http://yetl.yabesh.ir/yetl1/handle/yetl/19036 2026-08-28T08:08:55Z 2026-08-28T08:08:55Z Yu, Xinping Park, Dong-Yeob Wang, Xin http://yetl.yabesh.ir/yetl1/handle/yetl/4316887 2026-08-23T08:40:42Z 2026-01-01T00:00:00Z

Determination of Tensile Strain Capacity of Girth-Welded X70 and X100 Grade Pipelines With Surface Cracks Under Tension and Bending Yu, Xinping; Park, Dong-Yeob; Wang, Xin Abstract. This paper presents a comprehensive finite element analysis using abaqus to obtain the tensile strain capacity (TSC) of X70 and X100 pipelines with external semi-elliptical cracks in the heat-affected zone (HAZ) under tension and bending. The analysis estimates the crack driving forces using the J-integral in relation to the pipeline's remote strain. Subsequently, the evaluation of TSC was carried out employing both initiation and ductile tearing criteria. The study investigates the effects of internal pressures, HAZ softening levels, loading type, and weld strength overmatch ratios on TSC. The results reveal similar trends in TSC between the initiation and ductile tearing criteria, as well as between tension and bending for both types of steel. Notably, TSC decreases with increased HAZ softening and internal pressures, while higher overmatch ratios appear to enhance it. These findings highlight the critical influence of these factors on the structural integrity of pipeline girth welds, offering essential insights for the design and maintenance of pipeline systems.

2026-01-01T00:00:00Z Li, Dongrui http://yetl.yabesh.ir/yetl1/handle/yetl/4316885 2026-08-23T08:40:39Z 2026-01-01T00:00:00Z

Effects of Oblique Incident P-Waves on the Seismic Response of a Buried Pipeline With Double Corrosion Defects in Permafrost Regions Li, Dongrui Abstract. This study focuses on X80 pipelines and establishes a three-dimensional pipe–soil interaction model in abaqus. Based on wave theory, the loading of obliquely incident P-waves in the finite element model was implemented, and the effects of temperature, corrosion spacing, and incident angle on the stress, acceleration, and displacement responses of the pipeline were analyzed. The results indicate that at +0 °C, the stress response of the pipeline increases significantly due to the reduction in seismic wave velocity caused by the decrease in soil elastic modulus. When the axial spacing between double corrosion defects exceeds 4 times the wall thickness, the interaction between them becomes negligible. The stress response of the pipeline first increases and then decreases with the increase of the incident inclination angle (θi), while it continuously increases with the increase of the incident azimuth angle (θv). The most severe stress response and the highest safety risk occur when θi = 60 deg and θv = 90 deg. Additionally, the incident azimuth angle has a minor impact on the vertical acceleration and velocity of the pipeline but significantly affects the lateral and axial responses. In contrast, the incident inclination angle noticeably influences the acceleration and velocity responses in all three directions of the pipeline, with the most pronounced effect observed at θi = 60 deg.

2026-01-01T00:00:00Z Zhao, Chunhui Jiang, Wenchun Sun, Guanghua Wan, Yu Zhang, Xinjie http://yetl.yabesh.ir/yetl1/handle/yetl/4316876 2026-08-23T08:40:25Z 2026-01-01T00:00:00Z

Research on the Regulation Mechanism of Residual Stress in Tube-to-Tubesheet Welded-and-Expanded Joints of Shell-and-Tube Heat Exchanger Zhao, Chunhui; Jiang, Wenchun; Sun, Guanghua; Wan, Yu; Zhang, Xinjie Abstract. In shell and tube heat exchangers, welding residual stress has a crucial impact on reliability and structural integrity of the tube-to-tubesheet joints. This paper combines numerical simulation and theoretical analysis methods to investigate the welded-and-expanded process. Previous studies typically treated welding and expansion as isolated processes. This paper explains the regulation mechanism of the expansion load on the existing welding residual stress through analyzing the residual stresses on the surface of the tube sheet and at the weld root before and after expansion. The study suggests that the welding process generates high-magnitude tensile residual stress near and in the adjacent areas of the weld. The peak of this residual stress exceeds the yield strength of the material. The stress is mainly concentrated on the joint surface and gradually decays with the thickness of the tube sheet. The expansion process significantly alters the stress field induced by welding, achieving effective stress release and redistribution. A critical expansion pressure threshold was determined, approximately 280 MPa. If this threshold is exceeded, the stress relief effect will tend to saturation, and further loading may cause local yield on the surface of the tube sheet. In addition, the agreement between numerical simulations and experiments confirms the effectiveness of expansion load in mitigating welding residual stress and provides a theoretical foundation for optimizing the welded-and-expanded process.

2026-01-01T00:00:00Z Kim, Taeyoung Kim, Hwa Young http://yetl.yabesh.ir/yetl1/handle/yetl/4316874 2026-08-23T08:40:21Z 2026-01-01T00:00:00Z

Optimal Design of Type 2 High Pressure Vessel for Compressed Natural Gas Vehicles Kim, Taeyoung; Kim, Hwa Young Abstract. Compressed natural gas (CNG) pressure vessels are used for fuel storage in eco-friendly vehicles, providing a safe fuel supply under high pressure. Lightweighting of CNG pressure vessels while ensuring structural safety is an essential factor. In this study, liner and composite thickness designs were performed to reduce the weight of CNG pressure vessels. The stress behavior based on liner and composite thicknesses was analyzed using the commercial finite element analysis (FEA) software, ansysworkbench. To improve fatigue life and durability, considering failure due to buckling and burst, autofrettage pressure was applied. Using optimal design, a minimum-weight pressure vessel was achieved, meeting criteria for structural safety, fatigue life, and cost reduction. Therefore, a 6.6% reduction in weight was achieved compared to CNG pressure vessels currently manufactured in the field.

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