• Structural Engineering and Mechanics
• /
• v.9 no.1
• /
• pp.99-110
• /
• 2000

The objective of this paper is to extend the use of the improved degenerated shell element to the linear and the large displacement analysis of plates and shells with laminated composites. In the formulation of the element stiffness, the combined use of three different techniques was made. This element is free of serious shear/membrane locking problems and undesirable compatible/commutable spurious kinematic deformation modes. The total Lagrangian approach has been utilized for the definition of the deformation and the solution to the nonlinear equilibrium equations is obtained by the Newton-Raphson method. The applicability and accuracy of this improved degenerated shell element in the analysis of laminated composite plates and shells are demonstrated by solving several numerical examples.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.11 no.3
• /
• pp.1-10
• /
• 1991

The paper is concerned with the analysis of laminated composite shell structures using an improved degenerated shell element. In the formulation of the element stiffness, the combined use of three different techniques was made. They are; 1) an enhanced interpolation of transverse shear strains in the natural coordinate system to overcome the shear locking problem; 2) the reduced integration technique in in-plane strains to avoid the membrane locking behavior; and 3) selective addition of the nonconforming displacement modes to improve the element performances. This element is free of serious shear/membrane locking problems and undesirable compatible/commutable spurious kinematic deformation modes. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements. The resulting non-linear equilibrium equations are solved by the Newton-Raphson method. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1998.10a
• /
• pp.19-26
• /
• 1998

The isoparametric spline finite strip method for degenerated shells is presented. In the formulation, both the geometry and the displacement field are represented by uniform cubic B-spline curves. Spline shell strip is degenerated stress-resultant shell with 6 dof at each node;and the penalty function method is used to incorporated the six dof,

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.7 s.178
• /
• pp.1721-1730
• /
• 2000

An eccentric degenerated shell element with geometric non-linearity for the precise and efficient analysis of stiffened shell structures is developed. To deal with the eccentricity, we define the e ccentric shell and the master shell that constitute one combined shell. It is assumed that the sections remain plane after deformation. The internal force vector and the tangent stiffness matrix based on the virtual work principle in the natural coordinate system are derived. To enhance the robustness of the element, assumed strain method for transverse shear and membrane strains is used. Through numerical experiments the effectiveness of the proposed element is demonstrated.

• Steel and Composite Structures
• /
• v.17 no.6
• /
• pp.867-890
• /
• 2014

This paper deals with the geometric nonlinear bending analysis of laminated composite stiffened plates subjected to uniform transverse loading. The eight-noded degenerated shell element and three-noded degenerated curved beam element with five degrees of freedom per node are adopted in the present analysis to model the plate and stiffeners respectively. The Green-Lagrange strain displacement relationship is adopted and the total Lagrangian approach is taken in the formulation. The convergence study of the present formulation is carried out first and the results are compared with the results published in the literature. The stiffener element is reformulated taking the torsional rigidity in an efficient manner. The effects of lamination angle, depth of stiffener and number of layers, on the bending response of the composite stiffened plates are considered and the results are discussed.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.13 no.4
• /
• pp.449-459
• /
• 2000

The original Mindlin-type degenerated shell element perform reasonably well for moderately thick shell structures. However, when full integration for analysis of thin shell is used to evaluate the stiffness matrix, the stiffness of shell element is often over-estimated due to shear or membrane locking phenomena. To correct this problem, the formulation of the new degenerated shell element is derived by the combination of two different techniques. The first type of elements(TypeⅠ) has used assumed shear strains in the natural coordinate system to overcome the shear locking problem, the reduced integration technique in in-plane strains(membrane strains) to avoid membrane locking behaviour. Another element(TypeⅡ) has applied the assumed strains to both of membrane strain and transverse shear strains. The improved degenerated shell element has been tested by several numerical problems of shell structures. Numerical results indicate that this shell element shows fast convergence and reliable solutions.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1995.04a
• /
• pp.17-27
• /
• 1995

For the post-buckling and elasto-plastic analysis of shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors in the iteration process and evaluating the total Green-Lagrange stain corresponding U total displacements. In the calculation of the stiffness matrix, the element formulation takes into account the effect of finite rotation increments by retaining second order rotation terms in the incremental displacement field. The selective or reduced integration scheme using the heterosis element is applied in order to overcome both shear locking phenomena and the zero energy mode. The load/displacement incremental scheme is adopted for geometric non-linear F .E. analysis. Based on such methodology, the computer program is developed and numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references's results.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.13 no.2
• /
• pp.209-220
• /
• 2000

For non-linear analysis of stiffened shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors and taking into account second order rotational terms in the incremental displacement field. Assumed strain concept is adopted in order to overcome shear locking phenomena and to eliminate spurious zero energy mode. The post-buckling behaviors of stiffened shell structures are traced by modeling the stiffener as a shell element and considering general transformation between the main structure and the stiffener at the connection node. Numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references' results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.810-815
• /
• 2002

Vibration analysis of rotating blade is the main purpose of this study. In the present work, general formulation is proposed to analyze the rotating shell-type structures including the effect of centrifugal force, Coriolis acceleration and initial twist. Furthermore, simplified equations are derived for the case of an open circular cylindrical shell. Based on the concept of degenerated shell element with the Reissner-Mindlin's assumptions, the finite element method is adopted for solving the governing equations. In addition, it is investigated the effect of thermal load on the vibration characteristics of pretwisted blade. Numerical results are summarized for the various parameters such as rotating speed, angle of pretwist and stacking sequence of a composite blade. Also, present results are compared with the previous works and experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11a
• /
• pp.380.1-380
• /
• 2002

Vibration analysis of rotating blade is the main purpose of present study. In this work, general formulation is proposed to analyze rotating shell type structures including the centrifugal force, Coriolis acceleration and initial twist. Futhermore, simplified equations are derived for the case of an open circular cylindrical shell. Based on the concept of degenerated shell element with the Reissner-Mindlin's assumptions, the finite element method is adopted for solving the governing equations. (onitted)