Intensity of Singular Stress Fields of Fiber under Pull-out Force

There are several micromechanics tests available to study the fibre/matrix bond. The best-known are fragmentation, pull-out test and micro-bond test. This study focuses on study the constraints of micro-bond test, and the results are compared with the pull-out test, that have similar geometry, on the basis of intensity of singular stress fields. In order to study the effect of bonded length lb on the Intensity of Singular Stress Fields (ISSF) at the dagerous point, other constraints and material combination are set to be same in the Finite Element Method (FEM) analysis. Normal stress on the interface is tension at the near intersection (Point E), while it is compression at the far intersection (Point A). This stress condition is similar to that in pull-out test, in which normal stress along the axial interface is compression at the bured end (Point A*) and tension near the intersection (Point E*). No matter how the bonded length lb changes, the near intersection (Point E) in micro-bond test is the most dangerous point. The effect of bonded length lb on ISSF at the near end intersection (Point E) show similar trend in micro-bond test and pull-out test. For the material combination and constraints discussed in this paper, the ISSF of the most dangerous point in micro-bond test is about 1.5 times that of pullout test.