scholarly journals Fracture Characteristics Analysis of Pressured Pipeline with Crack Using Boundary Element Method

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Han-Sung Huang
Keyword(s):  
Boundary Element Method ◽  
Service Life ◽  
Boundary Element ◽  
Crack Growth ◽  
Longitudinal Crack ◽  
Fatigue Loading ◽  
Longitudinal Direction ◽  
Uniform Corrosion ◽  
Loading Cycle ◽  
Element Method

Metal materials can inevitably show deteriorated properties by the factors of stress, temperature, and environmental erosion in distinct operating environments. Without proper protection, the service life would be shortened or even deadly danger would be caused. This study aims to apply Finite Element Method and Boundary Element Method to analyzing the effects of corroded petrochemical pipes on the fatigue life and the fracture form. The research results of nondestructive testing and software analyses show that cracked oil pipes with uniform corrosion bear larger stress, mainly internal pressure, on the longitudinal direction than the circumferential direction. As a result, the maximal fatigue loading cycle of a circumferential crack is higher than that of a longitudinal one. From the growing length and depth of a crack, the final aspect ratio of crack growth appears in 2.42–3.37 and 2.71–3.42 on the circumferential and longitudinal direction, respectively. Meanwhile, the ratios of loading cycles of circumferential and longitudinal crack are 26.23 on uncorroded and 20.54 on general metal loss oil pipe. The complete crack growth and the correspondent fatigue loading cycle could be acquired to determine the service life of the oil pipe being operated as well as the successive recovery time.

scholarly journals Fatigue Life Prediction of the Zirconia Fixture Based on Boundary Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Y. W. Wang ◽  
J. J. Ye ◽  
W. P. He ◽  
G. G. Cai ◽  
B. Q. Shi
Keyword(s):  
Fatigue Life ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Crack Growth ◽  
Semiconductor Industry ◽  
Element Model ◽  
Stress Distributions ◽  
Paris Law ◽  
Initial Cracks ◽  
Element Method

Zirconia grinding fixtures have been widely used in semiconductor industry to improve the quality and precision of the products. For maximizing the service life and minimizing the risks of accidental damage, it is critical to have a better understanding of the fatigue life of zirconia grinding fixtures. To this end, a boundary element method is developed in this paper to investigate their crack growth and fatigue life. To validate the proposed method, the stress intensity factor of a typical plate structure with initial cracks is considered. On this basis, Paris Law is employed in the boundary element model to further study the crack growth and stress distributions in the zirconia fixture under cyclic loads. Numerical results show that stress concentration occurs at the pillar of the fixture, and crack growth is perpendicular to the loading direction.

Realistic Design of a Floating Breakwater Design with Moonpools

2015 ◽  
Vol 69 (7) ◽  
Author(s):  
Faisal Mahmuddin ◽  
Rahimuddin Rahimuddin
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
High Performance ◽  
3D Model ◽  
Longitudinal Direction ◽  
Realistic Model ◽  
The Body ◽  
Efficient Design ◽  
Floating Breakwater ◽  
Element Method

In an attempt to obtain a 2D floating breakwater model with high performance in wave reflection, genetic algorithm (GA) was combined with boundary element method (BEM) in the previous study. The performance of the obtained model was verified with numerical relations as well as an experiment in towing tank. Moreover, its performance and characteristics in 3D case were also evaluated in the subsequent study. However, because the 3D model is formed by simply extruding the 2D shape in longitudinal direction, it only produces a model with uniform transversal shape which is considered to be less effective and efficient in terms of technical and economical points of view. Consequently, it is needed to modify the model to obtain a more realistic and efficient design without reducing significantly the high performance obtained previously. In the present study, several modifications of the original 3D model are performed which include placing moonpools inside the body. The performance and characteristics of the modified models in terms of wave elevations on the free surface are evaluated at various wavelengths by using higher order boundary element method (HOBEM). The accuracy of the computed results is confirmed with Haskind-Newman and energy conservation relations. From the modifications and evaluations of the models, it could be realized that the moonpools inside the body could be used to obtain a more realistic model without reducing the optimum performance of the original model shape.  

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