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 330
Newest
#1Sonia Yanes-Armas (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Julia de Castro (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 15
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
view all 3 authors...
Abstract The structural behavior of GFRP-polyurethane (PUR) web-core sandwich structures subjected to sustained loading was investigated. As a basis, a study of the mechanical behavior of rigid PUR foams used as core materials was conducted, with emphasis on creep. The study showed that the foam anisotropy, its density and the loading type applied must be considered to assess the structural performance of the GFRP-PUR web-core sandwich. The influence of creep on the web-core interaction, i.e. on...
7 CitationsSource
In the field of timber engineering, adhesive bonding remains a promising, though poorly developed, joining technique that may increase the structural stiffness and capacity of timber joints and structures. Selecting ductile adhesives may further allow to conceive ductile joints, which can compensate for the missing material ductility of timber. To demonstrate the potential of this approach, adhesively bonded double-lap timber joints were manufactured using a ductile acrylic adhesive and then sub...
Source
#1Zhengwen Jiang (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
#2Shui Wan (SEU: Southeast University)H-Index: 2
Last. Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
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A two-dimensional analytical stress distribution model taking into account the effects of large deformation, bending-tension coupling and interfacial compliance on the quasi-static behavior of unbalanced FRP composite single-lap joints (SLJs) under tension is introduced in this paper. The model can accurately estimate the stress distributions in the adhesive layer of unbalanced composite SLJ. The analytical results are compared to numerical simulations from a nonlinear finite element model and r...
5 CitationsSource
#1Myrsini Angelidi (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#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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The effects of the loading type, i.e. tension or compression, and displacement rate on the Poisson ratio of a non-linear viscoelastic ductile structural adhesive have been investigated using digital image correlation-based strain fields. The results showed that the Poisson ratio should be based on true strains to take geometry changes into account. In tension, the ratio exhibited a slight dependency on the true strain level below the yield point and on the displacement rate. The rate dependency ...
13 CitationsSource
#1Maria Savvilotidou (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
Last. Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
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This paper presents the results of an experimental program designed to study the effects of aging and a wet environment on the fatigue behavior of epoxy resins used in bridge applications. Specimens were manufactured, cured, and treated, before the experiments, under a variety of conditions, in room and in water environments, in order to simulate the aging of adhesives in bridges for a period of up to 100 years. Experimental results indicated that a typical power law S-N equation could describe ...
15 CitationsSource
#1Wei Sun (UoB: University of Bristol)H-Index: 1
#2Wendel Michael Sebastian (UoB: University of Bristol)H-Index: 11
Last. Joel Ross (UoB: University of Bristol)H-Index: 5
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Abstract Mixed-mode bending tests were performed on fifty-three GFRP-adhesive-GFRP specimens. In each specimen the pre-crack was located near the GFRP adherend with fibres normal to the GFRP-adhesive interface, so as to encourage crack propagation along this interface rather than through the GFRP. The other GFRP adherend contained fibres parallel to the interface, leading to asymmetry of GFRP material (but not of specimen geometry) with respect to the adhesive layer in each specimen. This switch...
4 CitationsSource
#1Haifeng Fan (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
view all 3 authors...
Abstract An evaluation of cement- and resin-based grout materials for applications in carbon fiber-reinforced polymer (CFRP) ground anchor heads composed of high-strength grout and a CFRP strap was conducted. Uniaxial compression experiments were performed on cylinder specimens. Appropriate loading-control methods and boundary conditions were determined in order to obtain the softening branch of the compressive stress vs strain curves. The concrete compression model developed by Sargin was succe...
4 CitationsSource
#1Maria Savvilotidou (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#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 physical and mechanical properties of a cold-curing structural epoxy adhesive, exposed to a wet bridge environment, were investigated. A significant decrease of the glass transition temperature, tensile E-modulus and tensile strength was observed which could be attributed to plasticization. The retention of 70% of the E-modulus and strength at an average 10 °C reference temperature was predicted using the Arrhenius law after a 100-year bridge service life. Full recovery of the prope...
16 CitationsSource
#1Aida Cameselle-Molares (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Roohollah Sarfaraz (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 8
Last. Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
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A quasi-static progressive damage model for prediction of the fracture behaviour and strength of adhesively bonded fibre-reinforced polymer joints is introduced in this paper. The model is based on the development of a mixed-mode failure criterion as a function of a master R-curve derived from the experimental results obtained from standard fracture mechanics joints. Consequently, the developed failure criterion is crack-length and mode-mixity dependent, and it takes into account the contributio...
6 CitationsSource
#1Haifeng Fan (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
view all 3 authors...
AbstractPull-out experiments were performed on four carbon fiber–reinforced polymer (CFRP) ground anchors simulating their applications in rock and soil. The CFRP tendons used in these anchors comprise a single-strap end on both ground and air sides. On the ground side, the single-strap end is embedded in a prefabricated cylinder of high-strength grout that fits into the borehole. In rock applications, the ground-side anchor can be used without additional confinement, while in the case of soil, ...
7 CitationsSource