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      • Open Access Article

        1 - Modelling of Friction Stir Extrusion using Artificial Neural Network (ANN)
        Mohammad Ali Ansari Reza Abdi Behnagh Dong Lin Sarang Kazeminia
        In the present study, an artificial neural network (ANN) model is developed to predict the correlation between the friction stir extrusion (FSE) parameters and the recycled wires’ average grain sizes. FSE is a solid–state synthesis technique, in which machin More
        In the present study, an artificial neural network (ANN) model is developed to predict the correlation between the friction stir extrusion (FSE) parameters and the recycled wires’ average grain sizes. FSE is a solid–state synthesis technique, in which machining chips are firstly loaded into the container, and then a rotating tool with a central hole is plunged into the chips at a selected rotational speed and feed rate to achieve indirect extrusion. Selecting rotational speed (RS), vertical speed (VS), and extrusion hole size (HS) as the input and average grain size as the output of the system, the 3–6–1 ANN is used to show the correlation between the input and output parameters. Checking the accuracy of the neural network, R squared value and Root–Mean–Square–Error (RMSE) of the developed model (0.94438 and 0.75794, respectively) have shown that there is a good agreement between experimental and predicted results. A sensitivity analysis has been conducted on the ANN model to determine the impact of each input parameter on the average grain size. The results showed that the rotational speed has more effect on average grain size during the FSE process in comparison to other input parameters. Manuscript profile
      • Open Access Article

        2 - Application of the Relevance Vector Machine for Modeling Surface Roughness in WEDM Process for Ti-6Al-4V Titanium Alloy
        Abolfazl Foorginejad Nader Mollayi Morteza Taheri
        Cutting the Titanium alloys is a complicated task which cannot be performed by traditional methods and modern machining processes, such as Wire electro-discharge machining (WEDM) process which are mainly used for this purpose. As a result of the high price of the Ti-6Al More
        Cutting the Titanium alloys is a complicated task which cannot be performed by traditional methods and modern machining processes, such as Wire electro-discharge machining (WEDM) process which are mainly used for this purpose. As a result of the high price of the Ti-6Al-4V alloy, proper tuning of the input parameters so as to attain a desired value of the surface roughness is an important issue in this process. For this purpose, it is necessary to develop a predictive model of surface roughness based on the input process parameters. In this paper, The Taguchi method was used for the design of the experiment. According to their effectiveness, the input parameters are pulse-on time, pulse-off time, wire speed, current intensity, and voltage; and the output parameter is surface roughness. However, a predictive model cannot be defined by a simple mathematical expression as a result of the complicated and coupled multivariable effect of the process parameters on the surface roughness in this process. In this study, application of the relevance vector machine as a powerful machine learning algorithm for modeling and prediction of surface roughness in wire electro-discharge machining for Ti-6Al-4V titanium alloy has been investigated. The predicting result of model based on the root means square error (RMSE) and the coefficient of determination (R2) statistical indices, prove that this approach provides reasonable accuracy in this application. Manuscript profile
      • Open Access Article

        3 - The Effect of Focal Distance and Type of Auxiliary Gas on Cut Width in CO2 Laser Cutting of Stainless and Mild Steel Sheets
        Hossein Taheri Hamid Zarepour Firouzabadi Majid Hashemzadeh
        Lens focal distance and auxiliary gas type utilized in CO2 laser cutting are two important parameters affecting process measures such as cuts width and quality at desired cutting speeds. This research work focuses on cuts width and quality in CO2 laser cutting with a po More
        Lens focal distance and auxiliary gas type utilized in CO2 laser cutting are two important parameters affecting process measures such as cuts width and quality at desired cutting speeds. This research work focuses on cuts width and quality in CO2 laser cutting with a power of 4000W on two types of steel sheets at different focal distance values and using different types of auxiliary gas. The effect of focal distances of 5” and 7.5” as well as utilizing oxygen and nitrogen as auxiliary gas on cut width and quality in 304L stainless steel and St37 steel sheets were investigated. The size of cut widths was measured using an optical microscopy. The results demonstrate that cuts performed at the focal distance of 7.5” are wider than those created at the focal distance of 5”. It is also observed that with increased workpiece thickness, the use of focal distance of 7.5” is more feasible because cuts are faster; need lower laser power, and use less amount of auxiliary gas. When using oxygen as auxiliary gas, the main factor affecting the cutting efficiency is the oxidation reaction, whereby oxidation energy is added to laser power which results to an increased energy level in the cutting region. This means that using oxygen as auxiliary gas makes it possible to cut thicker sheets at higher cutting speeds as compared to that of nitrogen. However, when using oxygen as auxiliary gas, the quality of cuts appears to be lower and their width larger as compared to cuts performed by nitrogen auxiliary gas. Manuscript profile
      • Open Access Article

        4 - Numerical Investigation on Heat Transfer and Performance Number of Nanofluid Flow inside a Double Pipe Heat Exchanger Filled with Porous Media
        Ehsan Aminian Babak Ahmadi
        Two common methods to augment heat transfer are the application of nanofluids and porous inserts. In the present work, heat transfer inside a double tube heat exchanger filled with porous media is analyzed numerically using two phase mixture model for the nanofluid flow More
        Two common methods to augment heat transfer are the application of nanofluids and porous inserts. In the present work, heat transfer inside a double tube heat exchanger filled with porous media is analyzed numerically using two phase mixture model for the nanofluid flow and the Darcy-Brinkman-Forchheimer model for the flow inside porous media. Basically, porous media improve heat transfer at the expense of increasing pressure drop. A new PN (Performance number) -defined as the ratio of heat transfer to pressure drop on the base state (without porous media and nanoparticles)- is introduced to better judge the first law’s performance of configurations. Results indicated that by keeping and increasing Reynolds number from 500 to 2000, an increase of 56.09% was observed in the performance number. Furthermore, maintaining Reynolds number at Re=500 and changing from 0.0001 to 0.1, results in an increase of 138%. For pressure drop, by keeping and increasing Reynolds number from 500 to 2000, it is 40 times. Furthermore, maintaining Reynolds number at Re=500 and changing from 0. 1 to 0.0001, the pressure drop is 250 times. Besides, adding 3% nano particles to the base fluid enhances the performance number by about 50% and increase pressure drop by about 20%. Manuscript profile
      • Open Access Article

        5 - Experimental Investigation on Fatigue Evaluation of Orthopaedic Locking Compression Plate
        Saenoddin Mohajerzadeh Khalil Farhangdoost Pedram Zamani Kamal Kolasangiani
        Locking compression plate (LCP) is a common orthopedic instrument for internal fixation and healing of bone trauma. It is important to study on mechanical behavior and failure investigation of LCP because its failure leads to lots of cost and pain to the patient. In thi More
        Locking compression plate (LCP) is a common orthopedic instrument for internal fixation and healing of bone trauma. It is important to study on mechanical behavior and failure investigation of LCP because its failure leads to lots of cost and pain to the patient. In this paper, fatigue life of an eight-hole tibia LCP is evaluated under flexural loading. A four-point bending jig is manufactured and fatigue tests are performed for different compression loads. Fatigue life cycles are investigated for compression loads of 500, 600, 700, 800, 900 and 1000 N and relation between compression load and life cycles is estimated. 125 walking days is estimated for the patient during treatment period according to life cycle results. Post failure analysis results on fracture surface revealed that the crack initiated from the edge of compression hole and propagated from lower to the upper surface of LCP according to beach marks. Finally, Scanning electron microscopy (SEM) on the fracture surface revealed striations as a proof of fatigue crack growth. The striation spacing near the crack initiation site is found to be smaller than this spacing far from the initiation zone. The fatigue crack propagation life is estimated as 1600 cycles according to the number of striation spacings. Manuscript profile
      • Open Access Article

        6 - Picard Iteration Method to Kinetic Analysis of Thermal Inactivation of Enzyme as Applied in Biotechnology
        A. Olurotimi Adeleye M. Gbeminiyi Sobamowo
        In this work, Picard iteration method is used to obtain analytical expressions for the prediction of molar concentration of native and denatured jack bean urease (EC 3.5.1.5) through the three-reaction steps kinetic model of thermal inactivation of the urease. The obtai More
        In this work, Picard iteration method is used to obtain analytical expressions for the prediction of molar concentration of native and denatured jack bean urease (EC 3.5.1.5) through the three-reaction steps kinetic model of thermal inactivation of the urease. The obtained solutions are used to study the kinetics of thermal inactivation of the enzyme as applied in biotechnology. The analytical solutions are verified with numerical solutions using Runge –Kutta with shooting method and good agreements are established between the solutions. From the parametric studies using the iterative method, the molar concentration of native enzyme decreases as the time increases while the molar concentration of the denatured enzyme increases as the time increases. The time taken to reach the maximum value of the molar concentration of native enzyme is the same as the time taken to reach the minimum value of the molar concentration of the denature enzyme. The information given in this theoretical investigation will assist in the kinetic analysis of the experimental results over handling rate constants and molar concentrations. Manuscript profile
      • Open Access Article

        7 - A Surrogate Reduced Order Free Vibration Model of Linear and Non-Linear Beams using Modified Modal Coefficients and HOSVD Approaches
        Mohammad Kazem Moayyedi
        In the present work, two low-dimensional models are presented and used for vibration simulation of the linear and non-linear beam models. These models help to compute the dynamical responses of the beam with fast computation speed and under the effects of different cond More
        In the present work, two low-dimensional models are presented and used for vibration simulation of the linear and non-linear beam models. These models help to compute the dynamical responses of the beam with fast computation speed and under the effects of different conditions. Also the obtained results can be used in the conceptual and detailed design stages of an engineering system overall design. First, a finite element analysis based on Euler-Bernoulli beam elements with two primary variables (deflection and slope) at each node is used to find static and dynamic responses of the considered linear and non-linear beams. Responses to three different static load cases are obtained and applying them as initial conditions, the time responses of the beam are calculated by the Newmark's time approximation scheme. A low-dimensional POD model which was extracted from the ensemble under the effect of an arbitrary loading is reconstructed. To apply the model to simulate the response of beam under the effect of other loads, POD modal coefficients are updated due to change of initial condition. This modification is performed based on the recalculation of the eigenvalues due to a new initial condition. Also, another low-dimensional model is constructed which is developed based on an ensemble under the effect of several parameters. To apply the model to simulate the response of the beam under the effect of other loads and variations of beam thickness, POD-HOSVD modal coefficients are updated due to the change of desired parameters. The results obtained from the low-dimensional model are showing good agreement to the benchmark data and proving high level accuracy of the model. Manuscript profile
      • Open Access Article

        8 - Combining Magnetic Flux Leakage and Optical Inspection Technique for Identification of Nearby Pittings
        Turaj Azizzadeh Mir Saeed Safizadeh
        Magnetic Flux Leakage (MFL) is an indirect measurement technique. Therefore, calibration curves are generally used to estimate the depths of the defects from the measured MFL signals. This has been shown to give good results on varying degrees of the single defects. How More
        Magnetic Flux Leakage (MFL) is an indirect measurement technique. Therefore, calibration curves are generally used to estimate the depths of the defects from the measured MFL signals. This has been shown to give good results on varying degrees of the single defects. However due to the interaction between the leakage fluxes, nearby pittings can-not be discriminated and properly assessed using the conventional MFL technique. In order to ensure reliable measurement for this case, the MFL technique is combined with the optical inspection technique. The main contributions of this study are to develop a new calibration method based on the defect depth, defect area as well as the amplitude of the corresponding MFL signal and propose a novel combined approach for detection and identification of the nearby pittings. MFL and optical inspection techniques are applied to a test specimen containing the nearby pittings. The results obtained from the experimental tests demonstrate the efficacy of the proposed approach. Manuscript profile
      • Open Access Article

        9 - Simultaneous use of Acoustic Emission Signals and Statistical Analysis to Distinguish between Lubrication Modes in Rolling Element Bearings
        Seyed Ali Niknam
        The lack of lubricant in bearing surfaces could be considered as the main cause of wear and faults in bearing surfaces. To avoid unexpected failures, special emphasis on adequate evaluation of lubrication mode (lubricated/dry) on the bearing surfaces is demanded. To tha More
        The lack of lubricant in bearing surfaces could be considered as the main cause of wear and faults in bearing surfaces. To avoid unexpected failures, special emphasis on adequate evaluation of lubrication mode (lubricated/dry) on the bearing surfaces is demanded. To that end, the proper use of reliable techniques and tools, including sensory information from acoustic emission (AE) signals is among popular methods when real-time condition monitoring evolves. The current work intends to evaluate the sensitivity of AE parameters to different levels of process parameters on the basis of statistical analysis. In this context, rotational speed and radial load were used as the main experimental parameters. Following that, adequacy of a new AE signal parameter for real-time condition monitoring of rolling element bearing is presented. Experimental and statistical results confirmed the great capability of AE signals to differentiate between two types of bearing modes, in particular, dry and lubricated. Signal processing and statistical analysis conducted in this study exhibited that several time series AE parameters, in particular, Std, Max, Mean, and Variance are sensitive to the variation radial load and rotational speed. It was observed that radial load has insignificant effects on computed values of AE parameters from both bearing modes. The statistical analysis revealed that rotational speed (A) has a significant effect on all computed AE parameters from the dry bearing. Manuscript profile
      • Open Access Article

        10 - Investigating the Effect of Rotation Speed and Ultrasonic Vibrations in the Incremental Forming Process
        Saeed Amini Farshad Nazari Mohammad Baraheni Amir Hossein Ghasemi
        Incremental forming is one of the forming methods that is considered because of no need to specific die, especially for rapid prototyping. In this study, the incremental forming process is carried out by using a rotating tool and assisted ultrasonic vibration. Purpose o More
        Incremental forming is one of the forming methods that is considered because of no need to specific die, especially for rapid prototyping. In this study, the incremental forming process is carried out by using a rotating tool and assisted ultrasonic vibration. Purpose of this research is to investigate the effect of rotation speed and ultrasonic vibrations in the incremental forming process. According to the obtained results, mean and maximum values of forming force reduced by using a rotating tool and applying ultrasonic vibrations. The results of surface roughness tests demonstrated that by increasing rotational speed, the surface roughness improved 44% and applying ultrasonic vibrations with tool rotation can reduce surface roughness about 74%. Applying ultrasonic vibrations lead to increase micro-hardness up to 84%, but, by increasing rotational speed, surface hardness slightly reduces. Results of straight groove test determined ultrasonic vibrations with the rotating tool can increase stretching limit up to 41.79% due to the affect on the sheet plasticity behavior. Manuscript profile
      • Open Access Article

        11 - Experimental Investigation of the Formability Improvement of Brass 260 and Al5182-O in Various Strain Rate using Hydrodynamic and Electrohydraulic Forming Methods
        َAmin Ashrafi Tafreshi Mehdi Zohoor
        Studying the formability of the sheet metals have been the subject of many researches during the last decades. A number of experimental and numerical approaches were implemented to derive the formability diagrams of different materials. In this study, the formability of More
        Studying the formability of the sheet metals have been the subject of many researches during the last decades. A number of experimental and numerical approaches were implemented to derive the formability diagrams of different materials. In this study, the formability of two mostly used alloys, Brass 260 and Al5182-O as low and moderate formability materials, were investigated respectively. The forming limit diagrams of both materials were determined by using three experimental approaches such as Nakazima quasi-static as low strain rate method, hydrodynamic forming method as the moderate strain rate method and Electrohydraulic Forming process as high strain rate method. Three experimental results of forming limit diagram with the various strain rate were compared graphically. The results have shown that both of the materials could withstand higher strains when the electrohydraulic forming method was applied on the specimens and consequently, the forming limit diagrams for Brass 260 and Al5182-O shift up by 11% and 14%, respectively. In addition, it was concluded that the hydrodynamic forming method improves the formability of the materials by 4% and 6% for Brass 260 and Al5182-O, respectively. The outcomes of this study indicated that the formability of both materials was improved significantly by increasing the strain rate. Manuscript profile
      • Open Access Article

        12 - Field Performance of Inlet Liner for Centrifugal Slurry Pump Manufactured by NR/PBR Nanocomposite
        Puya Afsharjahanshahi Seyed Yousef Ahmadi-Brooghani Mehdi Raghebi Mohammad Ali Karimi
        Centrifugal slurry pumps are being used in many mineral companies to transport mineral materials. These materials are mainly abrasive and the liner of these pumps are eroded during their working life. Zinc oxide (ZnO) are usually used for enforcing rubber material but, More
        Centrifugal slurry pumps are being used in many mineral companies to transport mineral materials. These materials are mainly abrasive and the liner of these pumps are eroded during their working life. Zinc oxide (ZnO) are usually used for enforcing rubber material but, the ZnO is harmful to the environment. Nano ZnO (n-ZnO) particles seem to purvey higher activity. In this work, the inlet liner of a centrifugal slurry pump was fabricated with n-ZnO that decreases environmental concerns and improves its wear life. The composite of inlet liner is made of Natural rubber (NR) and Polybutadiene rubber (PBR). For determining the optimal dosage of n-ZnO within the composite, mechanical properties for rubber compounds comprising 1-2 unit(s) n-ZnO, were investigated comparing to those of the compound with 5 units conventional ZnO (c-ZnO). It was found that optimal amount of n-ZnO was 1 unit which it was enough to give equivalent or better mechanical properties compared to one containing a higher amount of, namely 5 units, c-ZnO in the composite. In addition, field-emission scanning electron microscopy (FESEM) photo showed that n-ZnO particles were homogeneously dispersed in the composite. Finally, two inlet liners were manufactured, one of them was with 1 unit of n-ZnO (n-liner) and the other one with 5 units of c-ZnO (c-liner). These two liners were used in service in a plant. The field study showed that the life of n-liner was 1/3 unit more than the life of c-liner and n-liner face has been worn less than c-liner one. Manuscript profile
      • Open Access Article

        13 - Steady State Creep Characteristics of a Ferritic Steel at Elevated Temperature: An Experimental and Numerical Study
        Roozbeh Alipour Ali Farokhi Nejad Hamid Nilsaz Dezfouli
        Prediction of creep life for a ferritic steel plate is significant in the context of its application as an element of steam generating systems. In this paper, the issue of elevated temperature creep in 2.25Cr–1Mo steel was investigated in detail, including the mec More
        Prediction of creep life for a ferritic steel plate is significant in the context of its application as an element of steam generating systems. In this paper, the issue of elevated temperature creep in 2.25Cr–1Mo steel was investigated in detail, including the mechanism and the compatibility of hyperbolic sine modeling methodology for the description of steady state creep behavior of this alloy. Creep rupture tests were conducted on the thin foil samples at an elevated temperature ranging from 973 to 1073 K at various stresses between 90 to 210 MPa. A hyperbolic sine model is then used to fit the experimental creep data and the corresponding best fit parameters are provided. Using these parameters, a finite element analysis employing ABAQUS was carried and the reliability of the hyperbolic sine model was investigated in relation to the creep curve and creep life in the steady state creep area. The main outcome of the current study is creep characterisation of 2.25Cr–1Mo steel foils at extreme elevated temperature and to propose a finite element model for simulating this condition which is not reported so far. The results of experimental, constitutive analysis and finite element simulation were compared to each other and it was shown that they are in a good agreement. Manuscript profile