Stress Distributions During Fiber Pull-Out

Fiber pull-out resistance is an important mechanism of energy absorption during the failure of fiber-reinforced composite materials. This paper deals with axial stress distribution in the fiber during a pull-out. The frictional constraint between the fiber and the matrix is modeled with a perturbed Lagrangian approach and Coulomb’s law of friction. Stress distribution has been determined for three cases, using the finite element method. The first case deals with the pull out of a fully embedded fiber. The second determines the stress distribution during fiber pull-out in the presence of a broken-embedded fiber. The third model attempts to solve the pull out of a coated fiber. The results for the first case compares favorably with those in existing literature. A local “pinching” effect, due to the matrix collapse behind the pulled fiber, is brought out clearly by this model. The second study indicates that the “plug” effect may not be significant in affecting the stress distribution. Lastly, the effects of coating stiffness and thickness are investigated.