Papers by Author: Yang Bae Jeon

Abstract: This research is concerned with a study of failure strength of natural fiber composite. Tensile-shear tests were carried out with the single-lap resistance welded joined specimens consisting of composite materials. Composite materials were manufactured using the polyester as a matrix and bamboo natural fiber layer as a reinforcement. Two types of specimen with different reinforcement positions were tested to evaluate the failure strength of natural fiber reinforced composite resistance welded joined specimens. The test results were presented by tensile-shear strength. The failure mechanism was discussed in order to explain the lower tensile-shear strength of composite and position of bamboo natural fiber layer on the failure strength properties were explained

Abstract: This research was concerned with study of failure strength of natural fiber reinforced composites. Tensile-shear tests were carried out with single-lap-adhesive-joined specimens consisting of polyester lap and composite lap. Composites were manufactured using the polyester as matrix and bamboo natural fiber layer as reinforcement. Two types of specimens with different reinforcement positions were tested to evaluate the failure strength of adhesive-single-lap-joined natural fiber reinforced composites. The test results were presented by tensile-shear strength graph comparing with finite element analysis. The failure mechanism was discussed in order to explain the lower tensile-shear strength of composite, and effect of position of bamboo natural fiber layer on the failure strength properties were explained.

Abstract: Using natural fibers that are inexpensive, lightweight and biodegradable, as the reinforcement for composites is difficult due to their poor interfacial properties between hydrophilic fiber and hydrophobic polymer matrices. It is necessary to evaluate fracture toughness of natural fiber reinforced composites according to water absorption rates to improve mechanical performance of those. In this study, compact tension fracture test was conducted to evaluate fracture toughness with the various specimens. The value of fracture toughness has the tendency to decrease as water absorption rate increases. And different surface treatment methods and different polymer matrices have influence on the value of fracture toughness.

Abstract: Spot welding is a process that sheet metals are joined in one or more spot by heating at the faying interface. In this process, the spatter is dispersed from melted area. It has been reported that spatter generation has adverse effects on weld quality. However, no systematic study has been carried out to find out its effect on weld quality in resistance spot welding processes. In this study, specially designed specimens are used to perform experimental investigation of spatter generation and its effect. Major finding of this study show trends in tensile-shear strength for various amounts of spatter generated during spot welding process. Thus, optimum welding conditions are proposed in view of spatter generation and tensile-shear strength.