G. Pappas
École Polytechnique Fédérale de Lausanne
Composite numberFinite element methodComposite materialEpoxyBridging (networking)Materials scienceElectronic engineeringTuftCarbon fiber reinforced polymerStrain energy release rateMicromechanicsComputer scienceFiber Bragg gratingFracture (geology)FiberFiber-reinforced compositeFracture mechanicsRealization (systems)DelaminationFibre-reinforced plasticMicrostructureFracture toughness
25Publications
8H-index
176Citations
Publications 26
Newest
#1G. Pappas (ETH Zurich)H-Index: 8
#2Arthur Schlothauer (ETH Zurich)H-Index: 2
Last. Paolo Ermanni (ETH Zurich)H-Index: 33
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Abstract null null In this work, the impact of high stress gradients, found in bending of thin unidirectional fiber reinforced shells (∼0.1 to 1 mm), on compressive micro-buckling failure, was analyzed. Such thin shells show increased resistance to compressive failure under high curvatures, which may even allow tensile fiber damage to drive ultimate failure for very low thickness (e.g.
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#1Maria Konstantaki (FORTH: Foundation for Research & Technology – Hellas)H-Index: 19
#2Georgios Violakis (FORTH: Foundation for Research & Technology – Hellas)H-Index: 4
Last. Stavros Pissadakis (FORTH: Foundation for Research & Technology – Hellas)H-Index: 24
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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 with gratings are embedded during shaft manufacturing, by an industrial filament winding process, along different orientations with respect to its central axis and surface mounted after production. Experimental results are supported by numerical ...
1 CitationsSource
#1C. BlondeauH-Index: 2
#2G. PappasH-Index: 8
Last. John BotsisH-Index: 37
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Abstract 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 material (CP004) presented a random distribution of fiber clusters and matrix-rich zones while the other (SE-84) had an ordered microstructure. The results showed that monotonic and fatigue delamination of CP004 presented similarities...
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#1Arthur Schlothauer (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
#2Dominik Cueni (EPFL: École Polytechnique Fédérale de Lausanne)
Last. Paolo Ermanni (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 33
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#1G. Pappas (NTUA: National Technical University of Athens)H-Index: 8
#2Vassilis Alimisis (NTUA: National Technical University of Athens)H-Index: 3
Last. Paul P. Sotiriadis (NTUA: National Technical University of Athens)H-Index: 19
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This paper explores a new integrated-circuit architecture of an analog, active, tunable and selectively fractional or integer-order PID controller using operational amplifiers. Controller’s major parameters are tuned via appropriate DC currents to the desired values. The proposed architecture is validated in a case study of a DC motor control and it can be used as a building block in industrial and commercial control systems. Circuit and physical design (layout) have been done in TSMC 90nm CMOS ...
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#1Vassilis AlimisisH-Index: 3
#2Christos DimasH-Index: 5
Last. Paul P. SotiriadisH-Index: 19
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This work compares two design methodologies, emulating both AgCl electrode and skin tissue Cole models for testing and verification of electrical bio-impedance circuits and systems. The models are based on fractional-order elements, are implemented with active components, and capture bio-impedance behaviors up to 10 kHz. Contrary to passive-elements realizations, both architectures using analog filters coupled with adjustable transconductors offer tunability of the fractional capacitors’ paramet...
3 CitationsSource
#1Arthur Schlothauer (ETH Zurich)H-Index: 2
#2G. Pappas (ETH Zurich)H-Index: 8
Last. Paolo Ermanni (ETH Zurich)H-Index: 33
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Abstract Very thin carbon fiber composite shells can withstand large bending curvatures without failure. The resulting high tensile and compressive strains require accurate modelling of the fiber-dominated non-linear effects to predict the mechanical response. To date, no universal modelling technique can precisely capture the behavior of such structures. In this work, successful representation of composite’s response was achieved by utilizing single fiber tension and compression experimental da...
1 CitationsSource
#1Vassilis AlimisisH-Index: 3
#2Georgios PappasH-Index: 1
Last. Paul P. Sotiriadis (NTUA: National Technical University of Athens)H-Index: 19
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This paper explores a new architecture for a fractional-order instrumentation amplifier for control applications. The proposed architecture provides electronic tuning capability and is reconfigurable. It can be configured as either a classic integer-order or a fractional-order instrumentation amplifier, with appropriate tuning of the parameters that define the characteristics of the components involved. The proposed design can be used as a fundamental building block in the implementation of more...
1 CitationsSource
#1Miguel González Herráez (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 12
#2N. Pichler (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
Last. John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
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Abstract 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 ° , ± 45 ° and ± 60 ° ) and compared to a unidirectional baseline under remote mode II loading. Fracture toughness at initiation was the same regardless of the ply orientation, nevertheless, the energy dissipated during crack propagation increased with...
4 CitationsSource
#1G. Pappas (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 8
#2John Botsis (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
Abstract In this work the differences in R-curve responfigse 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 moments (PM). To realize PM loading, a novel test-rig was designed, built and used to test adhesive joints with metallic substrates and unidirectional carbon fiber reinforced polymer (CFRP) specimens. In the adhesive joints, no pronounce...
4 CitationsSource