Joël Cugnoni
École Polytechnique Fédérale de Lausanne
Modal analysisComposite numberUltimate tensile strengthEngineeringFinite element methodBiomedical engineeringComposite materialEpoxyBridging (networking)Materials scienceShell (structure)Strain energy release rateFiber Bragg gratingFracture (geology)SolderingFracture mechanicsStructural engineeringModalDelaminationIdentification (information)Microstructure
99Publications
26H-index
1,584Citations
Publications 99
Newest
#1S. Kohler (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
#2Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
view all 4 authors...
Abstract Thin-ply composites were shown to exhibit significantly delayed transverse cracking, but the linear onset of damage scaling with ply thickness reported by Amacher et al. (2014) did not correspond to the established LEFM based in situ strength model. This study further investigates this experimental behaviour by simultaneously comparing in situ free edge crack observation with acoustic emission measurements as well as performing ex-situ X-ray tomography observations of crack propagation....
7 CitationsSource
#1Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
#2R. Amacher (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
Last. John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
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Abstract Thin-ply composites represent a promising approach to further improve the performance of carbon fibre composite structures thanks to their ability to delay the onset of matrix cracking and delamination up to the point of fibre dominated failure. However, this increased strength comes with a more brittle failure response which raises concerns on damage tolerance. Thus a careful material optimization is needed to address this trade-off. In this work, eight different formulations of thin-p...
42 CitationsSource
#1Guillaume Frossard (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
view all 4 authors...
Abstract The effect of ply thickness t in intralaminar fracture of unidirectional thin-ply carbon-epoxy laminates is characterized by testing double cantilever beam (DCB) and compact tension (CT) specimens with different t. While the average intralaminar energy release rate (ERR) at initiation is found equal to the corresponding interlaminar values, the steady-state intralaminar ERRs, only reached in the DCB configuration, are approximately three times higher than the corresponding interlaminar ...
7 CitationsSource
#1Lorenzo Mencattelli (UniPi: University of Pisa)H-Index: 5
#2M. Borotto (École Polytechnique)H-Index: 1
Last. John Botsis (École Polytechnique)H-Index: 37
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Abstract In this paper the attention has been focused on the evaluation of how friction can influence Four-point End-Notched Flexure test in carbon fibre-epoxy composite materials. The starting point has been the hysteresis loop in the experimentally obtained Load versus Displacement curve due to an unloading-loading cycle. Different locations for friction have been considered. Numerical simulations have been performed by using Finite Elements and an experimental test campaign has been also carr...
5 CitationsSource
#1Guillaume Frossard (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
view all 4 authors...
Abstract Fiber bridging is one of the main toughening mechanisms in mode I interlaminar and intralaminar fracture of laminated composites. Intact fibers exert closing forces on both faces of the crack, restraining crack propagation. An effective identification procedure is required to characterize bridging tractions and to develop accurate prediction models. The method proposed in this work is based on the resistance (R)-curve and assumes fiber bridging tractions decreasing non-linearly with res...
13 CitationsSource
#1S. Zabihzadeh (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. H. Van Swygenhoven (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 27
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Abstract Three-dimensional finite element simulations of nano-porous silver structures are performed to understand the correlation between the porous morphology and the mechanical behavior. The nanostructures have been obtained from ptychographic X-ray computed tomography. The simulations allow distinguishing between the interplay and role of the ligament size, the pore morphology and the porosity, and therefore provide a better comprehension of the experimental observations. We show that the pr...
8 CitationsSource
#1John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
#2E. Farmand-Ashtiani (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
Last. Luis P. Canal (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 11
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It is well known that large-scale bridging accompanying delamination and fracture in layered composites is among the most important toughening mechanisms. The resulting resistance to fracture, however, is dependent on the specimen geometry rendering its modeling difficult. As a consequence, characterization of the tractions on the wake of the crack, the so-called bridging zone, is very important in the efforts to predict the loading response of composite structures. In this chapter, experimental...
Source
#1E. Farmand-Ashtiani (École Polytechnique)H-Index: 5
#2Joël Cugnoni (École Polytechnique)H-Index: 26
Last. John Botsis (École Polytechnique)H-Index: 37
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Abstract Fatigue delamination growth in composites is accompanied by large scale bridging (LSB) that yields important toughening effects. However, the extent of this mechanism depends on the laminate geometry rendering its modeling a challenging task. This work presents a combined experimental/numerical study on characterization of specimen thickness dependence of LSB in fatigue delamination. Double cantilever beam specimens of different thicknesses (h = 2, 4 and 8 mm), equipped with arrays of m...
10 CitationsSource
#1Guillaume Frossard (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
view all 4 authors...
Abstract In this work, the influence of ply thickness on strain energy release rate (ERR) in delamination of carbon-epoxy laminates is addressed. Specimens with three ply thicknesses: 0.030, 0.075 and 0.150 mm are tested. While the ERR at onset of crack propagation is independent of ply thickness, the plateau level is much lower in thin-ply laminates than in thicker ply ones. This effect is attributed to changes in microstructure, caused by the tow spreading process involved in the fabrication o...
27 CitationsSource
#1Marco Piccinini (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 6
#2Joël Cugnoni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. Anselm Wiskott (University of Geneva)H-Index: 15
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Long term durability of osseointegrated implants depends on bone adaptation to stress and strain occurring in proximity of the prosthesis. Mechanical overloading, as well as disuse, may reduce the stability of implants by provoking bone resorption. However, an appropriate mechanical environment can improve integration. Several studies have focused on the definition of numerical methods to predict bone peri-implant adaptation to the mechanical environment. Existing adaptation models differ notabl...
15 CitationsSource