Cable chains are essential in the semiconductor industry for preventing the twisting or sagging of moving cables. They can be broadly categorized into two types based on their fastening methods, with rivet-based assembly being the most common. An alternative method utilizes integral locking features without rivets, which simplifies manufacturing and reduces production costs. However, integral cable chains are more susceptible to breakage during assembly, limiting their use in various industrial environments.This study introduces a structural design approach aimed at minimizing localized stress during assembly while ensuring the cable chain meets the required retention force. Design variables were selected from the modifiable features of the integral cable chain. Through sensitivity analysis, we identified key variables that significantly influence the retention force, which allowed us to reduce the number of design iterations. By employing finite element analysis and response surface methodology, we derived an optimal shape that achieved the target pull-out force and resulted in a 9.7% reduction in assembly stress compared to the original design.

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.

The use of environmentally friendly, lubricant-free plastic seals in the rotating parts of robots and machines is on the rise. However, variations in seal geometry and operating conditions can influence the contact pressure between the seal and shaft, potentially leading to poor sealing performance, premature wear, or debris ingress. Therefore, advanced design optimization is essential. In this study, we conduct a parametric study and sensitivity analysis to enhance the performance of plastic seals. Finite element analysis (FEA) is carried out using a 2D axisymmetric model with interference fit contact conditions to accurately simulate the behavior of the seal and shaft. We verify the reliability of the analysis by comparing the deformation of the seal diameter before and after shaft insertion with experimental measurements obtained using a 3D tactile measurement device. We analyze four design variables: pressure, temperature, seal diameter, and coefficient of friction, considering seal contact pressure as the objective function. Sensitivity analysis is performed to determine the impact of these design variables on contact pressure and to identify trends.

In the case of TV products, space constraints and design requirements make it advantageous to use a worm gear that has a small volume and a self-locking function. Single enveloping worm gear teeth are classified as ZA, ZN, ZK, ZI, and ZC according to international standards. However, combining worm shafts and worm wheels with different tooth profiles can significantly worsen meshing transmission errors and reduce the lifespan of the worm gear. Despite these challenges, due to processing limitations, ease of manufacturing, and cost reduction, combinations of worm shafts and worm wheels with different tooth profiles are still considered. In this study, we confirmed the meshing transmission error for a worm gear that combined a ZA tooth shape worm shaft with a ZI tooth shape worm wheel. Additionally, we examined the contact stress and fatigue life characteristics of the material combinations using finite element analysis (FEM).

Finite element analysis (FEA) was conducted to investigate the cutting process of a single-layer PET film during rotary die cutting. In a roll-to-roll system, cutting blades formed on rollers were modeled as rigid bodies, while the PET film was modeled as an elastoplastic material using a two-dimensional approach. Stress-strain behavior of the film was measured through experimental tensile testing and used as input data for FEA. Force-displacement data from vertical cutting experiments of PET film were collected to validate the FE model and compared with simulation results. Stress distribution of the film and cutting force per unit thickness during the rotary cutting process were analyzed. The cutting force and range of effective cutting angles were proportional to tip angle of the blade within a range of 25 to 60 degrees, showing a noticeable change in proportionality slope at a tip angle of 40 degrees. As the film tension increased, the cutting force in thickness direction decreased, while that in longitudinal direction remained almost constant. Errors in film feed velocity significantly affected the cutting force. When the film moved slightly slower than the reference velocity, the cutting force was minimized due to reduced contact between the film and blade surface.

Glass Molding Process (GMP) is an effective method for producing precise optical elements such as lenses. This simulation study aimed to predict the distribution of temperature and stress within a lens during a multi-stage cooling process of GMP. To develop an accurate simulation model including molds and lens, thermal contact conductance and boundary conditions were determined by analyzing experimental and simulation results. The developed model was used to investigate changes in temperature and maximum principal stress within the lens, considering variations in cooling time, speed, and method at each cooling stage. Simulation results indicated that trends of maximum temperature difference and maximum principal stress within the lens were consistent over time. Results also showed that the maximum principal stress inside the lens increased significantly with additional cooling after uneven temperature distribution caused by a relatively short cooling time. Compared to simulation results of the cooling process involving contact only with bottom surface of the mold, contact cooling with both top and bottom surfaces showed decreased residual stress at the end of cooling and maximum temperature difference within the lens. However, the maximum principal stress could be higher during the cooling process involving both surfaces.

This study focuses on preventing folding defects in the forging process of parachute harness parts. Through three- dimensional finite element analysis, it was determined that folding defects arise from uneven metal flow and timing differences in the filling of various regions. To address these issues, a preform die was designed and evaluated using multi-stage forging simulations. The results indicated that the preform die facilitated uniform metal flow, preventing folding defects and ensuring consistent filling across all key areas. To verify the simulation results, surface and cross-sectional metal flow analyses were conducted. Additionally, the preform die reduced the maximum die load, which is expected to extend die lifespan and improve overall process efficiency. These findings demonstrate that precise control of metal flow and the application of a preform die can significantly enhance the quality and durability of forged components, providing valuable insights for improving forging processes across various industries

A circular flexure hinge is a core element for force transmission and relative motion of precision stages used in semiconductor processes. When designing a circular flexure hinge, calculation formulas for axial and rotational compliance are essential. However, in the case of axial compliance, results of the existing calculation formulas have significant differences from reliable finite element analysis results. In this study, calculation formulas for axial compliance of the circular flexure hinges were derived based on stress distribution phenomenon. Comparison with finite element analysis results confirmed that the newly developed calculation formulas were more accurate than existing ones. It is anticipated that these enhanced formulas will lead to more precise designs, ultimately reducing both time and costs in research and industry.

This study proposed a method for simultaneously reducing mass imbalance and vibration in gimbal systems utilizing a tuned mass damper (TMD) as a balancing weight. Finite element analysis (FEA) and experiments were used for testing the method. Mass imbalance in gimbal systems generally causes external disturbance torque. To reduce this, a balancing weight can be used. However, weight increase due to balancing weight causes resonance in the gimbal system, which generates bias error in the gyroscope sensor. This study demonstrated that both mass imbalance reduction and vibration reduction effects could be achieved by utilizing a TMD as a balancing weight. FEA results showed that the mass imbalance reduction effect of the gimbal was not affected by TMD. The magnitude of vibration response at the resonance point was reduced by about 98% with TMD. When a TMD was applied, the magnitude of the vibration response at the resonance point was reduced by 98% to the same level as that of the gimbal. Bias error of the gyroscope sensor was reduced by about 95% or more. These results show that a TMD is useful for effectively reducing mass imbalance and vibration in gimbal systems while improving gyroscope sensor performance.

A strut tower brace is one of the components that can improve the driving stability of a vehicle. This component has received steady attention for a long time due to its affordable price and easy installation. However, strut tower braces sold in the market have different structures. Moreover, most of them do not contain sufficient information related to safety or stability. Thus, this study aimed to analyze and compare structural behaviors of strut tower braces having various body shapes under bending and compressive scenarios. For this purpose, this study selected six representative models in the market and calculated structural behaviors (stress and deformation) using finite element analysis. Results revealed the body shape had a decisive effect not only on the durability of the strut tower brace, but also on the safety and stability of the vehicle. Among the six models tested, the model having a body shape with a single-axis form utilizing a wide rectangular cross-sectional showed the best bending and compressive performances. This study also confirmed that bending and compressive performances could be simultaneously improved depending on body shape.

Railway axles are among critical components ensuring safe and efficient train operations. They are particularly susceptible to damage mechanisms such as fretting wear and fatigue. Fretting induced by high contact pressure and microslip between contact surface can significantly deteriorate fatigue strength at the contact edge of the press-fit section. Recent research has been conducted to enhance axle strength and reliability. However, fretting wear or microcrack formation at the wheel-press-fit zone of axles is still an active area of investigation. Accurately analyzing fretting wear is challenging due to its sensitivity to numerous factors such as changes in friction coefficient, influence of wear particles, and selection of an appropriate wear model. This paper aimed to establish a comprehensive analysis method for fretting wear in interference-fitted axles using finite element analysis (FEA) and numerical analysis techniques. Two wear models were applied in simulations: an Archard wear model and an energy-based wear model. Analysis results were compared with experimental data from rotating bending fatigue press-fit specimens. This comparison will help validate the proposed analysis method and assess the effectiveness and accuracy of different wear models in predicting fretting wear in press-fit axles.

A pod mounted on an aircraft external must be installed on an aircraft after its structural safety is verified under flight conditions. This paper presents methods of flight load and test load generation. Evaluation of test result data and standards for failure mode are also presented. First of all, to verify the static structural stability, flight loads for the aircraft maneuvering conditions were calculated. Finite element analysis was then performed with flight loads. As a result of the analysis, structures were verified to have a margin of safety for a given design requirement. In addition, it was confirmed that the launcher tube had enough rigidity to support the missile. Thus, the role of stinger such as longeron and hardback was insignificant. Finally, based on results of tests and analysis, the static structural stability of pod was substantiated and the reliability and effectiveness of the analysis model were obtained. These results and dynamic stability verification results suggest that an optimal design is necessary.

When a narrow gap was formed under appropriate welding conditions in the steel pipe manufacturing process using highfrequency resistance welding, temperature distribution was analyzed to predict the length of the gap. Assuming the length of the gap from the apex point to the welding point at an applied voltage, and calculating the temperature distribution around the gap, the length of the gap with an appropriate fusion width at the welding point could be estimated. Along with this, the current density and magnetic flux density distributions that appeared in the narrow gap were obtained according to the change in the applied voltage, and the distribution shape and size of the electromagnetic force acting on the gap were also predicted. The current density, magnetic flux density, and electromagnetic force gradually increased along the narrow gap, showing the maximum value at the welding point. In the temperature distribution in the narrow gap, the surface of the front end began to melt at an appropriate applied voltage, and the melting width was the largest at the welding point. As the applied voltage increased, the narrow gap became longer, and the appropriate gap length appeared in proportion to the applied voltage.

When laparoscopic surgery is performed, polymer clip blood vessel ligators are widely used to prevent bleeding and secure surgical vision. However, long-term use of such ligators can cause many structural problems, especially in the jaw part where the clip is mounted directly to the blood vessel. For example, jaws of the ligation device might be opened above the design value and upper and lower jaws might be twisted against each other. In addition, buckling or bending deformation can easily occur at the tip of the inner shaft. Due to these problems, the ligation machine cannot ligate the clip properly, which might lead to a medical accident. Therefore, in this study, the design was changed to improve these problems by increasing the pin diameter and contact surface, applying a double pin structure, and changing the structure of the shaft tip. As a result, the modified model showed 12.5% and 10.2% improvements in opening and twisting stiffness compared to the initial model with 7.2% and 58% improvements in critical buckling load and bending stiffness, respectively.