• 자동차안전학회지
• /
• 제13권4호
• /
• pp.92-98
• /
• 2021

Recently hydrogen fuel cell buses have been deployed for the public transportations. In order to introduce buses fueled by hydrogen successfully, the research results of hydrogen bus safety should be discussed and investigated significantly. Especially, Korean government drives research in terms of various applications of hydrogen energy to replace the conventional fuel energy resources and to improve the safety evaluation. Thus it is necessary to examine vehicle crashworthiness under side impact loadings. This study was focused on the simulation result evaluation of full bus model and simplified bus model with hydrogen fuel tank module and mounting system located below floor structure due to the significance of bus side impact accidents. The finite element models of hydrogen bus, fuel tank system and side impact moving barrier were set up and simulation results reported model performance and result comparison of two side impact models. Computational results and research discussion showed the conceptual side impact framework to evaluate hydrogen bus crashworthiness.

• Structural Engineering and Mechanics
• /
• 제71권5호
• /
• pp.515-524
• /
• 2019

The present study deals with the simulation of low velocity impact on prestressed and reinforced concrete (RC) slabs supported with different end conditions. The prestress is pre-applied on the RC slab in an analytical approach for the prestressed slab. RC slabs with dimensions $500{\times}600{\times}60mm$, $500{\times}600{\times}80mm$ and $500{\times}600{\times}120mm$ were used by changing support condition in two different ways; (i) Opposite sides simply supported, (ii) Adjacent sides simply supported with opposite corner propped. Deflection response of these specimens were found for the impact due to three different velocities. The effect of grade of concrete on deflection due to the impact of these slabs were also studied. Deflection result of $500{\times}500{\times}50mm$ slab was calculated numerically and compared the result with the available experimental result in literature. Finite element analyses were performed using commercially available ANSYS 16.2 software. The effectiveness of prestressing on impact resistant capacity of RC slabs are demonstrated by the way of comparing the deflection of RC slabs under similar impact loadings.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.773-777
• /
• 1995

This thesis attempt to explore the shape of stress wave propagation of 3-dimensional stress field which is made in the process of time increment. A finite element code about 3-dimensional stress wave propagation is developed for investigating the changing shape of the fracture by the impact load. The Finite Element Code, which is the solution for the 3-dimensional stress wave analysis, based on Galerkins and Newmark- .betha. method at time increment step. The tensile stress and compressive stress become larger with the order of the middle, the upper and the opposite layers when the impact load is applied. In a while the shear stress become larger according to the order of the upper, the middle and the opposite layers when impact load applied.

• 소성∙가공
• /
• 제24권5호
• /
• pp.323-331
• /
• 2015

Impact extrusion is an economical and productive process that can replace the multistage deep drawing process for producing deep rectangular cases. In the current work, a three-dimensional finite element analysis of the impact extrusion process of a commercial purity aluminum alloy (AA1070) was performed to predict loads, material flow, and deformed shapes using the Hansel-Spittel rheology law, which describes the flow stress at various temperatures and strain rates. The role of various process parameters such as friction, clearance between punch and die, aspect ratio and thickness of billet on the process and the shapes was analyzed.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2002년도 추계학술발표대회 논문집
• /
• pp.170-174
• /
• 2002

In this study, the material characterization and the dynamic behavior of 3D orthogonal woven composite materials has been studied under transverse central low-velocity impact condition by means of the micromechanical model using finite elements. To build up the micromechanical model considering tow spacing and waviness, an accurate unit structure is stacked in x-y-z direction repeatedly. First, the mechanical properties of 3D orthogonal woven composites are obtained by means of virtual experiment using full scale Finite Element Analysis based on the DNS concepts, and the computed elastic properties are validated by comparison to available experimental results[9]. Second, using the implementation of this validated micromechanical model, 3D transient finite-element analysis is performed considering contact and impact, and the impact behavior of 3D orthogonal woven composite is investigated. A comparison study will be carried out in terms of energy absorption capabilities.

• 대한기계학회논문집A
• /
• 제26권12호
• /
• pp.2656-2661
• /
• 2002

Multiple impact models to examine the effect of stress interference are proposed and investigated. The single shot model analysis, which used various shot ball conditions, was carried out to compare with multiple impacts analysis. Then the multiple impact analysis were performed to predict the effect of the shot ball distances. The results showed that the stress interference in the multiple impact model significantly reduced the maximum value of the compressive residual stresses. The residual stress profiles were strongly effected by the shot ball distances. The multiple impact model can simulate a realistic shot peening process rather than a single shot model does. It is concluded that the proposed model predicts the real process more accurately.

• 대한안전경영과학회지
• /
• 제16권3호
• /
• pp.421-432
• /
• 2014

This study is intended to analyze the relation between G. D. Weisman's Way finding 4 elements the accessibility and efficiency of consumers as to eternal area for Seoul historical museum. The findings are summarized as the following three aspects. First, G. D. Weisman's Way finding element introduced in this study had a significant impact on visitor satisfaction.. It leads to the following conclusion: The higher the impact is, the greater accessaccessibility and efficiency are. Second, among 4 elements, the factor that had the biggest impact on the accessibility was 'visual-perceptual accessibility'. Thus, 'visual-perceptual accessibility' should be considered first to boost the accessibility to consumers. Third, among 4 elements, the factor that had the biggest impact on the efficiency was 'sign system'. Thus, 'sign system' should be considered first to boost the efficiency to consumers.

• 대한기계학회논문집A
• /
• 제33권5호
• /
• pp.536-543
• /
• 2009

Dynamic behaviour of a package of a microwave oven under the drop-impact conditions is evaluated by the finite element analysis and tests. PAM-CRASH software is used for the finite element analysis and the tests are performed according to the ISTA(International Safe Transit Association) specification. Results of the analyses are compared with those of the tests and accuracy is shown to be favourable. Under the drop-impact condition of the original design, severe deformation occurs and an improved design is proposed to reduce it. The approach presented in this research can be successfully applied to reduce costs and time required to develop new models of the microwave oven.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.919-922
• /
• 2003

The correlation between noise and vibration by a heavy-weight floor impact was studied. The triggering technique was used for increasing the reliability and stability to measure the level of sound pressure, sound intensity and vibration acceleration. The simple finite element and rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The result show that the isolation material adapted to reduce the light-weight floor impact noise, causing the natural frequency lower, make resonance with dominant driving frequency, and increase the noise level very sharply. Therefore the noise level Peak in the region of low frequency, below 63Hz, would be related with the natural frequencies of the floor system.

• 소성∙가공
• /
• 제19권4호
• /
• pp.217-223
• /
• 2010

The objective of this study is to propose the FE model for mechanical clinched joint using cohesive zone model to analyze its failure behavior under impact loading. Cohesive zone model (CZM) is two-parameter failure criteria approach, which could describe the failure behavior of joint using critical stress and fracture toughness. In this study, the relationship between failure behavior of mechanical clinched joint and fracture parameters is investigated by FE analysis with CZM. Using this relationship, the critical stress and fracture toughness for tensile and shear mode are determined by H-type tensile test and lap shear test, which were made of 5052 aluminum alloy. The fracture parameters were applied to the tophat impact test to evaluate the crashworthiness. Compared penetration depth and energy absorption at the point where 50% of total displacement in result of FE analysis and experiment test for impact test, those has shown similar crashworthiness.