Analytical Fracture Mechanics Analysis of the Pull-Out Test Including the Effects of Friction and Thermal Stresses

Abstract

The energy release rate for propagation of a debond in a single-fibre pull out test was derived analytically. The key finding was that an accurate analysis can be derived by a global energy analysis that includes effects of residual stresses and interfacial friction but does not need to include the details of the stress state at the interfacial crack tip. By comparison to finite elements analysis, it was verified that the analytical results are very accurate provided the debond tip is not too close to either end of the specimen. By casting the results in terms of net-specimen stress, it was possible to derive a general energy release rate result that applies to both the pull-out test and the related microbond test. The energy release rate expressions can be used to determine interfacial fracture toughness from single-fibre pull-out tests or microbond tests.

Effect of filler content on the adhesion strength between UD fiber reinforced and particulate filled composites

“…The predicted steep increase of the shear stress near the end of the lap joint substantially above the mean shear stress in the joint causes initiation of the joint failure. Increasing the crack resistance of the adhesive resulted in improved performance of the joint (22). Based on the arguments put forward above, the enhancement of the shear bond strength obtained from the pull-out test with increasing filler loading was related to the changes in mechanical properties of the PFC.…”

“…3) for the 3 mm embedded length was related to the increase of the elastic modulus of the PFC with the filler volume fraction leading to a more even shear stress distribution along the bonded surface of the test specimen [22,23]. In addition, fracture toughness of the PFC was also increasing with v f .…”

“…Shear adhesion strength was measured using a modified fiber pull-out test originally used to measure shear strength of the interface in a model single fiber composite (22). Special steel clamp was used to mount the specimens (Fig.…”

“…Test methodology based on the concept of the modified pull-out test used to measure shear strength of the interface in model single fiber composites was employed (22). In addition to the measurement of the average nominal shear adhesion strength, investigation of the loci of failure and the crack path were attempted using scanning electron microscopy (SEM) of the failed test specimens.…”

Fiber/matrix interfacial shear strength measured by a quasi-disk microbond specimen

“…This interfacial strength is affected by the type of fiber and matrix resin as well as by the condition of the fiber surface treatment [1,2]. A pull-out test [3], a micro-debonding test [4], a fragmentation test [5,6], a micro-indentation test [6] and a droplet microbond test [5][6][7][8][9][10][11][12] were performed for evaluating the fiber-matrix interfacial shear strength. Herrera-Franco and Drzal [6] reviewed the testing techniques for the measurement of fiber/matrix adhesion and discussed the advantages and limitations of each test.…”