Thomas Keller
École Polytechnique Fédérale de Lausanne
Composite numberUltimate tensile strengthGlass transitionEngineeringFinite element methodComposite materialEpoxyGlass fiberMaterials scienceGirderJoint (geology)DeckStiffnessFracture (geology)PolymerPultrusionFracture mechanicsStructural engineeringAdhesiveFibre-reinforced plasticForensic engineeringStress (mechanics)
332Publications
45H-index
4,885Citations
Publications 328
Newest
#1A. Vahid Movahedi-Rad (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 5
#2Ghazaleh Eslami (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract null null This paper introduces a new fatigue life prediction methodology for viscoelastic materials in the tension–tension fatigue loading region. The model was established based on the total amount of energy dissipated during fatigue loading, and offers two main advantages with respect to existing models in the literature, i.e. it considers the creep effect on fatigue behavior and requires less input data. The model was applied to three different materials - an angle-ply glass/epoxy f...
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#1Gisele G. Cintra (PUC-Rio: Pontifical Catholic University of Rio de Janeiro)H-Index: 1
#2Daniel C.T. Cardoso (PUC-Rio: Pontifical Catholic University of Rio de Janeiro)H-Index: 7
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract null null This paper aims to present an experimental investigation on the behavior of web-flange junctions (WFJs) rotational stiffness of pultruded fiber-reinforced polymer composites (FRP). Channels and I-sections were tested using a simple set-up, which was developed in order to experimentally characterize the junctions in a direct manner. The Digital Image Correlation (DIC) technique was used, allowing overall deflections and relative rotations between web and flange to be monitored....
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#1Lulu Liu (SEU: Southeast University)H-Index: 1
#1Lulu Liu (SEU: Southeast University)H-Index: 8
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract The tension-tension fatigue behavior of ductile adhesively-bonded double-lap FRP joints was experimentally investigated. An acrylic adhesive, which was in the rubbery state at ambient temperature, provided the joint ductility. The fatigue degradation of the joints was characterized by the cyclic energy dissipation, cyclic stiffness, cyclic creep displacement and self-generated temperature. The effects of elevated temperature on the joints’ static tensile and pure creep behaviors were al...
3 CitationsSource
#1Congzhe Wang (EPFL: École Polytechnique Fédérale de Lausanne)
#2Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract The two-dimensional (2D) delamination growth in fiber-reinforced polymer (FRP) laminates with in-plane isotropy under Mode I loading condition was numerically investigated using finite element analyses. Two sizes of plate models were developed, focusing on different fracture stages. Cohesive elements were employed to simulate the fracture behavior in the presence of large-scale bridging (LSB). The influences of the pre-crack shape/area, loading zone shape/area and fracture resistance we...
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#1Yuntong Du (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
#2Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
Last. Jian Xiong (HIT: Harbin Institute of Technology)H-Index: 28
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Abstract A folding fabrication method inspired by origami for carbon fiber-reinforced composites to fabricate three-dimensional structures is presented. PMI foams serve as substrates, making it possible to manufacture this kind of origami-inspired composite sandwich materials in a single-step process. Analytical models are proposed to provide upper and lower bounds of the out-of-plane compressive strength of the origami-inspired composite sandwich materials. Finite element analysis (FEA) and exp...
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Abstract The aim of this work is the investigation of mesoscale/local variability in mechanical properties of clear timber in the radial direction. Clear Norway spruce wood, Picea abies, was used for cutting specimens of different lengths with a small cross-sectional area of 4 × 4 mm2, in the radial direction of timber boards, and tested under tensile loading. In some boards, specimens were positioned regularly and, in some others, randomly, and local deformations in each specimen were measured ...
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#1Yuntong Du (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
#2Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
Last. Jian Xiong (HIT: Harbin Institute of Technology)H-Index: 28
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Abstract A methodology for designing cylindrical origami with different patterns and different cross-sectional shapes is presented. Planar and cylindrical origami with curved-crease patterns are designed and proved to be foldable and developable regardless of the type of crease line. Specifically, cylindrical origami structures with arc-Miura pattern and circular cross section, arc pattern and circular cross section, arc-Miura pattern and triangular cross section, arc pattern and triangular cros...
1 CitationsSource
#1Lulu Liu (SEU: Southeast University)H-Index: 2
#1Lulu Liu (SEU: Southeast University)H-Index: 1
Last. Thomas KellerH-Index: 45
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Abstract An experimental investigation of the load-bearing behavior and ductility of FRP hybrid double-lap joints composed of both adhesively-bonded and bolted connection parts was conducted. Amongst other things, the effects of the adherends’ fiber architecture (uni- or multidirectional), adhesive type (stiff or flexible), and displacement rate were examined. The resistances of the hybrid joints with flexible adhesive corresponded to the full summation of the resistances of the bonded and bolte...
2 CitationsSource
#1Chao Wu (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 29
#2Niloufar Vahedi (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract Balsa wood is an appropriate core material for structural sandwich applications due to its high strength- and stiffness-to-weight ratios. However, the mechanical properties vary considerably owing to the inherent scattering of natural wood materials. One approach to reduce this scatter and tailor the mechanical properties according to specific application needs is to recompose the natural material into a veneered material consisting of veneer layers of different grain orientations, whic...
1 CitationsSource
#1Lulu Liu (SEU: Southeast University)H-Index: 2
#1Lulu Liu (SEU: Southeast University)H-Index: 8
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
view all 4 authors...
Abstract In view of the low structural efficiency of bolted joints in pultruded fiber-reinforced polymer (FRP) profiles with mainly unidirectional (UD) fiber architecture, off-axis plies were considered as an effective way to improve bolted joint performance. An experimental study of bolted joints was conducted with laminates composed of UD basalt fiber fabrics laid-up at different ply angles and stacking sequences to optimize the lay-up with regard to the integral structural performance of FRP ...
6 CitationsSource