• Steel and Composite Structures
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• v.50 no.6
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• pp.659-674
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• 2024

Casting Ultra High-Performance Concrete (UHPC) on an orthotropic steel deck and forming a composite action by connectors could improve the steel deck fatigue performance. This study presents the mechanical performance of a proposed post-combination connection between UHPC and steel, which had a low constraint effect on UHPC shrinkage. A total of 10 push-out tests were conducted for static and fatigue performance investigations. And the test results were compared with evaluation methods in codes to verify the latter's applicability. Meanwhile, nonlinear simulation and parametric works with material damage plasticity models were also conducted for the static and fatigue failure mechanism understanding. The static and fatigue test results both showed that fractures at stud roots and surrounding local UHPC crushes were the main failure appearances. Compared with normally arranged studs, group arrangement could result in reductions of static stud shear stiffness, strength, and fatigue lives, which were about 18%, 12%, and 27%, respectively. Compared with the test results, stud shear capacity and fatigue lives evaluations based on the codes of AASHTO, Eurocode 4, JSCE and JTG D64 could be applicable in general while the safety redundancies tended to be smaller or even insufficient for group studs. The analysis results showed that arranging studs in groups caused obviously uneven strain distributions. The severer stress concentration and larger strain ranges caused the static and fatigue performance degradations of group studs. The research outcome provides a very important basis for establishing a design method of connections in the novel post-combination steel-UHPC composite deck.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.36-40
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• 2008

This study is analyzed by the simulation of automotive steering system. The maximum equivalent stress of $2.2418{\times}109Pa$ and the maximum total displacement of 0.014929m are shown at the universal joint and its lower part respectively. As the minimum cycle of 34.047 is shown at the universal joint in case of fatigue analysis, it is possible to have greatest damage at this part. In case of natural frequency analysis at vibration, its frequency of 47 to 59Hz is occurred generally. The maximum total displacement of 0.5m is shown at handle on the natural frequency of 57 to 58Hz. And the displacement over 2m is shown at the lower part of universal joint on the natural frequency of 58 to 59Hz. As the basis of the simulation analysis of steering system, passenger's comfort of car body can be improved in the design of practical part and the design effect necessary to safe driving can be promoted.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.604-609
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• 2003

Flaw geometries, applied stress, and material properties are major input variables for the fracture mechanics analysis. Probabilistic approach can be applied for the consideration of uncertainties within these input variables. But probabilistic analysis requires many assumptions due to the lack of initial flaw distributions data. In this study correlations are examined between initial flaw distributions and in-service flaw distributions on structures under cyclic load. For the analysis, LEFM theories and Monte Carlo simulation are applied. Result shows that in-service flaw distributions are determined by initial flaw distributions rather than fatigue crack growth rate. So initial flaw distribution can be derived from in-service flaw distributions.

• Transactions of Materials Processing
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• v.14 no.2 s.74
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• pp.133-138
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• 2005

This paper presents a study on defects in pearlite lamella structure of high carbon steel by means of finite-element method(FEM) simulation. High-carbon pearlite steel wire is characterized by its nano-sized microstructure feature of alternation ferrite and cementite. The likely fatigue crack is located on interface of the lamella structure where the maximum amplitude of the longitudinal shear stress and transverse shear stress was calculated during cyclic loading. The FEM is proposed for maximum shear stress from loading of lamella structure, and a method is predicted to analyze the likely fatigue crack generation. It is possible to obtain the important basic data which can be guaranteed in the ductility of high carbon steel wire by using FEM simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.93-96
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• 2004

This paper presents a study on defects in pearlite lamella structure of high carbon steel by means of finite-element method(FEM) simulation. High-carbon pearlite steel wire is characterized by its nano-sized microstructure feature of alternation ferrite and cementite. The likely fatigue crack is located on interface of the lamella structure where the maximum amplitude of the longitudinal shear stress and transverse shear stress was calculated during cyclic loading. The FEM is proposed for maximum shear stress from loading of lamella structure, and a method is predicted to analyze the likely fatigue crack generation. It is possible to obtain the important basic data which can be guaranteed in the ductility of high carbon steel wire by using FEM simulation.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.100-106
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• 2010

In this paper crack propagation analyses in the dissimilar metal weldment of a nozzle were performed using a finite element alternating method (FEAM). A two-dimensional axisymmetric finite element nozzle model was prepared and welding simulation including the thermal heat transfer analysis and the thermal stress analysis was performed. Initial cracks were inserted at weld and heat affected zone in the finite element model which has welding residual stress distribution obtained from the welding simulation. To calculate crack propagation trajectories of these cracks, a new fatigue crack evaluation module was developed in addition to the previous FEAM program. With the new FEAM fatigue crack evaluation module, crack propagation trajectory and crack growth time were calculated automatically and effectively.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.15-20
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• 2006

The finite element alternating method is a convenient and efficient method to analyze three-dimensional cracks embedded in an infinite or a finite body because the method has the property that the uncracked body and cracks can be modeled independently. In this paper the method was applied for fatigue crack growth simulation. A surface crack in a cylinder was considered as an initial crack and the crack configurations and stress intensity factors during the crack growth were obtained. In this paper the finite element alternating method proposed by Nikishkov, Park and Atluri was used after modification. In the method, as the required solution for a crack in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear was used. And a crack was modeled as distribution of displacement discontinuities, and the governing equation was formulated as singularity-reduced integral equations.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.614-620
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• 2009

A fuel tank of a vehicle is an important part due to its flammable contents ant its importance during crash conditions. Therefore, the fuel tank's design should be assessed for durability and robustness to ensure safety during the early development phase. Previously, evaluation for the durability was done by testing in physical driving conditions which could only be done after the completion of the vehicle. Computation simulation is a more effective method to evaluate the strength and durability of the fuel tank during the early stage. In this paper, two outstanding computational simulation methods are studied. One evaluates PV cycle fatigue due to build up pressure in the fuel tank and the other evaluates the PSD vibration fatigue from modal characteristics. The results show that computational methods agree with physical tests and are thus suitable to analyze the strength and durability of the fuel tank at early development phase.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.133-138
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• 2007

The balance shaft housing in the recent engines tends to have the high cycle fatigue crack caused by increased engine power. In this paper, a CAE procedure is introduced to predict the durability of the balance shaft housing. The procedure is performed through two analysis steps. In the first step, the multibody dynamic simulation is used to obtain more accurate loading boundary conditions applied to the finite element model for the following step. Next, the finite element analysis is performed to predict the durability of the balance shaft housing through the calculation of the safety factor. Through this CAE procedure, the revised balance shaft housing was developed to improve the durability. And the durability of the housing was confirmed experimentally.

• 한국도로학회:학술대회논문집
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• 2006.10a
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• pp.131-136
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• 2006