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Wire EDM (WireCut) is a machining process utilizing electric discharge to gradually cut a workpiece with a spark-generating thin wire. It offers benefits like non-contact cutting, versatility with materials, and precise dimensional accuracy. However, it is important to note that surfaces cut by WireCut process may exhibit tensile residual stresses with significant values in the surface layers. Ultrasonic Peening Treatment (UPT) can be employed as a new approach to modify the surface structure of wire EDMed workpieces. UPT, which induces compression in the surface layers of the workpiece, generates compressive residual stress and enhances mechanical properties including hardness. In this study, UPT was performed on wire EDMed workpieces made of alloy steel Mo40 (DIN 1.7225) using an ultrasonic vibrating tool on a lathe, at 3 levels: finishing, semi-finishing, and roughing. The impact of parameters such as the number of passes, feeding rate, and the type of wire EDM cut on the constant amplitude of vibration were studied to understand their effect on the residual stress generated. The experiments conducted using the Taguchi method revealed that in every case, this process resulted in the conversion of tensile residual stresses into substantial compressive residual stresses in wire EDMed workpieces. The compressive residual stress also reached 1654 MPa. More passes lead to higher compressive residual stress, while a higher feeding rate leads to a decrease. Surface hardness increased by 30%, 31%, and 48% for the semi-finishing, finishing, and roughing workpieces in the initial pass. This trend continued with each subsequent pass.Key words: Residual stress - Surface hardness -Wire Electric Discharge Machining (WEDM) - Ultrasonic Peening Treatment (UPT) - Mo40 alloy steel

Turn-milling is a new process that uses, turning and milling operations together, so that the tool and the work piece rotate simultaneously, for this reason, it has a wide ability in machining curved and complex surfaces. The Main subject of this research is Conducting research on the effect of changes in machining parameters, including work piece rotational speed, tool rotational speed and feed rate, on cutting parameters such as cutting force, cutting pressure, and surface finish parameters. The order and the number of experiments is designed based on the full factorial method. Experiments for each of the mentioned parameters were performed at three levels, which includes 27 tests in total. The results were analyzed with the help of Minitab software. The mentioned process was performed with a φ6 diameter end mill on a steel work piece 1.7225. As a result, increasing feed rate by three times increases the machining force by about two times and reduces the cutting pressure by about 27%, Also, the surface finish quality parameters R a  and R z  increased by 74% and 61%, respectively. The upward or downward trend of cutting forces, cutting pressure and the surface finish quality did not occur with the increase in the rotational speed of the work piece and the rotational speed of the tool, in fact, an extremum range was achieved in the increasing trend of the mentioned speeds. So that the minimum resultant force and also the cutting pressure were observed in the range of rotational speed of 950rpm of the tool and 300rpm of the work piece.

Achieving the required dimensional and geometrical accuracy as well as the appearance and performance quality in the production of industrial parts and the availability of interchangeability in the assembly and supply of spare parts for products has been one of the important challenges of the industry. In this research, the effect of adding axial ultrasonic vibration to the tool on the geometric accuracy of the Al6061-T6 work piece in the milling process was investigated. By analyzing the results, it was found that the presence of axial ultrasonic vibration improves the parallelism and flatness of the wall and the smoothness of the bottom surface as well as the perpendicularity of the wall with the bottom. It was also observed that a higher feed speed increases geometric deviations and surface roughness, while a higher cutting speed reduces them. By comparing the graphs, it was found that the positive effect of ultrasonic vibrations on the quality of the surface and the geometric accuracy of the work piece is more noticeable in the conditions of lower cutting speed and higher feed; That is, the condition in which we face the worst surface quality and the lowest geometric accuracy in conventional milling.

Nowadays, the number of oscillations applied to some parts reaches the range of 107 and higher. Recently, researchers have used ultrasonic fatigue tests to study the fatigue behavior in these parts. This device is considered because of the high frequency of loading and as a result, achieving a higher number of oscillations in a shorter time. There is no universally accepted standard for this test, therefore, one of the geometries that are often used as a sample in this test is the geometry in the form of an hourglass In this research, while investigating this geometry in order to achieve optimal geometry or achieve maximum stress, the effect of geometric parameters on temperature increase during high-frequency vibration or the thermoelastic effect, which is known as one of the disadvantages of ultrasonic fatigue testing, has been investigated. This effect should also be minimized. For this purpose, the dimensions of the hourglass geometry were defined as parameters and its changes were investigated using the simulation. The results showed by decreasing the radius of curvature, along with the stability of the middle diameter and the diameter of the cylindrical part, the amount of stress increases and also the amount of temperature changes decreases. On the other hand, the diameter of the cylindrical part increases, while the middle diameter and the amount If the curvature is constant, it will increase the amount of stress and temperature. The above results were evaluated using the experimental arrangement and a good match was observed in them.

In this paper, an ultrasonic horn based on the PSO algorithm for emulsion homogenization is optimized and fabricated. The application of various ultrasonic instruments such as horns in different industrial procedures is increasingly expanding and developing. Horn is a tool that has played a crucial role in the energy transfer to fluid. Longitudinal frequency, vibration amplitude, length-to-diameter ratio, a distance of frequency from other frequency modes, wide distribution of cavitation along with the horn’s length, and increasing the area of acoustic energy transfer are the main characteristics of the horn design procedure. Therefore considering these important features with using the PSO algorithm and electro-mechanical circuit method to finding resonance frequency, the design procedure of the optimized horn is performed. The definition of the objective function is based on the horn’s amplification factor, and the rest of the other characteristics are defined as design constraints. The simulation results show a 15% improvement in the natural frequency compared to the target frequency and a suitable frequency distance of 2.5 kHz between the previous and next modes. According to the barbell part of the horn, the amplification factor of 14 was obtained for the proposed horn, the frequency and amplitude of the vibration were evaluated. The experimental results were very close in terms of amplification factor and frequency to the simulation results with reasonable accuracy.

Machining of hard workpieces is one of the most important challenges of the manufacturing industry. Hence, new methods were added to traditional machining. Ultrasonic vibration machining is one of these methods. The advantages of using ultrasonic vibrations compared to traditional machining include reducing machining forces, reducing tool wear and friction, increasing tool life, creating intermittent cutting conditions, increasing surface quality, and so on. To vibrate the tool, a horn with a resonant frequency of 20,633 Hz was analyzed by Abacus software. In this study, the effects of cutting speed, feed rate, conventional machining conditions, and vibration machining conditions at three different hardness of 15, 30, and 45 Rockwell C for the workpiece on surface roughness and tool wear were evaluated. The experiments were designed at full factorial, and a total of 54 experiments were performed. The results showed that at higher workpiece hardness by applying vibration the surface roughness was reduced. The surface roughness (Ra) in machining by means of ultrasonic vibrations is up to about 36% less than conventional machining in various machining parameters. In addition, the temperature in vibration machining is lower about 15% at higher stiffness of the workpiece. Also, with the increase in the hardness of the workpiece, the tool wear was increased, which is less by applying ultrasonic vibrations. Also, by applying vibrations, tool wear was reduced in total, which can be minimized by selecting cermet tools and applying vibrations in 4140 AISI steel machining.

The high amount of nitrogen in the composition of AISI 440C stainless steel reduces the machinability of this steel due to the increase in hardness and generates high heat at the cutting edge and the chip-tool contact area. The use of new cooling technologies such as cryogenic machining using liquid nitrogen LN2, leads to increase the life of the tool and improve the cutting speed compared to other common methods. In this research, the effect of cryogenic machining is investigated on roughness and hardness of AISI 440C stainless steel. The results showed that using cryogenic machining, the surface roughness of AISI 440C stainless steel was significantly reduced even at high feed rate. The morphology of the chips showed that with the use of cryogenic machining, the surface burn and the accumulation of materials on the inner surface of the chips has been significantly reduced. In this study, it was found that in cryogenic machining, the tool wear pattern is the erosion pit on the chip surface and has increased the tool life by 400% compared to the dry machining.

Ultrasonic energy is used for applying severe plastic deformation on metal surfaces. In the present work, the effect of ultrasonic vibration on the formability, microhardness and microstructural properties of St14 steel sheet has been investigated. To be precise, a semi-hemispherical-head forming tool had shaped the specimens until the necking started to happen. Conventional as well as the ultrasonic-assisted biaxial stretch forming test has been performed on St14 steel sheets and obtained data has been used to compare the hardness and microstructure of the specimen with and without superimposing the ultrasonic vibration. It was observed that the hardness of the samples which have been shaped by applying ultrasonic vibrations to the tool with an amplitude of 15µm at 20.5 kHz increased significantly in compared with the samples which have been shaped without using ultrasonic vibration, revealing the efficiency of the ultrasonic operation in increasing the hardness.

In this study, turning operation of Monel K500 copper-nickel super-alloy was evaluated. Ceramic cutting tools with two different cutting noses (conventional and wiper) were utilized. At first, the experimental tests were designed by using central composite design method. After implementation of the tests, the statistical models for output data (surface roughness, cutting force, and flank wear) have been developed. Furthermore, the effect of cutting parameters on output data was taken into account with help of analysis of variance. In third step, the optimal cutting condition was introduced for both cutting tools by using response surface method. In total, it was revealed that low depth of cut and feed rate coupled with high cutting speed is an optimal condition for turning of Monel super-alloy when ceramic tools are selected. In particular, the positive effect of wiper tool on output data was more when depth of cut has been lower than the length of wiper edge.

In this research, finite element analysis of the conventional drilling and vibration assisted drilling is carried out. The ABAQUS software is employed for FE analysis. The Johnson-Cook models for both plastic deformation and damage are employed for FE simulation.The results of the FE analysis are then verified with experimental results in both conventional and vibration assisted drilling on Al 7075 with HSS drill in terms of the drilling axial force and torsional torque. There is a good agreement between the experimental results and the FE simulation results. The results also show that the drilling axial force and torsional torque are reduced in vibration assisted drilling in comparison with that in conventional drilling process. The surface roughness of the holes is also studied in conventional drilling and vibration assisted drilling. The results showed that the surface roughness is exceled in vibration assisted machining in comparison with that in conventional drilling.

In this study, a non-distractive method of x-ray diffraction (XRD) was used to determine residual stress of rolling mill rolls made of graphite steel (GSH48). This method utilizes the variations of distance between crystal planes as strain. The determination of residual stress was performed samples in different depths before and after conducting ultrasonic peening technology. In UPT process, impacts were exerted on the workpiece ball tool, resulting in the improvement of some mechanical properties such as residual stress by creating work hardening and compression. After the simulation and manufacturing of ultrasonic vibratory tool and then the installation of that on lathe machine, UPT operations were conducted on the prepared samples. Measuring residual stress from surface to 0.5 mm depth was performed before and after the UPT process. After the numerical simulation of the UPT, the distribution of experimental residual stress and numerical simulation was compared that the results suggested the increase of compressive residual stress about 0.4 mm from the surface after the UPT process. The rise of compressive residual stress in the rolling mill rolls leads to the increase of their strength and fatigue life and as a result, their working efficiency is boosted. After the UPT process, the grain size of the surface was calculated from the model of the x-ray diffraction using Viliamson-Hall relation that grain size was obtained 60.2 nm. The refinement of surface structure arises because of displacement arrangement again due to vibration with high frequency and severe plastic deformation after the UPT process.

A new dynamic friction model for modeling of elliptical vibration assisted turning (EVAT) was developed in this research. The periodic change of the friction force direction is known to be one of the most important causes of this phenomenon. In modeling of machining processes (including the EVAT process), static Coulomb friction model was employed by most of the researchers. Because of the periodic change in the friction force direction during the elliptical vibration path, the simple Coulomb friction model could not reflect the dynamic friction phenomena between the chip and the tool such as stick-slip and dynamic breakaway. In this research the LuGre dynamic friction model, which had been successfully employed for modeling of EVAT process, was modified in compliance to the machining process. To modify the LuGre model, the LuGre model coefficients were modified so that the effect of the temperature change of the contacting surfaces (which plays a key role in the friction behavior between the chip and the tool) could be reflected by the model. To determine the coefficients, orthogonal machining tests were performed and the Genetic Algorithm optimization method was carried out to derive the coefficients. Afterward, the results achieved from both dynamic models were compared with experimental results and Coulomb model results. The results from the new modified LuGre model were in better agreements with the experimental results.

In this research, a reliable method for estimating the amount of tool wear is presented using image processing in MATLA5 software. Program code that can display wear of the blade milling numerically in the chart is designed to showcase all stages of wear. Preparation of experiments is done. The preparation process includes milling operations, tool, workpiece, vision measuring machine (VMM) and camera were provided for testing. First, the initial configuration for milling machine process (such as: spindle rotational speed, feed rate, depth removal) on the AISI10+0 steel workpiece with covered plating tool was done and picture was taken from all stages of cutting condition. In addition for verifying the performance of the designed code in MATLA5, after each time the edge of tool observed by VMM and wear rate was recorded and data of experiments were stored. As a result, the possibility of determining tool life was carried out with the help of image processing in the milling process. The output data from image processing can specify the tool life and trend of tool life completion.

Due to the trunk muscle weakness after chronic low back pain (CLBP), the evaluation of their function is an important part of rehabilitation protocols for CLBP. Therefore, providing the appropriate tools to measure trunk rotation torque is important. This study has been designed to evaluate the reliability and validity of the attached instruments to Biodex 4Pro for the measuring of isometric and isokinetic torque of trunk rotator muscles. 17 patients with CLBP and 17 healthy subjects (aged and sex matched) participated in the study. The isometric and isokinetic torques of trunk rotator muscles to the left and right were evaluated in 3 sessions with 7 days interval by 2 different examiners. The Persian version of disability Oswestry questionnaire was used to evaluate the validity of instrument. The findings showed that isokinetic and isometric torque of trunk rotator muscles are significantly lower in patients with CLBP than healthy subjects (P=0.013). The findings also indicate a good inter-tester reliability (r=0.62 to 0.82, P<0.01) and intra-tester reliability (r=0.53 to 0.84, P<0.01) of designed attached instrument. Intraclass correlation coefficient calculation between the disability score and trunk rotator muscle torque data from CLBP patients showed a high degree of reverse correlation (ICC= -0.596 to -0.812, P<0.01). The results of present study indicated that the attached instrument has a good validity and reliability to measure trunk rotator muscle torque in patients with CLBP. According to these findings, it is advisable to use of the designed device to evaluate the change of trunk rotator muscle torque after applying the treatment protocols for CLBP patients.

Ultrasonic vibration assisted single point incremental forming (UVaSPIF) is based on localized plastic deformation in a sheet metal blank. It consists to deform gradually and locally the sheet metal using vibrating hemispherical-head tool controlled by a CNC milling machine. The ultrasonic excitation of forming tool reduces the vertical component of forming force. In addition, application of ultrasonic vibration reduces the surface roughness of the specimen. Surface roughness is one of the quantitative and qualitative parameters, which is used to assess the quality of the final product. In the present paper, a statistical analysis and optimization of effective factors on this parameter is performed in the UVaSPIF. For this purpose, response surface methodology (RSM) is selected as the experiment design technique. The controllable factors such as vertical step size, sheet thickness, tool diameter, wall inclination angle, and feed rate is specified as input variables of the process. The obtained results from analysis of variance (ANOVA) and regression analysis of experimental data confirm the accuracy of mathematical model. Furthermore, it is shown that the linear, quadratic, and interactional terms of the variables are effective on the surface roughness parameter. To optimize the surface roughness parameter, the finest conditions of the experiment are determined using desirability method, and statistical optimization is subsequently verified by conducting the confirmation test.

Ultrasonic Vibration assisted Single Point Incremental Forming (UVaSPIF) process is an attractive and adaptive method in which a sheet metal is gradually and locally formed by a vibrating hemispherical-head tool. The ultrasonic excitation of forming tool reduces the average of vertical component of forming force and spring-back rate of the formed sample. The spring-back phenomenon is one of the most important geometrical errors in SPIF process, which appear in the formed sample after the process execution. In the present article, a statistical analysis and optimization of effective factors on this phenomenon is performed in the UVaSPIF process based on DOE (Design of Experiments) principles. For this purpose, RSM (Response Surface Methodology) is selected as the experiment design technique. The controllable factors such as vertical step size, sheet thickness, tool diameter, wall inclination angle, and feed rate is specified as input variables of the process. The obtained results from ANOVA (Analysis of Variance) and regression analysis of experimental data, confirm the accuracy of mathematical model. Furthermore, it is shown that the linear, quadratic, and interactional terms of the variables are effective on the spring-back phenomenon. To optimize the spring-back phenomenon, the finest conditions of the experiment are determined using desirability method, and statistical optimization is subsequently verified by conducting the confirmation test.

This research is carried out to design and manufacturing of lathe vibration tool and their tests. Firstly، one-dimensional vibration tool is designed and made of the bending vibration mode. One-dimensional vibration tool with half piezoelectric rings is considered to excite the bending mode of tool. Structure of vibration tool is designed in Abaqus software about 20 KHz and then is made with respect to the best obtained geometry of tool for bending vibration mode. Finally، two- dimensional vibration tool is designed and made in Abaqus software for elliptical vibration mode. Also، experiment tests are done in turning operations using one- and two-dimensional vibrating tools with bending and elliptical modes on the copper، respectively and the accuracy of the made instruments is investigated. Results show that vibration tool in turning process reduces the main cutting force.

Incremental Sheet Metal Forming (ISMF) is based on localized plastic deformation. In this process, a hemispherical-head tool, controlled by a CNC milling machine, shapes a sheet metal according to a defined path. Study of the forming force is one of the most important topics in this process. Increasing of vertical step size, tool diameter, wall angle and sheet thickness together with using of high strength sheet metals and lightweight alloys, leads to an increase in the forming force. In this paper, the performance of a novel forming process, named Ultrasonic Vibration assisted Incremental Sheet Metal Forming (UVaISMF) has been investigated. The procedure of design, manufacture and test of vibratory forming tool, is presented. The occurrence of longitudinal mode and resonance phenomenon has been confirmed by the results of modal analysis and experimental test. Furthermore, the effect of ultrasonic vibration on the vertical component of forming force and spring-back has been studied. Aluminium sheet of grade Al 1050-O is used as a work material. Experimental results obtained from straight groove test, indicate that ultrasonic excitation of forming tool, will reduce the average of vertical component of forming force and spring-back in comparison to conventional process.

In this paper an innovative vibration rotary tool was designed and manufactured. Vibration turning tool is a compound of turning rotary tool and ultrasonic assistant turning. In this tool، an ultrasonic wave generator with power equal to 20 KHz transducer that has a rotational motion during the process was used. For tool vibration، a stainless horn with resonance frequency equal to 20618 Hz، were designed and manufactured. Round insert with 10 millimeter diameter were used. One of the most important key points in this setup is that the simultaneous rotation and vibration has to be achieved. For rotational motion a motor power and a rack and pinion were used. Also a structure with ability to mount on turning machine were designed and manufactured. Cutting force and surface roughness for each experiment were measured and compared with data collected from conventional rotary tool on 7075 aluminum material. Results shows that ultrasonic vibration cause decreasing in cutting tools and surface roughness، tremendously.

In this work, the influence of different EDM parameters (pulse current, pulse voltage, pulse on-time, pulse off-time) in finishing stage on the surface roughness (Ra) as a result of application copper electrode to a workpiece(cold work steel DIN1.2379) has been investigated. Design of the experiment was chosen as full factorial. Statistical analysis has been done and artificial neural network has been used to choose proper machining parameters and to reach certain surface roughness. The experiment results indicated a good performance of proposed method in optimization of such a complex and non-linear problems.

Lack of balance during sport activities may results in the possibility of sports injuries. Recently, it has been shown that using of warm-up exercise may enhance sensitivity of mechanoreceptors, namely muscle spindle, and so preventing of injury during sport activities. This study was designed to find out the acute effect of warm-up training on the static and dynamic balance indices in athletic and non-athletic subjects. 64 university athletic students (16 male and 16 female) and university non-athletic students (16 male and 16 female) participated in a cross over study and were randomly assigned in one of the two experimental groups: warm-up group (5 minutes running on treadmill) and control group (no intervention), so that all participants attended in both warm-up and control groups in two assessing sessions with 2 weeks interval. Falling risk index, dynamic (bilateral standing) and static (single leg standing) overall, anterior-posterior and medial-lateral indices were assessed by measuring centre of pressure displacement during both eye-open and closed-eye condition before and after the intervention. The comparison of mean changes before and after intervention in both groups showed no significant difference in static balance indices in eye-open condition between groups (p>0.05), while static balance indices in closed-eye condition and dynamic balance indices in both, eyes-open and eyes-closed conditions were significantly improved after warm-up, compared to the control group (p<0.05). After warm-up intervention, falling risk index was reduced significantly (p<0.05) in both athletic and non-athletic participants. No significant difference was found between athletic and non-athletic subjects, in term of static and dynamic balance indices. These results showed that general warm-up training may improve static and dynamic balance control and falling risk in both athletic and non-athletic groups. From these findings may conclude that performing general warm-up training prior to sport activity may prevent of sport injuries by enhancing balance control.