Showing papers by "Federico París published in 2014"

Effect of a secondary transverse load on the inter-fibre failure under compression

Abstract: At present, the progress in the failure criteria of unidirectional reinforced laminates requires the study of the evolution of the mechanisms of damage at micromechanical level. The objective of this paper is the study of the influence (at micromechanical scale) of a secondary transverse load (tension or compression), perpendicular to the transverse compression nominally responsible for the failure, on the inter-fibre failure under compression. The Boundary Elements Method and Interfacial Fracture Mechanics concepts are employed. It is shown that a secondary tension accelerates the generation of failure whereas a secondary compression inhibits it.

Effect of Friction on the Size of the Near-Tip Contact Zone in a Penny-Shaped Interface Crack

Abstract: Relations between different solutions of an interface crack in a neighborhood of the crack tip given by the open model, frictionless and frictional contact models of interface cracks are analyzed numerically for a penny-shaped interface crack subjected to remote tension. A new analytic expression for the size of the near-tip contact zone in presence of Coulomb friction between crack faces is proposed in the so-called case of the contact zone field embedded in the oscillatory field.

Fatigue crack initiation and damage characterization in Brazilian test specimens for adhesive joints

Abstract: The present study is focused on the fatigue failure initiation at bimaterial corners by means of a configuration based on the Brazilian disc specimens. These specimens were previously used for the generalized fracture toughness determination and prediction of failure in adhesive joints, carried out under static compressive loading. Under static loading, local yielding effects might affect the asymptotic two-dimensional linear elastic stress representation under consideration. Fatigue loading avoids this fact due to the lower load levels used. The present tests were performed using load control; video microscopy and still cameras were used for monitoring initiation and crack growth. The fatigue tests were halted periodically and images of the corner were taken where fatigue damage was anticipated. Damage initiation and subsequent crack growth were observed in some specimens, especially in those which presented brittle failure under static and fatigue tests. These analyses allowed the characterization of damage initiation for a typical bimaterial corner that can be found in composite to aluminium adhesive lap joints.