• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.407-412
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• 1998

In this work, a new time integration method is proposed using the generalized derivative concept to simulate the dynamic phenomena having sudden constraint occurring in dynamic contact/impact problems. By the adoption of the generalized derivative concept and jump assumption, discontinuity can be incorporated in time integration and as a result, the algorithm does not need any other special consideration of jumps in dynamic field variables due to sudden constraint like dynamic contact-release conditions. To observe the characteristics of the proposed time integration method, the stability and convergence analyses are carried out. In numerical tests, several dynamic contact/impact problems are analyzed by straightforward application of the proposed time integration method with the exterior penalty method.

• Structural Engineering and Mechanics
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• v.27 no.5
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• pp.609-623
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• 2007

The problem of a semi-infinite magneto-electro-elastically impermeable mode-III crack in a magneto-electro-elastic material is considered under the action of impact loads. For the case when a pair of concentrated anti-plane shear impacts, electric displacement and magnetic induction impacts are exerted symmetrically on the upper and lower surfaces of the crack, the magneto-electro-elastic field ahead of the crack tip is determined in explicit form. The dynamic intensity factors and dynamic energy density factor are obtained. The method adopted is to reduce the mixed initial-boundary value problem, by using the Laplace and Fourier transforms, into three simultaneous dual integral equations, one of which is converted into an Abel's integral equation and the others into a singular integral equation with Cauchy kernel. Based on the obtained fundamental solutions of point impact loads, the solutions of two kinds of different loading cases are evaluated by integration. For some particular cases, the present results reduce to the previous results.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.17-25
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• 2010

This paper studied on stability of the U-channel segmental concrete bridge under vehicle-impact loads. The U-channel bridge has advantages in that it reduces an additional dead load and the edge beams role as a barrier. But it has a dangerous factor which collapses the bridge structure when the edge beams are ruptured. Therefore, it is necessary to verify behaviors of the bridge system under vehicle-impact loads. Static and dynamic vehicle impact simulations were carried out on the basis of AASHTO LRFD design specifications. In case of the static analysis, equivalent static loads specified in the AASHTO codes are loaded on the edge beams and in case of the dynamic analysis, FEM vehicle models are modeled by applying the dynamic test specifications of AASHTO codes. As a result, it is shown that U-channel bridge system has sufficient safety against static and dynamic impact loads specified in the AASHTO LRFD design specifications.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.393-403
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• 2019

The cycling impact test of red sandstone soil under different axial pressure and different impact loads are conducted to reveal the mechanical properties and energy consumption mechanism of red sandstone soil with static-dynamic coupling loading. The results show that: Under the action of different axial pressure and different impact loads, the peak stress of the specimen increases, and then tends to be stable with the times of impact. With the increase of impact times, the specific energy absorption value of the red sandstone soil specimen is increased first and then gentle development trend. When the impact loads are certain, the larger the axial pressure is, the smaller the peak value of energy absorption, which indicates that the energy utilization rate is not high under the condition of large axial pressure. Through the analysis of energy utilization, it is found that the smaller the impact load, the higher the energy utilization rate. The greater the axial pressure, the lower the energy utilization rate. when the axial pressure is large, the impact loads corresponding to the maximum values of reflectivity, transmissivity and absorptivity are the same. The relationship between reflectivity and transmissivity is negatively correlated.

• Computers and Concrete
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• v.22 no.6
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• pp.515-525
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• 2018

This paper presents a numerical study on the performance of reinforced concrete (RC) bridge structures subjected to heavy goods vehicle (HGV) collision. The objectives of this study are to investigate the dynamic response and failure modes of different types of bridges under impact loading as well as to give an insight into the simplified methods for modeling bridge structures. For this purpose, detailed finite-element models of HGV and bridges are established and verified against the full-scale collision experiment and a recent traffic accident. An intensive parametric study with the consideration of vehicle weight, vehicle velocity, structural type, simplified methods for modeling bridges is conducted; then the failure mode, impact force, deformation and internal force distribution of the validated bridge models are discussed. It is observed that the structural type has a significant effect on the force-transferring mechanism, failure mode and dynamic response of bridge structures, thus it should be considered in the anti-impact design of bridge structures. The impact force of HGV is mainly determined by the impact weight, impact velocity and contact interface, rather than the simplification of the superstructure. Furthermore, to reduce the modeling and computing cost, it is suggested to utilize the simplified bridge model considering the inertial effect of the superstructure to evaluate the structural impact behavior within a reasonable precision range.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.170-177
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• 1997

In this study, an analysis technique using simple beam model for predicting structure crashworthiness of the passenger car side impacted with an angle by another passenger car was investigated. The simple model was composed of major beam-like side structure which carry almost all side impact load. A procedure of component collapse test, calculation of load carrying capability and dynamic simulation was carryed out sequentially. Transient dynamic algorithms and a computer program to simulate deformations and motions of the impacted car was developed. The developed procedure was applied to a 3 door passenger car side impacted with an angle of 75 degree and the analysis results show good agreements with the actual test results.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.797-803
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• 2010

A dynamic analysis procedure is developed to provide a better estimation of the dynamic responses of pre-stressed concrete (PSC) box girder bridges on the Korea high speed railway. Particularly, a three dimensional numerical model including the structural interaction between high speed vehicles, bridges and railway endures to analyze accurately and evaluate with in-depth parametric studies for dynamic responses of bridge due to the high speed railway vehicles. Three dimensional frame element is used to model the PSC box girder bridges, simply supported span lengths 40 m. The high-speed railway vehicles (K-TGV) including a locomotive are used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) as well as three rotational components (pitching, rolling, and yawing) are considered in the 38-degree of freedom model. The dynamic analysis by Runge-Kutta method which are able to analyze considering the dynamic impact factors are compared and contrasted. It is proposed as an empirical formula that the impact factors damaged the bridge load-carrying capacities occurs to the bride due to high-speed vehicle.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.254-260
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• 2000

The spacer grid is one of the main structural components in fuel assembly, which supports the fuel rods, guides cooling water, and protects the fuel assembly from the external impact load such as earthquakes. The nonlinear dynamic impact analysis is conducted by using the finite element code ABAQUS/Explicit. Boundary condition for dynamic analysis is well applied to the test condition. Simulation results also similarly predict the local buckling phenomena. In addition to the buckling parameter, the local buckling cause is examined by both simulation and test method. It is found to correspond well with the test results. Impact tests are also carried out for some specimens of the spacer grid in order to compare the results between the test and the simulation. This test is accomplished by a free fall dummy weight onto the specimen. From this test, only the uppermost and lowermost layers of the multi-cell are buckled, which implies the local buckling at the weakest point of the grid structure.

• Structural Monitoring and Maintenance
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• v.2 no.1
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• pp.65-75
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• 2015

Among the destruction instances of half-through arch bridges, the shorter hangers are more likely to be ruined. For a thorough investigation of the hanger system durability, we have studied vehicle impact effect on hangers with vehicle-bridge coupling method for a half-through concrete-filled-steel-tube arch bridge. A numerical method has been applied to simulate the variation of dynamic internal force (stress) in hangers under different vehicle speeds and road surface roughness. The characteristics and differences in impact effect among hangers with different length (position) are compared. The impact effect is further analyzed comprehensively based on the vehicle speed distribution model. Our results show that the dynamic internal force induced by moving vehicles inside the shorter hangers is significantly greater than that inside the longer ones. The largest difference of dynamic internal force among the hangers could be as high as 28%. Our results well explained a common phenomenon in several hanger damage accidents occurred in China. This work forms a basis for hanger system's fatigue analysis and service life evaluation. It also provides a reference to the design, management, maintenance, monitoring, and evaluation for this kind of bridge.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.183-188
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• 1996

The compressive stress-strain response of Low Density Polyurethane foam material is modeled using the finite element method. A constitutive equation which include experimental constants based on quasi-static and dynamic uniaxial compression test is proposed. Impact test with different impactor masses and velocities are performed to verify the proposed model. The comparison between impact test and finite element analysis shows good agreements.