SKD 11 tool steel is among the most popular metals in mold industries for making different kinds of cold work molds and dies with high accuracy and long service life. The demand for higher quality, lower manufacturing costs, particularly the environmentally friendly characteristics, have provided the stimuli for manufacturers and researchers to find alternative solutions. An excellent media is formed in the cutting zone by using MQL nanofluids in order to enhance the thermal conductivity and tribological characteristics; therefore, improving the machining performance. The formation of the lubricating film as well as the rolling action of nanoparticles in contact zones has gained much attention in the machining field. In this research work, the application of MQL Al2O3 nanofluids with vegetable oils and emulsion 5% is developed for SLOTTING end milling of SKD 11 steel using normal HSS tool. The cutting forces, tool wear, tool life, and surface roughness are investigated to evaluate the effectiveness of MQL nanofluid on cutting performance. The experimental results reveal that the cutting forces and cutting temperature decrease and the surface quality and tool life enhance. Furthermore, the improvement of the thermal conductivity of nanofluids is proven when compared to pure fluids. Due to the rise of viscosity and thermal conductivity, the soybean oil-based nanofluid, which is almost inherently nontoxic, gives superior lubricating and cooling properties suitable for MQL application compared to emulsion-based nanofluids. The novel environmental friendly technology definitely brings out many technological and economic benefits in machining practice.

Composites reinforced with carbon fibers have various applications in different industries, due to their physical and mechanical properties. In this regard, multi-walled carbon nanotubes are used to strengthen the epoxy resin base, which is one of the emerging and important materials. Since machining is required to repair reinforced composite parts, in this research, the damages caused during the process should also be investigated and solutions should be provided. In this study, the delamination damage in the machining of composite parts of epoxy reinforced with carbon fibers and multi-walled carbon nanotubes has been discussed. In this regard, experiments have been conducted with a carbide end-mill at different cutting speeds and feed speeds. Then the delaminations created in these tests are studied. In the analysis of the results, by increasing the rotational speed from 500 to 2500, the amount of delamination increased by 25% and the force decreased by 87%. Also, solutions that include reducing the feed speed will have a significant effect on improving the final quality of the machined part.

Cold work hardening and nonlinear strain path, cause the failure strain change. Therefore, it is necessary to consider the created cold-work hardening and its distribution for predicting and simulating the behavior of products. The composite rupture disc cold-work hardened during manufacturing and burst and release pressure in a pressure commensurate with this hardening. In this case, the sheet metal undergoes a nonlinear strain path during forming and after SLOTTING during the burst test. In this paper, the burst pressure of a composite rupture disc is estimated by using finite element simulation in Abaqus-implicit and explicit and by considering the strain hardening during bulge forming before the SLOTTING process. The burst pressure is estimated according to the maximum plastic failure strain that changes due to nonlinear strain path and work hardening. The burst pressure predictions were compared and validated by experimental tests. In this paper, the effect of SLOTTING pattern is investigated by using FEM simulations and experiments. In the prepared samples for this paper, by SLOTTING after bulge forming, the burst pressure reduced more than 80%. The simulation with this method predicted this pressure reduction with an error of about 3%.

The purpose of this paper is to introduce a new type of a load commutated voltage-forced synchronous machine drive which is capable of controlling the stator current waveforms, an approximate to sine wave. Then, Schawarz-Chirstoffel transformation is utilized to obtain the harmonic series of the air gap magnetic conductances of the mentioned machine due to the stator SLOTTING with smooth rotor and vice versa. These harmonic series are used to calculate the rotor to stator mutual inductances for both types of the skewed and unskewed rotor machines. The drive system equations are derived and used to develop a C++ computer program to model the machine drive system on PC. Finally, the system simulation results obtained are compared to some available practical results.

The purpose of this paper is to present a new hybrid analytical model (HAM) based on winding function theory (WFT) for electromagnetic analysis of performance of one typical unbalanced two-phase induction motor (UTPIM). Different indexes of electromagnetic modeling such as winding distribution, SLOTTING effect, and magnetic saturation can be accurately considered by using the proposed HAM. For obtaining this new hybrid technique, the winding function theory is reformulated for considering the magnetic saturation in addition to the influence of SLOTTING and winding distribution. The conformal mappings (CMs) are used to accurately calculate the slotted air-gap length. The magnetic equivalent circuit (MEC) model is used to consider the magneto-motive force (MMF) drop in iron parts of stator and rotor due to the excitation of one phase-winding. The obtained results of CMs and MEC are then utilized in reformulated WFT to calculate the inductances of respective phase-winding. Transient analysis is then done to calculate the indexes of performance such as air-gap magnetic field, phase currents, electromagnetic torque, and rotor speed by using the lookup table of inductances while considering different capacitors in auxiliary phase. In each step, the accuracy of analytical results is verified by comparing with corresponding results obtained through FEM.

The helium compressor has the inherent characteristics of a lower single-stage pressure ratio and a higher number of stages than an air compressor. The highly loaded design method effectively addressed the compressibility issue of the helium compressor. However, the compressor designed with this technique has narrow passages, short blades, and a large bending angle, making the end-wall secondary flow more intense than a conventional compressor. In this paper, numerical simulation and experimental validation has been conducted to identify the effectiveness of the axial slot close to the blade root in improving end-wall secondary flow in a high-load helium compressor cascade, and to provide data and experimental support for the engineering application of high-load helium compressors. The analytical results show that SLOTTING can utilize the self-pressure difference to generate gap leakage vortices, and the axial momentum generated by the leakage vortices blows away the vortices formed due to the separation of corner area. The airflow flows close to the suction surface of the blade and breaks away at the trailing edge of the blade, merges with the main flow and forms a new vortex. As the height of the channel increases, the blowing away of the vortices in the corner region becomes more pronounced and the cascade improvement performance is better. The test results show that the total pressure loss coefficient at the design operating point is reduced by 6.167% when a slot height of 8.53 mm is positioned at 65% Ca (axial chord length). The improvement effect becomes 16.469% better at a 4° attack angle.

Examining the mechanical properties of polymer materials has particular importance due to the increasing usage of these materials. In this paper, the crack development process was identified using the experimental data obtained from the tensile tests of polyvinyl chloride polymer (PVC) to reduce the experimental test number. Some pre-cracks were created on the experimental samples by SLOTTING and broaching methods and the experimental results of force versus displacement were recorded for each sample. In the next step, some mathematical pre-processing operations including equating the sampling intervals using interpolation and integration using trapezoidal methods were performed on the experimental data. In the third stage, by using the pre-processed data and the Least Squares (LS) identification method, the mathematical model of the system, the frequency domain discrete transfer function of the crack development process, was obtained. Finally, after evaluating and verifying the obtained mathematical model with other experimental results, it was proposed to predict the crack development process. The obtained results showed that by identifying the crack development process for limited samples, it is possible to avoid the number of experimental tests that are time-consuming and costly. In addition, the second-order two-stage least squares method with five unknown parameters was promisingly able to estimate crack development dynamics with acceptable accuracy, particularly in the first half of the development process.

An exact 2D analytical method for magnetic field and electromagnetic torque calculation in high speed spoke type interior permanent magnet Machines considering SLOTTING effects, magnetization orientation and winding layout has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in polar coordinate by using sub-domain method and applying hyperbolic functions. The proposed method is applied on the performance computation of a prototype spoke type permanent magnet machine, i. e., a 3-phase 18S-8P motor. The analytical results are validated through FEA method and experimental tests.

This paper analyzes an induction motor with high temperature superconducter (HTS) coated slotted solid rotor. By SLOTTING the solid rotor, the electromagnetic torque near synchronous speed will increase but the starting torque will decrease. To improve starting torque, rotor slots are coated with HTS materials. Using HTS material vary the rotor resistance to great extends in starting step and this means the starting torque will be maximized. Also the torque near synchronous speed will be higher than before because of the resistance of the HTS is completely zero in this period. This would help the torque become more than the case without any coating. It is concluded that, HTS coating of slotted solid rotor will increase the starting torque by 42 and 74% than smooth type rotor and slotted one, respectively. For case-study motor, the torque near synchronous speed these improvements were 75% and 33%, respectively. The performance of the proposed motor is simulated using finite element method (FEM).

In this paper, a dynamic model is provided to obtain the waveform of the unbalanced magnetic force in the wound rotor induction machines with static eccentricity. The provided dynamic model is based on the voltage state-space equations of the coupled circuits in the eccentric induction machine. In the model the SLOTTING effect and saturation is neglected and the slot ampere turn is distributed on the slot opening. To avoid computation of the air gap flux density and evade of magnetic pressure integration in each time-step of Runge-Kutta computations and consequently reducing the computation time of dynamic simulations, a static function of the stator and rotor windings’ currents are proposed for computation of the unbalanced magnetic force. The parameter of the proposed function is obtained by analyzing the air gap field density by using winding function theory. Finally, the waveform of the unbalanced magnetic force of the eccentric induction machine is obtained and verified by time-stepping finite elemnt analysis.