• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.160-165
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• 1998

In this paper, We discuss the directional stability of a Mini-bus with varying suspension design parameters. We analyzed the vehicle behavior during the cornering in a transient steering condition. We made a vehicle model by use of DADS, which is dynamic analysis software, in order to carry out many cases of simulation with varying design parameters. The effect of toe-geometry change to vehicle stability is evaluated by computer simulation and the actual test. In order to reduce the under steer characteristics of a mini-bus, the amount of toe geometry change should be less than current value.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.186-193
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• 1999

In this paper, a full vehicle model is developed to analyze toe and camber changes due to rack height variation and compliance. The AutoDyn7 program developed in G7 project is used for the computer simulation. Steady state cornering test was done to find the understeer gradient. Imposing a pulse steer input, Frequency Response Function(FRF) of yaw rate and lateral accelerations were evaluated. To verify the stability, the rhombus using four parameters is employed. Steer characteristics were evaluated by changing the rack height and the bushing lateral stiffiness. which installed between the low control arm and the chassis.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.113-119
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• 2012

CTBA(Coupled Torsion Beam Axle) has been adapted as the rear suspension of a compact car. Because that has the advantage of cost and weight in comparison with multi-link type. But CTBA has the disadvantage in vehicle stability to become oversteer occurring toe-out of the rear wheel when cornering and braking. In this study, we suggested CTBA Geometry Compensation System to overcome the disadvantage of CTBA. We predicted braking and cornering vehicle performance from proposed equation and numerical simulation. And also, the results were compared to objective and subjective evaluation in vehicle.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.121-127
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• 2013

In this study, suspension geometry is controlled to improve vehicle handling performance. The toe and camber of the rear suspension is controlled independently by using a double knuckle structure designed to enhance the vehicle cornering stability. Camber and toe changes in the rear wheel during high speed turning maneuver are important factors that influence the vehicle stability. Toe in the rear outer wheel plays a dominant role in cornering. A control algorithm for the camber and the toe angle input is developed to carry out the control simulation of the vehicle such as single lane change, the steady state cornering, the double lane change and the step steering simulation. Effects of the camber and toe angle control are analyzed from the computer simulations. A double lane change simulation revealed that the suspension mechanism with variable camber angle and variable toe angle decreases the peak body slip angle and peak yaw rate, 50% and 10%, respectively.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.303-307
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• 2006

This paper presents the enhancement of vehicle stability by active geometry control suspension(AGCS) system as the world-first, unique and patented chassis technology, which has more advantages than the conventional active chassis control systems in terms of the basic concept. The control approach of the conventional systems such as active suspensions(slow active, full active) and four wheel steering(4WS) system is directly to control the same direction with acting load to stabilize vehicle behavior resulting from external inputs, but AGCS controls the cause of vehicle behaviors occurring from vehicle and thus makes the system stable because it works as mechanical system after control action. The effect of AGCS is the remarkable enhancement of avoidance performance in abrupt lane change driving by controlling the rear bump toe geometry.

• Geomechanics and Engineering
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• v.31 no.4
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• pp.375-384
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• 2022

The variation of the undrained shear strength (c_u) is an important consideration for assessing slope stability in engineering practice. Previous studies focused on the three-dimensional (3D) stability of slopes in normally consolidated clays generally assume the undrained shear strength increases linearly with depth but does not vary in the horizontal direction. To assess the 3D stability of slopes with spatially varying undrained shear strength, the kinematic approach of limit analysis was adopted to obtain the upper bound solution to the stability number based on a modified failure mechanism. Three types failure mechanism: the toe failure, face failure and below-toe failure were considered. A serious of charts was then presented to illustrate the effect of key parameters on the slope stability and failure geometry. It was found that the stability and failure geometry of slopes are significantly influenced by the gradient of c_u in the depth direction. The influence of c_u profile inclination on the slope stability was found to be pronounced when the increasing gradient of c_u in the depth direction is large. Slopes with larger width-to-height ratio B/H are more sensitive to the variation of c_u profile inclination.

• Journal of Welding and Joining
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• v.29 no.4
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• pp.67-72
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• 2011

The proportion of the welding in the production process of machinery, buildings and marine structures is increasing and the joining are mainly conducted by butt and fillet weld. In the case of fillet weld, the shape of structures is complicated depending on the constraint on the geometry of the structures, therefore, the full penetration is mostly difficult. Accordingly, it is necessary to establish safe and economical criteria of design of the structures through the strength based on the penetration state of the fillet weld. Patterns of fatigue failure in cruciform fillet weld jont appear in the form of the root, toe and mixed failure. In the case of toe and mixed failure, the fatigue strength is higher than root failure. Therefore, we have to make the enough depth of penetration or perform the welding work through improving the fatigue strength of cruciform joints in welded structures. So it is necessary to optimize the penetrated depth in the range of the possible mixed failure and find the way in the cost-effective design to lessen the amount of the welding work.

• Proceedings of the KWS Conference
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• v.43
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• pp.275-277
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• 2004

Fictitious notch radius approach is based on the Neuter's microstructural support hypothesis which assumes that fatigue crack is governed by highly stressed volume of the material right on the weld toe area rather than the surface stress at a pin point of weld toe area. Variety of successes have been achieved in applying this methodology to the fatigue of welded joint, hence, it became one of recommended design procedure in IIW's recommendation as well as many ship classification societies. 1mm fictitious notch radius approach was applied to the various fatigue problems of welded joints in this study covering the effect of weld size, notch stress calculation for 3D geometry and low cycle fatigue problem. It was found that fictitious notch radius approach fumed out to be very effective and accurate in dealing with fatigue strength of welded joint.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.133-141
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• 1996

The mode of fatigue failure is depended on the characteristics of the fatigue crack initiated and propagated from the weld toe and the weld root in the load-carrying fillet welded joints. The characteristics of fatigue crack are deeply affected by the geometry of fillet and the stress range. The purpose of this study is to investigate critical weld size and stress range in order to occur toe failure under pulsating tension loading in the load-carrying fillet welded cruciform joints.

• International journal of steel structures
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• v.18 no.5
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• pp.1589-1597
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• 2018

Fatigue tests and numerical analysis were carried out to evaluate the fatigue performance at the U-rib to deck welded joint in steel box girder. Twenty specimens were tested corresponding to different penetration rates (80 and 100%) under fatigue bending load, and the fatigue strength was investigated based on hot spot stress (HSS) method. The detailed stress distribution at U-rib to deck welded joint was analyzed by the finite element method, as well as the stress intensity factor of weld root. The test results show that the specimens with fully penetration rate have longer crack propagation life due to the welding geometry, resulting in higher fatigue failure strength. The classification of FAT-90 is reasonable for evaluating fatigue strength by HSS method. The penetration rate has effect on crack propagation angle near the surface, and the 1-mm stress below weld toe and root approves to be more suitable for fatigue stress assessment, because of its high sensitivity to weld geometry than HSS.