http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Buckling Analysis of Grid-Stiffened Composite Plates Using Hybrid Element with Drilling D.O.F.
Cho, Maenghyo,Kim, Won-Bae Computational Structural Engineering Institute of 2003 Computational structural engineering Vol.3 No.1
In the present study, finite element linear buckling analysis is performed for grid-stiffened composite plates. A hybrid element with drilling degrees of freedom is employed to reduce the effect of the sensitivity of mesh distortion and to match the degrees of freedom between skins and stiffeners. The preliminary static stress distribution is analyzed for the determination of accurate load distribution. Parametric study of grid structures is performed and three types of buckling modes are observed. The maximum limit of buckling load was found at the local skin-buckling mode. In order to maximize buckling loads, stiffened panels need to be designed to be buckled in skin-buckling mode.
Maenghyo Cho,Jinho Oh,Jun-Sik Kim,Michel Grediac 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.5
A finite element formulation based on an enhanced first order shear deformation theory is developed to accurately and efficiently predict the behavior of laminated composite and sandwich structures. An enhanced first order shear deformation theory is systematically derived by minimizing the least-squared energy error between the first order shear deformable plate theory and a higher order shear deformable plate theory. In this way, the strain energy of a higher ship between them that is also used to improve the accuracy of predicted streses and displacements. The key feature of the proposed theory is in that it can be implemented to comercial FEM packages by simply changing the input, and the results obtained can be also enhanced by post-processing them via a differential quadrature method. Thus, a pro-posed finite element formulation can be widely used in various application problems. Through numerical examples, the accuracy and robustness of the present formulation are demonstrated.
A Coupled Finite Element Analysis of Independently Modeled Substructures by Penalty Frame Method
Maenghyo Cho,Won Bae Kim 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.10
A penalty frame method is proposed for the coupled analysis of finite elements with independently modeled substructures. Although previously reported hybrid interface method by Aminpour et al (IJNME, Vol 38, 1995) is accurate and reliable, it requires non-conventional special solution algorithm such as multifrontal solver. In present study, an alternative method has been developed using penalty frame constraints, which results in positive symmetric global stiffness matrices. Thus the conventional skyline solver or band solver can be utilized in the solution routine, which makes the present method applicable in the environment of conventional finite element commercial software. Numerical examples show applicability of the present method.<br/>
물성치의 불확실성을 고려한 적층평판 강도의 GA 최적화
조맹효(Maenghyo Cho),이승윤(Seung-Yun Rhee) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.11
The layup optimization by genetic algorithm (GA) for the maximum strength of laminated composites with free-edge is presented. For the calculation of interlaminar stresses of composite laminates with free edges, extended Kantorovich method is applied. In the formulation of GA, repair strategy is adopted for the satisfaction of given constraints. In order to consider the bounded uncertainty of material properties, convex modeling is used. Because interlaminar strength can change rapidly with respect to the deviation of the values of the material properties, application of linear convex model is not proper. Thus in the present study, two-point exponential approximation(TPEA) is employed in the construction of convex set. Results of GA optimization with scattered properties are compared with those of optimization with nominal properties. The GA combined with convex modeling can work as a practical tool for light weight design of laminated composite structures since uncertainties are always encountered in composite materials.