN for both years. Electrical peak reduction is a vital component of any plan for managing energy demand, and forecasting electric load assists in planning peak load demand reductions to meet energy demand management targets. It can be concluded that the FL gives us a better prediction than the ANN for both years. Home, energy management research will benefit from the new load forecasting models proposed in this study.
MODELING SURFACE WATER QUALITY AND NUTRIENT CORRELATION WITH SEDIMENT OXYGEN DEMAND AT DAM WATER RESERVOIR
(2022-09-12) ABDULQADER, Noor N.; GÜLER, Enver; NUMANOĞLU, Aslı
The work presented here is a model approach based on WASP8 (Water analysis simulation program) a water quality model simulated to represent contaminants at the surface and bottom sediments of the Kurtboğazı dam reservoir in Ankara. Investigated water quality output variables were temperature, nitrate, total phosphorus, total Kjeldahl, dissolved oxygen, Chlorophyll a, and ammonium. To ensure that the model represents the actual case at the reservoir, the results from our simulation model were calibrated using actual data from the Kurtboğazı dam site, and the calibration utilizes statistical techniques. The novelty of this research is the development of a quality model to predict the reactions of state variables that are occurring at the water body and how they interact with each other and their influence on the overall quality status of the Kurtboğazı reservoir, as well as the crucial factors influencing the depletion of oxygen at the water column. The accuracy of the model was checked using statistical techniques in the form of coefficient of determination and relative error which produced excellent ranges of results indicating that our simulated model was able to represent the features at the reservoir site. The Kurtboğazı dam reservoir had been affected by the negative impact arising from dissolved oxygen depletion in the hypolimnetic layer during stratification periods. However, the processes of oxygen consumption at the sediment-water interface are still difficult to grasp conceptually and are mainly linked to sediment oxygen depletion and the phenomena of sediment oxygen demand SOD. The work here presents a simulation model that can be utilized as a helpful tool by any person working in the sector of water management, to estimate and predict the parameters influencing the anoxic condition and benthic flux.
A BIOINSPIRED CONCEPTUAL DESIGN METHODOLOGY FOR BIOROBOTS
(2013-05-21) KONEZ EROĞLU, Aylin; ERDEN, Abdülkadir; ERDEN, Zühal
The main aim of this thesis is to develop a Bioinspired Conceptual Design (BICD) methodology for design of biorobots. Within the context of the dissertation, a novel BICD procedure has been developed based on existing BID approaches and systematic engineering design steps. This procedure is applied on several case studies, namely a dog biorobot (BioDog) for walking and trotting, a cockroach biorobot (BioCoc) for climbing, a jumping (grasshopper) biorobot for jumping and a hybrid (dog and lobster) biorobot for walking. A BICD process has been developed using the implementation results. Classic DEVS (Discrete Event System Specification) coupled model is used to formally represent the BICD process in order to develop a BICD methodology. The proposed BICD methodology transforms customer needs into a concept design of biorobot with clear and well-defined six design steps. In order to overcome the drawbacks of existing BIDs, the biological system analysis and the bioinspired transformation design steps have been considered in detail. In this thesis, although four case studies have been implemented to demonstrate the BICD methodology, fourteen biological systems and twenty four locomotion types are investigated by using content analysis and/or observation methods. The literature survey has been used for the content analysis method, while an experimental set-up is used to analyze the biological systems for the observation method. Required knowledge on morphology, function and behavior of biological systems are obtained using a high speed camera. During the bioinspired transformation step, the knowledge about the biological system has been transformed systematically into knowledge about the biorobots and this knowledge is used to develop the concept design of biorobots.
DEVELOPING NEW EVALUATION METRICS TO MEASURE AND IMPROVE SUPPLY CHAIN PERFORMANCE AND FLEXIBILITY WITH SUCCESSFUL ERP IMPLEMENTATION AND BPR APPLICATION: A HYBRID FUZZY AHP / ANP / STATISTICAL ANALYSES APPROACH
(2013-06-21) BAÇ, Uğur; ERKAN, Turan Erman
Supply Chain Management and flexibility has gained a great importance nowadays. Consideration of performance and flexibility of supply chains are popular research topics. To maintain competitive advantage on the market, continuous benchmarking and improvement in performance is mandatory. To adapt continuously changing market conditions, supply chain structure should be flexible. Successful ERP implementation has a considerable effect on supply chain flexibility when it is supported by a BPR application. Some special metrics are needed to evaluate overall supply chain performance and flexibility to achieve and track improvements. In this study, two new evaluation metrics have been developed to evaluate performance and flexibility by a hybrid approach with MCDM models and statistical analyses. Also prerequisites needed for a successful ERP implementation and BPR application have been specified. As a result of this study, a road map has been prepared for benchmarking and improving Supply Chain performance and flexibility by successfully implementing ERP and applying BPR.
ASSESSMENT OF INTELLECTUAL CAPITAL BY USING NEW FUZZY ANALYTIC NETWORK PROCESS APPROACH
(2013-06-14) ÖZDEMİR, Yavuz Selim; ERKAN, Turan Erman
The value of an enterprise is made of financial assets and intangible assets which called as Intellectual Capital. Intellectual Capital has always existed, but only in the last decades awareness of its strategic importance has increased becuase of the shift in modern economy from the industrial to the knowledge era. Both academics and experts in the business world agree that Intellectual Capital is one of the most important points to maintain competitive advantage in today's markets. Intellectual Capital consists of non-physical sources of value related to Human Capital and Structural Capital. IN the scope of this thesis, a new Fuzzy Analytic Network Process approach was proposed for evaluation of the relative importance of Intellectual Capital components and it has been investigated in terms of satisfaction indicators of Intellectual Capital. This proposed new methodolgy compared with other most commonly used Fuzzy Analytic Network Process methodologies in the literature. A group of experts has been chosen for IC criteria evaluation. The obtained results used for evaluation of sectorial awareness levels for manufacturing and service sectors in Ankara area.
PROPOSING AN HYBRID MODEL AND METHODOLOGY FOR THE OPTIMIZATION OF THE CASTING PARAMETERS
(2013-08-14) DEVRİM İÇTENBAŞ, Burcu; ÖZAKTAŞ, Hakan; GÜRAY, Cenk
Casting defects cause losses for a foundry: loss of time for reworked items and loss of material for scrapped unusable products. Investigating the reasons followed by eliminating the causes will reduce the defect percentages and positively contribute to productivity. The main goal of this study is to propose a hybrid model based on experiments by using Artificial Neural Networks (ANN) and Decision Trees (DT) for estimating casting defects. This study also proposes an individual model of ANN and DT for prediction of casting defects and compare the performance of these models. The primary objective is to make use of these models to develop a decision support system for engineers and executives working for describing the relationship between the casting parameters and casting quality .
AN ORGANIZATION IMPROVEMENT MODEL FOR SMALL AND MEDIUM SIZED ENTERPRISES (SMEMM)
(2015-01-31) ERGİN, Merve Hande; ÇELEBİ, Neş'e
Small and Medium Sized Enterprises’ (SMEs) development and improvement have impact on national economies. However, SMEs may have difficulty in providing sustainable business practices for organizational improvement. Improvement is a complex phenomenon; it needs assessment of current situation of organizational factors whereas weight of the factors change as organizations develops. Besides, SMEs may have deficiencies in assessment due to shortcomings in processes and resources. In this study, a new model which considers organizational development as a sequence of activities is proposed for the process improvement of Turkish Manufacturing SMEs. These improvement activity series aimed at having defined, manageable and measurable organizational processes. The model provides a reference point that evaluates current processes and a guideline that aligns prerequisite practices. The Capability Maturity Model (CMM) framework which consists of process management and quality improvement concepts is used for this new model. The new model is empirically tested and necessary modifications are carried out to fit the model to the structure and characteristics of Turkish manufacturing SMEs. The model can be used as a tool to identify the complete and missing activities at each level and as a roadmap for future requirements of the organization.
ELASTIC ANALYSIS OF POLAR ORTHOTROPIC FUNCTIONALLY GRADED ROTATING ANNULAR DISKS
(2015-01-30) ESSA, Saad; ARGEŞO, Ahmet Hakan
Semi-analytical and analytical solutions are presented for polar orthotropic annular functionally graded rotating disks by taking also thickness variation into account. The formulations are performed by referring to polar coordinate system and the material properties are assumed to vary in radial direction. The governing equation of the problems are obtained under the assumptions of plane stress and small deformations. Disks having two types of boundary conditions are considered. The first one is an annular disk having traction free inner and outer surfaces, whereas, the second has a rigid inclusion within and traction free outer surface. Semi-analytical solution is obtained by assuming that elasticity moduli and disk thickness vary according to a nonlinear function in which its shape is controlled by three parameters. Poisson’s ratios are assumed to be constant valued and the variation of density can be described by any form of continuous function. The three parametered nonlinear function is formed by combining the exponential and power forms of variation functions that are widely used in literature for describing material gradation. The analytical solution is determined by considering that the Elasticity moduli, disk thickness and density vary according to power law. Solutions are verified numerically by using a computational method which is based on nonlinear shooting method. Verification examples are given first. Then, parametric analysis that inspects the effects of the degree of orthotropy and material gradation on the elastic responses of rotating disks are presented. In the analysis, elastic limit angular velocities of the disks are evaluated according to Hosford’s criteria.
THE DEVELOPMENT OF A METHOD TO IMPROVE THE LIMIT DRAWING RATIO OF BLANKS USING PREFERENTIAL HEATING
(2015-01-30) KAYHAN, Erdem; KAFTANOĞLU, Bilgin; KONCA, Erkan
The method developed in the current thesis can shortly be described as the application of nonisothermal local heating in the flange region of the blank to improve the formability of sheet metals in deep drawing. The use of elevated temperature gives the possibility of significantly increasing the ductility of the material and the associated forming capability. It also drastically reduces the yield point and hence the forming forces and required pressures. One of the advanced high strength sheet steels (AHSS), DP600, widely used in the automotive industry due to enabling the reduction in car weigth and increasing the crash safety is chosen as a work material in this reasearch. Using AHSS steels also reduce the material thickness and lower fuel consumption. The three different types of steels, two HSLA and one IF steels, are additionally examined to observe the validity of the developed method. As a result of the experiments conducted within the temperature limits 180oC to 275oC in flange region, the Limiting Drawing Ratio in deep drawing (LDR) is increased up to 25.58 %. Since the temperature range stays in the warm region, material properties are not influenced; but the strength remains the same while the required forming forces are reduced.
DESIGN AND IMPLEMENTATION OF A PARALLEL BOUNDARY ELEMENT METHOD SOLUTION FOR 3D PARTICLE FLOW PROBLEMS IN MICROCHANNELS
(2015-01-30) KARAKAYA, Ziya; BARANOĞLU, Besim; YAZICI, Ali
A new formulation for tracking multiple particles in slow viscous flow for microflu idic applications is presented. The method employs the manipulation of the boundary element matrices so that a system of equations is obtained relating to the rigid body velocities of the particle to the forces applied on the particle. The formulation is spe cially designed for particle trajectory tracking and involves successive matrix multi plications for which Symmetric Multiprocessing (SMP) parallelisation is applied. It is observed that the present formulation offers an efficient numerical model to be used for particle tracking and can easily be extended for multiphysics simulations in which several physics are involved.
A PROPOSED INTEROPERABLE MODEL FOR THE REPUBLIC OF TURKEY ON PUBLIC ELECTRONIC PROCUREMENT SYSTEM
(2015-02-27) YILDIRIM İMAMOĞLU, Meltem; REHAN, Mohammed
Approximately 15% of the government‘s Gross Domestic Products (GDP) is spent on public procurement process. Therefore, accountability and transparency in public procurement is very important. For the regulation of public expenditures and effective use of the budget, not only public procurements but also efficient use of infrastructure that make up the system for public procurements should be considered. As a result, the importance of the public electronic procurement (PeP) processes is emphasized in this thesis. Public Procurement Authority (PPA) and the State Procurement and Supply Office (SPSO) responsible for public tenders in the Republic of Turkey, are two organizations affiliated to the Ministry of Finance. However, in public procurement process, both institutions have their own system, own business processes and legal obligations. Yet is it a privilege to have two different systems? To find the answer to this question and to analyze the current situation in both systems, satisfaction measurement surveys for both public and private organizations are conducted. In addition to the surveys, interviews are carried out by authorized people from different organizations concerned with public procurement process in the European Union (EU) and in the Republic of Turkey. In light of the information obtained from these interviews, the best three countries (England, Germany and Denmark) are investigated in detail. The results of these studies showed that EU countries, are paying an increasing importance to the efficient use of resources by the Digital Single Market system, a shift to a more centralized application is noted. In the thesis, based on the current Public electronic Procurement (PeP) system analysis, Critical Success Factors (CSFs) and required performance criteria in public procurement for achieving these success factors have been identified. It seems that the execution of public procurement process from a single platform is inevitable for the Republic of Turkey. Transparent and accountable systems are necessary to increase the participation of the public institutions and Small and Medium Sized Enterprises (SMEs) into the PeP system. All of results after the research study indicate that an interoperable PeP system is inevitable for the Republic of Turkey. This study may be claimed to be a pioneer for the use of supply chain management in public procurement process.
FRACTIONAL MODELING OF OSCILLATING DYNAMIC SYSTEMS
(2015-06-25) AGİLA, Adel; İRFANOĞLU, Bülent; EİD, Rajeh
In recent years, a special attention is given to model fractional dynamical systems. These systems include fractional oscillating dynamical systems. Many methods are used to model the fractional oscillating dynamical systems. The responses of some systems are obtained by means of fractional calculus and calculus of variations. In this thesis, fractional representations based on fractional calculus, calculus of variations are classified into two types: The first type is the fractional Euler-Lagrange equations representations of free oscil lating fractional systems. The fractional representation appears in the coefficients of damping terms of variable coefficient second order homogeneous differential equa tions. In the second type, the differential operators are subjected to fractional orders. The considered case studies are models given by second order homogeneous and non homogeneous three-term fractional order differential equations with fractional damp ing terms. The two types are combined to produce extended fractional Euler-Lagrange equations models. In these models the differential operators are subjected to fractional orders in the damping term of the system. Additionally, the time varying coefficients of the damping terms contain a fractional integral order. A hybrid method is introduced to obtain the responses of fractional oscillating sys tems. These systems are modeled by means of second order homogeneous three-term fractional order differential equations with fractional damping terms. The responses are compared with Wright function based solutions.
EXPERIMENTAL AND NUMERICAL INVESTIGATION OF STRETCH FORMING PROCESS FOR AEROSPACE APPLICATIONS
(2015-10-25) HATİPOĞLU, Hasan Ali; KARADOĞAN, Celalettin
Stretch forming process is commonly used in the aerospace industry for forming large sheet panels. In this process, a flat sheet is stretched over a form-block that acts by hydraulic power. During this action, the sheet is gripped from the sides by jaws which are also hydraulically moved. Process parameters like die-jaw movements and lubrication conditions have to be determined properly in order to produce good quality parts. In the present situation, those parameters are determined by production experience and traditional methods which slow down the process and increase the scrap risk. This study aims to optimize the stretch forming process by establishing a finite element model which provides numerical tryouts instead of physical ones. The success of the numerical analysis is highly dependent upon proper modeling of material behavior and friction. In order to capture the correct material behavior, tensile tests, bulge tests and forming limit diagram tests of commonly used sheet alloys were conducted. The results were then used for defining the hardening curves, yield loci, anisotropic constants and forming limit curves. In another study, the friction coefficients for various conditions between the tool and the sheet surfaces were determined by doing distinctive tests. Experiments were conducted by forming marked aluminum alloy sheets on a semi-circular form-die and measuring the deformation optically. They were used for the validation of the established numerical model. Finally, a method was proposed to determine the tool movements and applied successfully on a real aircraft part.
ARTIFICIAL NEURAL NETWORK BASED DECISIVE PREDICTION MODELS ON HIGH FREQUENCY FINANCIAL DATA
(2017-01-07) Karaçor, Adil Gürsel; Erkan, Turan Erman
High frequency financial data are somewhat hard to model or predict, if not totally impossible, as stochastic processes and many other random factors are involved. In this thesis; a novel Artificial Intelligence model is designed and developed for financial time series prediction and decision making. Possibility to enhance prediction accuracy for foreign exchange rates is investigated in two ways: first applying an outside the box approach by bringing about methodology and techniques to facilitate the use of predictive models in engineering design to model price graphs by exploiting their visual properties together with principles of chaos theory, and secondly employing the most efficient methods to detect patterns to classify the direction of movement. The approach that exploits the visual properties of price graphs makes use of density regions along with high and low values describing the shape just as in Machine Vision. Mainly Artificial Neural Networks are used in modeling. However, other state-of-the-art methods; Extreme Gradient Boosting and Support Vector Machine are too used for comparison. The designed system is also software coded as a real-time trading robot. Comparable prediction results and profits are achieved in tests and simulations.
NEURAL NETWORK BASED FEATURE EXTRACTION FOR HANDWRITTEN DIGIT RECOGNITION
(2017-01-07) Günler Pirim, Mine Altınay; Tora, Hakan; Öztoprak, Kasım
In this dissertation, it is proposed that hidden layer output weights of semi-trained neural network to be used as feature vectors. In pattern recognition neural network is a training algorithm which provides classification. In this thesis in addition to this fact, it has been shown that semi-trained neural network can be used as a tool to extract hidden layer output vectors that are used as features of the image. The system is mainly composed of three steps: preprocessor, feature extractor, and classifier. Only the classifier layer differs for each experiment, the other two layers are used as default for all experiments. Support vector machine, neural network, and Euclidean distance classifiers are utilized. The experiments were conducted on MNIST and USPS benchmark datasets to evaluate the performance of the proposed approach.
A GENERIC ONTOLOGY CREATION TOOL: A CASE STUDY ON BUSINESS SECTORS
(2022-03-01) Yılmaz, Ekrem Çağlar; Turhan, Çiğdem; Güray, Cenk
To retrieve any information from the Web, a search has to be performed on billions of documents which are unorganized, unstructured and unreadable by machines. To overcome this problem, the data on the Web has to be formalized in a machine readable format. One of the solutions is to use the Semantic Web technology which provides structure and meaning to data on the Web. In order to provide machine readable and semantically identified information, the Semantic Web technology utilizes ontologies which include resources, properties and their relations to identify metadata about data. The current ontology editors require expertise to create, organize, edit and manage ontologies. In this study, a generic ontology creation tool is developed for users with no expertise in ontology creation. The tool which can be easily and effectively used at every level of a business gathers information about the ontology from a non-expert providing step by step guidance with user interfaces.The aim is to enable any employee of a firm to create an ontology in their domain to be able to share information in machine-readable form with the rest of his/her company or other companies. The tool is tested on users who have different working experiences in terms of years and sectors of business. The results are evaluated with statistical methods which show that on the average, the users are satisfied with the tool and are able to create ontologies in their own domains.
A STUDY ON THE WIRE ARC ADDITIVE MANUFACTURING OF DUPLEX STAINLESS STEEL PLATES: OPTIMIZATION OF PROCESS PARAMETERS AND INVESTIGATION OF MECHANICAL PROPERTIES
(2022-03-01) SAADAWI, HASSAN; Konca, Erkan; Tur, Kâzım
In recent years, additive manufacturing (AM) for metals, which is used to create products using layer-by-layer deposition of materials, has been a subject of interest as a means of enhancing the efficiency of manufacturing processes in various industries. In this thesis, super duplex stainless steel parts have been wire arc additively manufactured (WAAM) using the cold metal transfer welding technique. To obtain the optimum combination of additive manufacturing parameters (voltage, current and speed) that yields the desired bead quality, response surface method has been used to build statistical models based on numerical simulation of additive welding process. COMSOL Multiphysics 5.5 software has been used to perform the experimental instead of real process and Expert-Design software was used to obtain the statistical models. The optimal values of the controlled variables were found as 200 amperes and 15 volts for current and voltage, and 10 mm/s for welding speed. Then, the fracture toughness tests using the single edge notched tension (SENT) specimens were implemented at a sub-zero temperature. Fracture toughness data has been used to establish crack-growth resistance curves for both, as-received rolled plate and additively manufactured parts and compare the results based on J-integral (energy release rate). The J-integral value at the initiation of stable crack growth (Ji) of SDSS Grade 2507 as-received plate specimens is approximately 17% higher than the (Ji) value of WAAM’d DSS Grade 2209 and 31% higher than the (Ji) value of WAAM’d SDSS Grade 2509.
A GENERIC ONTOLOGY CREATION TOOL: A CASE STUDY ON
(2022-02-28) Yılmaz, Ekrem Çağlar; Turhan, Çiğdem; Güray, Cenk
To retrieve any information from the Web, a search has to be performed on billions of documents which are unorganized, unstructured and unreadable by machines. To overcome this problem, the data on the Web has to be formalized in a machine readable format. One of the solutions is to use the Semantic Web technology which provides structure and meaning to data on the Web. In order to provide machine readable and semantically identified information, the Semantic Web technology utilizes ontologies which include resources, properties and their relations to identify metadata about data. The current ontology editors require expertise to create, organize, edit and manage ontologies. In this study, a generic ontology creation tool is developed for users with no expertise in ontology creation. The tool which can be easily and effectively used at every level of a business gathers information about the ontology from a non-expert providing step by step guidance with user interfaces.The aim is to enable any employee of a firm to create an ontology in their domain to be able to share information in machine-readable form with the rest of his/her company or other companies. The tool is tested on users who have different working experiences in terms of years and sectors of business. The results are evaluated with statistical methods which show that on the average, the users are satisfied with the tool and are able to create ontologies in their own domains.
INVESTIGATION OF FRICTION IN SHEET METAL FORMING
(2022-02-28) Kalkan, Hakan; KAFTANOĞLU, Bilgin
Investigation of friction is carried out in the radial drawing region between the die and blank holder and also in the stretching zone over the punch in deep drawing. Two methods are developed to calculate the coefficient of friction in each zone using the experimentally determined data such as punch force diagrams and strain distributions obtained by an optical scanning system. The current methods differ from the existing techniques which are obtained in simulative tests. The proposed methods can be applied at room temperature and at elevated temperatures. In deep drawing tests, EN 10268 steel is used with dry and graphite lubrication and hot deep drawing tests are performed at . Deep drawing tests are performed at different lubrication and temperature conditions. Blank holder load is another parameter which changes the punch loads. 9 different stretch forming tests are performed to determine the coefficient of friction in this zone. Three different materials are used with dry and paraffin lubricated conditions. Comparisons of friction coefficients are made with those obtained by other techniques.

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