Abstract: A method for fabricating composite parts having improved pulloff strengths between portions of the composite part. In one embodiment, a sine wave spar is formed from two U-shaped channels having opposing flanges and a central web. The U-shaped channels are joined along the webs. The triangular gaps between the edges of the joined U-shaped channels are filled using a titanium radius filler that is configured to fit within the gaps. After the titanium radius filler is placed within the gaps, additional layers of composite material are placed over the titanium radius filler and the flanges of the U-shaped channels to form the caps of the I-beam. The resulting composite workpiece is then placed within appropriate tooling and cured within an autoclave. In other embodiments, the method of the invention is used to form spars, ribs, stringers, or bulkheads from composite materials.