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As a new vehicle is based on common vehicle platform, the durability problems of chassis components in development stage are decreasing. However a vehicle body structure is changed by exterior design and a chassis and a suspension are tuned by vehicle performance targets. The main issue on developing a new vehicle is to satisfy the durability target of a body structure and tuned suspension components. The accuracy of durability Computer Aided Engineering analysis is mainly depending on the accuracy of input loads and boundary conditions on suspension system. The input loads should be estimated accurately. These could be changed by vehicle specifications such as vehicle weight, wheel base and so on. It is also affected by the change of suspension types and tuning parameters. This paper presents the experimental parametric study results using road load data analysis techniques.

The various seat problems are happening in the field. Customers are getting more sensitive to the quality of a vehicle than ever these days. The long-term accumulated staining of iInterior trim contamination, as a result, is one of the most important factors in regarding that of the vehicle and newly reflected in IQS in 2007 and VDS in 2008 respectively. In particular, seat staining contamination has been mainly responsible for the decrease of vehicular marketability and used-car price. Therefore seat must be improved not to be stained contaminated easily. The stain accumulation contamination mechanism of both natural genuine and artificial leather seats is different from that of fabric cloth seat and we hereby verified them systematically. We developed the test method regarding the actual-conditioned wears (abrasions), soil contamination resources and environment circumstances and that it'll be of service to the vehicle development test.

A study for improving the resistance to fretting corrosion of SCr 420 pinion gear was conducted. Fretting is the damage to contacting surfaces experiencing slight relative reciprocating sliding motion of low amplitude. Fretting corrosion is the fretting damage to unlubricated contacting surfaces accompanied by corrosion, mostly oxidation that occurs if the fretting occurs in air. Two kinds of conventional heat treatment and a newly designed one suggested for improving the resistance to the fretting corrosion of pinion gear were compared each other to find out what is the main factor for generating fretting corrosion phenomenon. Increased carbon potential at both the heating and diffusing zone and reduced time of tempering was found out to be a solution for improving the resistance to fretting corrosion of forged and heat treated gear steel. On the contrary, modified carbo-nitriding using ammonia gas has been getting worse the fretting corrosion problem.

An automobile's structure is generally connected by spot welding the sheets together. Sometimes more than three layers of sheets can be used in a certain location for spot welding due to the limits of design conditions. Static strength and the fatigue life characteristics can be changed according to the welding conditions, which depend on the material, the thickness, and the number of sheets. Setting the appropriate conditions of multi-layer spot welding can be determined by analyzing static strength and fatigue life. For converting multi-layer spot welding to that of twofold layer with equal strength, the converting method can be suggested from static and fatigue test results. The increasing rate of static strength is larger than that of fatigue life, so it is reasonable to use fatigue life for limit condition.

Vehicle body structures are formed by thousands of spot welds, and fatigue failure of vehicle structures occur near the spot welds after driving a long way at a durability test road. It is necessary to know accurately the reason of the fatigue failure of the spot weld in the developing stage in order to reinforce it. Many investigations have been done regarding the strength of spot welded joints, contributing to understand its fatigue strength. In the developing process, a fatigue failed spot welded area can be repaired by CO2 welding or another method to continue the test. To know the effect of reinforcing these welds, several methods of welding were analyzed and compared to spot welding. With the results of this test, the appropriate repair method can be used instead of spot welding during the development of a new car and the best design guide can be given for the strength.

This report explains the basic theory of designing the accelerating durability test road and the role of each factors contributing to the test road surface profile. Also this road is designed by considering the charactors of vehicle suspension system and conditions of driving. In test road, the factors affecting to the vehicle structural durability are correlation among surface shape of road profile, frequency of vehicle suspension system,distribution of axle twist angle and vibration of road profile height. Road PSD magnitude and frequency delay is used to control these factors relation.

Vehicle life prediction is method that can predict fatigue life each part of vehicle, using strain gauge, stress wave analyzer, and computer. Theoretically, it is impossible to adapt S-N curve from specimen to minor's rule, because there isn't consideration of difference of shape, effect of notch, condition of welding. But, data of crack and failure parts can be obtained by durability test of proving ground. Using this data, S-N curve can be modified to adapt to vehicle.