3차원 솔리드 요소를 이용한 용접부 핫스팟 응력 계산에 대한 연구
Study on Hot Spot Stress Calculation for Welded Joints using 3D Solid Finite Elements
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Because of the high stress concentration near the toe of a welded joint, the calculation of local stress using the finite element methodwhich is relevant to the fatigue strength of the weld toe crack, is a challenging task. This is mainly caused by the sensitivity of finite elementanalysis, which usually occurs near the area of a dramatically changing stress field. This paper presents a novel numerical method through whicha less mesh-sensitive local stress calculation can be achieved based on the 3D solid finite element, strictly sticking to the original definition of hotspot stress. In order to achieve the goal, a traction stress, defined at 0.5t and 1.5t away from the weld toe, was calculated using either aforce-equivalent or work-equivalent approach, both of which are based on the internal nodal forces on the imaginary cut planes. In theforce-equivalent approach, the traction stress on the imaginary cut plane was calculated using the simple force and moment equilibrium, whereas theequivalence of the work done by both the nodal forces and linearized traction stress was employed in the work-equivalent approach. In order toconfirm the validity of the proposed method, five typical welded joints widely used in ships and offshore structures were analyzed using fivedifferent solid element types and four different mesh sizes. Finally, the performance of the proposed method was compared with that of thetraditionally used surface stress extrapolation method. It turned out that the sensitivity of the hot spot stress for the analyzed typical welded jointsobtained from the proposed method outperformed the traditional extrapolation method by far.
Abstract
Because of the high stress concentration near the toe of a welded joint, the calculation of local stress using the finite element methodwhich is relevant to the fatigue strength of the weld toe crack, is a challenging task. This is mainly caused by the sensitivity of finite elementanalysis, which usually occurs near the area of a dramatically changing stress field. This paper presents a novel numerical method through whicha less mesh-sensitive local stress calculation can be achieved based on the 3D solid finite element, strictly sticking to the original definition of hotspot stress. In order to achieve the goal, a traction stress, defined at 0.5t and 1.5t away from the weld toe, was calculated using either aforce-equivalent or work-equivalent approach, both of which are based on the internal nodal forces on the imaginary cut planes. In theforce-equivalent approach, the traction stress on the imaginary cut plane was calculated using the simple force and moment equilibrium, whereas theequivalence of the work done by both the nodal forces and linearized traction stress was employed in the work-equivalent approach. In order toconfirm the validity of the proposed method, five typical welded joints widely used in ships and offshore structures were analyzed using fivedifferent solid element types and four different mesh sizes. Finally, the performance of the proposed method was compared with that of thetraditionally used surface stress extrapolation method. It turned out that the sensitivity of the hot spot stress for the analyzed typical welded jointsobtained from the proposed method outperformed the traditional extrapolation method by far.
참고문헌 (13)
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