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DESIGN OPTIMIZATION OF A REAR INDEPENDENT SUSPENSION FOR THE KOREAN LIGHT TACTICAL VEHICLE
Kwonhee Suh,Hi Seak Yoon 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.2
Steering and suspension handle the direction of a vehicle according to the driver's intentions and control the disturbance from the road surface while supporting the vehicle body. The static and dynamic characteristics of two systems are critical factors for the ride comfort and the directional stability. In the layout stage, the hard points of steering and suspension systems are determined. In the next design stage, the detailed design of the system, including gearboxes, springs, shock absorbers, and control links, is carried out. While the optimal hard points of a suspension are determined at the precedent design, interference with other peripheral components should be carefully examined in the detailed design process. In the case of the design point change should be made to avoid the interference, subsequent position and shape changes of the link mechanism are required. Therefore, there is a need to examine the optimization of suspension compliance characteristics with chassis design changes and the durability performance of the modified design. This study proposes an integrated analysis method for the design optimization and the durability evaluation of such optimized design specifications of the rear independent suspension for a military vehicle.
LIFTING CAPABILITY AND STRESS ANALYSES OF THE CRANE SYSTEM FOR A LARGE-SIZED TACTICAL WRECKER
Kwonhee Suh,Hi Seak Yoon 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.5
A large-sized tactical wrecker is a special-purpose vehicle that lifts and tows tactical vehicles and heavy loads. It consists of a crane, a post structure, outriggers and a suitable chassis truck, and during its initial design, the structural safety and tipping stability should be preemptively examined in terms of the layout of these components. This paper proposes computer-aided engineering (CAE) methods to evaluate the maximum lifting capacity of the wrecker and the structural safety of its crane during the initial design. The analytical model for the large-sized wrecker is constructed with 236 degrees of freedom by combining the crane system developed using the ADAMS macros with the dynamic model of large chassis truck with an axle suspension. The design parameters for the wrecker model that influence the tipping stability are selected, and then the maximum lifting loads with the corresponding changes are calculated. This parametric study shows that the characteristics of the boom and the layout of the outriggers greatly affect the maximum lifting capacity. Finite element (FE) analyses of the 1st stage boom and the 3rd stage boom show the stresses under the maximum overturning moment condition are within the allowable strength.
Analytical method to develop airlift equipment for Korean light tactical vehicle
Kwonhee Suh,Bugeun Song,Hi Seak Yoon 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3
The Korean light tactical vehicle (KLTV) is developed to meet the demands for a new military vehicle that fulfills certain conditions, such as multi-purpose, high mobility and survivability. Double-wishbone independent suspension is developed to improve the ride and handling performance and maximize the off-road driving performance of the new tactical vehicle. In particular, the KLTV is equipped with front and rear lifting provisions that support the vehicle safely during airlift operations. In this paper, a comprehensive analytical method to evaluate the structural safety of these components is presented. First, a vehicle dynamic model of the KLTV and a test rig for airlift simulation are developed using MSC.ADAMS/Car. Second, a finite element model of airlift kits, which are newly installed in the KLTV, is constructed. Third, stress analyses on vertical load conditions, MIL-STD-209K, and helicopter flight speeds are performed using ABAQUS. Finally, a dummy apparatus test and an actual vehicle test are conducted to verify the suitability of the airlift equipment for the KLTV. The computational method presented herein will provide useful information on the structural safety of airlift equipment during the early stages of a military-vehicle-designing process.
Jong Youn Son,Hi Seak Yoon,Ki Yong Lee,박상후,Do Sik Shim 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.3
This paper presents an investigation of the interfacial strength between a material deposited on a substrate via direct energydeposition (DED) process. Using the DED process, a powder of the hot work tool steel H13 was deposited onto a substrateof SKD61 steel, and shear tests were performed at various temperatures (25 °C, 200 °C, 400 °C, 600 °C, and 800 °C) toinvestigate the strength of the interface between the deposited material and the substrate. After the shear test, the fracturedspecimens were also analyzed. As a tested result at room temperature (25 °C), the cracks in the specimen were initiated inthe deposited region; however, at high temperatures, the specimens were fractured only in the substrate regions. However,despite the difference in the location of the fracture-containing region, at no test temperature did interfacial cracking ordelamination occur between the deposited material and the substrate. Thus, the interface demonstrated high bonding strength.
홉킨슨 압력봉법을 이용한 Fe-6.5wt.%Si 합금의 고변형률속도 거동
Yoon, Young-Ki,Yoon, Hi-Seak,Umakoshi, Yukichi,Yasuda, Hiroyuki Y. 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.7
Many researches have published numerous papers about the high-strain-rate obtained from Split Hopkinson Pressure Bar(SHPB) tests. And 6.5wt%Si steel is widely known as an excellent magnetic material because its magnetostriction is nearly zero. Single crystals are prepared by the Floating Zone(FZ) method, which melts the alloy by the use of a high temperature electron beam in a pure argon gas condition. In this paper, the fracture behavior of the poly crystals and single crystals (DO$_3$phase) of Fe-6.5wt%Si alloy by SHPB test is observed. The comparison of high-strain-rate results with static results was done. Obtained main results are as follows: (1) Fe-6.5wt%Si alloy has higher strength at high-strain-rate tensile. SHPB results of polycrystal are twice as high as static results. (2) From the fractography, the cleavage steps are remarkably reduced in the SHPB test compared with the static test.