مجله مهندسی ساخت و تولید ایران
سال دهم شماره 1 (فروردین 1402)

In recent years, the oscillations use of ultrasonic waves has been strongly increased in various industries. Therefore, respecting to the application type of these waves in different industrial fields, extensive and wide researches have been started which can be helpful and competent in optimizing the effective parameters in methods based on the ultrasonic waves application. One of the special uses of them is in machining. The ultrasonic machining is a mechanical material removal which is applied for creating various holes and cavities on the brittle and fragile materials. In this study, in order to ensure the practical behavior of the machine, be able to investigate the resulted findings and also obtain the optimized machining parameters, the drilling operation was performed on the glass workpiece of super clear crystal type by designing the experiment. The results in different conditions show that the material removal has been increased by increasing the frequency, the static load and the machining power. The highest material removal has been achieved by choosing a frequency of 40 kilohertz, static load of 1080 grams and power of 130 watts. Also, the created holes have a desirable quality of roundness tolerance.

Investigating the behavior of fiber/polymer composite structures and the effect of various factors on their mechanical properties is vital in defining the design, manufacturing and troubleshooting process. In this paper, the changes in the mechanical behavior of the E-glass fiber/polyester composite structure under the influence of thermal preloading on the glass fiber fabric have been studied. For this purpose, in addition to performing mechanical tests, scanning electron microscopy (SEM) has been used to investigate the manner and nature of glass fiber breakage as well as the cross-sectional area of fiber fracture. Also, the changes in the state of the bonding agent on the surface of the glass fibers used in the woven fabric, in the initial conditions of as received fabric and also in its secondary conditions after applying thermal preload by placing it in an oven at 350 °C temperature was studied. In this regard, the Attenuated Total Reflectance (ATR) infrared spectroscopic analysis method was used. The results indicate a significant decrease in the mechanical properties of the manufactured composite, as a result of applying thermal preloading on plain fabric made of E-class glass fibers, before the impregnation stage with unsaturated polyester resin.

Incremental forming of metal sheets is one of the new methods of forming, in which the local exertion of forming forces and the absence of a matrix enhances the forming limit of the sheet and extends the flexibility of process in producing of complex geometries. In this research, the forming limit of aluminum/copper bilayer sheets in the single-point incremental forming of different geometries was studied. Considering the instability mechanism of the sheet, the Xue-Wierzbicki damage criterion was used in the form of the VUMAT subroutine of Abaqus in the numerical prediction of the growth and damage initiation of bilayer sheets. Experimental tests showed that the type of geometry has influences on the forming height limit due to the different induced stress and strain states on the sheet. The prediction of the numerical model of the forming height limit on average for different geometries with difference of 8% compared to the experimental tests, which indicates the validity of the numerical model. Accordingly, using the numerical model, the effect of changes in equivalent plastic strain and triaxial stress as crucial variables on the distribution of surface strains and damage was analyzed. Also, cyclic and nonlinear loading in this process was shown by plotting the strain path for different geometries.

Tubular channel angular pressing (TCAP) process is one of the new methods to produce tubes with very good mechanical and microstructural properties. The trapezoidal channel cross-section is preferred in this process due to its high strain homogeneity and low required load compared to other channel cross-sections. In this research, the TCAP process with a trapezoidal channel cross-section was modeled using different channel and curvature angles in Abaqus software and then one pass of the process was applied to annealed aluminum 6061 samples. After that, the effect of these angles on the effective strain as well as process load was shown. For validation, the results of the finite element method (FEM) were compared and analyzed with the analytical model. The results of the processed samples showed that reducing the channel and curvature angles increases the applied effective strain. By increasing the curvature angle, the strain homogeneity has increased, and as a result, the hardness and microstructure homogeneity have increased. The process load has also decreased with the increase of channel and curvature angles. Also, there was a good agreement between the FEM results and the analytical model.

In tube hydroforming, by applying internal pressure using a fluid such as water or oil, bulging is created in the tube and the tube conforms to the inner walls of the die. In this paper, using hydroforming process in manufacturing of a branched joint with two branches on copper tubes has been investigated. This type of joint is used in various fluid transmission lines. Simulation of the forming process has been done in Abaqus finite element software. The effect of four important process parameters on the quality of the formed product has been studied. Considering the complex shape of the desired product, effect of four parameters of initial feeding, final feeding, yielding pressure and bursting pressure have been investigated and the effect of these parameters on the height of the formed branches and the maximum thinning has been determined. The results showed that with the appropriate selection of process parameters, a product with two branches with good quality can be obtained in one forming step. The most effective parameter on the height of the formed branch is the final feeding, so that increasing final feeding leads to more height of formed branches. On the other hand, bursting pressure has the most important parameter affecting the thinning. The initial feeding has the least effect on the thinning and the height of the formed branch.

In this paper, the mechanical behaviors of beams with square and circular cross-sections that are hollow and filled with foam have been studied under three-point bending using finite element analysis. Aluminum alloy AA6063-T6 and AlSi7 foam are considered tube materials and foam, respectively. The amount of deformation, bending strength, and energy absorption of the beams under different conditions were investigated and compared with each other; finally, sections with the highest bending strength and energy absorption capacity were determined. The results showed that in foam-filled beams, the bending strength has increased compared with hollow ones; also, the bending strength during loading is preserved after the first damage, even increasing. Double beams filled with foam (hollow composite beams) showed higher bending strength as well as energy absorption compared to solid composite beams, in spite of their lower weight. The highest amount of bending strength was observed in square-section beams filled with foam.