ISSN:
1573-2673
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Results on strength, apparent toughness, fatigue crack growth and fiber debonding on specially made composite materials are reported. The compact tension composite specimen used consisted of an epoxy matrix and layers of long aligned glass or kevlar fibers that were equally spaced. The experimental data on crack initiation strength showed that for a range of fiber spacing λ, the composite's strength δ A , scaled with the fiber spacing in the form of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaOqaaiabeo8aZnaaBa% aaleaaieGacaWFbbaabeaakmaakaaabaGaeq4UdWgaleqaaOGaeyyp% a0JaeqOUdSgaaa!3EB5!\[\sigma _A \sqrt \lambda = \kappa \]. The apparent toughness of the composite specimens increased with a decrease in fiber spacing. Two sets of fatigue crack propagation experiments were performed. The first one was on specimens with the same fiber spacing and under different applied loads. The second set was on specimens with different fiber diameter and the same loading conditions. While crack arrest was observed in the first set, crack arrest was seen in the second set for the relatively large diameter fibers and specimen fracture for the relatively thin fibers. A method, based on fracture mechanics principles and crack opening displacements, for evaluating bridging tractions is outlined. Using this method, simulations for the bridging tractions and stress intensity factor were carried out using a linear crack opening profile. The total stress intensity factor was found to decrease with crack length. The debonding in the bridging zone, on specimens with different fiber spacing, was evaluated using a one dimensional debonding analysis. The model was calibrated with the debonding on the first fiber and consequently used to describe debonding on the bridging zone of specimens with different fiber spacing. In spite of the assumptions adopted in the present studies, the model seems to describe debonding well.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00034661
Permalink