Publications by John Botsis | EPFL Graph Search

A functional approach towards the design, development, and test of an affordable dynamic prosthetic foot

Joël Cugnoni, Klaus Benedikt Schönenberger, Kamiar Aminian, John Botsis, Véronique Michaud, Mathieu Pascal Falbriard, Rajasundar Chandran

Humanitarian actors involved in physical rehabilitation, such as the International Committee of the Red Cross (ICRC), usually provide their beneficiaries with lower-limb prostheses comprising Solid Ankle Cushion Heel (SACH) feet as these are considered app ...

PUBLIC LIBRARY SCIENCE2022

Monitoring of Torque Induced Strain in Composite Shafts with Embedded and Surface-Mounted Optical Fiber Bragg Gratings

John Botsis, Georgios Violakis, Georgios Pappas

In this study, silica glass, optical fiber Bragg gratings (FBGs) are used for torque-induced strain monitoring in carbon fiber reinforced polymer (CFRP) hollow shafts toward the development of a methodology for structural load monitoring. Optical fibers wi ...

2021

Crack propagation in CFRP laminates under mode I monotonic and fatigue loads: A methodological study

John Botsis, Charlie Joseph Simon Blondeau, Georgios Pappas

Delamination in composite materials is often accompanied by fiber bridging that increases resistance to crack growth. Here, delamination of two unidirectional carbon/epoxy systems was studied under monotonic and displacement-controlled fatigue loading. One ...

ELSEVIER SCI LTD2021

Variations on R-curves and traction-separation relations in DCB specimens loaded under end opening forces or pure moments

John Botsis, Georgios Pappas

In this work the differences in R-curve response and traction-separation relations due to a finite damage zone or large-scale bridging (LSB) in mode I fracture on double cantilever beams (DCB) were investigated under end opening forces (EOF) and pure momen ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Experiments and numerical modelling on angle-ply laminates under remote mode II loading

John Botsis, Charlie Joseph Simon Blondeau, Georgios Pappas

Delamination is a very frequent damage mechanism that affects the integrity of laminated composites. In this study, the effect of ply orientation on crack growth resistance was analyzed for three different anti-symmetric interfaces (+/- 30 degrees, +/- 45 ...

ELSEVIER SCI LTD2020

Towards a geometry independent traction-separation and angle relation due to large scale bridging in DCB configuration

John Botsis, Georgios Pappas

Traction-separation relations due to large scale bridging in composites are very important in modeling their fracture response. Several works demonstrated that such relations are dependent upon the specimen's stiffness and loading conditions. Experimental ...

ELSEVIER SCI LTD2020

Mixed-mode fracture response of anti-symmetric laminates: Experiments and modelling

John Botsis

Multidirectional laminates are very often used in advanced structures. However, the existing data in the literature regarding their fracture response is not conclusive. In this work, the fracture response of a +45 degrees// -45 degrees interface is investi ...

ELSEVIER SCI LTD2020

Improving delamination resistance through tailored defects

John Botsis

Delamination is a well-known damage mode exhibited by laminated composites which has been extensively studied in unidirectional laminates (UD). In this work, a novel strategy consisting of the introduction of a small interlaminar defect to enhance the frac ...

2020

Transverse cracking in the bulk and at the free edge of thin-ply composites: experiments and multiscale modelling

Joël Cugnoni, John Botsis, Robin Amacher, Sébastien Kohler

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 s ...

2019

Design optimization of a CFRP-aluminum joint for a bioengineering application

John Botsis, Georgios Pappas

Lightweight design demands and complexity requirements of modern high-end structures in aerospace, automotive, sports and bioengineering can be successfully covered by a combination of fiber reinforced polymers (FRPs) with metallic components. Conventional ...

2019

Micromechanical study on the origin of fiber bridging under interlaminar and intralaminar mode I failure

John Botsis, Georgios Pappas, Fernando Naya Montans

Fiber reinforced polymers (FRPs) subjected to mode I fracture show important toughening due to the development of large scale bridging (LSB). Experimental studies of this phenomenon in unidirectional carbon/epoxy laminates using double cantilever beam spec ...

ELSEVIER SCI LTD2019

A comparative study of mode I delamination behavior of unidirectional glass fiber-reinforced polymers with epoxy and polyurethane matrices using two methods

John Botsis, Georgios Pappas

The mode I delamination behavior of a unidirectional glass-fiber reinforced polymer with a prototype elasto-plastic polyurethane matrix (GF/PU) was investigated and compared with that of glass/epoxy (GF/EP) using double cantilever beam specimens. Fracture ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Influence of ply-angle on fracture in antisymmetric interfaces of CFRP laminates

John Botsis, Charlie Joseph Simon Blondeau, Georgios Pappas

Laminated composites are prone to fracture at layer interfaces. Such damage impairs their structural response and engenders important constraints in design. In this work, the influence of ply orientation on crack growth resistance was studied for three dif ...

ELSEVIER SCI LTD2019

Analysis and evaluation of friction effects on mode II delamination testing

Joël Cugnoni, John Botsis, Marco Borotto, Lorenzo Mencattelli

2018

On the validity of the J-integral as a measure of the transverse intralaminar fracture energy of glass fiber-reinforced polyurethanes with nonlinear material behavior

John Botsis, Luis Pablo Canal Casado

2018

Ply thickness dependence of the intralaminar fracture in thin-ply carbon- epoxy laminates

Joël Cugnoni, Thomas Gmür, John Botsis, Guillaume Frossard

2018

Towards aerospace grade thin-ply composites: Effect of ply thickness, fibre, matrix and interlayer toughening on strength and damage tolerance

Joël Cugnoni, John Botsis, Robin Amacher, Larissa Sorensen, Sébastien Kohler

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, t ...

ELSEVIER SCI LTD2018

The influence of through-thickness reinforcement geometry and pattern on delamination of fiber-reinforced composites: Part I - Experimental results

John Botsis, Véronique Michaud, Georgios Pappas

This experimental study reports effect of tuft geometry i.e., standard tufts and loops milled-down, and tufting pattern on Mode I interlaminar fracture in a GFRP. Standard tufting geometry is responsible for an increase in fracture resistance by 3.5-6 time ...

Elsevier2018

The influence of through-thickness reinforcement geometry and pattern on delamination of fiber-reinforced composites: Part II - Modeling

John Botsis, Véronique Michaud, Georgios Pappas

This article reports modeling techniques and results based on experimental Mode I characterization of a layered woven GFRP material with tufting reinforcement. Standard tuft and loop-less geometries are investigated on three different areal patterns to eva ...

Elsevier2017

On the mechanical characteristics of a self-setting calcium phosphate cement

John Botsis, Dimitrios Karalekas, Luis Pablo Canal Casado, Alexios Bimis

Objective: To perform a mechanical characterization of a self-setting calcium phosphate cement in function of the immersion time in Ringer solution. Materials and methods: Specimens of self-setting calcium phosphate cement were prepared from pure alpha-TCP ...

Elsevier2017