• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.4
• /
• pp.39-45
• /
• 2008

Breakaway support for small signs of size $0.293\;m^2{\sim}0.360\;m^2$ using indented tube type bolt of D12 mm with 6 mm inner diameter has been developed and the structural strength of the support system for the wind load was verified through static shear and tension tests. One important value in understanding the dynamic behavior of sign post and impact vehicle is the fracture energy of the sign support. In this study, fracture energy needed to break the sign support was estimated by pendulum test and computer simulation using LS-DYNA program. Support system composed of 3 indented bolts was found to sustain the 43.1 kg$\sim$51.2 kg wind load safely. Fracture energy for one indented bolt was measured as 163.3J from the pendulum test, and was calculated as 153J from the LS-DYNA simulation. The closeness between these two values verified the validity of the simulation model.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.1 no.2
• /
• pp.82-95
• /
• 1998

In this paper, two series of numerical simulations are performed using LS/DYNA3D: The first series of numerical simulations are collision events between a 310,000 DWT double hull VLCC (struck ship) and two 35,000 and 105,000 DWT tankers (striking ships). Collisions are assumed to occur at the middle of the VLCC with the striking ships moving at right angle to the YLCC centerline. The second ones, grounding accidents of two 40,000 DWT Conventional and Advanced Double Hull lanker bottom structures, CONV/PD328 and ADH/PD328 models. The overall objective of this study is to understand the structural failure and energy absorbing mechanisms during collision and grounding events for double hull tanker side and bottom structures, which lead to the initiation of inner shell rupture and cause the kinetic energy dissipation to bring the ship to a stop. These numerical simulations will contribute to the estimation of damage extents of collision and grounding accidents and the future improvements in lanker safety at the design stage.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.5
• /
• pp.499-506
• /
• 2011

In this study, the performance of composite safety barriers was evaluated through computer simulation. A composite safety barrier of SB4 grade was modeled. The MAT58 material model provided by LS-DYNA software was used to model composite material. The performance of composite material varies according to fiber, resin type, and fiber direction. Polyurethane resin and glass fiber were used. The performance of three different stacking designs was evaluated by carrying out vehicle impact simulation. The performance evaluation based on the vehicle crash manual includes the structural strength performance, the passenger protection performance, the vehicle behavior after crash, scattering of the guardrail. As the result of the finite element analysis, the barrier composed of the more transverse direction fibers shows the better performance on the impact simulation.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.4
• /
• pp.293-300
• /
• 2013

In this study we proposed a simplified finite element model of anchor bolt system inserted through concrete structures considering clamping forces. The three different finite element types using LS-DYNA are applied for numerical efficiency of the anchor bolt modeling. Combined beam and solid elements are used to reflect the tension state at internal part of anchor bolt due to torques. The clamping forces due to torques are considered by introducing a compression for a nut plane modeled by beam elements. The numerical examples show good agreement with different element types. Parametric studies are focused on the various effects of different element types on the induced axial and shear forces of anchor bolts considering clamping forces.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.5
• /
• pp.561-565
• /
• 2011

The structural vehicles are steel members of square or circle tube with definite shape. These members support various components and absorb impact energy to protect passengers during accidentswhen crash happen. Structural members need to be lightweight and stable. In this study, we do an impact simulation of a CFRP square member using finite element analysis program Ls-Dyna in order to predict fracture shape and energy absorb feature of CFRP member. Also, we make square member shape of CFRP and do an impact experiment. We compare the analytical and experimental results and consider the fracture shape and energy features of CFRP members.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.5
• /
• pp.391-399
• /
• 2011

The purpose of this paper is to predict the shock absorbing characteristics of the aluminum honeycomb in a lunar lander. Aluminum honeycomb has been used for shock absorbers of lunar lander due to its characteristics such as light weight, high energy absorption efficiency and applicability under severe space environments. Crush strength of the honeycomb should have strength to endure during shock energy absorbing process. In this paper, the crush strength, which depends on the shape of honeycomb and impact velocity, is estimated using FEM. Ls-dyna is used for finite element analysis of the honeycomb shock absorber. The unit cells of the honeycomb shape are modeled and used for the finite element analysis. Energy absorption characteristics are decided considering several conditions such as impact velocity, foil thickness and branch angle of the honeycomb.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.4
• /
• pp.155-164
• /
• 2011

In the case of impact loading test, measurement of the test data has difficulties due to fast loading velocity. In addition, the dynamic behaviors of specimens are distorted by ignoring local fracture. In this study, therefore, finite element analysis which considers local fracture and strain rate effect on impact load was performed by using LS-DYNA, an explicit analysis program. The one-way and two-way specimens strengthened with FRP Sheets and steel fibers were considered as analysis models. The results showed that the impact resistance of steel fiber reinforced concrete (SFRC) and ultra high performance concrete (UHPC) was enhanced. In the case of specimens strengthened with FRP Sheets, GFRP was superior to CFRP in the performance of impact resistance, and there was little effect of the FRP Sheet orientation. The reliability of this analysis model was verified by comparing with previous experimental results.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.6
• /
• pp.726-734
• /
• 2008

While the structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers has to be carried out in consideration of sloshing impact pressure, it is very difficult to figure out its dynamic response behaviors due to its very complex structural arrangements/materials and complicated phenomena of sloshing impact loading. For the development of its original technique, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In this study, for the exact understanding of dynamic response behavior of CCS structure in membrane Mark III type LNG carriers under sloshing impact pressure, its wet drop impact response analyses were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. It might be thought that the structural response behaviors of impact response analysis, such as impact pressure impulses and resulted strain time histories, generally showed very good agreement with experimental ones with very appropriate use of FSI analysis technique of LS-DYNA code, finite element modeling and material properties of CCS structure, finite element modeling and equation of state(EOS) of fluid domain.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.6
• /
• pp.39-46
• /
• 2010

The past studies on reinforced earth retaining wall have been mostly focused on the internal and external failure of reinforced earth retaining wall, and the research for external impact was limited on earthquake. However, the potential external impact such as vehicle collision to reinforced earth retaining wall near the road are increasing with development of roads. Therefore, in this study, the reinforced earth retaining wall was modeled by using LS-DYNA, which is a general purpose finite element program recognized for its reliability. The behavior of reinforced earth retaining wall by vehicle speed was analyzed with Ford single unit truck offered by NCAC (National Crash Analysis Center), which is 8 tons weight. In addition, in order to obtain stability of reinforced earth retaining wall for vehicle collision, the gravity retaining wall was applied at the bottom of reinforced earth retaining wall. With varying the height of retaining wall (0.5m, 1.0m, 1.5m), the numerical study was performed to analyze the stability and behavior of reinforced earth retaining wall.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.2553-2558
• /
• 2014

Military rotorcraft should be designed taking into account the condition of the fuel cell bullet impact. The internal fluid pressure, stress of metal fitting and fuel cell, bullet kinetic energy can be included as the design factor for the fuel cell. The best way to obtain the important design data is to conduct the verification test with actual product. But, the verification test requires huge cost and long-term effort. Moreover, there is high risk to fail because of the sever test condition. Thus, the numerical simulation is required to reduce the risk of trial-and-error together with prediction of the design data. In the present study, the bullet impact simulation based on SPH(smoothed particle hydrodynamics) is conducted with the commercial package, LS-DYNA. As the result of the numerical simulation, the internal pressure of fuel cell is calculated as 350~360MPa and the equivalent stress caused by hydro-ram effect is predicted as 260~350MPa on metal fittings.