• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2006년도 학술발표대회 논문집
• /
• pp.357-361
• /
• 2006

Fatigue fracture behavior of a hybrid joint part with bolting was evaluated in comparison to the case of static fracture. Hybrid joint part specimens for bending test were made with layers of CFRP and aluminum honeycomb. Characteristic fracture behaviors of those specimens were obviously different under static and cyclic loads. Static bending load showed the shear deformation at the honeycomb core, whereas cyclic bending load caused the delamination between CFRP skin layers and honeycomb core. Experimental results obtained by static and fatigue tests were considered in modifications of design parameters of the hybrid joint.

• 한국해양공학회지
• /
• 제18권6호
• /
• pp.70-78
• /
• 2004

In order to increase the load carrying capacity of tubular structures, the joints of tubular members are usually reinforced with various reinforcement system. A stiffening method with internal ring stiffeners is effectively used for the steel tubular joint with a large diameter. In this study, the behavior of internally ring-stiffened tubular T-joints subjected to axial loading is assessed. For the parametric study, nonlinear finite element analyses are used to compute the static strength on non-stiffened and ring-stiffened T-joints. Based on the numerical results, an internal ring stiffener is found to be efficient in improving the static strength. The influence of geometric parameters has been determined, and the reinforcement effect are evaluated. Based on the FE results, regression analises are performed considering the practical size of ring stiffener. Finally strength estimation formulas for ring-stiffened tubular T-joints are proposed.

• Advances in materials Research
• /
• 제12권2호
• /
• pp.83-100
• /
• 2023

In this paper, sandwich plate, constructed with orthotropic and isotropic composite materials, is analyzed to obtain the static and harmonic behavior. The analysis is done by using ANSYS APDL FEM tool. A solid-shell 190 and an 8-node solid 185 elements are employed for face and core material respectively to analyze the plate. Results was attained by using Reissner-Mindlin theory. Effect of increasing thickness ratio of face sheet to depth of the plate is presented on static, vibration and harmonic response on the sheet and the results are discussed briefly. Published work in open domain was used to validate the results and observed excellent agreement. It can be stated that proposed model presents results with remarkable accuracy. Results are obtained to reduce the weight of the plate and minimizing the vibration amplitudes.

• 대한기계학회논문집A
• /
• 제31권2호
• /
• pp.166-173
• /
• 2007

Fatigue fracture behavior of a hybrid bolted joint was evaluated in comparison to the case of static fracture. Two kinds of specimens were fabricated for the mechanical tests; a hybrid bolted joint specimen for the shear test and a hybrid joint part specimen applied in the real tilting car body for the bending test. Characteristic fracture behaviors of those specimens under cyclic toads were obviously different from the case under static loads. For the hybrid bolted joint specimen, static shear loading caused the fracture of the bolt body itself in a pure shear mode, whereas cyclic shear loading brought about the fracture at the site of local tensile stress concentration. For the hybrid joint part specimen, static bend loading caused the shear deformation and fracture in the honeycomb core region, while cyclic bend loading did the delamination along the interface between composite skin and honeycomb core layers as well as the fracture of welded joint part. Experimental results obtained by static and fatigue tests were reflected in modifications of design parameters of the hybrid joint structure in the real tilting car body.

• Journal of Electrical Engineering and Technology
• /
• 제9권4호
• /
• pp.1258-1268
• /
• 2014

Improving grid connection of wind farms is a relevant issue to be addressed, especially for fixed-speed wind turbines. Certain elements, such as FACTS (Flexible AC Transmission Systems), are able to perform voltage and reactive power regulation in order to support voltage stability of wind farms, and compensate reactive power consumption from the grid. Several devices are grouped under the name of FACTS, which embrace different technologies and operating principles. Here, three of them are evaluated and compared, namely STATCOM (Static Synchronous Compensator), SVC (Static Var Compensator) and SSSC (Static Synchronous Series Compensator). They have been modeled in MATLAB/Simulink, and simulated under various scenarios, regarding both normal operation and grid fault conditions. Their response is studied together with the case when no FACTS are implemented. Results show that SSSC improves the voltage stability of the wind farm, whereas STATCOM and SVC provide additional reactive power.

• Steel and Composite Structures
• /
• 제25권6호
• /
• pp.727-734
• /
• 2017

This paper describes a quasi-static finite element analysis, which uses the explicit integration method, of the apex joint of a cold-formed steel portal frame. Such cold-formed steel joints are semi-rigid as a result of bolt-hole elongation. Furthermore, the channel-sections that are being connected have a reduced moment capacity as a result of a bimoment. In the finite element model described, the bolt-holes and bolt shanks are all physically modelled, with contact defined between them. The force-displacement curves obtained from the quasi-static analysis are shown to be similar to those of the experimental test results, both in terms of stiffness as well as failure load. It is demonstrated that quasi-static finite element analysis can be used to predict the behavior of cold-formed steel portal frame joints and overcome convergence issues experienced in static finite element analysis.

• Geomechanics and Engineering
• /
• 제36권3호
• /
• pp.247-258
• /
• 2024

Tailings are waste materials of mining operations, consisting of a mixture of clay, silt, sand with a high content of unrecoverable metals, process water, and chemical reagents. They are usually discharged as slurry into the storage area retained by dams or earth embankments. Poor knowledge of the hydro-mechanical behaviour of tailings has often resulted in a high rate of failures in which static liquefaction has been widely recognized as one of the major causes of dam collapse. Many studies have dealt with the static liquefaction of coarse soils in saturated conditions. This research provides an extension to the case of silty tailings in unsaturated conditions. The static liquefaction resistance was evaluated in terms of stress-strain behavior by means of monotonic triaxial tests. Its dependency on the preparation method, the volumetric water content, the void ratio, and the degree of saturation was studied and compared with literature data. The static liquefaction response was proved to be dependent mainly on the preparation technique and degree of saturation that, in turn, controls the excess of pore pressure whose leading role is investigated by means of the relationship between the -B Skempton parameter and the degree of saturation. A preliminary interpretation of the static liquefaction response of Stava tailings is also provided within the Critical State framework.

• 설비공학논문집
• /
• 제30권1호
• /
• pp.33-43
• /
• 2018

This study numerically investigated statistic and dynamic behaviors of the water droplet on plate with or without various structured-pillars at nano-scale by molecular dynamics simulation. This study considered smooth plate, plate with the rectangular-structured pillar, and the plate with dual-structured pillar under various characteristic energy conditions. The static behavior of water droplet depending on the plate shape, plate surface energy, and the pillar characteristics were examined. After the water droplet reaches its steady state, this study investigated the dynamic behavior of the water droplet by applying a constant force. Finally, this study investigated the static and dynamic behaviors of the water droplet by measuring its contact angle and contact angle hysteresis. As a result, we found that the structure was more hydrophobic.

• Earthquakes and Structures
• /
• 제6권4호
• /
• pp.335-350
• /
• 2014

Historical masonry mosques are the most important structures of Islamic societies. To estimate the static and dynamic behavior of these historical structures, an examination of their restoration studies is very important. In this study, Kara Mustafa Pasha Mosque, which was built as a domed mosque by Kara Mustafa Pasha between 1666-1667 in Amasya, Turkey, has been analyzed. This study investigates the structural behavior and architectural features of the mosque. In order to determine specific mechanical properties, compression and three-point bending tests were conducted on materials, which have similar age and show similar properties as the examined mosque. Additionally, a three-dimensional finite element model of the mosque was developed and the structural responses were investigated through static and dynamic analyses. The results of the analyses were focused on the stresses and displacements. The experimental test results indicate that the construction materials have greatly retained their mechanical properties over the centuries. The obtained maximum compression and tensile stresses from the analyses have been determined as smaller than the materials' strengths. However, the stresses calculated from dynamic analysis might cause structural problems in terms of tensile stresses.

• 한국도로학회논문집
• /
• 제19권1호
• /
• pp.21-28
• /
• 2017

PURPOSES : This paper presents a finite element model to accurately represent the soil-post interaction of single guardrail posts in sloping ground. In this study, the maximum lateral resistance of a guardrail post has been investigated under static and dynamic loadings, with respect given to several parameters including post shape, embedment depth, ground inclination, and embedment location of the steel post. METHODS : Because current analytical methods applied to horizontal ground, including Winkler's elastic spring model and the p-y curve method, cannot be directly applied to sloping ground, it is necessary to seek an alternative 3-D finite element model. For this purpose, a 3D FHWA soil model for road-base soils, as constructed using LS-DYNA, has been adopted to estimate the dynamic behavior of single guardrail posts using the pendulum drop test. RESULTS : For a laterally loaded guardrail post near slopes under static and dynamic loadings, the maximum lateral resistance of a guardrail post has been found to be reduced by approximately 12% and 13% relative to the static analysis and pendulum testing, respectively, due to the effects of ground inclination. CONCLUSIONS : It is expected that the proposed soil material model can be applied to guardrail systems installed near slopes.