• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.359-371
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• 1994

A drop weight type impact test system is designed and set up to experimentally investigate impact responses of composite laminates subjected to the low-velocity impact. Using the test system, the impact velocity and the rebound velocity of the impactor as well as the impact force history are measured. An error of the measured data due to a difference in measuring position of the sensor is corrected and, for the estimation of real contact force history, a method of correcting an error due to friction forces is developed. Experimental methods to fix the boundary edgy of laminate specimens in impact testing are investigated and the impact tests on the specimens fixed by those methods are performed. Impact force histories and dynamic strains measured from the tests are compared with numerical results from the finite element analysis using the contact law. Consequently, the nonlinear numerical results considering the large deflection effects are agreed with the experimental results better than the linear ones.

• Journal of Conservation Science
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• v.38 no.4
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• pp.277-288
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• 2022

'Eve 58-1', the subject of this study is a statue made of plaster and its structural stability was evaluated by utilizing the CAE program in order to prevent the risk of damage arising from impact and vibration that are generated during the packaging and transportation process given its material characteristics. CAE is an abbreviation for Computer Applied Engineering for realization by predicting changes at the time of application of virtual physical energy. It is applied by reflecting the physical property conditions and each boundary condition of plaster, and the digital images of the internal and external structure of the work were acquired through 3D scanning and CT analysis for interpretation by executing finite element modeling. When acceleration is applied to the work in the direction of its own weight, the left-right side and the front-rear side, it was possible to confirm a maximum displacement value of 15.24 mm in the head section of the front-rear side direction that has been tilted by approximately 27° from the Y-axis and the largest stress value of 12.46 MPa was at the left ankle section. The corresponding results confirmed that the left ankle section is the most vulnerable area and the section for which precautions need to be exercised and supplemented at the time of transporting the work by means of objective values.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.971-977
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• 2015

Because foam metal has the excellent physical characteristics and mechanical performance, they are applied extensively into a lot of advanced technology areas. The aluminum foam with closed cell is one of the foam metals. It is applied widely into automobile and airplane because of the excellent absorption performance of impact energy. In this study, the mechanical characteristics by thickness was analyzed through the impact experiment of closed-cell aluminum foam, and the simulation analysis was performed for the verification. As the simulation analysis method, a finite-element analysis was carried under the same boundary conditions as the experiment by using ANSYS. By comparing with the results of experiment and simulation, it was thought that the case of thickness of 20mm was the most efficient of among the cases of thicknesses of 10mm, 20mm and 30mm. At the case of thickness of 20mm, the absorption energy by comparing with the specimen thickness is shown to become the most among three models. By using the result of this study, it is thought that it can apply the material necessary to develop the mechanical structure with aluminum foam.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.177-185
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• 2000

The deformation characteristics is one of the major factors to resume the crash configuration in collision accident reconstruction. Crash analysis are carried out using finite element method and body stiffness equations representing force-deformation relationship are derived, Two different crash conditions : 1) frontal barrier impact 2) frontal impact between cars are given for the derivation of the equations. The stiffness coefficient of equation by method 2) is larger than that by method. 1). Crash analysis between two vehicles is accomplished with three crash angles and three velocities for each angle condition. The deformations are measured for six selected points and deformation energies are calculated using the derived equations. Equation by method 2) results in better estimation of deformation energy than that by method 1) for all crush configurations. The estimated energies can be utilized as one of indices to identify the type of the collision accident result.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.22-29
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• 2010

In this study, computational multi-body dynamics and structural vibration analyses including some impact condition have been conducted for the ground flight test system of the developed smart UAV model. Designed ground test system has four degree-of-freedom motions with limited motion control mechanism. Design safety margin designs for several structural components are tested and verified considering expected critical motions (pitching and rolling) of the test smart UAV model. Computational results for various analysis conditions are practically presented in detail. Futhermore, proper design modifications of the initially designed test equipment in order to guarantee or increase structural safety have been successfully conducted in the design stage.

• KIEAE Journal
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• v.9 no.6
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• pp.81-87
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• 2009

The purpose of the present study is to establish structural noise analyzing method for apartments building floor with structural-acoustic coupling analysis modeling. Noise through floor in the room is recognized as a significant problem with the consequence that noise isolation technique has been studied in the various fields of industry. From among noise factors, resonance sound is the main reason for solid noise of the floor, which is occurred by mechanical vibrations of the acoustic boundary line and the change of velocity. To analyse this phenomenon, numerical computation methods are provided in many fields, In this study, evaluation method for slab is established using finite element method, and a case study for analyzing acoustic phenomenon was suggested. The results show that numerical method, especially F.E.M, has a good approximation to predict noise at floors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.414-419
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• 1997

The free vibration analysis of cantilever CFRP and GFRP composite rectangular plates with point supports at the free edge and interior position is performed. The natural frequencies and mode shapes of plates are experimentally determined by impact testing using an impact hammer. To compare and verify these experimental results, the finite element analysis is also carried out and the non-dimensional frequency parameters are compared with FE analysis results. The effects of the number and location of the point support on the frequencies are examined. In the experimental results, it is found that a significant increase in frequencies occurs when the point supports are added on certain parts of plates.

• Journal of Hydrogen and New Energy
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• v.32 no.3
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• pp.172-179
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• 2021

The drop impact analysis was carried out on Type 4 pressure containers, and the degree of damage to the falling environment was predicted and determined using smoothed particle hydrodynamics (SPH) techniques. The purpose of the design and the optimization process of the winding pattern of the pressure vessel of the composite material is to verify the safety of the container in actual use. Finally, an interpretation process that can be implemented in accordance with domestic test standards can be established to reduce the cost of testing and containers through pre-test interpretation. The research on the fall analysis of pressure vessels of composite materials was conducted using Abaqus, and optimization was conducted using ISIGHT. As a result, the safety of composite pressure vessels in the falling environment was verified.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.102-105
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• 2000

Recently, applications of integrated large composite structures have been attempted to many structures of vehicles. To improve the cost performance and reliability of the integrated composite structures, it is necessary to judge structural integrity of the composite structures. For the judgement, we need fracture simulation techniques for composite structures. Many researches oil the fracture simulation method using FEM have been reported by now. Most of the researches carried out simulations considering only matrix cracking and fiber breaking as fracture modes, and did not consider delamination. Several papers have reported the delamination simulation, but all these reports require three-dimensional elements or quasi three- dimensional elements for FEM analysis. Among fracture mechanisms of composite laminates, delamination is the most important factor because it causes stiffness degradation in composite structures. It is known that onset and propagation of delamination are dominated by the strain energy release rate and interfacial moment. In this study, laminated composite has been described by using 3 dimensional finite elements. Then impact behavior of the laminated composite is simulated using FEM(ABAQUS/Explicit) with progressive failure mechanism. These results are compared with experimental results.

• Advanced Composite Materials
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• v.17 no.4
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• pp.373-407
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• 2008

This paper will examine the possibilities of the virtual tests of composite structures by simulating mechanical behaviors by using supercomputing technologies, which have now become easily available and powerful but relatively inexpensive. We will describe mainly the applications of large-scale finite element analysis using the direct numerical simulation (DNS), which describes composite material properties considering individual constituent properties. DNS approach is based on the full microscopic concepts, which can provide detailed information about the local interaction between the constituents and micro-failure mechanisms by separate modeling of each constituent. Various composite materials such as metal matrix composites (MMCs), active fiber composites (AFCs), boron/epoxy cross-ply laminates and 3-D orthogonal woven composites are selected as verification examples of DNS. The effective elastic moduli and impact structural characteristics of the composites are determined using the DNS models. These DNS models can also give the global and local information about deformations and influences of high local in-plane and interlaminar stresses induced by transverse impact loading at a microscopic level inside the materials. Furthermore, the multi-scale models based on DNS concepts considering microscopic and macroscopic structures simultaneously are also developed and a numerical low-velocity impact simulation is performed using these multi-scale DNS models. Through these various applications of DNS models, it can be shown that the DNS approach can provide insights of various structural behaviors of composite structures.