Welding residual stress in the engineering structure has a non-negligible influence on crack propagation,and crack closure is a significant factor affecting the crack propagation.Based on the elastoplastic finite elem...Welding residual stress in the engineering structure has a non-negligible influence on crack propagation,and crack closure is a significant factor affecting the crack propagation.Based on the elastoplastic finite element method and crack closure theory,we studied crack closure and residual compressive stress field of butt-welded plates under constant amplitude loading and overloading regarding the stress ratio,maximum load,overload ratio,and number of overloads.The results show that the welding residual tensile stress can decrease the crack closure because of a decrease in the residual compressive stress in the wake zone,but the effect is gradually reduced with increased stress ratio or maximum load.And the combined effect of welding residual tensile stress and overload can produce a stronger retardation effect on crack propagation.展开更多
This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned submersible.The finite element model of the spherical hull is established,and a semi-elliptic...This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned submersible.The finite element model of the spherical hull is established,and a semi-elliptical surface crack is inserted in the welding toe of the spherical hull as the main crack.Considering the combined effect of external uniform pressure and welding residual stress at the weld toe,the stress intensity factor(SIF)is obtained based on the M-integral method.Inserting disturbing cracks at different positions on the spherical hull surface,the interaction and influence between multi-cracks are revealed by numerical calculation.The results show that the existence of the disturbing crack has a great influence on the stress intensity factor of the main crack,and the influence is different with the different location of disturbing crack.The study of the interaction of multiple cracks under different interference factors and the influence of disturbing cracks on the main crack can provide some reference for future engineering applications.展开更多
The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in shipbuilding.During the welding process,the nonuniform heating and rapid...The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in shipbuilding.During the welding process,the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual stresses.Owing to these imperfections,the fabricated structural members may not attain their design load,and removing these imperfections will require extra man-hours.The present work investigated controlling these imperfections at both the design and fabrication stages.A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding.A numerical simulation based on finite element modeling(FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the T-girder.The FEM results were validated with the experimental measurements of a double-sided fillet weld.Regarding the design stage,the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane distortion.Furthermore,regarding the fabrication stage,a parametric study with two variables(geometrical properties and welding sequence)was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane distortion.Increasing the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane distortion.Noncontinuous welding produced a significant reduction in the out-of-plane distortion,while an insignificant increase in the compressive residual stress occurred.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 51779198)
文摘Welding residual stress in the engineering structure has a non-negligible influence on crack propagation,and crack closure is a significant factor affecting the crack propagation.Based on the elastoplastic finite element method and crack closure theory,we studied crack closure and residual compressive stress field of butt-welded plates under constant amplitude loading and overloading regarding the stress ratio,maximum load,overload ratio,and number of overloads.The results show that the welding residual tensile stress can decrease the crack closure because of a decrease in the residual compressive stress in the wake zone,but the effect is gradually reduced with increased stress ratio or maximum load.And the combined effect of welding residual tensile stress and overload can produce a stronger retardation effect on crack propagation.
基金This work was supported by the State Key Program of National Natural Science of China(Grant No.51439004)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.19KJA530002)the Open Project Foundation of State Key Laboratory of Ocean Engineering(No.2006).
文摘This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned submersible.The finite element model of the spherical hull is established,and a semi-elliptical surface crack is inserted in the welding toe of the spherical hull as the main crack.Considering the combined effect of external uniform pressure and welding residual stress at the weld toe,the stress intensity factor(SIF)is obtained based on the M-integral method.Inserting disturbing cracks at different positions on the spherical hull surface,the interaction and influence between multi-cracks are revealed by numerical calculation.The results show that the existence of the disturbing crack has a great influence on the stress intensity factor of the main crack,and the influence is different with the different location of disturbing crack.The study of the interaction of multiple cracks under different interference factors and the influence of disturbing cracks on the main crack can provide some reference for future engineering applications.
文摘The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in shipbuilding.During the welding process,the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual stresses.Owing to these imperfections,the fabricated structural members may not attain their design load,and removing these imperfections will require extra man-hours.The present work investigated controlling these imperfections at both the design and fabrication stages.A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding.A numerical simulation based on finite element modeling(FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the T-girder.The FEM results were validated with the experimental measurements of a double-sided fillet weld.Regarding the design stage,the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane distortion.Furthermore,regarding the fabrication stage,a parametric study with two variables(geometrical properties and welding sequence)was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane distortion.Increasing the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane distortion.Noncontinuous welding produced a significant reduction in the out-of-plane distortion,while an insignificant increase in the compressive residual stress occurred.
