• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.565-573
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• 1999

Hihg Tensile Steel enables to reduce the plate thickness comparing to the case when Mild Steel is used. From the economical view points this is very preferable since the reduction in the hull weight. however to use the High Tensile Steel effectively the plate thickness may become thin so that the occurrence of buckling is inevitable and design allowing plate buckling may be necessary. If the inplane stiffness of the plating decreases due to buckling the flexural rigidity of the cross sect6ion of a ship's hull also decreases. This may lead to excessive deflection of the hull girder under longitudinal bending. In these cases a precise estimation of plate's behavior after buckling is necessary and nonliner analysis of isolated and stiffened plates is required for structural sys-tem analysis. In this connection this paper discusses nonlinear behaviour of thin plate under thrust. Based on the analytical method elastic large deflection analysis of isolated plate is perform and simple expression are derived to evaluated the inplane rigidity of plates subjected to uniaxial compression.

• Journal of the Korean Institute of Navigation
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• v.20 no.1
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• pp.47-58
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• 1996

The use of high tensile steel plates is increasing in the fabrication of ship and offshore structures. The main portion of ship structure is usually composed of stiffened plates. In these structures, plate buckling is one of the most important design criteria and buckling load may usually be obtained as an eigenvalue solution of the governing equations for the plate. To use the high tensile steel plate effectively, its thickness may become thin so that the occurrence of buckling is inevitable and design allowing plate buckling may be necessary. When the panel elastic buckling is allowed, it is necessary to get precise understandings about the post-buckling behaviour of thin plates. It is well known that a thin flat plate undergoes secondary buckling after initial buckling took place and the deflection of the initial buckling mode was developed. From this point of view, this paper discusses the post-buckling behaviour of thin plates under thrust including the secondary buckling phenomenon. Series of elastic large deflection analyses were performed on rectangular plates with aspect ratio 3.6 using the analytical method and the FEM.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1996.09a
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• pp.95-110
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• 1996

High Tensile Steel enables to reduce the plate thickness comparing to the case when Mild Steel is used. From the economical view point this is very preferable since the reduction in the hull weight. However to use the High Tensile Steel effectively the plate thickness may become thin so that the occurrence of buckling is inevitable and design allowing plate buckling may be necessary. If the inplane stiffness of the plating decreases due to buckling, buckling may be necessary. If the inplane stiffness of the plating decreases due to buckling the flexural rigidity of the cross section of a ship's hull also decreases. this may lead to excessive deflection of the hull girder under longitudinal bending. In these cases a precise estimation of plate's behavior after buckling is necessary and nonlinear analysis of isolated and stiffened plates is required for structural system analysis. In this connection this paper discusses nonlinear behaviour of thin plate under thrust. Based on the analytical method elastic large deflection analysis of isolated plate is perform and simple expression are derived to evaluate the inplane rigidity of plates subjected to uniaxial compression.

• Advances in concrete construction
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• v.15 no.3
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• pp.161-170
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• 2023

Ultra-high-performance concrete (UHPC) is produced using high amount of cementitious materials, very low water/cementitious materials ratio, fine-sized fillers, and steel fibers. Due to the dense microstructure of UHPC, it possesses very high strength, elasticity, and durability. Besides that, the UHPC exhibits high ductility and fracture toughness due to presence of fibers in its matrix. While the high ductility of UHPC allows it to undergo high strain/deflection before failure, the high fracture toughness of UHPC greatly enhances its capacity to absorb impact energy without allowing the formation of severe cracking or penetration by the impactor. These advantages with UHPC make it a suitable material for construction of the structural members subjected to special loading conditions. In this research work, the UHPC mixtures having three different dosages of steel fibers (2%, 4% and 6% by weight corresponding to 0.67%, 1.33% and 2% by volume) were characterized in terms of their mechanical properties including facture toughness, before using these concrete mixtures for casting the slab specimens, which were tested under high-energy impact loading with the help of a drop-weight impact test setup. The effect of fiber content on the impact energy absorption capacity and central deflection of the slab specimens were investigated and the equations correlating fiber content with the energy absorption capacity and central deflection were obtained with high degrees of fit. Finite element modeling (FEM) was performed to simulate the behavior of the slabs under impact loading. The FEM results were found to be in good agreement with their corresponding experimentally generated results.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.2
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• pp.105-114
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• 2000

An output feedback control (OFC) is presented for a linear stochastic system with known disturbance and applied to a flexible spacecraft for the reduction of residual vibration while allowing the natural deflection during operation. By converting the tracking problem into regulator problem, the OFC minimizes the expected value of a guadratic objective function composing of error stats which always remain on the intersection of sliding hypersurfaces. For the numerical evaluation with a flexible spacecraft, a large slewing maneuver strategy is devised with a tracking model for nominal trajectory and start-cost-stop strategy for economical maneuver in conjunction with the input shaping technique. The performance and efficacy of the proposed control scheme are illustrated with the comparison of different maneuver strategies.

• Journal of Adhesion and Interface
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• v.16 no.4
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• pp.137-145
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• 2015

This study aimed to develop epoxy putty as a multi-purpose connection and restoration material that can be used for material-specific restoration work such as metal, wood, ceramics, earthenware and stone artifacts by replacing synthetic resins currently being used for preservation treatment of cultural assets. Existing synthetic resins have the issue of cutting force resulting from high strength, deflection resulting from long hardening time, contaminating the surface of artifacts through staining on tools or gloves and need for re-treatment resulting from material discoloration. Accordingly, paste type restoration material most widely being used in the field of cultural assets preservation treatment was selected and examined the property to select it as an object of comparison. Based on such process, epoxy putty was developed according to the kind of agent, hardener and filler. For the purpose of solving the issues of existing material and allowing the epoxy putty developed to have similar property, property experiments were conducted by selecting agents and hardeners with different characteristics and conditions. The study findings showed that both kinds are paste type that improved work convenience and deflection issue as a result of their work time of within 5~10 minutes that are about 3~10 times shorter than that of existing material. In regards to wear rate for increasing cutting force, it improved by about 3 times, thereby allowing easy molding. For the purpose of improving the issue of surface contamination that occurs during work process, talc and micro-ballon were added as filler to reduce the issue of stickiness and staining on hand. Furthermore, a multi-purpose restoration material with low shrinkage, low discoloration and high cutting force was developed with excellent coloring, lightweight and cutting force features.

• Structural Engineering and Mechanics
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• v.24 no.6
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• pp.709-725
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• 2006

In this paper the buckling and post-buckling behavior of slender bars under self-weight are studied. In order to study the post-buckling behavior of the bar, a geometrically exact formulation for the non-linear analysis of uni-directional structural elements is presented, considering arbitrary load distribution and boundary conditions. From this formulation one obtains a set of first-order coupled nonlinear equations which, together with the boundary conditions at the bar ends, form a two-point boundary value problem. This problem is solved by the simultaneous use of the Runge-Kutta integration scheme and the Newton-Raphson method. By virtue of a continuation algorithm, accurate solutions can be obtained for a variety of stability problems exhibiting either limit point or bifurcational-type buckling. Using this formulation, a detailed parametric analysis is conducted in order to study the buckling and post-buckling behavior of slender bars under self-weight, including the influence of boundary conditions on the stability and large deflection behavior of the bar. In order to evaluate the quality and accuracy of the results, an experimental analysis was conducted considering a clamped-free thin-walled metal bar. As this kind of structure presents a high index of slenderness, its answers could be affected by the introduction of conventional sensors. In this paper, an experimental methodology was developed, allowing the measurement of static or dynamic displacements without making contact with the structure, using digital image processing techniques. The proposed experimental procedure can be used to a wide class of problems involving large deflections and deformations. The experimental buckling and post-buckling behavior compared favorably with the theoretical and numerical results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.40-48
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• 2013

Eco deck plate system is a construction method that deconstruction of galvanized steel sheets is possible by integrating steel-wire-integrated girders and the galvanized steel sheets with bolts. Therefore, compared with previous steel-wire-integrated deck plates which were joined by welding, the system is acknowledged as the construction method possible management and repair. This study conducted an experimental research by manufacturing total 24 full size specimens in a same condition for 12-shape specimens by two parts to evaluate structural behaviors of the eco deck plates. In the results after the test, permissible deflection for the construction load action was shown to be values under design values and satisfactory. The processing of lattice steel wires was presented to be structurally advantageous in being manufactured by cutting downward. Also, in case of a specimen that D13 as a steel wire was used, destruction occurred at the welding part of the bottom steel wire and the lattice steel wire, so improvement measures for the welding in factory manufacture are necessary.

• Structural Engineering and Mechanics
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• v.16 no.5
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• pp.519-531
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• 2003

Piezoelectric actuators have long been recognised for use in aerospace structures for control of structural shape. This paper looks at active control of the swept shock wave/turbulent boundary layer interaction using smart flap actuators. The actuators are manufactured by bonding piezoelectric material to an inert substrate to control the bleed/suction rate through a plenum chamber. The cavity provides communication of signals across the shock, allowing rapid thickening of the boundary layer approaching the shock, which splits into a series of weaker shocks forming a lambda shock foot, reducing wave drag. Active control allows optimum control of the interaction, as it would be capable of positioning the control region around the original shock position and unimorph tip deflection, hence mass transfer rates. The actuators are modelled using classical composite material mechanics theory, as well as a finite element-modelling program (ANSYS 5.7).

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.595-606
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• 2017

During their life span, post-tensioned concrete structures may be exposed to thermal loads. Therefore, there has been a growing interest in research on the advanced analysis and design of post-tensioned concrete slabs subjected to thermal loads. This paper investigates the structural behaviour of post-tensioned one-way spanning concrete slabs. A nonlinear finite element model for the analysis of post- tensioned unbonded and bonded concrete slabs at elevated temperatures was developed. The interface between the tendon and surrounding concrete was also modelled, allowing the tendon to retain its profile shape during the deformation of the slab. The load-deflection behaviour, load-force behaviour in the tendon, and the failure modes are presented. The numerical analysis was conducted by the finite element ANSYS software and was carried out on two different one-way concrete slabs chosen from literature. A parametric study was conducted to investigate the effect of several selected parameters on the overall behavior of post-tensioned one-way concrete slab. These parameters include the effect of tendon bonding, the effect of thermal loading and the effect of tendon profile. Comparison between uniform thermal loading and nonuniform thermal loading showed that restrained post tensioned slab with bottom surface hotter has smaller failure load capacity.