an epoxy resin was modified by silica nanoparticles and cured with an anhydride. the particles with different batches of 12, 20, and 40 nm sizes were each distributed into the epoxy resin ultrasonically. electron microscopy images showed that the silica particles were well dispersed throughout the resin. tensile test results showed that young’s modulus and tensile strength increased with the vo...

‘Curving’ could occur in Mode I brittle fracture and it can be attributed to the constraint. The variation of the apparent fracture toughness with constraint with or without crack curving is investigated. Using a critical opening or hoop stress as the fracture criterion, it is demonstrated that a fracture event can be quantified by two mechanics parameters, i.e. K and A3 for fracture without cu...

1359-835X/$ see front matter 2008 Elsevier Ltd. A doi:10.1016/j.compositesa.2008.03.011 * Corresponding author. Tel.: +1 617 252 1539. E-mail address: [email protected] (B.L. Wardle). An interlaminar reinforcement using aligned carbon nanotubes (CNTs) is demonstrated for prepreg unidirectional carbon tape composites. Aligned CNTs are grown at high temperature and then transferprinted to prepreg at...

The mode I fracture toughness as a function of crack length of medium density fiberboard (MDF), particle board (PB), and Douglas-fir (DF) were all measured using a new energy-based method. PB and MDF are examples of composites that develop fiber bridging during crack propagation, which causes their toughness to increase with crack length. Longitudinal cracks in DF also displayed fiber bridging ...

An analysis is presented for transient response of a mode-III interfacial crack propagating between two dissimilar piezoelectric half spaces. The dynamic fracture toughness of a piezoelectric interface is examined, which is a central issue related to the interface strength of multi-layered sensors and ferroelectric thin film devices. For the mode-III crack propagation in piezoelectric materials...

Abstract In this contribution, a novel framework for simulating mixed-mode failure in rock is presented. Based on hybrid phase-field model fracture, separate variables are introduced tensile (mode I) and shear II) fracture. The resulting three-field problem features length scale parameters mode I II cracks. contrast to the classic two-field approaches, it can thus account different strength of ...

In this paper, the use of a cohesive-zone approach to model the mode-I fracture of adhesive joints made from a polymer-matrix composite is demonstrated. Cohesive-zone parameters were obtained by matching numerical results to experimental observations. It is shown that there is a distinction between the characteristic strength of the interface associated with the toughness, and the intrinsic coh...