Toward a design method for metal-composite co-cured joints based on the G-SIFs

Abstract

In this work, a systematic study of the singular stress field in the zone where the interface intersects the free edge surfaces of bonded metal-composite co-cured joints, has been performed. The obtained theoretical, numerical and experimental results have permitted to detect the relationships between the joint configuration and the singular stress field, as well as to implement a new design method based on the so called generalised stress intensity factors. Such a proposed method allows the user to predict the static strength of a generic metal-composite co-cured joint, vs. the main influence parameters as the elastic modulus of the coupled materials, the overlap length, the taper angle, the imbalance, etc. The accuracy of the theoretical and numerical analyses performed in the present study, as well as the reliability of the strength predictions provided by the proposed method, have been tested by means of experimental assessments carried out by using aluminum-GFRP and aluminum-CFRP co-cured double lap joints.

Analysis and optimization of hybrid double lap aluminum-GFRP joints

“…In accordance with the results shown in literature for brittle adhesive (see as an example Ref. [21]), when SX-10 epoxy resin is used as adhesive in co-cured joints, then the damaging process of the joint follows always the nucleation and the successive propagation of a crack inner the adhesive (or at the adherent-adhesive interface if the relative adhesion is weaker [22]), until catastrophic failure.…”

“…In more detail, it is seen that for a joint with a finite width the most stressed point is the outer point of the attach edge of the GFRP. Consequently, an accurate evaluation of the tensile strength of such joints should consider the interlaminar stresses in this particular point, combined with an appropriate failure criterion as the point or the average stress criterion [31,32] or proper criterions based on GSIFs [22]. Fig.…”

Adhesive selection for hybrid spot-welded/bonded single-lap joints: Experimentation and numerical analysis

“…Under the scope of fracture mechanics-based approaches, the Generalized Stress Intensity Factor (G-SIF) approach has been used for the strength prediction of bonded joints [3]. Russo and Zuccarello [4] used the G-SIF methodology as a design method for the strength prediction of metal-to-composite co-cured joints. A theoretical stress analysis was performed by the Lekhnitskii theory enabling computing the singularity orders of the singular stress field in the joints.…”

Preparation and thermodynamic analysis of the porous functionally graded bolted joint

“…Many efforts have been done on metallic thermal protection system, including the design and characterization of thermal insulation material/structure [3][4][5][6][7][8], however, heat shorts blocking joints have been rarely studied. Also, most researches focused on metal joints [9][10][11][12][13][14][15], which had quite poor heat insulation properties. Some studies were carried out on C/SiC joints [16][17][18], yet the complicated fabrication approaches for geometrically complex composites such as bolted joints have certain limitations in terms of size and shape, which have greatly limited their wider applications.…”