• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.761-765
• /
• 2001

Shock responses of the MIL-S-901D standard floating shock platform("SFSP") subject to underwater explosions(UNDEX) are analyzed by using the LS-DYNA/USA. For the analysis, surrounding fluids as well as the SFSP are included in a 3D FE model to consider the cavitation effects of the UNDEX shock wave. The calculated results are compared with the existing test results and it is confirmed that the analysis results predict accurately the shock behaviors of the SFSP.

• 천문학회보
• /
• 제44권2호
• /
• pp.66.1-66.1
• /
• 2019

We study cosmological shock waves in and around protoclusters at cosmic noon in the Horizon Run 5 Simulation (HR5), one of the world's largest hydrodynamic cosmological simulations. We select the local peaks of X-ray luminosity at z=2.5-3 in the HR5 lightcone volume as protocluster candidates. We find shock waves with Ms > 1.3 within the virial radii of the HR5 protocluster candidates by applying several shock-finding algorithms based on the Rankine-Hugoniot jump condition. We compare the properties of shock waves from different shock-finding algorithms.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권4호
• /
• pp.467-478
• /
• 2003

Automotive shock absorber may not be regarded as only one(simple) damping machine because it is composed of many components, and shows non-linear damping characteristics. No matter how advanced form of shock absorber is developed, the oil shock absorber can not be neglected. because their structures are based on the oil shock absorber. Therefore it is essential to accurately analyze the dynamic characteristics of oil shock absorber. It stands mainly roi damper valve tuning which nowadays is still exhaustively done by means of ride work. In this study, damping mechanism and dynamic characteristics for oil shock absorber of twin tube type are analyzed, based on the mathematical model considering internal flow and pressure. For the reliability of numerical prediction. the database is constructed within the limit of adequate reliability. Finally, the programmed system that gives out necessary specification by inputting damping specification and tolerance is to be constructed.

• 대한기계학회논문집
• /
• 제14권1호
• /
• pp.130-137
• /
• 1990

본 연구에서는 Bueckner의 가중함수법을 열충격 문제에 도입하여 열충격 응력 세기계수를 구하고, 평면변형을 파괴인성치와 비교하여 재료가 열충격을 받은 후 파괴 되는 시간을 이론적으로 계산한다. 또한 음향 방출법을 이용하여 파괴시간을 측정하 고 이론치와 비교한다.

• 한국소음진동공학회논문집
• /
• 제16권11호
• /
• pp.1132-1139
• /
• 2006

Non-contact underwater explosions against surface ship could cause extensive equipment damage during wartime service. Thus, the need to develop methods for the design of shock resistant equipment structures and systems was strongly established. In analytical methods, DDAM(Dynamic Design and Analysis Method) and transient repsonse method are used for ship shock design. In this paper, to analyze the characteristics of DDAM, medium weight shock test, DDAM and transient response analysis for missile system equipment are performed.

• 동력기계공학회지
• /
• 제15권4호
• /
• pp.11-18
• /
• 2011

A Shock absorber is one of the most important components in vehicle suspension systems. In general, many repeated analyses are required for the design of a shock absorber to satisfy the suspension characteristics of a specific automobile, like fluid flow analysis and mechanical analysis. The purpose of this study is to develop a fast design tool for shock absorber designers. One of the efficient solutions for this can be an empirical design method considering phenomenological effects from the shock absorber design variables. In order to extract the shock absorber's experimental characteristics, we used Taguchi method. This method showed that which design variables have major effects for the shock absorber's damping characteristics. This empirical design method also showed the direction of the design changes to satisfy the designer's intension.

• 한국안전학회지
• /
• 제13권4호
• /
• pp.102-112
• /
• 1998

Shock absorber has a great influence on the performance of the vehicle(ride comfort, manipulation, noise, vibration, turning, stability). Therefore, in this study we consider theoretically about general damper, variable damping oil damper, the control of vehicle Characteristics for the suspension, and undesirable phenomenon. And we measured the vibration/noise characteristics of shock absorber for the real car experimentation, strain change, and noise characteristics of shock absorber using experimental equipment. The study of domestic company and research institute on the vehicle shock absorber is active, but that of basis is not. So we think that they should be accomplished actively. Therefore, this paper will develop theoretical system on the vibration/noise characteristics of shock absorber by theoretical consideration and experimental result analysis of dynamic characteristics of shock absorber that were accomplished in this study. Then we will use it as the optimistic design data for shock absorber development.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.365-367
• /
• 2010

In this paper, we presented the exact Riemann solver for the air-water two-phase shock tube problems where the strength of the propagated sock wave is moderately weak. The shock tube has a diaphragm in the middle which separates water medium in the left and air medium in the right. By rupturing the diaphragm, various waves such as rarefaction wave, shock wave and contact discontinuity are propagated into water and air. Both fluids are treated as compressible, with the linearized equations of state. We used the isentropic relations for the air and water assuming a weak shock wave. We solved the shock tube problem considering a high pressure in the water and a low pressure in the air. The numerical results cleary showed a left-traveling rarefaction wave in the water, a right-traveling shock wave in the air, and the right-traveling material interface.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.1742-1747
• /
• 2003

When a shock wave is discharged from the exit of a duct, complicated flow is formed near the duct exit. The flow field is much more complicated under the ground effects or any other objects near the exit of a duct, such as the circumstance near the exit of the high-speed railway tunnel. The resulting flow is essentially three-dimensional unsteady with the effects of strong compressibility. In the current study, three-dimensional flow fields of the weak shock wave which is discharged from the exit of a duct are numerically investigated using a CFD method. Computations are performed for the weak shock wave in the range below 1.5. The results obtained show that the directivity and magnitude of the weak shock discharged strongly depend upon the Mach number of initial shock wave and are significantly influenced by the ground effects.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2004년도 추계학술대회 논문집
• /
• pp.72-75
• /
• 2004

The present study describes a computational work to investigate detailed behaviors of the twin shock waves discharged from the exits of two-parallel ducts. In computations, the Yee-Roe-Davis's TVD scheme was used to solve the unsteady, three-dimensional, inviscid, compressible, Euler equations. The distance between two ducts is varied and the Mach number of the incident shock wave is changed below 2.0. The results obtained show that on the symmetric axis between two-parallel ducts, the maximum pressure achieved by the merge of twin shock waves and its location strongly depend upon the distance between two-parallel ducts and the Mach number of the incident shock wave. It is also found that the twin shock waves discharged from the exits of two-parallel ducts leads to the complicated flow fields, such as Mach stem, spherical waves, and vertical structures.