An analytical model for the translaminar fracture toughness of fibre composites with stochastic quasi-fractal fracture surfaces

The translaminar fracture toughness of fibre-reinforced composites is a size-dependent property which governs the damage tolerance and failure of these materials. This paper presents the development, implementation and validation of an original analytical model to predict the tensile translaminar (fibre-dominated) toughness of composite plies and bundles, as well as the associated size effect. The model considers, as energy dissipation mechanisms, debonding and pull-out of bundles from quasi-fractal fracture surfaces; the corresponding lengths are stochastic variables predicted by the model, based on the respective bundle strength distributions and fracture mechanics. Parametric studies show that composites are toughened by stronger fibres with large strength variability, and intermediate values of interfacial toughness and friction. Predictions are validated against four different composite ply systems tested in the literature, proving the model’s ability to capture not only size effects, but also the influence of different fibres and resins

Multiple length/time-scale simulation of localized damage in composite structures using a Mesh Superposition Technique

A Mesh Superposition Technique (MST) for the progressive transition between differently-discretized subdomains is proposed and implemented in an FE code. The interfaces between these subdomains are replaced by transition regions where the corresponding meshes are superposed. The MST is applied to the multiple length/time-scale analysis of a low-velocity impact of a projectile on a composite plate. Unlike using a sudden discretization-transition approach, the use of the MST eliminates the undesirable stress disturbances at the interface between differently-discretized subdomains and, as a result, it correctly captures the impact-induced damage pattern at a lower computational cost. Finally, the MST is coupled with an implicit/explicit co-simulation technique for a multiple time/length-scale analysis. The results indicate that, if the length-scale transition is performed using the proposed MST instead of a sudden discretization-transition, the CPU time can be nearly halved

Realising damage-tolerant nacre-inspired CFRP

Inthiswork,anacre-inspiredCarbonFibreReinforcedPolymer(CFRP)compositeis designed,synthesisedandtested. Analyticalandnumericalmodelsareusedtodesign a tiled micro-structure, mimicking the staggered arrangement of ceramic platelets in nacreandexploitinggeometricalinterlocksforcrackdeflectionanddamagediffusion. The designed pattern of tiles is then laser-engraved in the laminate plies. In order to increase the damage-spreading capability of the material, a thin layer of poly(lactic acid) (PLA) is film-cast on the interlaminar region, both as a continuous film and as a pattern of fractal-shaped patches. Three-point bending tests show how the nacre-like micro-structure succeeds in deflecting cracks, with damage diffusion being significantly improved by the addition of PLA at the interface between tiles. It is observed that a texture of discontinuous fractal-shaped PLA patches can increase damage diffusion, by promoting the unlocking of tiles whilst preserving the interface strength

The Great Lockdown Recession and International Business

The global health pandemic and the ensuing global recession has caused unprecedented uncertainty, risks, and devastation to individuals, families, societies, and organizations. In this context, a central question arises: what are the prospects for globalization? This article addresses five pressing questions that affect globalization for multiple stakeholders: (1) How is this pandemic different from previous disruptive events? (2) Are there silver linings to this economic disruption? (3) What are current and future impacts on globalization? (4) How will different entities be affected? and (5) What will be the likely impact on major economies? We have opportunities to fundamentally shift international business for economic, environmental, and social advancements that offer hope during this overwhelming health crisis