This study introduces a novel retainer ring design aimed at mitigating the edge effect during chemical mechanical planarization. The innovative design features an arch-shaped geometry that creates a bending effect, thereby reducing excessive pressure on the wafer's edge. A two-dimensional axisymmetric finite element model was developed, and simulation data were utilized to create a metamodel. Multi-objective optimization was conducted using an evolutionary algorithm, focusing on the normal contact stress on the wafer surface. Representative Pareto-optimal designs were analyzed to assess the distribution of normal contact stresses. The results demonstrated that the proposed design significantly reduced peak normal stresses and enhanced stress uniformity, especially at the wafer edge. This optimized retainer ring is anticipated to improve wafer edge quality and increase semiconductor yield.
In Hopkinson bar theory, stress, strain, and strain rate can be determined by analyzing the dimensions of the specimen. When conducting Split-Hopkinson Pressure Bar (SHPB) experiments, the stress-strain curve is obtained by considering the entire length and width of the specimen. However, in Split-Hopkinson Tensile Bar (SHTB) experiments, it is important to only consider the regions where deformation occurs in order to accurately determine the dynamic material properties. This study introduces a method for selecting the dimensions of the deformed region (LD and WD) in plate specimens for SHTB experiments using Finite Element Analysis (FEA). The analysis involved varying the length and width of a 1 mm thick SUS430 specimen, and the deformed region was determined using the proposed method. The stress-strain curves obtained from this region were then compared with the input Cowper-Symonds model. The validity of the proposed approach was confirmed, as the percentage error between them ranged from 2.54 to 6.62%.
This paper proposes a high-fidelity finite element model of a permanent synchronous motor (PMSM) to predict electromagnetic responses. The proposed method aims to generate electromagnetic responses from the PMSM under various operational conditions-including normal and faulty conditions-by coupling several partial differential equations governing the electromagnetics of a PMSM. The rotor eccentricity is considered to be a representative fault of a PMSM, which has electromagnetic characteristics that differ from the healthy state of a PMSM. Note that eccentricity is the most frequent fault during PMSM operation. Therefore, the proposed model could replicate the defected torque responses of an actual motor system. The effectiveness of the proposed model is validated using measurements from a PMSM test bench. Quantitative comparison reveals that the proposed model could replicate both the transient- and steady-state torque responses of the PMSM of interest at a variety of operational conditions, including a faulty status. The proposed model could be used to generate virtual electromagnetic responses of a PMSM, which could be used for data-driven fault detection methods of electric motor systems.
Ground drilling technology for drilling has an environment where the major parts are prone to damage due to high stress, torque, and harsh operating conditions that can occur in the rotary power transfer structure. Research for preventing this damage is very important, as it can be coupled with the nature of drilling operations that take a long time in operation, which can lead to enormous cost and time consumption. Previous work investigated the cause of damage by analyzing the working environment and breakage of drilling holes for connecting rods, and a power transfer component of directional mud motors used in ground drilling systems. The material properties by heat treatment conditions for applied materials were analyzed. Based on prior work, we evaluated whether the stress concentration part shown in the analysis results matched the actual damage occurring point by conducting a structural analysis of the connecting rod, a damaged part, using the finite element analysis. We also analyzed how to reduce the stress concentration phenomenon that occurs during the mud motor operation by conducting part shape and design changes between the connecting rod and key parts.
Until recently, solar energy has been considered as a promising regeneration energy source in the future. Solar cell wafer production involves ingot cutting, cleaning, and packaging processes. In this research, design, fabrication, and testing of a batch-type midsonic for cleaning solar cell wafers were carried out. To reduce the damage compared to conventional systems, we decided to use 400 kHz in a midsonic wave range, and we used far-field to obtain a more regular acoustic pressure. Finite element analysis with Ansys software predicted an anti-resonance frequency of 458 kHz for an ultrasonic waveguide, and the measured result of the fabricated system was 454 kHz with a 0.9% error. Acoustic pressures were measured, and the result confirmed regular and high distributions. Finally, cleaning tests were performed, and a 90% particle removal efficiency (PRE) was achieved at 900 W. Thus, the newly developed midsonic cleaning system can be considered to clean particles on solar cell wafers efficiently while preventing damage.
Research on the application of additively manufactured polymer (AMP) to the conventional manufacturing process is underway. In this study, an additively manufactured die-set (AMDS) was used and applied to the warm forming of the magnesium alloy. Heat transfer and coupled temperature-displacement analysis were conducted in the V-Bending and UBending processes to study the applicability of the AMDS to the warm-forming process of the magnesium alloy sheet (AZ31B). A heat transfer experiment was conducted to determine the thermal contact conductance between the AZ31B material and two types of die-set, the metal and AMP. V-Bending and U-Bending experiments were conducted at 373 and 423 K; reduction in temperature between metal die-set and the additively manufactured polymer die-set were compared. The springback after the bending process with different initial temperatures and die materials was investigated. The simulation model showed good agreement. The springback of AZ31B was more decreased with the additively manufactured polymer die-set than with the metal die-set. The stress of the additively manufactured polymer die-set in the bending process was very small. It was confirmed that in the AZ31B material, the additively manufactured polymer die set helps increase the formability and decrease springback by keeping the temperature of AZ31B better.
Since its introduction, the Modified Maximum Force Criterion proposed by Hora et al., has been widely used to theoretically estimate the forming limit curve of metal sheets. On the basis of this criterion, a graphical method was presented in our previous study to simplify the evaluation of the forming limit curve (FLC) of metal sheets. This paper presents an application of the graphical method to estimate the FLCs of an advanced high-strength steel sheet material, DP590. The material is frequently used in the automotive industry. To verify the ability of the graphical method, various hardening laws and yield functions were used to estimate the forming limiting curves for the examined material. The calculated forming limiting curves are then adopted for the finite element method (FEM) to predict the fracture heights of different notch specimens desired by the Hecker’s punch stretching tests. The results of the finite element method simulations agree well with the values of the fracture heights, in comparison to the experimental data. This verifies the ability and potential of the graphical method in industrial engineering.
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In recent years, machinery industries such as aerospace and automotive industries have adopted high-precision machining. Cutting fluids increase the tool life and productivity through cooling and lubricating the machinery during processing. However, the cutting oil causes environmental pollution while the reuse of waste fluids negatively affects the tool life and machining quality. Therefore, it is important to study cutting oil environmental reuse methods and develop eco-friendly equipment such as a DC (Dust cake) filter system. In this study, the structural analysis was done using finite element method (FEM) to verify the stability and a study of the DC filter frame design improvementdone. Based on the damage on the DC filter system, the cause of the damage was assessed and an improvement to the structure suggested. Finally, the structural stability of the improved design was verified through analysis. The results of this analysis could be applied in order to further research.
Linear roller bearings are often used for linear positioning systems due to high load-carrying capacity, precision, and durability. In this paper, guide rail deformation of linear roller bearings under vertical and horizontal loads, has been experimentally investigated. An experimental system was made to measure displacement of the carriage and guide rail deformation of a bearing with varying load. Guide rail deformation inaccessible inside the carriage, was estimated by measured carriage displacement subtracted from calculated carriage displacement from a commercial program, that does not consider flexibility of guide rail and base. In addition to estimated deformation, guide rail deformation outside the bearing carriage was measured to make a complete guide rail deformation curve due to external loads. Results revealed deformations occurring in guide rail and base are significant, as to affect bearing accuracy. Thus, deformations in guide rail and base should be considered, to estimate stiffness and motion accuracy of linear roller bearing under external loading conditions.
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For 3D printing of high-strength polymers, such as PC (Polycarbonate) and PEI (Polyetheimide), the temperature of the nozzle should exceed the melting temperature of the high-strength materials. At the same time, the temperature of the transfer part, composed of the shaft extruder and the Teflon hose, should be cooled below the glass transition temperature and below the limit temperature of the transfer part. In this study, we analyzed the effect of the flow rate of the cooling fan when the extruder nozzle is heated to 300oC. We compare the natural convection environment, in which the cooling fan is not operated, and the forced convection condition, in which the cooling fan is operated, and analyze the effect on the cooling fan flow rate. The simulation considered the heat transfer in the air and the nozzle, as well as the flow characteristics of the air.
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FEM (Finite Element Method)-based numerical analysis model, which is known as CAE (Computer Aided Engineering) technology, has been adopted for the visual/mechanical analysis of machining process. The essential models for the FEM analytical model are the plasticity model of workpieces, friction model, and wear rate model. Usually, the outputs of the FEM analytical model are the cutting force, the cutting temperature, and chip formation. Based on these outputs, the machining performance can be virtually evaluated without experiments. Nowadays, there are emerging machining technologies, such as cryogenic assisted machining and CFRP machining. Therefore, FEM technique can be one of the good candidate to virtually evaluate emerging developed machining technologies.
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Recent use of mobile phones as a multimedia device has increased the development of micro-speaker modules having high quality and a compact size. Micro-speakers use polymer diaphragms fabricated by the thermoforming process. To improve the sound quality, micro-speaker diaphragms are usually designed to contain a number of micro-corrugations. This study investigated the effects of the corrugation depth on the acoustic characteristics of the diaphragm, using finite element (FE) analysis. Structural FE analysis was performed to investigate the stiffness change according to the corrugation depth. Modal FE analysis was used to compare the change in natural frequencies for each case. Harmonic response analysis further investigated the resulting variation in acoustic power. The effects of the corrugation depth on the acoustic characteristics of the diaphragm were discussed by reviewing all the FE analysis results synthetically.
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This paper describes the design of the beam of a gantry robot for Computer numerical control (CNC) lathe that can automatically attach and detach a workpiece. The gantry robot takes the unprocessed workpiece from the stoker and mounts it on the chuck of a CNC lathe. The robot then removes the processed workpiece fixed to the chuck and places it in the processed workpiece stoker. The workpiece consists of a body, x-axis beam, x-axis driving device, y-axis beam, yaxis driving device, z-axis beam and z-axis driving device. Finite element analysis was performed to design the x-axis beam, the y-axis beam, and the z-axis beam. Based on the results, the optimal size of the x-axis beam was designed to have a size of 150 mm × 150 mm × 4681 mm with a thickness of 9 mm. The x-axis beam is less eccentric in the position of the chuck of the CNC lathe.
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