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.
With advancements in semiconductor manufacturing processes and the development of precision processing technology, flexure hinge-based ultra-precision positioning stages are widely used. In the flexure hinge, axial and bending stiffness properties greatly influence positioning performance. This study examined the stiffness properties of elliptic and parabolic 2-degrees-of-freedom (DOF) hinges, which have not been extensively discussed. The Timoshenko beam theory was applied to derive the stiffness equations for the axial and bending directions of each hinge. The stiffness properties were examined in several design conditions by comparing theoretical and finite element analyses. Based on the results of the analyses, an empirical formula in exponential form for the design of an elliptic hinge was constructed through surface-fitting. The elliptic hinge was found to be a better alternative to a circular hinge under certain design conditions by adjusting two design parameters. In the future, we will develop sophisticatedly designed hinges with improved axial and bending stiffness properties compared to the existing circular and elliptic hinges.
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Derivation and Verification of Novel Phenomenon-based Theoretical Formulas for the Axial Compliance of Circular Flexure Hinges Jun-Hee Moon, Hyun-Pyo Shin Journal of the Korean Society for Precision Engineering.2025; 42(1): 47. CrossRef
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 earth pressure changes depend on soil depth and surrounding situations, the construction of earth retaining temporary structures should be able to measure the change of the earth pressure and cope with the changes. When the underground excavation and construction of earth retaining temporary structure repeatedly occur, the excavation should be less interfered by the earth retaining structure. A PS synchronize wale measures the horizontal deflection of the structure and generates tension on the wire rope by controlling the hydraulic cylinder so that the wale is in safe range. Since the horizontal load is canceled by pre-stress bending moment, the number of struts the horizontal load is reduced making the excavation interference is small. We evaluated the horizontal deflection of the PS synchronize wale with increasing tension and verified that the deflection of the PS synchronize wale can cancel out the horizontal load in the safety range of 5 mm. This occurs through a universal testing machine experiment simulating earth pressure. We are in the process of applying the PS synchronize wale to a test bed and expect it to be safer and more efficient than existing methods.
We investigated fatigue in the erector spinae, upper trapezius muscles and changes in the cervical flexion-extension angle when individuals watched 360° videos, general videos using virtual reality (VR), and smartphones. The subjects included 34 young, healthy, South Korean college students. The systems VR Gear3, the Galaxy S8, and “STAR WARS 360 VR” made by the manufacturer Cube CZ were utilized. The subject test conditions were: 1) watching 360° video with VR (V360), 2) watching 360° video on a smartphone (S360), 3) watching general video with VR (VG), 4) and watching general video on a smartphone (SG). The subjects watched a video for 10 min under each condition, where median frequencies of the erector spinae and upper trapezius muscles were measured using electromyography, while changes in the cervical flexionextension angle were measured with an electrogoniometer. The results noted that the erector spinae and upper trapezius muscles were significantly fatigued over time in all conditions, with significant differences relating to time and conditional effect. Watching 360° videos was less fatiguing than watching general videos and neck muscles moved the most when watching V360, and least watching general videos. These results suggest that neck muscles are less fatigued when watching 360° videos.
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Investigating Virtual Reality for Alleviating Human-Computer Interaction Fatigue: A Multimodal Assessment and Comparison with Flat Video Xinyi Wang, Jing Qu, Lingguo Bu, Shantong Zhu IEEE Transactions on Visualization and Computer Graphics.2025; 31(5): 3580. CrossRef
Human Factors/Ergonomics (HFE) Evaluation in the Virtual Reality Environment: A Systematic Review Reza Kazemi, Seul Chan Lee International Journal of Human–Computer Interaction.2024; 40(17): 4533. CrossRef
Design guidelines for limiting and eliminating virtual reality-induced symptoms and effects at work: a comprehensive, factor-oriented review Alexis D. Souchet, Domitile Lourdeaux, Jean-Marie Burkhardt, Peter A. Hancock Frontiers in Psychology.2023;[Epub] CrossRef
A narrative review of immersive virtual reality’s ergonomics and risks at the workplace: cybersickness, visual fatigue, muscular fatigue, acute stress, and mental overload Alexis D. Souchet, Domitile Lourdeaux, Alain Pagani, Lisa Rebenitsch Virtual Reality.2023; 27(1): 19. CrossRef
Recently, the metal grid electrode drew attention as a flexible transparent conductive electrode for touch screen panels. In metal grid electrodes, various shapes of grid patterns were used to avoid the moiré phenomenon. In this study, we investigated the effects of the metal grid shapes - such as the honeycomb, diamond, and square - on the flexibility and durability of the metal grid film using an experimental and numerical analysis. The flexibility of the metal grid film was evaluated via the following: bending, cyclic bending fatigue and stretching tests; it was compared with the numerical stress analysis. In the bending test, the resistance of the honeycomb grid sample increased by 10% at a bending radius of 10 mm. On the other hand, the diamond grid showed almost no change in resistance up to a bending radius of 6 mm. When the substrate was stretched to 5%, many cracks appeared on the surface of the honeycomb pattern sample. On the other hand, no cracks were found in the diamond pattern sample. Therefore, the diamond pattern exhibited superior flexibility and durability to the honeycomb pattern. The numerical stress analysis also showed that the honeycomb pattern had the highest stress and the diamond pattern had the lowest stress during bending and stretching, which corresponded with the experimental results.
The flexural characteristics of corrugated sandwich panels are anisotropic and depend on its corrugation geometry and load position. The objective of this paper is to examine the influence of corrugation angle and load position on the flexural characteristics of plastic sandwich panels with trapezoidal corrugated cores subjected to ASTM three-point bending via finite element analysis. The stress distributions at mid span have been plotted to determine the stress concentration at different corrugation angle and load position. The specific flexural stiffness and modulus have been estimated from the loaddisplacement and stress-strain curves, respectively. The failure of the specimen due to stress or strain limit has been examined via maximum limit stroke. Results have shown that the specific flexural stiffness and modulus improve as the corrugation angle decreases. The load position has influenced the flexural characteristics due to the occurrence of local bending and local tension.
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A Study on the Effects of the Corrugated Angle on Low Velocity Impact Characteristics of the Lightweight Sandwich Plate with Corrugated Cores Produced by FDM Process Yong Hun Jang, Dong-Gyu Ahn, Bo Sung Shin Journal of the Korean Society for Precision Engineering.2017; 34(12): 939. CrossRef
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