Failure of NCF composites subjected to combined compression and shear loading

On the transition from shear-driven fibre compressive failure to fibre kinking in notched CFRP laminates under longitudinal compression

“…It can be seen in Fig. 9b that an in-plane kink-band, label (4), and an out-of-plane kink-band, label (5), appear to be connected to the splits originating from the notch tip, label (6), and the shear crack tip, label (3) in Fig. 9d.…”

“…Typical kink-band parameters such as the width w, the propagation angle b and the fibres' rotation angle a are also shown in this figure. Failure by kink-band formation can be found in many other engineering materials such as non-crimp fabric [6], wood [7], paper [8].…”

Damage tolerance analysis of NCF composite sandwich panels

“…In [15] 25 mm wide unnotched NCF specimens were loaded in compression. The loading on some specimens was interrupted prior to failure and the specimens were subjected to fractographic studies.…”

“…The measured unnotched unidirectional compressive strength of the T700 carbon fibre NCF /vinyl ester material is 1020 MPa (from reference [15] adjusted for a nominal thickness of 5.4 mm) and together with the stiffness properties reported in Table 1 Young's modulus of the NCF quasi-isotropic panel estimated by the laminate plate theory is 38.3 GPa (=E eff ) and the measured average failure strain of the unnotched laminate equal to 0.95%.…”

A numerical model for delamination growth simulation in non-crimp fabric composites

“…At meso-scale level (preform level) the defects in the NCFs (as, for example, the waviness of the tows) need to be considered in order to set up a realistic three-dimensional effective model for the determination of the mechanical performances of the NCFs. The failure mechanisms and the fracture toughness properties are also influenced by the micro-structure and the meso-structure of the NCFs as shown in [13,14], where the formation of damage and its progression are investigated by fractography and the influence of stitching on NCFs toughness properties is assessed by experimental tests [15,16]. Very few examples of failure analytical models can be found in literature.…”