C. Furtado

• Assistant Professor at University of Porto

The Mode I, Mode II, and mixed-mode interlaminar failure behavior of a thin-ply (54 gsm) carbon fiber-epoxy laminated composite reinforced by 20 μm tall z-direction-aligned carbon nanotubes (CNTs), comprising ∼50 billion CNT fibers per cm², is analyzed following J-integral-based data reduction methods. The inclusion of aligned CNTs in the ply inter...

Large-scale aerospace composite parts utilizing autoclave-required carbon fiber reinforced plastic (CFRP) epoxy prepreg were manufactured with a novel Nano- Porous Network (NPN) enabled and CNT-heater based out-of-oven (OoO) for a combined out-of-autoclave (OoA) approach. While prior work has established open porosity carbon nanotube films as effec...

The heterogeneity of the microstructure and the anisotropy of the mechanical properties of carbon fiber reinforced polymer composites (CFRP) are associated with complex damage mechanisms that make failure prediction highly challenging. Typical damage mechanisms for CFRP include: (i) interlaminar cracking (delamination), (ii) matrix cracking, and (i...

The failure envelope of composite fastened joints under combined bearing and pull-through loading conditions is obtained by developing, testing and validating a new experimental procedure. The new device proposed here is compatible with standard testing machines and captures the critical interactions between the two loading mechanisms for pull-thro...

The deadline for proposals submission is on the 15th of November, 2022. To submit your proposal, please fill the form available in conference website, where you must provide the title of the minisymposium, a brief description, and information about the organizer (and co-organizers, if applicable). 19 – 21 June 2023 / yic2023.fe.up.pt / yic2023@fe....

The submission of extended abstracts is now open and authors will be able to submit their contributions until the 15th of January 2023.

Scarf repairs are regarded as a highly effective repairing method to recover most of the load-carrying capabilities in primary aircraft structures. In this article, an Improved Semi-analytical Method (ISM) is proposed as a quick design tool for the strength prediction and the optimization of composite scarf repair structures made from fabric or uni...

This work represents the first step towards the application of machine learning techniques in the prediction of statistical design allowables of composite laminates. Building on data generated analytically, four machine algorithms (XGBoost, Random Forests, Gaussian Processes and Artificial Neural Networks) are used to predict the notched strength o...

A meso-scale damage modelling framework for composite laminates is assessed against multiaxial experimental data obtained from specimens subjected to combined tension/compression and shear loading using a modified Arcan fixture (MAF). Two laminates made from unidirectional carbon fibre-reinforced epoxy plies of different thickness are considered to...

This work presents an experimental study on the effect of: ply thickness; ply-level hybridization; and type of ply architecture on the damage mechanisms that dominate failure and strength of multidirectional laminates. Nine effectively equivalent 0°dominated multidirectional laminates made from unidirectional carbon fibre tapes (UD), non-crimp fabr...

In situ X-ray synchrotron radiation computed tomography (SRCT) of carbon fiber composite laminates reveals the first-ever qualitative and quantitative comparisons of 3D progressive damage effects introduced by two mechanical enhancement technologies: aligned nanoscale fiber interlaminar reinforcement and thin-ply layers. The technologies were studi...

The apparent crack resistance curves associated with longitudinal tensile failure of carbon fibre reinforced epoxy composite systems with ply thicknesses of 0.075 mm, 0.134 mm and 0.268 mm are determined experimentally from the size effect law of geometrically similar double edge notch tension cross-ply specimens. An increase in notched strength as...

The introduction of the spread-tow thin-ply technology enabled the development of composite plies as thin as 0.020 mm. The availability of composite plies with a broader thickness range makes the understanding of the effects of ply thickness more pertinent than ever, therefore, a comprehensive literature review is presented in this paper. The micro...

Aerospace-grade unidirectional carbon microfiber reinforced epoxy prepreg composite laminates were reinforced in the relatively weak interlaminar regions with high densities (>10 billion nanofibers per cm²) of uniformly-distributed vertically aligned carbon nanotubes (A-CNTs), creating a hierarchical architecture termed “nanostitch”. Such nanostitc...

This paper presents the development and validation of a mesoscale numerical model for predicting damage and failure of bolted joints in laminated composites with different configurations and geometries. Double-shear and single-shear composite bolted joints with different widths and end distances were analyzed. The composite material model combined...

The development of numerical tools to complement the experimental determination of structural design parameters is of key importance to hasten the certification process of new materials and structures. In this work, a methodology to simulate elastic and inelastic deformation of composite laminates at the subcomponent level based on finite element a...

To simplify the analysis and characterisation of composite laminates, an invariant-based approach to stiffness that takes the trace of the plane stress stiffness matrix as a material property was recently proposed. In the present work, a study based on micro-mechanical models brings new insight to this invariant-based approach. The Rule of Mixtures...

High densities (>10 billion fibers per cm ² ) of aligned carbon nanotubes (A-CNTs) are used to reinforce the interlaminar resin-rich region of aerospace-grade unidirectional carbon microfiber plies in a hierarchical carbon fiber reinforced plastic (CFRP) laminate architecture. Such nano-engineered interfaces have been shown to increase interlaminar...

The design of composite structures relies on the accurate determination of design allowables, which are statistically based material parameters that take into account manufacturing, geometrical and microstructure variability. The accurate determination of these design parameters requires extensive experimental testing, which makes the certification...

Thin-ply carbon fiber laminates have exhibited superior mechanical properties and damage resistance when compared to standard thickness plies and enable greater flexibility in laminate design. However, the increased ply count in thin-ply laminates also increases the number of ply-ply interfaces, thereby increasing the number of relatively weak and...

Advanced non-linear Finite Element models for the strength prediction of composite laminates normally result in long computing times that are not suitable for preliminary sizing and optimisation of structural details. Macro-mechanical analytical models, in spite of providing quick predictions, are based on properties determined from tests performed...

The effect of through-thickness compressive stress on mode II interlaminar fracture toughness is investigated experimentally and replicated numerically. The modified Transverse Crack Tensile specimen recently proposed by the authors is used, together with an experimental device designed to apply a constant transverse compressive stress on the surfa...

Advanced non-linear Finite Element models for the strength prediction of composite laminates normally result in long computing times that are not suitable for preliminary sizing and optimisation of structural details. Macro-mechanical analytical models, in spite of providing quick predictions, are based on properties determined from tests performed...

This work presents an experimental study on the effect of ply-level hybridisation on the tensile unnotched and notched response of composite laminates. In a first assessment, notched tests were performed on laminates with nominal ply thicknesses between 0.03 mm and 0.30 mm. From the understanding of the effect of ply thickness on the damage mechani...