FABER TT Fiber Debonding and Partial Interfacial Sliding Fiber Fracture 20 Release of stored Strain Energy 10 Matrix Fracture Fiber pullout 01020304050 708090100 COD (um) re 5 Continuous load-displacement curve from the modified single-fiber pullout test(from sliding distance leads to underestimates of the friction stress in pullout tests and overestimates in push-out tests due to the poisson contraction and expansion, A modified fiber pullout test has been developed by Mumm Faber(37)that affords the measurement of the continuous force-displacement response for a single crack-bridging fiber shown in Figure 5. A rectangular parallelepiped having a single fiber aligned along the long axis of the beam comprises the test geometry. The specimen is notched at the mid-point to have a greatly reduced cross-section of matrix material through which a crack is propagated, leaving the fiber as a bridging element. The specimen is pulled in tension by bonding the specimen to the load train of a mechanical test system. Crack opening displacement measurements are collected continuously from two linear voltage transducers mounted on opposite sides of the sample, and averaged to eliminate any error due to bending n comparison with earlier interfacial properties tests, the modified fiber pull out test does not rely on an artificial matrix crack(as seen in a conventionalP1: ARK/MBL/rkc P2: MBL/vks QC: MBL/agr T1: MBL May 16, 1997 13:47 Annual Reviews AR034-16 508 FABER Figure 5 Continuous load-displacement curve from the modified single-fiber pullout test (from 36). sliding distance leads to underestimates of the friction stress in pullout tests and overestimates in push-out tests due to the Poisson contraction and expansion, respectively. A modified fiber pullout test has been developed by Mumm & Faber (37) that affords the measurement of the continuous force-displacement response for a single crack-bridging fiber shown in Figure 5. A rectangular parallelepiped having a single fiber aligned along the long axis of the beam comprises the test geometry. The specimen is notched at the mid-point to have a greatly reduced cross-section of matrix material through which a crack is propagated, leaving the fiber as a bridging element. The specimen is pulled in tension by bonding the specimen to the load train of a mechanical test system. Crack opening displacement measurements are collected continuously from two linear voltage transducers mounted on opposite sides of the sample, and averaged to eliminate any error due to bending. In comparison with earlier interfacial properties tests, the modified fiber pull￾out test does not rely on an artificial matrix crack (as seen in a conventional