• Advances in Computational Design
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• 제9권3호
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• pp.167-186
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• 2024

Implementing isogeometric methodology in micromechanical analysis of composite materials has been recently investigated in some research studies. These research studies are based on multi-patch modeling which requires coupling constraints among the NURBS patches, and the domain decomposition effort in model preparation stage. This approach has been employed for small representative volume elements (RVE). However, small RVE neglects some characteristics of microstructure and larger one increases the number of required NURBS patches in multi-patch framework. As a step forward, this research presents a framework which simulates the RVE using a single NURBS patch. the presented framework has been used to include the effects of fiber distribution and porosities in simulated RVEs. In this regard, heterogeneity and 2D/3D voids within RVE are modeled only by inserting knots and modifying the control points. In addition to beneficial advantages of isogeometric methodology for RVE-based models, this framework simplifies isogeometric modeling of more complicated RVEs by eliminating the domain decomposition stage and avoiding coupling constraints between non-matching patches. The performance of the presented model has been verified by performing micromechanical damage analysis on several generated RVEs of unidirectional fiber-reinforced composites, in which matrix and fiber/matrix interfaces experience damage. The predicted damage evolutions under different loading conditions are in excellent agreement with prior experimental and numerical studies that demonstrate the veracity of the presented model.

• 대한건축학회논문집:구조계
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• 제35권9호
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• pp.171-182
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• 2019

Isogeometric concept is introduced to carry out free vibration analysis of plane structures. The geometry of structures is represented by using non-uniform rational B-spline surface (NURBS) and its basis function is consistently used in the formulation of plane stress element. In addition, multi-patch strategy is introduced to deal with the openings in building. The performance of the present isogeometric plane stress element is investigated by using five numerical examples. From numerical results, it is found to be that the isogeometric concept can successfully identify reliable natural frequencies and associated mode shapes of plane structures with/without openings in efficient way.

• 한국전산구조공학회논문집
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• 제31권2호
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• pp.71-78
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• 2018

본 연구에서는 NURBS 기반 아이소 지오메트릭 쉘 해석을 위해 다중 패치 해석 모델을 정식화하였다. 기존 연구를 통해 개발된 단일 패치로 구성된 전단 변형을 고려한 쉘 요소에 대해 일반 좌표계에서 기하학적으로 엄밀한 쉘 구조물의 아이소 지오메트릭 해석 모델을 도입하고 매개변수 연속성을 고려하여 다중 패치 모델로 확장하였다. 인접 곡면의 노트 요소가 결합 경계를 통해 조화를 이루는 경우에 대해 0차와 1차 매개변수 연속성 조건을 고려하였으며, 두 패치 간 마스터-슬레이브 관계를 정립하여 종속된 한 곡면의 자유도를 상대 곡면의 자유도로 표시하여 모델 크기를 줄이면서 두 곡면을 결합하였다. 다중 패치 쉘 예제에 대해 0차와 1차 연속성 조건을 각각 적용하여 구조해석을 수행하여 1차 연속성 조건의 주요한 특성들을 확인하였다. 또한 각 연속성 조건에 대한 해의 수렴 특성을 검토하였으며 결합 경계에서의 두 패치의 연속성을 확인하였다.