An influence of overhang on fracture toughness in impact 3-point bending test.

Abstract

In the impact 3-point bending test, it had been shown that a loss of contact between specimen and anvils occurred in the early stage of impact, and after that the specimen was subjected to the reaction force from the anvils. As a loss of contact is induced by the inertia effects, the dynamic fracture behavior in the test depends on the dimensions of specimen. In this paper, the dynamic fracture behavior of the specimen made of epoxy resin is investigated by changing the specimen length. In the impact 3-point bending test, the stress intensity factor at the crack tip is analyzed by the strain gage technique and the dynamic photoelastic technique using high speed camera. The loss of contact between the specimen and the anvils are also examined. The experimental results are compared with the theoretical values by using the simple method evaluating the dynamic stress intensity factor and dynamic finite element method. The influence of overhang on the fracture toughness in this test are presented.