• Computational Structural Engineering
• /
• v.8 no.4
• /
• pp.107-115
• /
• 1995

The long term behavior of the Waste Isolation Pilot Plant(WIPP), a nuclear waste repository currently under construction near Carlsbad at New Mexico, depends upon the fracture and deformation behavior of bedded rock salt. Although many numerical analyses of the WIPP have been conducted, to our knowledge none have included the ability to simultaneously predict the effects of fracture and nonlinear deformation of the salt continuum. We are in the process of developing a finite element program to simulate the effects of nonlinear fracture mechanics and nonlinear continuum behavior of rock salt simultaneously.

• 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.

• Proceeding of KASS Symposium
• /
• 2005.05a
• /
• pp.89-98
• /
• 2005

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. Therefore membrane structures arc unstable structures initially. These soft structures need to be introduced initial stresses first because of its initial unstable state, and it happens large deformation phenomenon. To find the structural shape after large deformation caused by initial stiffness introduced, we need the shape analysis considering geometric nonlinearity in structural design procedure. In this study, we investigate into the stress concentration at crack of membrane structures. Therefore, using the nonlinear analysis program that NASS (Nonlinear Analysis for Spatial Structures) perform nonlinear analysis, and stress distribution for creak length investigate for using linear elastic fracture mechanics.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.9
• /
• pp.151-156
• /
• 2002

A new position correction method using four fiducials as reference points was developed and examined. It was aimed to calibrate nonlinear deformation by numerous error sources. A correlation for correction was derived from the geometric relationship between four fiducials and chip position. Compared with three points method, it exhibited more accurate correction, especially for inner area of a quadrilateral composed of four fiducial points. Its accuracy was found to be increased as fiducials moves outwardly within a printed circuit board (PCB) and/or as they form more rectangle-like shape As for arbitrarily nonlinear deformation, this method can be applied using more than five fiducials. In this case, local-area calibration is carried out by sectioning a board area into several rectangular are as.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.10
• /
• pp.2574-2581
• /
• 1993

A Shadow mask in C. R. T. (Cathod Ray Tube) undergoes a temperature increase due to impinging electron beams emitted from guns, and thermal deformation from such temperature rise may cause the electron beams to island on the panel, and thus give rise to depolarization. Hence the analysis of temperature distribution for a shadow mask is an important procedure for designing the shadow mask. In this paper, we are concerned with nonlinear finite element analysis of the temperature distribution on a shadow mask. First of all, we replace shadow mask, containing numerous apertures of a slit type, by an orthotropic shell without apertures, and calculate the apparent thermal conductivities. Because of thermal radiation, which is one of the major heat transfer mechanism for shadow masks, the resulting finite element equation is nonlinear and solved by the Newton method. Finally numerical examples are illustrated for a 21" FST(Full Square Tube) shadow mask, and followed by discussion.sion.

• Structural Engineering and Mechanics
• /
• v.15 no.4
• /
• pp.463-476
• /
• 2003

This paper deals with nonlinear asymmetric dynamic buckling of clamped laminated angle-ply composite spherical shells under suddenly applied pressure loads. The formulation is based on first-order shear deformation theory and Lagrange's equation of motion. The nonlinearity due to finite deformation of the shell considering von Karman's assumptions is included in the formulation. The buckling loads are obtained through dynamic response history using Newmark's numerical integration scheme coupled with a Newton-Raphson iteration technique. An axisymmetric curved shell element is used to investigate the dynamic characteristics of the spherical caps. The pressure value beyond which the maximum average displacement response shows significant growth rate in the time history of the shell structure is considered as critical dynamic load. Detailed numerical results are presented to highlight the influence of ply-angle, shell geometric parameter and asymmetric mode on the critical load of spherical caps.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.11
• /
• pp.2049-2054
• /
• 2006

This paper demonstrates a comparison of linear and nonlinear analyses for thermo-optic effects of optical temperature sensor based on the etched silica-based planar waveguide Bragg grating. Topics include theoretical analyses and experiment of the etched planar waveguide Bragg grating optical temperature sensor, Theoretical models with nonlinear than linear temperature effect for the grating response based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

• Structural Engineering and Mechanics
• /
• v.17 no.6
• /
• pp.829-862
• /
• 2004

This paper presents a method for the nonlinear analysis of beam elements subjected to the cyclical combined actions of torsion, biaxial flexure and axial forces based on an extension of the disturbed compression field (DSFM). The theoretical model is based on a hybrid formulation between the full rotation of the cracks model and the fixed direction of the cracking model. The described formulation, which treats cracked concrete as an orthotropic material, includes a new approach for the evaluation of the re-orientation of both the compression field and the deformation field by removing the restriction of their coincidence. A new equation of congruence permits evaluating the deformation of the middle line. The problem consists in the solution of coupled nonlinear simultaneous equations expressing equilibrium, congruence and the constitutive laws. The proposed method makes it possible to determine the deformations of the beam element according to the external stresses applied.

• Journal of the Society of Naval Architects of Korea
• /
• v.42 no.5 s.143
• /
• pp.466-471
• /
• 2005

The out-of-plane deformation in thin plate structure has been a serious qualify problem. It has been known that the out-of-plane deformation is caused by the angular deformation of welded joint. However, experimental results show that the conventional theory based on angular deformation is not appropriate for prediction of the out-of-plane deformation in thin plate structure. In this study, large deformation plate theory is introduced to clarify the effect of residual stress on the out-of-plane deformation. A simple equation is proposed to predict the out-of-plane deformation. The results by the proposed method show good agreement with the experimental results.

• Journal of the Korea Concrete Institute
• /
• v.11 no.5
• /
• pp.89-98
• /
• 1999

This paper evaluates nonlinear response characteristics of precast concrete frame buildings. where plastics hinging occurs in the precast connection. Designs were developed for buildings of 5, 10 and 15 stories in hight for moderate seismic risk regions of the U. S. The responses of the buildings were analyzed using DRAIN-2DX and following Nonlinear static analysis procedure of ATC 19. The main variables of the analyses were the strength and stiffness of the connection. Also, for the analysis, the bi-linear response model, developed and inserted into the DRAIN-2DX program by Shan Shi and D. Fouch, was used. With the results of analysis, the deformation demands of the connection of precast concrete frame buildings are proposed by using equal-dissipated energy capacity. It was shown that the strength of the buildings as well as their displacement capacities decreased with the decrease of either the strength or stiffness in the connections. Therefore such changes also require reductions in the response modification factors for such buildings. However, if the precast concrete frame building has plastic hinging in the connection, and has a more ductile connection than the monolithic frame building, then no reduction in R may be necessary. The deformation demand required of the connection to achieve that condition is evaluated and a simple relation is suggested in the paper.