Determining strength and micro-structure on uni-directional carbon fiber after machining using carbide inserts

Venkatachalam Nachiappan, University of Texas at El Paso


Carbon fibres, after a period of 40 years of development and use in specialized applications, are now on the brink of broad commercialization. All carbon fiber composites used in today's applications are manufactured through a molding or extrusion manufacturing process. The finished product is normally not machined. However there are instances where machining to a finished size is desirable. This research is focused on determining the strength and micro-structural characteristics of Uni-Directional vinyl ester-carbon fibre rod after machining with a carbide insert. This study examined the surface fractures, and the micro-structural changes before and after machining the carbon fibre rod. As part of the study, the tensile strength of the carbon fibre rod after machining was observed and stress and strain graphs were plotted. The machining of the carbon fibre was performed with cold compressed air as the coolant and a carbide insert having a trade name of Sandvik was utilized to perform the turning operations. The study was conducted to determine, whether machined vinyl ester-carbon fibre rod retains a tensile strength comparable to virgin solid carbon fibre rod. Also the study determined the changes in the micro-structure of the surface after machining. The hypothesis of this thesis is that the strength of vinyl-ester carbon fiber rod after machining is adequate for use in fields such as automotive, paper production, aerospace and industrial applications. This study also determined a testing method for carbon fibre composite rod. This technique relied on bonding the test rods into machined aluminum holders that could be gripped in an Instron tensile test machine.

Subject Area

Mechanical engineering

Recommended Citation

Nachiappan, Venkatachalam, "Determining strength and micro-structure on uni-directional carbon fiber after machining using carbide inserts" (2005). ETD Collection for University of Texas, El Paso. AAI1430263.