Tensile Fracture Behaviors of Helical Fiber Reinforced Composites

Abstract

The fracture behaviors of copper matrix composites reinforced with helical tungsten fibers have been investigated experimentally. A length of tungsten fiber 150 μm in diameter was formed into a helix, whose helical angle was 78.4° and helical radius was 75 μm. Helical fibers were embedded in a copper matrix by mens of electrodeposition and vacuum hot-pressing techniques. Specimens were tensile-tested and their fracture behaviors were investigated. Observations of fracture surfaces and deformation of fibers in the matrix were also made. The results were compared with those on the straight fiber reinforced composites.
It was found that the tensile fracture behavior of the helical fiber composite was not so catastrophic as the straight fiber composite. As to the two kinds of composites of the same volume fraction, fairly larger ultimate tensile strains were obtained with a small decrease in the ultimate tensile stresses by using the helical fibers instead of the straight ones as the reinforcing component. The portions of fibers pulled out were seen much longer for the helical fiber composites than for those with the straight fibers. Considerable debonding between the fiber and the matrix was observed near the fracture surface especially for the helical fiber reinforced composites.