Silvestre Pinho

Silvestre Pinho
Imperial College London | Imperial · Department of Aeronautics

PhD

About

206
Publications
50,408
Reads
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7,287
Citations
Introduction
Silvestre is currently an EPSRC Research Fellow and Professor in the Mechanics of Composite Materials at Imperial College. Silvestre was awarded in 2010 by the European Society for Composite Materials (ESCM) the prize for best young researcher in Composites active in Europe. Silvestre is since June 2012 a member of the Council and of the Executive Committee of ESCM.
Additional affiliations
January 2005 - present
Imperial College London
Position
  • Professor in the Mechanics of Composite Materials
September 2000 - November 2005
University of Porto
Position
  • Lecturer

Publications

Publications (206)
Article
In this work, we design, prototype, test and analyse the first high-performance Herringbone-Bouligand microstructure (with Carbon Fibre Reinforced Plastic (CFRP)) inspired to the high-impact-resistant mantis shrimp’s dactyl club. To this end, we devised the first prototyping procedure to manufacture point-by-point tailorable Herringbone-Bouligand C...
Article
This paper describes the fractographic observations from the study of embedded defects subject to compression. The fractographic observations aim to characterise the interaction between intralaminar and interlaminar fractures and to understand their role in the delamination growth and the delamination migration. The influence of the stacking sequen...
Article
Carbon fiber layer failure is vital for the tensile behavior of interlayer hybrid carbon fiber (CF)/self-reinforced polypropylene (SRPP) composites. Introducing cuts, termed here as discontinuities, into the carbon layer is a promising way to tailor its failure behavior. Inspired by structural features of biological composites, we designed and prod...
Article
We demonstrate for the first time that the inherent low performance to through-the-thickness loads of thin-ply carbon fibre composites can be tackled with tailored bio-inspired Bouligand design. To this end, we designed, manufactured ultra-thin-ply CFRP Bouligand laminates and conducted an original study which combines full-penetration quasi-static...
Article
Translaminar fracture toughness is a vital property governing the notch sensitivity and damage tolerance of composites. Nature has shown that incorporating material transitions can increase toughness significantly. This work presents finite element models demonstrating that such transitions can indeed increase the translaminar fracture toughness. T...
Article
This work explores the potential of discontinuities combined with hybridization in controlling the failure mechanisms of composite materials. Laser cuts, termed as discontinuities, with a predefined staggered pattern were introduced into the carbon layer of hybrid carbon fiber (CF)/self-reinforced polypropylene (SRPP) composites. Three geometrical...
Article
An original concept for improving the delamination resistance and damage tolerance of a composite laminate is proposed. The concept is to insert interlocked thin-ply reinforcement units between the laminae. Each reinforcement unit consists of two thin-ply layers with tabs cut into one layer, and slits cut into the other layer. The slits, and the lo...
Article
Bio-inspired strategies have been frequently used in the past years to devise original microstructures aiming at improving the damage tolerance of CFRP structures. Specifically, Bouligand architectures have been widely studied to design impact damage-tolerant CFRPs structures. An example of a Bouligand structure can be found on the mantis shrimp da...
Article
In this paper, we examine the fracture toughness of a self-reinforced polypropylene/carbon fibre polypropylene cross-ply hybrid laminate and design techniques to improve two damage tolerance requirements: (i) enhancing the energy dissipation capability via promoting sub-critical diffused damage and (ii) enhancing the damage tolerance to impact. For...
Article
In this paper, failure initiation in composite structures due to high out-of-plane load components is predicted. The predictions are based on finite element models built with shell elements, intended for global models. The full 3D stress state is estimated through stress recovery by the extended 2D FEM approach. Failure initiation is predicted with...
Article
Full-text available
In this paper, the non-linear mechanical response of triaxial braided composites under multiple loading conditions was investigated with a meso-scale simulation strategy. Numerical predictions made by three-dimensional finite element unit cells with a realistic internal geometry in two nesting configurations correlated well with experimental stress...
Article
Full-text available
Carefully placed patterns of micro-cuts have been inserted in the microstructure of Cross-Ply (CP) and Quasi-Isotropic (QI) thin-ply CFRP laminates to engineer their translaminar fracture behaviour with the purpose of increasing their damage resistance under different loading conditions. A novel Finite Fracture Mechanics model has been developed to...
Article
Full-text available
In this paper, we propose a novel simulation framework for accurately predicting the mechanical response of highly compacted triaxial braided composites using meso-scale finite element models. Unit cells with a realistic internal geometry are generated within an automated simulation work-flow. Local volumetric interpenetrations are removed from a n...
Article
The impact resistance of fibre-reinforced composites is vital in many applications, and can be improved by exploiting synergies in fibre-hybridisation. These effects are however not sufficiently well understood in the literature. Penetration impact tests were hence performed on carbon/glass hybrids, and the results were linked to the flexural behav...
Conference Paper
Full-text available
Both discontinuous fiber-reinforced composites and hybrid composites show the potential to overcome the stiffness-toughness dilemma that conventional fiber reinforced polymer composites suffer from. To fully utilize the advantages of discontinuities and hybridization, careful design of the configuration of discontinuities is required. In this paper...
Article
In this paper, a bio-inspired carbon-fibre/epoxy composite with nacre-like tiled microstructure is designed, synthesised and tested. Analytical models are developed to predict the energy dissipation and crack deflection properties of such composite, and the predictions for the stress-strain response during tile pull-out are validated against direct...
Article
Full-text available
Damage and failure of triaxial braided composites under multi-axial stress states was investigated. In order to introduce different multi-axial stress states in the material, uni-axial tensile tests were performed at different off-axis orientations. Three braid architectures, comprising braiding angles of 30°, 45° and 60° were each loaded parallel...
Conference Paper
Full-text available
In this paper, the potential and limitations to a proposed methodology for finding hot spots in large and complex composite structures are explored. The methodology uses shell elements in combination with a stress recovery process to establish the full 3D stress tensor. These stresses can then be used in state of the art failure criteria for compos...
Article
A key aspect of the longitudinal tensile failure of composites is the stress redistribution that occurs around broken fibres. Work on this topic has focussed mainly on the stress field surrounding a single broken fibre; however, this is an important limitation as unstable failure in carbon fibre bundles occurs when a cluster of about 16 or more bro...
Article
Full-text available
This paper presents a numerical study of the delamination migration in angle-ply laminates observed in experiments reported in the literature, where the delamination originally propagates along the lower, interface and later migrates onto the upper, interface. The recently-developed Floating Node Method (FNM) is used for modelling this problem. The...
Conference Paper
Full-text available
The translaminar fracture toughness determines in many cases the damage tolerance of composite components, and this property is strongly influenced by the microstructure. A finite element model was developed that can aid in the optimisation of the microstructure for maximising the translaminar fracture toughness of composites hybridised at the tow...
Conference Paper
Full-text available
In this paper, intrabundle failure initiation in NCF reinforced composite materials is predicted based on a finite element model built with shell elements. The full 3D stress state is estimated based on the shell results and used in a state of the art 3D failure criterion. The procedure considers predictions of the transverse shear and normal stres...
Conference Paper
Full-text available
The translaminar fracture toughness of composites is a crucial parameter for the damage tolerance of composite parts and the microstructure is known to affect this parameter. A finite element model was therefore developed that is capable of predicting the translaminar fracture toughness of a complex microstructure. This model revealed that interfac...
Conference Paper
In this work, a novel, bio-inspired carbon/epoxy composite with nacre-like tiled microstructure is designed and synthesised. Analytical models were developed to predict the strength and toughness of such composite, and the predictions for the stress-strain response during tile pull-out were validated against FE. Suitable configurations for tile geo...
Conference Paper
Full-text available
n the presented work, we propose a framework for predicting the non-linear mechanical response of triaxial braided composites using meso-scale finite element unit cells. Based on a reduced unit cell concept which exploits symmetries to minimise computational expense, a compacted and interpenetration-free yarn geometry is created within a three stag...
Article
Full-text available
This paper presents the modelling of tensile failure of composites using novel enriched elements defined based on the floating node method. An enriched ply element is developed, such that a matrix crack can be modelled explicitly within its domain. An enriched cohesive element is developed to incorporate the boundaries of matrix cracks on the inter...
Article
Bio-inspired patterns of micro-cuts perpendicular to the fibre direction in thin-ply CFRP laminates have been used to increase the translaminar fracture toughness of the material. An analytical model to predict the probability of bundle pull-out during translaminar crack propagation was developed and validated through an experimental parametric stu...
Article
Full-text available
The concept of translaminar fracture toughness of 0° plies has enabled the development of a considerable number of ply-level numerical models for structural failure of laminated composites. Using thin-ply pre-pregs, this paper demonstrates that this translaminar toughness is not an absolute, but rather in-situ, property and depends strongly on the...
Research
Full-text available
This document present a comprehensive review of the failure modes found in fibre reinforced composites with a unidirectional architecture. It also provides a short review on existing failure criteria.
Article
In this paper, the translaminar initiation fracture toughness of a carbon-epoxy Non-Crimp Fabric (NCF) composite laminate was measured using a Compact Tension (CT) test. The translaminar fracture toughness of the individual UD fibre tows was related to that of the NCF laminate and the concept of an homogenised blanket-level translaminar fracture to...
Article
Full-text available
This paper illustrates a multiple length/time-scale framework for the virtual testing of large composite structures. Such framework hinges upon a Mesh Superposition Technique (MST) for the coupling between areas of the structure modelled at different length-scales and upon an efficient solid-to-shell numerical homogenization which exploits the inte...
Article
In this paper, a novel analytical model for predicting the post-crushing compressive response of progressively crushable sandwich foam cores is presented. The calibration of the model is performed using experimental measurements obtained exclusively from standard monotonic compressive tests. Therefore , the need for performing time-consuming compre...
Conference Paper
Full-text available
A novel set of Periodic Boundary Conditions named Multiscale Periodic Boundary Conditions (MPBCs) that apply to reduced Unit Cells (rUCs) and enable the two-scale (solid-to-shell) numerical homogenization of periodic structures, including their bending and twisting response, is presented and implemented in an FE code. Reduced Unit Cells are domains...
Article
In this paper, a novel set of Periodic Boundary Conditions named Multiscale Periodic Boundary Conditions (MPBCs) that apply to reduced Unit Cells (rUCs) and enable the two-scale (solid-to-shell) numerical homogenization of periodic structures, including their bending and twisting response, is presented and implemented in an FE code. Reduced Unit Ce...
Chapter
The use of carbon fibers has been growing exponentially, prompting the development of sustainable recycling routes for the carbon fiber reinforced polymer (CFRP) waste generated. Mechanical and thermochemical (e.g. pyrolysis) fiber reclamation processes are reviewed; it is shown that, under optimized conditions, most processes can recover fibers wi...
Article
Predictive models have struggled to accurately simulate progressive delamination growth in composite structures, often due to the challenges associated with modelling delamination migration phenomenon. This paper presents a methodology with which to model such migration. Firstly, the interlaminar shear at a delamination front were partitioned into...
Article
This work investigates the potential of interleaving to delay catastrophic translaminar failure in unidirectional Carbon Fibre Reinforced Polymers (CFRPs) under tensile load. A Finite Element Model of a damaged Polymer Interleaved Composite (PIC) specimen was built by considering an initial translaminar crack in a CFRP ply, and cohesive zones acros...
Article
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-vel...
Article
SUMMARYA new Molecular Dynamics Finite Element Method (MDFEM) with a coupled mechanical-charge/dipole formulation is proposed. The equilibrium equations of Molecular Dynamics (MD) are embedded exactly within the computationally more favourable Finite Element Method (FEM). This MDFEM can readily implement any force field because the constitutive rel...
Conference Paper
Full-text available
A Mesh Superposition Technique (MST) for the transition between differently-discretized subdomains is proposed and implemented in an FE code. The interfaces be-tween these subdomains are replaced by transition regions where the corresponding meshes are superposed. The MST is applied to the low-velocity impact of a projectile on a composite plate. T...
Article
Full-text available
A material model for unidirectional fibre-reinforced composites coupling damage to the friction acting on newly created microcracks is developed. While existing material models accounting for progressive damage assume that microcracks remain traction free under compressive load, the present model accounts for contact and friction at microcrack clos...
Article
Different geometric configurations of the compact tension (CT) specimen have been investigated for the characterisation of the tensile intralaminar fracture toughness of woven composite laminates. The objective is to ensure that the required crack extension for experimental characterisation will occur in the absence of any other damage mechanism. P...
Article
Full-text available
The tensile intralaminar fracture toughness of the carbon/epoxy 5HS-RTM6 woven composite material has been experimentally characterised, using the doubly-tapered compact tension (2TCT) specimen. This specimen geometry was found to achieve lower values for the failure indices described in the first part of the article. Two different configurations o...
Conference Paper
Full-text available
A novel Mesh Superposition Technique (MST) for the transition between differently-discretized subdomains is proposed and implemented in a FE code. The interfaces between these subdo-mains are replaced by transition regions where the corresponding meshes are superposed. As a result, the artificial stress wave reflections and stress concentrations at...
Article
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 b...
Article
Technologies for recycling carbon–fibre composites are now becoming mature, so a key challenge is to establish applications for the recycled products. This paper aims to further our understanding on the mechanical response of recycled composites, so as to guide the optimisation of recycling processes and support their use in non-critical structural...
Article
This paper presents a new method suitable for modelling kinking discontinuities within a finite element framework. The proposed method effectively implements local remeshing in terms of solution, but is computationally more efficient than remeshing; it can be readily implemented in relatively closed FE codes; and it allows (sub-)elements near a cra...
Article
The work that will be presented concerns the development of a damage model intended to capture the delamination failure exhibited by notched laminates under mixed-mode in-plane loading. The model will be validated against an experimental program which uses a new type of tensile specimen, designed to trigger the desired failure mode. The advantage o...
Article
A new multi-physics and multi-scale Molecular Dynamics Finite Element Method (MDFEM) is proposed, which allows for advanced mechanical and multi-physics charge-dipole MD force fields to be implemented exactly in the computationally more favourable FEM. The proposed model has produced novel mechanical and electrical charge-dipole FEM results. In par...
Conference Paper
Full-text available
The simulation of the mechanical response of large composite structures often requires that differ-ent parts of the structures are modelled at different scales, eventually even using different physics. In dynamic problems and during fracture, abrupt changes in both finite element type and size provoke spurious stress wave reflections at the interfa...
Article
This paper showcases the authors' predictions for the 13 challenging test cases of the third World Wide Failure Exercise. The cases involve the prediction of lamina biaxial stress-strain curves, matrix cracking and delamination in various cross-ply and quasi-isotropic laminates under uniaxial loading, variation of thermal expansion coefficient of a...
Conference Paper
Full-text available
A new Multi-Physics Molecular Dynamics Finite Element Method (MDFEM) is proposed, which exactly embeds the equilibrium equations of Molecular Dynamics (MD) within the computationally more favourable Finite Element Method (FEM). This MDFEM can readily implement any force field because constitutive relations are explicitly uncoupled from the geometri...
Conference Paper
Full-text available
Emerging Graphene-based structures hold the highest transformative potential for the composite landscape, with worldwide research developing a myriad of novel electronic, structural and coating applications. Progress in synthesis has led to Graphene, Carbon Nanotubes (CNT) and complex 3D Pillared Graphene (PGS) being precisely manufactured with dim...
Article
Full-text available
The project objective encompassed a biologically inspired aerial construction of a web, for use as a landing platform, using a swarm of quadcopters. This was successfully implemented as individual factions in the respective work-package teams, although complete integration of all work-package deliverables into a final cohesive demonstration was not...
Article
This paper presents the application of a new constitutive damage model for an epoxy matrix on micromechanical analyses of polymer composite materials. Different representative volume elements (RVEs) are developed with a random distribution of fibres. Upon application of periodic boundary conditions (PBCs) on the RVEs, different loading scenarios ar...
Article
Micromechanical analyses of unidirectional continuous-fibre reinforced composite materials were performed to study the mechanisms of deformation and fracture of the constituents, and their influence on the mechanical properties of the composite. Special focus was given to the matrix material behaviour as well as to the interface between constituent...
Article
This paper presents an analytical model for size effects on the longitudinal tensile strength of composite fibre bundles. The strength of individual fibres is modelled by a Weibull distribution, while the matrix (or fibre–matrix interface) is represented through a perfectly plastic shear-lag model. A probabilistic analysis of the failure process in...