Dynamic compressive response of wrapped carbon fibre composite corrugated cores

The experimental study on the compressive response of the carbon fibre composite sandwich structures with corrugated cores is reported. The corrugated core was manufactured from unidirectional carbon fibre pre-impregnated lamina wrapped around destructible triangular prisms. Individual wrapped triangular composite cores of relative density are cut from the sandwich beams and tested under both quasi-static compression and dynamic compression at a strain rate up to 8200s-1 using an instrumented direct impact Kolsky bar experiment. Under quasi-static compressive test, as the cores were provided with no lateral confinement, the failure mechanism of the composite core was that of progressive unwrapping of cores due to matrix cracking at the joints of the core webs. Under the dynamic compressive tests, the composite cores demonstrated rate-dependent behaviour. The strain rate dependency was attributed to the suppression of the quasi-static “unwrapping” failure mechanism, and inertial stabilisation of the struts against buckling leading to an upper-bound failure mechanism of crushing of carbon fibre material within the struts

Influence of the Loading Path on the Strength of Fiber-Reinforced Composites Subjected to Transverse Compression and Shear

The influence of the loading path on the failure locus of a composite lamina subjected to transverse compression and out-of-plane shear is analyzed through computational micromechanics. This is carried out using the finite element simulation of a representative volume element of the microstructure, which takes into account explicitly fiber and matrix spatial distribution within the lamina. In addition, the actual failure mechanisms (plastic deformation of the matrix and interface decohesion) are included in the simulations through the corresponding constitutive models. Two different interface strength values were chosen to explore the limiting cases of composites with strong or weak interfaces. It was found that failure locus was independent of the loading path for the three cases analyzed (pseudo-radial, compression followed by shear and shear followed by compression) in the composites with strong and weak interfaces. This result was attributed to the fact that the dominant failure mechanism in each material was the same in transverse compression and in shear. Failure is also controlled by the same mechanisms under a combination of both stresses and the failure locus depended mainly on the magnitude of the stresses that trigger fracture rather than in the loading path to reach the critical condition

ECCO Essential Requirements for Quality Cancer Care: Primary care.

ECCO Essential Requirements for Quality Cancer Care (ERQCC) are checklists and explanations of organisation and actions that are necessary to give high-quality care to cancer patients. They are written by European experts representing all disciplines involved in cancer care. This paper concerns the integration of primary care into care for all cancers in Europe. Primary care integration

A microscale integrated approach to measure and model fibre misalignment in fibre-reinforced composite

peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 30/08/2021Computational micromechanics of fibre-reinforced polymers (FRPs) relies on the ability of the representative volume elements (RVEs) to take into account the different features that characterise the geometry of the material system under consideration. Fibre misalignment has been proven experimentally to have a significant effect on the mechanical properties at the macroscale, but is not currently taken into consideration in models at the individual fibre level, perhaps due to the difficulty in statistically characterising the fibre misalignment. In this work, an integrated approach is presented to measure and model fibre misalignments in FRPs. A computed tomography (CT) scan is used to identify the fibre geometry and statistically characterise the fibre misalignment angle distribution. Using a methodology recently developed by the authors, three-dimensional (3D) RVEs were generated by requiring their misalignment angle distribution to fit the empirical distribution. The methodology proposed provides a framework for the systematic numerical analysis of the influence of fibre misalignment on mechanical properties of FRPs