Journal of Simulation and Analysis of Novel Technologies in Mechanical Engineering
Volume:9 Issue: 4, 2017

In this research, optimization of the pulsed gas tungsten arc welding including pulse current, background current, pulse frequency and on time were investigated in welding of non-similar materials of austenitic stainless steel AISI 316L and nickel-base super alloy of Monel 400 by using ERNiCr3 filler metal. In order to obtain optimum conditions of welding the Taguchi method with the L9 array was used. The mechanical properties such as bending, tesile test and hardness test were performed on the samples and after that analysis of the variance was performed. By predicting optimal conditions, the proposed model was examined and the results of computational analysis shows a significant similarity with results of the experiment. Optimal parameters of pulsed tungsten arc welding were the pulse current of 140 mA, background current of 60 mA, pulse frequency of 3 Hz and the ON periods of pulse was 50%. The optimized sample with the Taguchi method and the welded sample shows the similarity of 98.7%. Pulse current percentage of 23.4 and pulse frequency of 28.2 were identified as the most influential parameters during the welding. Tensile test results showed that the failure occurs on the side of the base metal on Monel 400 one and hence the failure is the ductile one. These results show the strength of the weld metal confirmed the tensile and bending tests.

This work presents a model for calculating the effective ýthermal conductivity of nanofluids. The proposed model ýincludes the effects of nanoparticles and thermal conductivity ýbase fluid.We will focus on experimental of the volume ýconcentration parameter and temperature on thermal ýconductivity, nano-fluid combination and Multi-Walled ýCarbon nanotubes-Oxide / Copper-paid deionized Water. This ýwater-based nanofluids, For two-step volume fractions of the ýý0.1, 0.2, 0.6 Percentage produced And then, Effective thermal ýconductivity is measured precisely. In order to measure the ýthermal conductivity of nanofluids. To measure the thermal ýconductivity coefficient in THW method, KD2-pro and KS1 ýprobe was used, also with the fluid significantly enhancement ýshows in thermal conductivity coefficient. Also with the fluid ýsignificantly enhancement shows in thermal conductivity ýcoefficient. In lower volume fractions we observed ýsignificantly increase in thermal conductivity and receive high ýdegree thermal. Due to the lack of similar studies Due to the ýlack of similar studies to comprehensively and inefficient of ýclassical thermal conductivity, In order to estimate the thermal ýconductivity of nanofluids An empirical model that estimates ýthe thermal conductivity of nanofluids model with deviation ýmargin is very lowþþ.

Friction-stir welding process is a novel method of solid state welding, which produces heat due to friction between the pin, the shoulder and the workpiece. This heat causes a paste area. Shoulder pressure and pin spin cause edges integration and lead to welding. In this study, firstly, the feasibility of welding of steel sheet (EN10130) with a thickness of 1.5mm has been tested by 58 experiments. After making perfect welds, the ranges of 500-1000 RPM and 30-160 mm/min were selected as the suitable upper and lower levels, respectively, for rotational speed and linear speed. To achieve a maximum tensile strength, 29 tests were designed by using the Box-Benken method considering specified levels of the parameters. Then, the response surface methodology was used for optimization of the parameters. Results showed that the optimal outputs and experimental data were in good agreement, which indicate the adequacy of the design of experiments and optimization predict results. Micro-hardness tests, metallography and normal tensile test were carried out on three series of plates produced with the most appropriate tensile strength and elongation. Results showed that heat-affected zone weaked the sheet of advancing side compared to other welding zones.

Hot metal gas forming of tubes can be used in various industries such as automotive and aerospace industries. In this process tube is formed at elevated temperatures, by using gas instead of fluid pressure. Lower required pressure and low power are its advantages in comparison to hydroforming process. In this paper, a hot metal gas bulging process of an aluminum alloy tube has been investigated by finite element method. In addition, The HMGF process was simulated by ) Dynamic, Temp-Disp, Explicit( because of the temperature distribution along the tube length, whereas temperature was simplified and assumed to be uniform in analytical method. The bulge height parameter was investigated by changing the input variations such as internal pressure, outer diameter, die entry radius, initial tube length and initial tube wall thickness in numerical method. The numerical result shows that the input variations have significant effects on tube bulge height in this process.

The crankshaft is one of the most critically loaded components as it experiences cyclic loads in the form of bending and torsion during its service life. Its failure will cause serious damage to the engine so it’s important at the time of design to verify fatigue strength. More challenges in crankshaft design due to increasing vehicle payloads, lower weight requirement, higher efficiency and longer durability life. In this study a dynamic simulation was conducted on a crankshaft from a V8 diesel four stroke engine. Finite element analysis was performed to obtain and analysis the variation of the stress magnitude at every location of crankshaft especially at critical points. Results obtained from the aforementioned analysis were then used in optimization of the crankshaft. Also accumulated fatigue damage caused by the change in loading in different crankshaft speeds was determined. The goal of this study is designing crankshaft with suitable and optimum dimensions which can serve the longer durability life without any failures.

Free vibration of sandwich plates with temperature dependent functionally graded (FG) face sheets in various thermal environments is investigated. The material properties of FG face sheets are assumed to be temperature-dependent and vary continuously through the thickness according to a power-law distribution in terms of the volume fractions of the constituents. Also, the material properties of the core are assumed to be temperature dependent. The governing equations of motion in polar system and in free natural vibration are derived using Hamilton’s principle and Galerkin method is used to solve the equations and obtain the natural frequency. In-plane stresses of the core that usually are ignored in the vibration characteristics of the sandwich structures are considered in this formulation. The results obtained by Galerkin method for symmetric circular sandwich plate with fixed support is compared with finite element method that obtained by ABAQUS and good agreement is found. The results show that varying the power-law index and temperature have important effects on natural frequency.

A multi-component force/torque sensor using strain gauges is applied to measure the static or dynamic forces and also the moments in all axis simultaneously. The applied column-type six-component force/torque sensor is composed of two flanges and a cylindrical elastic force-sensing element with a particular pattern of installed strain gauges. In this research the pattern of strain gauges on sensor is presented to electrically decouple each component of the applied loads. The theoretical model was developed for the presented pattern. Also the finite element simulation carried out with ABAQUS for whole model to evaluate the accuracy of the pattern in different situations. Furthermore, variety of load cases including the axial loads, the torsional torque and bending moments were applied to the prototype sensor to report the percentage deviations of experimental strains related to the equivalent theoretical model and the simulations. The results show that the actual values of the main diameter components of the calibration matrix not only are different from the theoretical values but also this matrix would not necessarily be diagonal. It is observed that the percent deviation of the simulation strains from theoretical values in all loading cases would be under 3%. As a prominent result, the minimum and maximum deviation between theoretical and experimental is related to shear force (Px) and bending moment (Mx) respectively by values of 0.27% and 8.12%.

In this paper the numerical analysis of flow and time dependent heat transfer of micro-tube conveying nanofluid in laminar flow is investigated. In this study, convection heat transfer of nanofluid and base fluid and transient analysis for time-varying heat flux for time step of 0.0001 second are elucidated. It is observed that the pumping power of nanofluid flowing and the maximum temperature of micro-tube wall, respectively, is increased and decreased with increases in the volume fraction of nanoparticle. The maximum temperature of base fluid (water) is 305.6K and the maximum temperature is 304.2K for alumina oxide nanoparticle AF with volume fraction 3%. In addition, the results show that using nanofluid has the advantage of heat transfer despite periodic heat flux. However, the results show that these parameters are vital in investigation of the heat transfer of system. Also, It is obvious that the maximum temperature of micro-tube wall decreases with increase in the Reynolds number. For example, for Reynolds numbers 180, 360 and 720, the maximum temperatures occur at 307.8K, 304.6K and 302.8K, respectively. In addition, it is indicated that the variation of temperature decreases when the volume fraction of nanoparticles increases. Also the results of numerical modeling are compared with those available in literature and good agreement is observed.

In this paper, the Accumulative Channel-die Compression Bounding (ACCB) method is investigated as a new method of severe plastic deformation to produce Nano-crystalline bulk metals on the basis of pressing in a channel mold. Aluminum as One of the most usable metal in industry is processed using this method. Analyzing the processed samples show that after four passes of ACCB method, the ultimate strength of samples reaches to 120 from 60 Mpa. The grain sizes of samples reaches to 627 nm from 8-6µm in annealed phase after four passes of ACCB method. Also, the vicker's hardness of samples reaches to 51.8 from 20 HV after four passes. These changes consist of the increasing the hardness and strength of aluminum sample and achieving to the high ratio of strength to weight of sample can help us to better use this materials to fabricate less weight structures for using in automotive and airplane industry.

In this study, the effects of linear and rotational speed of the friction stir welding tool was investigated on the heat generation and distribution at surface and inside of workpiece, material flow and geometry of the welding area of poly methyl methacrylate (PMMA) workpiece. The commercial CFD Fluent 6.4 software was used to simulation of the process with computational fluid dynamic technique. To increase the accuracy of simulation, weld area was modeled as a non-Newtonian fluid with pseudo melt behavior around tool pin. The results of the simulation showed at the higher the proportion of rotational speed to linear speed, the material flow in front of the tool and the welding region became bigger. The maximum temperature and turbulence generated heat and material flow were observed at the advancing side. The simulation results were showed acceptable agreement with experimental results. Based on the studied parameters, the maximum generated heat was of 115° C, the maximum material velocity was 0.24 m/s around tool shoulder and maximum pressure on the workpiece was predicted 9 MPa.

A wide range of electronic components are affected by dynamic loading during its lifetime mostly included variable frequencies and amplitude called random vibration. In order to evaluate the life cycle and endurance resistance of such components, fatigue analysis under different working condition is necessary. An effective solution for improving life cycle of the components could be making the natural frequencies of the components far away from the range of loading frequencies in random loading. In this paper a printed circuit board (PCB) with two BGA electronic components has been considered in order to optimize natural frequency. The PCB simulated using ABAQUS FEM software and published experimental test has been used for validation of results. The optimization has been performed by two different algorithms including GA and a DOE based RSM. The obtained responses have been compared and validated.

In this paper deflection and free vibration of sandwich panel is studied. The core of Sandwich panels is made of hexagonal honeycomb and faces are made of two different materials of Carbon Fiber Reinforced Plastic and K-aryl/epoxy covering. The governing equations are deduced from the First order Sheer Deformation Theory (FSDT) and they are solved using Generalized Differential Quadrature Method (GDQM). The classical method in the references is used to verify the DQ method and to show that the applied GDQM method has a good results with compared to the references. Deflection of sandwich panel is investigated with two different load types. Finally natural frequency for the first 4 modes and the two different faces materials are calculated and the effect of various lengths to core thickness ratios and faces to honeycomb core thickness ratios are studied. Further, the effect of foundation stiffness coefficient on deflection and natural frequency are showed.

Cylindrical thin-walled tubes due to construction and easy installation, high energy absorption capacity are used in the automotive industry as an impact energy absorber. However, the main weakness of cylindrical tubes is in the high initial peak load. Therefore, in this paper, to overcome this weakness, a buckling initiator is used at the top of the tube. This buckling initiator is a steel rod that is installed by stretching strips at the edge of tubes. In this study, the parameters related to the initiator, including different number of pulling strips N, pre-hit height h and inclined angle of the pulling strips θ are studied. For this purpose, quasi-static simulation was conducted to determine the maximum crushing load, specific energy absorption and crush force efficiency using the software Ls-Dyna. To verify the numerical simulation, the results were compared with experimental testing. The results show that the crashworthiness characteristics and performance of the cylindrical tubes significantly improved with buckling initiator.

longevity of osseointegrated implants are intensely influenced by biomechanical factors. Control of these factors prevents mechanical complications, which include fracture of screws, components, or materials veneering the framework. In this study, the impact of length and threads pitch of dental implants on the stress distribution and maximum Von Mises stress in implant-abutment complex and jaw bone are studied using finite element method. The implant length changes from 8.5 mm to 13 mm and a range of 0.6 mm to 1 mm is considered for the threads pitch of implants. The maximum stresses are observed in implant-abutment complex, cortical bone and cancellous bone, respectively. Results suggest a length of 13 mm in a pitch of 0.7 mm for implants. Also, an optimal ratio for the pitch and length of an implant is proposed.

The aim of this research was manufacturing a parabolic trough solar collector in which reflecting surface is made of mirror steel rather than usual mirror and also predicting its theoretical performance.by adjusting planar ⩝ -shaped structures parallel to each other and welding them together, the main supporting structure was assembled and a parabolic-shape Teflon arc was installed in the aperture of each ⩝-shaped structure. Then the steel plate was installed on the main structure to form a parabolic trough surface. Other components were manufactured and assembled according to conventional methods. In order to predict performance, efficiency was formulated as a function of incident angle according to the related theory. By programing in MATLAB, net rate of heat absorption and efficiency were calculated and corresponding diagrams plotted against apparent solar time for several days of the year. The results indicated that when solar radiation was close to vertical, efficiency increased form fifty percent in the morning to sixty at noon and decreased to fifty again in the afternoon. Otherwise it decreased from sixty percent in the morning to fifty at noon and increased to sixty again in the afternoon. Maximum net rate of heat absorption (w/m 2) occurred at noon (450-550) and the minimum at sunrise and sunset (400-450). Although the efficiency of the manufactured collector is slightly different from that of usual ones, less assembly time and cost and higher quality of surface geometry and more durability of reflecting surface are considerable compared with conventional collectors of this type.

In this study the effects of machining parameters such as shearing speed, feed rate, tool diameter and machining depth on different milling strategies i.e. 3D offset, spiral, raster and radial to produce the convex surface made of epoxy/glass composites is investigated. The effects of mentioned strategies on output parameters such as surface roughness and milling removal rate is also studied. The results show that the output of radial strategy has the minimum roughness with the highest surface quality. The raster strategy gives the maximum roughness with the lowest surface quality. Also it can be seen that in 3D offset strategy, the removal rate is maximum and subsequently the time of machining is minimum. In addition the optimized values of machining parameters to achieve the best conditions for surface smoothness and removal rate is obtained. The results of this work can be used in research and development units of industries for operational purposes.