본 연구는 EBROG공법을 적용한 CFRP 판 보강 보의 휨거동에 대한 유한요소 해석으로 ABAQUS 프로그램을 사용하였으며 실험결과와 해석결과를 비교함으로써 유한요소 해석 프로그램의 신뢰성을 검증하는 기준을 제시하는데 있다. 총 모델 4개에 대하여 ABAQUS의 Dynamic Explicit 기법을 이용하여 해석을 수행하였다. 중요한 요소인 하중-처짐 곡선, CFRP의 부착 박리 거동, 그리고 균열 모습을 종합적으로 비교하였다. 해석 결과에 따르면 실험결과처럼 콘크리트 인장면에 홈을 형성하여 CFRP 판의 박리 과정을 지연 시킬 경우 최대 56% 까지 극한 강도가 증가하는 것으로 나타난다. 또한 EBROG 공법을 적용할 경우, 기존의 EBR 공법에 비해 CFRP의 부착 박리 과정을 효과적으로 지연시킬 수 있는 것으로 확인되었다. 전체 해석 결과를 종합한 결과, 유한요소해석 결과는 실험 결과 대비 오차율 10% 이내로 나타났다.

유리섬유강화폴리머(GFRP) 보강근은 굽힘부에서 크린클링에 의해 유효 단면이 물리적으로 감소하면서 강도 저하가 발생한 다. 현재 유한요소 모델링에서는 재료 강도만을 저감할 뿐, 이에 따른 강성 저하는 고려하지 않고 있다. 본 연구에서는 물리적 단면 손실을 직접 반영하는 등가 환산 단면법을 제안하고, ABAQUS를 이용하여 기존의 강도 감소법과 비교하였다. 3가지 직선부 직경(13, 16, 19 mm)에 대한 2차원 보 해석 결과, 정규화된 굽힘 인장강도는 직경 비에만 의존하여 하나의 2차 곡선으로 수렴되었다. 등가 환산 직경을 적용할 경우 축강성은 68∼76%, 휨강성은 47∼58%로 감소하였다. 콘크리트 방음벽 기초에 대한 3차원 비선형 해석 결 과, 강도 감소법은 인위적으로 낮춘 파단 기준에 의해 GFRP가 조기 파단함으로써 극한 하중을 약 11% 과소 평가하는 것으로 나타났 다. 등가 환산단면법은 GFRP 보강근 굽힘부의 유한요소 모델링에 있어 보다 물리적으로 합리적인 접근법을 제공한다.

This study investigated the structural performance of Cast-in-Place (CIP) pile-integrated composite basement walls (CIP-CBW) featuring socket-type shear connectors (SSCs) in both steel and RC applications through finite element analysis. The results demonstrated that while the height and spacing of SSCs significantly influenced the ultimate load and corresponding displacement of the CIP-CBW, their impact on initial stiffness was negligible. Due to the leverage effect, shear forces along the interface between the CIP pile and the basement wall were resisted by both the front and rear bolts of the SSC. The failure mechanism of the SSC joint was characterized by concrete crushing and cracking around the connector, followed by the formation of plastic hinges in both bolts. Bending moment analysis revealed that the rear bolt is particularly susceptible to flexural yielding. Furthermore, the slip tendency at the interface was more pronounced in the steel scheme than in the RC scheme. Notably, the effect of SSC spacing on slip was significant, whereas SSC height exhibited minimal influence.

본 연구는 3차원 비선형 유한요소해석을 이용하여 고속도로 2주형 교각 코핑부에서 철근을 유리섬유보강폴리머(GFRP) 보강 근으로 대체하는 경우를 평가하였다. 콘크리트의 균열, 손상 및 보강근 응답을 모사하기 위해 콘크리트 손상소성(CDP) 모델을 적용하 였다. 단조하중 조건에서 철근 기준 Case와 다수의 GFRP Case를 비교하였다. 주요 변수로는 GFRP의 강성, 콘크리트와의 부착계수 영향, 그리고 수직 전단보강근 상세 배근을 포함하였다. 수치해석 모델은 실험 경향과의 비교를 통해 검증되었으며 전반적인 거동이 일관되게 나타났다. GFRP로의 대체는 철근 대비 강성과 하중 전달 메커니즘을 변화시켰다. 또한 콘크리트 손상이 전체 응답과 파괴 진행을 지배하는 주요 요인으로 나타났다. GFRP 강성이 높고 부착성능이 우수할수록 구조 효율과 상세설계의 실현성이 향상되었다. 적절한 설계가 전제될 경우 전단보강근의 양은 전체 거동에 미치는 영향이 제한적인 범위에서 최적화가 가능하였다. 이상의 결과는 GFRP 적용의 실무적 가능성을 뒷받침하는 동시에, GFRP의 선형탄성ㆍ취성 거동과 국부 응력집중 가능성을 고려할 필요가 있음을 시사한다.

본 연구의 목표는 정적 탠덤 진수 조건에서 대형 선박 블록의 효율적이고 정확한 종방향 강도 평가를 위한 표준화된 유한 요소 (FE) 메쉬 크기를 확정하는 것이다. FE 해석은 높은 정확도를 제공하지만, 과도한 모델링 및 계산 비용으로 인해 조선소에서의 일상적인 사용에 제약이 있다. 반대로, 간소화된 규칙 기반 빔 이론 평가는 효율적이지만, 복잡하고 부분적으로 용접된 블록 형상을 적절하게 표현 하지 못하여 생산 단계 평가의 정확성에 대한 문제를 갖고 있다. 이러한 격차를 해소하기 위해, 국부적인 용접과 스트롱백 구속 조건을 포함한 실제 제작 단계 조건을 명시적으로 반영한 174K급 LNG 운반선(LNGC) 후미 블록의 상세한 FE 모델을 분석하였다. MSC.NASTRAN 선형 정적 해석법을 사용하여 20mm에서 1,200mm까지의 요소 크기에 걸쳐 조합 응력 응답을 평가하는 체계적인 메쉬 수렴 분석을 수행하 고, 그 결과를 ABS 규칙 기반 계산 결과와 비교 분석하였다. 조밀한 요소 크기(20~100mm)는 국부적인 응력 집중에 의한 응력 차이가 크게 발생하고, 메쉬 크기가 약 800mm 이상에서는 최대응력이 일정하게 수렴하는 결과를 나타냈다. 유한 요소법으로 계산된 조합 응력은 허용 단면 계수 및 구조적 안전성 평가를 포함한 규칙 기반 평가 결과와 높은 일치도를 보였다. 따라서 요소 크기 800mm는 전체적인 종방향 강도 평가에 있어 계산 효율성과 구조적 정확도 사이의 최적의 결과를 제공하는 것으로 확인되었다. 이러한 결과는 선급 협회의 요구 사 항을 준수하면서 신뢰할 수 있고 생산 지향적인 평가를 가능하게 하는 실용적인 유한 요소 모델링 지침을 제공하고 있다.

This study investigates the thermo-mechanical behavior and residual stress characteristics of friction stir welding (FSW) in an aluminum inverter housing using finite element analysis (FEA). FSW experiments were first conducted under various tool rotation and traverse speed conditions, and temperature histories were measured using K-type thermocouples. The optimal process condition was identified through tensile testing, and the heat input was estimated by comparing experimental and numerical results. The estimated heat source was incorporated into a transient thermal elasto-plastic analysis to evaluate deformation and residual stresses in an inverter housing model. The results indicated that residual stress distributions varied depending on the welding start position. In particular, when welding started at P3 (near thick ribs and bosses) residual stresses were reduced by approximately 30% compared to P1, owing to the higher local stiffness and enhanced heat dissipation that mitigated temperature gradients. Conversely, welding initiated at P1, a flat region with insufficient reinforcement, resulted in higher stress concentrations. These findings confirm that the welding start position significantly influences residual stress behavior in inverter housings and provide fundamental insights for developing residual stress control strategies in FSW of large-scale components.

This study proposes a surrogate model framework that integrates finite element analysis and deep learning to rapidly estimate equivalent material properties of patterned sheets. Conventional homogenization methods can only be applied after the pattern geometry has been finalized, requiring additional modeling and simulation. In contrast, the proposed approach establishes a surrogate model in advance, enabling the immediate estimation of equivalent material properties once the pattern geometry is defined. A dataset of 5,000 cases was generated using simulations, and Bayesian hyperparameter optimization was applied to improve model performance. The surrogate model achieved R² values above 0.99 for all target properties, confirming high internal consistency. Experimental validation with patterned STS304 specimens yielded meaningful results, with all errors remaining within 15%, which demonstrates the reliability of the proposed surrogate model despite minor deviations caused by fabrication imperfections and limited training data. Despite these limitations, the proposed system enables instant estimation of equivalent properties from pattern geometries, offering significant reduction in computational cost and design time. This approach enhances design reliability and provides a practical tool for the application of patterned materials in industrial engineering.

This study presents the results of compression, drop impact, and vibration durability analyses conducted to evaluate the mechanical reliability of Battery Pack Cases (BPCs) in electric vehicle (EV) systems. BPCs are essential structural components that must endure compressive loads, impact forces, and vibrational fatigue. Finite Element Analysis (FEA) was applied to a representative BPC model to assess deformation, impact resistance, and vibration endurance. The results indicate that the BPC maintained integrity within yield strength limits under compressive loading and effectively absorbed energy under drop impact. Furthermore, Power Spectral Density (PSD) analysis identified stress concentration regions, providing insights for structural optimization. Overall, the findings support the development of lightweight and reliable BPC designs for advanced EV applications.

This study investigates the vibration characteristics of an aluminum subframe for small and high-speed vessels through modal and resonance analysis using the finite element method (FEM). Due to the low stiffness and damping of aluminum, concerns arise over structural resonance and fatigue. A 3D model based on actual design drawings was analyzed to extract six natural frequencies and corresponding mode shapes. Significant deformation was observed in the first and second modes (90.65 Hz, 110.60 Hz), which may overlap with operational frequencies. The fifth mode (263.70 Hz) showed high amplitude with Y-axis concentration, indicating lateral resonance vulnerability. Deformation ratios were used to identify dominant vibrational directions. Based on the findings, design strategies such as structural reinforcement, RPM adjustment, and damping device application were proposed to improve vibration safety in the early design stage.

In this study, structural analysis was performed to select the optimal design shape through failure identification and design changes in turbine housing. Damage in the inlet flange is considered to be high cycle fatigue due to the vibration excitation in the engine full load test. Therefore, the FE analyses were performed natural vibration analysis and frequency response analysis for the initial shape and design change models. The stress magnitudes were obtained as a function of frequency through frequency response analysis according to engine vibration excitation. As a result, the dynamic stiffness of Case (1) increased by approximately 3.6% compared to the initial model, and Case (2) increased by 4.6%. In addition, the stress magnitude was greatly reduced in the design improvement. Therefore, the model with only the flange thickness increased is thought to be optimal design for securing the durability of the turbine housing.

In apartment buildings in Korea, irregular walls, such as T-, L-, and U-shaped walls, are commonly used. However, in practical design, the geometric irregularities of walls are often neglected when determining the length of the lateral confinement region. Further, although earthquake loads apply from various directions, the lateral confinement region is typically determined for the in-plane direction of the web. Thus, using finite element analysis, this study investigated the structural performance of irregular walls subjected to various loading directions. As the design parameters, wall shape, cross-sectional aspect ratio, and loading direction were addressed. According to the parametric analysis results, as the length of flange in tension increased, the lateral confinement region should be evaluated with consideration of the geometric irregularity. Further, for the L- and U-shaped walls, it is recommended to evaluate the lateral confinement region for various loading directions. Based on these results, a design method to determine the lateral confinement region of irregular walls was suggested.

The purpose of this study is to evaluate by experiments and 3-D finite element predictions of strain-hardening cementitious composite(SHCC) structural walls. The specimen of concrete wall used shear reinforcements to satisfy with design shear strength, while the specimen of a SHCC wall used minimum shear reinforcement. The finite element prediction is based on the total strain crack model, and appropriate tensile models were applied according to the material characteristics of concrete and SHCC. The accuracy of the finite element prediction was verified by comparison with experimental results, and the SHCC wall showed superior structural performances in overall load-carrying capacity as well as in reductions of damages caused by crack localizations, even with minimum use of shear reinforcements.