مجله مهندسی ساخت و تولید ایران
سال دوم شماره 3 (پاییز 1394)

This research has been investigated the heat distribution in butt frictional stir welding for dissimilar metals by aluminum alloy of 1100 and copper using finite element analysis and experimental tests. As the temperature distributions in turbulent region directly effect the microstructure and mechanical properties¡ thus¡ determining of temperature distribution¡ during the process is very significant. Temperature distribution is simulated by ABAQUS software. To determine the thermal profile of the metal¡ the temperature has been recorded using thermocouples. The experimental data had a good agreement with the finite element analysis. As a result¡ other investigations can be done using the finite element method without conducting different experiments on thermal behavior of this kind of welding for other dissimilar metals under different conditions.

Digital shearography is an optical method based on LASER interferometry can be used to determine the displacement gradients of surface of materials. This approach can be used as a tool for non-destructive testing. In this research¡ a method based on digital shearography is provided to estimate the depth and length of sub-surface cracks in glass-epoxy composite plates. Hence¡ the digital shearography of the studied specimen was simulated by Abaqus finite element software and a secondary program written in Matlab; A shearography setup established in order to verify the simulation. Comparing results of simulations to experiments confirmed the accuracy of simulations. Then¡ by design of experiment method¡ shearography of studied specimen with different crack geometry and testing load was simulated and number and density of fringes were extracted in each test. The equations to estimate the depth and length of crack were provided by curve fitting of obtained data. Validation of provided equations with experimental results shows acceptable accuracy of the equations and algorithm used to estimate the depth and length of cracks in composite plates.

Incremental sheet forming process (ISF) is a dieless forming method capable to produce small-batch of sheet metal components economically. This makes ISF attention-grabbing for research and development. Use of ultrasonic vibration is a modern approach implemented to improve ISF process. In this article¡ the effects of process parameters of ultrasonic vibration assisted incremental sheet forming (USVAISF) such as tool diameter¡ pitch size and vibration amplitude on forming force¡ fracture depth and percent reduction of forming force is investigated experimentally through response surface method. Results indicate that decreasing tool diameter and increasing ultrasonic vibration amplitude decrease the forming force and make the ultrasonic vibration more effective (increase the percent reduction of forming force) in USVAISF process. Fracture depth decreases with increasing pitch size and vibration amplitude. The influences of tool diameter on fracture depth and pitch size on forming force are complicated and different effects are seen in various conditions. Results show 33% to 63% reduction in forming force and 2% to 29% reduction in fracture depth in ultrasonic vibration assisted incremental sheet forming (USVAISF) compared with conventional ISF (without ultrasonic vibration). Eventually¡ optimal process parameters are predicted for ultrasonic vibration assisted incremental sheet forming and validated experimentally.

Increasing in the adhesive joint strength is followed by expanding on its application. Employment of wavy edge configuration in comparison to the traditional single lap joint is a one way to increase the adhesive joint strength with thin adherent. In this paper the effects of wavy configuration on the strength of the wavy joints were studied. Araldite 2015 was employed in this study. Araldite 2015 is a two component¡ room temperature curing paste adhesive giving a resilient bond. It was observed that the wavy joints have more strength than the single lap joint about 35%. For more investigation¡ a 3D finite element model was developed. In this study the cohesive zone model (CZM) was used for simulating the adhesive behavior. The effects of wave shape and number on the strengthening of wavy joints were studied. The finite element results were in good accordance with the experimental outcomes for the strengthening of wavy edges.

Bilayer clad sheets normally consist of two or more dissimilar metals of different thickness bonded together. Clad sheets are of great interest in different industries while having the advantages of all base metals. In this research¡ laser forming of Cu-stainless steel (SS) clad sheet is experimentally studied. This composite can be used in microelectronics industry while having the anti-corrosion and strength capability of stainless steel¡ and electrical superiority of copper. The specimens are bent using Ytterbium fiber laser irradiated on a straight path along the sheet width. The effects of main forming parameters including the number of passes¡ scanning velocity¡ beam diameter and laser power are discussed on bilayer sheet¡ and compared with its constituent steel and copper layers. It is found that the thin copper mid-layer strongly affects the rate of bending per pass due to its high thermal conductivity. It was concluded that the increase of laser power increases the bending angle¡ and increase of scanning velocity and beam diameter decreases the bending angle.

The present research is aimed to study on effect of friction stir welding process parameters on aluminum alloy 1100-H18 to pure copper joints. The effect of welding parameters¡ including rotational speed¡ feed rate and pin offset on the tensile strength of samples investigated and were optimized by response surface method. In order to verify the results of tensile tests¡ metallographic evaluation¡ microhardness and X-ray diffraction tests were conducted. Microstructural evaluation of the weld samples revealed that the interfacial regions are characterized by mixture layers of aluminum and copper. High Vickers microhardness values were measured at the joint interfaces¡ which corresponded with the intermetallic compounds. The diffractograms of the X-Ray Diffraction analysis showed small peaks for intermetallics in the welds. Welds produced with low heat input did not have intermetallics formed at the joint interface¡ whereas welds produced by highest heat input¡ have the highest content of intermetallics. As well as to determine the maximum temperature in weld nugget¡ FEM analysis have been conducted and formation temperature of intermetallic components was determined. To evaluate the effect of welding parameters¡ including rotational¡ linear speed and tool offset¡ on weld properties¡ optimization using Response Surface method is performed and highest tensile strength is achieved. By increasing the rotational speed and tool offset to aluminum side and reducing the linear speed¡ the generated heat input during welding was increased and this caused to increasing UTS to a maximum and then decreased. By varying the process parameters and increasing the heat input until optimize strength¡ mixing operations are performed as appropriate and increases the tensile strength¡ with a further increasing in heat input¡ grains are being coarse and intermetallic compounds increases and then tensile strength has been decreased.

In this paper manufacturing process and mechanical properties has been investigated in Pultrusion process using natural jute fiber HDPE and starch. Pultrusion process has been used for manufacture of wire shape prepregs. Natural jute fiber has been impregnated in impregnation die using extruder. The results show tensile strength has been decreased up to 19% in wire shape prepregs that produced using three impregnated pin in comparison to no pin. Also tensile strength of wire shape prepregs that has been produced using HDPE are 31% higher than wire shape prepregs with starch matrix. By increasing number of jute up to 3 fibers¡ Tensile strength has been increased up to multiple 2.. Impregnation of wire shape prepreg with starch matrix shows less jute impregnation than HDPE matrix. So that Jute has been exposure on one side and starch has been exposure other side and jute has been exposure symmetric in the HDPE matrix.

In this paper¡ finite element method and large deformation theory has been used in order to find a Limit load force of parts and a correlation between experimental tests and numerical results. The numerical process for simulating mechanical loading on parts until fracture¡ considering fracture load level and plastic deformation simulation using the von Mises yield criterion with the associated flow rule and isotropic (work) hardening have been described. It is shown that the results of numerical analysis are in accordance with experiments¡ and good correlation is achieved. Therefore¡ this approach may be recommended for designing of light weight mechanical parts.