The purpose of this study is to investigate the fatigue strength of butt-welded joints with special attention paid to employing different kinds of backing plates. The effect of the undermatched weld was also considered. Four different cases of backing scenarios for butt-welded specimens such as steel backing, ceramic backing, CMT (no backing by cold metal transfer) and UM (under-matched welded specimen) were investigated. A series of fatigue tests was performed to compare the fatigue strength of butt-welded joints with respect to different backing scenarios. Effective notch stress was used for the interpretation of fatigue strength of butt-welded specimens with backing plates based on finite element analyses for calculating fatigue notch factors. When results were presented from the effective notch stress, all backing scenarios considered in this study exhibited the fatigue strengths corresponding to the FAT 225 curve. From the experimental results of this study, it was determined that the fatigue strengths of butt-welded joints were found to be in the order of CMT, ceramic backing, UM, and steel backing. No significant decrease in fatigue strength, however, was observed when backing plates were steel backing and ceramic backing types.

As vehicles become more intelligent, in-vehicle networking (IVN) systems such as controller area network (CAN) are essential for the convenience and safety of drivers. To expand the applicability of IVN systems, attention is currently being focused on chassis networking systems that require increased network capacity and real-time capabilities. FlexRay was developed to replace CAN protocol in chassis networking systems, to remedy the shortage of transmission capacity and unsatisfactory real-time transmission delay of conventional CAN. However, FlexRay network systems require a complex scheduling method, which is a barrier to their implementation as chassis networking systems. In particular, if we want to migrate from a CAN network to a FlexRay network using the well-defined CAN message database, which has been specifically constructed for chassis networking systems by automotive vendors, a new type of scheduling method is necessary to reduce scheduling efforts during the software development process. This paper presents a node-based scheduling method for easy migration from a CAN network to a FlexRay network system. To demonstrate the feasibility of the technique, its performance is evaluated in terms of various software complexity indices.