• 대한기계학회논문집A
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• 제25권9호
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• pp.1376-1383
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• 2001

Meshless methods, developed in various ways over the past decade, have been attractive as new computational methods in that they do not need mesh generation in analyzing procedure. But most of these methods were not truly meshless methods because background meshes were required for the spatial integration of a weak form. Accordingly, in this paper, nodal integration for truly meshless methods has been studied, and an improvement scheme is proposed. To improve stabilization and accuracy, which are the weak points in previous nodal integration methods, the integration area is transformed to circle and then numerically integrated. This method does not need any adding term for stabilization in the variational formulation and then simplifies the integration procedure. Numerical test results show that the proposed method is more accurate, stable, and reasonable than the existed nodal integration methods.

• 소성∙가공
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• 제12권7호
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• pp.615-622
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• 2003

In the automobile industry, the design of optimal blank shape becomes a significant part of the stamping. It provides many evident advantages, sush as enhancement of formability, reduction of material cost and product development period. However, the nesting process, required for the optimal usage of materials in the blanking becomes more complicated as the blank shape becomes complicated, like most optimal blank shape. In this study, stamping process optimization system for the optimal usage of material has been developed through the integration of optimal blank design and optimal nesting. For optimal blank design, a radius vector method, the modified version of the initial nodal velocity method, the past work of the present author, have been proposed. Both the optimal blank design and optimal nesting programs have been developed under the GUI environment for the convenience of engineers. The efficiency of the optimization system has been verified with some chosen problems.

• 한국항공우주학회지
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• 제46권3호
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• pp.210-218
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• 2018

항공기와 같은 복잡한 구조물의 유한요소해석을 위해 자동요소망을 생성하면 일반적으로 삼각형 요소가 많이 생성되게 된다. 하지만 삼각형 요소는 사각형 요소에 비해 정확도가 떨어지므로 신뢰성 있는 해를 도출하기 어렵다. 이와 같은 문제는 배경셀 적분을 이용한 무요소법(Meshfree Method)을 통해 개선할 수 있으나 이 또한 적분점의 과다사용, 적분영역의 비효율성 등의 문제가 발생하게 된다. 이를 개선하기 위해 절점 기준으로 적분영역을 설정하여 적분을 수행하는 방법이 제안되었지만 비압축성 문제의 경우 해의 진동현상이 일어나는 등 수치 정확도가 떨어지게 된다. 따라서 본 연구에서는 적분영역을 절점영역이 아닌 요소영역으로 설정하는 수정된 무요소법을 통해 요소의 형태에 따른 정확도 저하가 발생되지 않고 기존의 무요소법에서 발생되는 수치 불안정성 등을 개선하였다. 2차원 예제를 통해 수정된 무요소법의 효용성을 검증하였다.