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Thomas Keller

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Publications associées (309)

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Experimental investigation on temperature-dependent thermo- physical and mechanical properties of pultruded GFRP composites

Thomas Keller, Yu Bai

The temperature-dependent thermo-physical and mechanical properties of a pultruded E-glass fiber-reinforced polyester (GFRP) composite are investigated in this paper. Fitting of theoretical models of the material properties to results of TGA, DSC, hot disk ...

2008

Thermal and mechanical performances of GFRP sandwich structures with integrated amorphous silicon photovoltaic cells

Thomas Keller, Yu Bai

Applications of photovoltaic (PV) cells in buildings are often excluded from locations with major mechanical strains because of their brittleness and possible damages at small mechanical strains. Combinations of glass fibre reinforced polymer (GFRP) compon ...

ELSEVIER SCI LTD2022

Numerically-based method for fracture characterization of Mode I-dominated two-dimensional delamination in FRP laminates

Thomas Keller, Anastasios Vassilopoulos, Aida Cameselle Molares

A new numerically-based method suitable for determining the total strain energy release rate (SERA) involved in two-dimensional (2D) Mode I-dominated delamination under opening loads in FRP laminates is presented. The method is based on the mutual dependen ...

2019

Modeling of thermal responses for FRP composites under elevated and high temperatures

Thomas Keller, Till Vallée, Yu Bai

Based on temperature-dependent thermo-physical property models developed previously, a one-dimensional model was proposed to predict the thermal responses of FRP composites in time and space domain, up to high temperatures. An implicit finite differential ...

2008

Random field-based modeling of size effect on the longitudinal tensile strength of clear timber

Thomas Keller, Anastasios Vassilopoulos, Alireza Farajzadeh Moshtaghin

In the current study, a random field-based size effect model has been proposed for the longitudinal tensile strength of clear timber. Since the failure mode is brittle, the problem is basically an extreme value problem of finding the distribution of minima ...

Elsevier2016

Effects of core air gaps and steel inserts on thermomechanical response of GFRP-balsa sandwich panels subjected to fire

Thomas Keller, Anastasios Vassilopoulos, Niloufar Vahedi

Composite sandwich panels composed of a balsa core and glass fiber-reinforced polymer (GFRP) face sheets may offer attractive applications for building slabs and bridge decks. Such composite panels may contain air-filled gaps (caused by initial defects or ...

ELSEVIER SCI LTD2023

Composite engineering structures in seawater − Review of durability and environmental performance

Shahin Maghsoudi Zand, Thomas Keller, Tara Habibi

Shoreline protection systems composed of fibre-polymer composite structures immersed in seawater may efficiently contribute to mitigate impacts of climate change, such as more frequent and severe coastal flooding and storm surges, and significant rises of ...

2025

Shear mechanical characterization of balsa wood as core material of composite sandwich panels

Thomas Keller, Anastasios Vassilopoulos, Julia De Castro San Roman Fest, Michael Osei-Antwi

An experimental study was performed using Iosipescu specimens to evaluate the effects of parameters such as shear plane, density and adhesive joints on the shear stiffness and strength of balsa wood panels as well as the variation of ductility with respect ...

Elsevier2013

Modeling of thermo-physical properties for FRP composites under elevated and high temperatures

Thomas Keller, Till Vallée, Yu Bai

A decomposition model for resin in glass fiber-reinforced polymer composites (GFRP) under elevated and high temperature was derived from chemical kinetics. Kinetic parameters were determined by four different methods using thermal gravimetric data at diffe ...

2007

A novel fatigue life prediction methodology based on energy dissipation in viscoelastic materials, synergistic effects of stress level, stress ratio, and temperature

Thomas Keller, Lulu Liu, Abdolvahid Movahedirad

This work introduces a new methodology to predict the fatigue life of viscoelastic materials by considering the creep effect on fatigue behavior under the concurrent effects of stress level, stress ratio, and temperature. The model established based on the ...

2024

Modeling of stiffness properties of FRP composites under elevated and high temperatures

Thomas Keller, Till Vallée, Yu Bai

When subjected to elevated and high temperatures, the mechanical properties of FRP composites, such as the E- modulus and viscosity, experience significant changes. At a certain temperature, a composite material can be considered a mixture of materials tha ...

2008

Thermophysical properties of balsa wood used as core of sandwich composite bridge decks exposed to external fire

Thomas Keller, Anastasios Vassilopoulos, Niloufar Vahedi

The load-bearing performance of sandwich bridge decks comprising a balsa core and fiber-reinforced polymer composite face sheets exposed to fire is a main concern regarding the application of these deck systems. In order to obtain the thermal responses of ...

ELSEVIER SCI LTD2022

Stress mitigation for adhesively bonded photovoltaics with fibre reinforced polymer composites in load carrying applications

Thomas Keller, Yu Bai

Structural loads, especially in-plane compression, may cause local buckling and debonding of the photovoltaic (PV) cells that are mechanically integrated with structural members and this may lead to degradation in their electrical performance. This paper p ...

ELSEVIER SCI LTD2019

Thermomechanical characterization of a balsa-wood-veneer structural sandwich core material at elevated temperatures

Thomas Keller, Anastasios Vassilopoulos, Niloufar Vahedi

The tensile, compressive and shear behavior of standardized specimens cut from a veneered balsa wood used as structural sandwich core was investigated at ambient temperatures of up to 250 degrees C. The average moisture content was 9.1%. The specimens' res ...

ELSEVIER SCI LTD2020

Physically Based Modeling of Shear Modulus-Temperature Relationship for Thermosets

Thomas Keller, Anastasios Vassilopoulos, Wei Sun

A new physically based model for the simulation of the imaginary part of the shear modulus-temperature (G ''-T) curve of thermosets is introduced in this paper. The model is based on the modification of the G ''-T equation used for thermoplastic polymers v ...

Wiley-Blackwell2015

Adhesively bonded lap joints from pultruded GFRP profiles. Part I: stress-strain analysis and failure modes

Thomas Keller, Till Vallée

Quasi-static axial tension experiments were performed in a laboratory environment on epoxy bonded, balanced double-lap and single-lap joints from pultruded GFRP flat sections. Full-scale specimens were used to avoid size effects. Parameters investigated we ...

2005

Fire protection systems for building floors made of pultruded GFRP profiles. Part 1: Experimental investigations

Thomas Keller, Yu Bai

This paper presents results of experimental investigations on the behaviour of GFRP pultruded profiles exposed to fire, in order to study the viability of their structural use in floors of buildings, taking into account the fulfilment of fire resistance re ...

Elsevier2010

Effect of thermal lag on glass transition temperature of polymers measured by DMA

Thomas Keller, Anastasios Vassilopoulos, Wei Sun

This paper investigates the influence of thermal lag on the glass transition temperature of polymers measured under different heating rates during dynamic mechanical analysis (DMA). The E-modulus-temperature curves of a two-component epoxy adhesive and a p ...

Elsevier2014

Static and dynamic mechanical properties of nanosilica and multiwalled carbon nanotube reinforced acrylonitrile butadiene styrene composites: theoretical mechanism of nanofiller reinforcement

Thomas Keller

Experimental and theoretical approaches were employed to analyze the static and dynamic mechanical properties of acrylonitrile butadiene styrene (ABS) nanocomposites reinforced with multiwalled carbon nanotube (MWCNT) and nanosilica. Enhanced stiffness and ...

SPRINGER2021

Structural behavior of multifunctional GFRP joints for concrete structures

Thomas Keller, Florian Riebel

A multifunctional all-FRP joint has been developed for the transfer of bending moments and shear forces in thermal insulation sections of concrete slab structures used in building construction. Tensile forces from moments are transferred by horizontal GFRP ...

2009