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Ultrasonic technology has been applied in many industrial processes such as ultrasonic machining, welding, cutting, sewing, homogenizing, etc. In an ultrasonic system, acoustic horn transmits the vibration energy of ultrasonic transducer to the application area and amplifies the oscillation amplitude. Depending on the application and industrial operating conditions, different horns with different geometries and magnifications are required to be designed. In the present study exponential horns with rectangular cross-section for application in ultrasonic assisted grinding process are designed and analyzed. An analytical approach is applied to model this type of horns. For evaluating the analytical model, some acoustic horns are designed using analytical method and then analyzed by the finite-element method (FEM) in ANSYS. Then, their design parameters such as resonance frequency and amplification factor are compared and verified. A very good agreement is obtained between the results of analytical modeling and those of FEM simulation. Furthermore, geometrical modification was introduced as a solution to coincide the vibration related parameters of the horn to the desired design values. Moreover, a horn-workpiece assembly for applying in ultrasonic assisted grinding was simulated.

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Plasma assisted machining (PAM) is a method to improve machinability of hard turning. The process of plasma assisted machining for turning applications utilizes a high-temperature plasma arc to provide a controlled source of localized heat, which softens only that small portion of the work material removed by the cutting tool. The goal of this study is to present a methodology for determination cutting force during plasma enhanced turning of hardened steel AISI 4140. In this regard, a finite differential model was made to estimate the uncut chip temperature under different plasma currents, cutting speeds and feeds during PAM. A mechanistic model developed to estimate cutting force under different PAM conditions by considering shear stresses in the primary, secondary shear zones and force on the tool edge. The proposed model was calibrated with experimental hard turning data, and further validated over practical PAM conditions. Mean errors of predicted values and experimental data is lower than 10 percent. It is shown that PAM can decrease main cutting force in comparison to convectional to 40 percent in turning of hardened steel at high levels of uncut chip temperature due to softening the material.

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The two thermal effects, thermophoresis and photophoresis phenomena that cause particle movements due to thermal gradient through the liquid and thermal gradient through the particle, respectively, have been widely studied over the past years because of their wide range of applications. This thermal gradient can be made by laser beam. There are a few studies concerning these two effects, especially photophoresis, in liquid media. In this paper, these two effects and their induced velocity to particles are studied in liquid media. The affecting parameters on these effects are studied and their effect on particles are determined. Effect of laser parameters like laser power and wavelength in the channel are discussed and the maximum velocity and temperature inside the channel are calculated. Also in the photophoresis part, the effect of parameters like laser power, particle and laser beam diameter is calculated. By considering the existing models for calculation of thermophoretic velocity, Brenner model is chosen as the most accurate model and will be used in calculations. It is also found that the effect of laser wavelength on thermophoretic velocity is more than changing laser power. In the photophoresis part, photophoretic velocity is calculated by using existing analytical models. The calculated velocities of thermophoresis and photophoresis are compared with the experimental values and there is an acceptable matching between them. The results of this paper will be used for designing and making a particle separator tool.

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In this research the influence of the striker shape on orthotropic composite plates for states, no damage (delamination) and damaged (delamination) are studied. In the analytical method, the spring mass system is used and new analytical model for flat and conical strikers are investigated. In the numerical method, the impact of different strikers on the composite laminate is simulated by using of finite element package (AnsysLs Dyna). These studies have been done on plates made of carbon and epoxy and the sheet thickness has been investigated in the size of 2, 4 and 6 mm. The striker mass is 3 g and its velocity for each thickness is different. To investigate the effects of the striker shape, three nose shapes spherical, conical and cylindrical with flat nose are modeled. The impacting time, the displacement time history and the maximum central deflection, and the contact force for all strikers are obtained and compared with each other. The results of analytical model are good agreement with numerical simulation. According to the results, when the delamination occurs, the maximum central deflection is more than once that damage dose not occurs. According to the results, the maximum central deflection of the flat striker on for both cases, with and without delamination, is less than the other strikers, conversely, the maximum contact force is more than the other strikers.

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In this study, the influences of drying conditions on the mass transfer characteristics of kiwi slices are investigated using the analytical model proposed by Dincer and Dost. The experiments were conducted at temperature range of 50–80°C with 0.5 m s^-1 air velocity for convective drying and in the microwave power range of 200–500W for microwave drying as single layers with sliced thickness of 3, 6, and 9 mm. The results show that the mass transfer characteristics strongly depend on the drying conditions. Through the convective drying method, parameters including moisture diffusivity, mass transfer coefficient, Biot number, and drying time were varying from 0.16-1.45×10^-8 m² s^-1, 1.93-4.95×10⁻⁷ m s^-1, 0.103-0.225, and 90-604 minutes, respectively. In comparison, for microwave drying, they were within the ranges of 0.66-25.60×10^-8 m² s^-1, 0.62-5.64×10⁻⁵ m s^-1, 0.960-1.742, and 4-23.5 minutes, respectively. Results reveal that the activation energy for moisture diffusion is higher than that needed for the convective mass transfer process.

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The grinding process is one of the most important and widely used machining processes to achieve the desired surface quality and dimensional accuracy. Since the undeformed chip thickness is not a constant value in the grinding process and is changing independently and momentarily for each abrasive, the determination of the undeformed chip thickness accurately is essential to determine the grinding forces and surface topography of the grinding wheel. Previous studies on grinding forces were mainly regardless of the micro-mechanisms between the abrasive and the workpiece. On the other hand, only the average values ​​of forces could be calculated by determining the average value for undeformed chip thickness. In this study, a new analytical model with the approach of kinematic-geometric analysis of abrasive grain trajectory is presented to determine the undeformed chip thickness and subsequent grinding forces. This model predicts the components of normal and tangential grinding forces (including sliding, plowing, and cutting forces) accurately and in detail based on the instantaneous undeformed chip thickness obtained from the kinematic analysis of abrasive movement and micro-mechanisms between abrasive and the workpiece. In the end, experimental tests were performed to validate the theoretical model.

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