Publications related to Sandwich theory

Proposed Panel Zone Model for Beam-To-Column Joints in Steel Moment Resisting Frames

Dimitrios Lignos, Andronikos Skiadopoulos, Ahmed Mohamed Ahmed Elkady

In capacity designed steel moment resisting frames (MRFs), beam-to-column joints (i.e., panel zones) are designed to remain elastic. To potentially exploit the beneficial aspects of the stable panel zone hysteretic response in shear, a robust panel zone mo ...

2023

Welded moment connections with highly dissipative panel zones for enhanced seismic performance of steel moment frames

Andronikos Skiadopoulos

Research conducted after the 1994 Northridge earthquake in the U.S. and the 1995 Kobe earthquake in Japan led to the development of today's pre-qualified beam-to-column connections for capacity-designed steel moment resisting frames (MRFs). Welded moment c ...

EPFL2022

Origami-inspired carbon fiber-reinforced composite sandwich materials - Fabrication and mechanical behavior

Thomas Keller, Yuntong Du

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 sandwic ...

ELSEVIER SCI LTD2021

Flexural behaviour of post-tensioned glass beams: Experimental and analytical study of three beam typologies

Alain Nussbaumer, Pieter Christian Louter, Jagoda Cupac

The concept of post-tensioned glass beams builds on the concrete analogy of the reinforced glass beams. By additionally prestressing the reinforcement in a post-tensioned system, a compressive pre-stress is applied on the glass, enhancing the initial fract ...

2021

Design and Manufacturing of an Electrostatic MEMS Relay for High Power Applications

Yves Perriard, Yoan René Cyrille Civet, Christian Köchli, Florian Louis Copt

This paper addresses the design and manufacturing of a crab-leg based MEMS relay for a high power application. Thanks to a contact resistance lower than 100 mΩ, the relay can hold a current in the order of magnitude of an Ampere without further thermal lim ...

2021

A "combi-encapsulant" for enhanced performance of glass-free lightweight crystalline silicon solar PV modules

Christophe Ballif, Alessandro Francesco Aldo Virtuani, Fabiana Lisco

Lightweight crystalline silicon (c-Si) PV modules with a weight of 5kg/m(2), by substituting the typical front glass with a thin polymer sheet and the standard back sheet by a composite sandwich structure are presented here. With this work, we propose the ...

IEEE2021

Cold stiffening of orthotropic steel decks by a composite UHPFRC layer

Eugen Brühwiler, Lan Duan, Shichao Wang

Cold stiffening of the plate of Orthotropic Steel Deck (OSD) of bridges can be achieved by adding a layer of Ultra-High Performance Fiber Reinforced Cementitious Composite material (UHPFRC) on top of the deck plate by composite design, thus expecting to re ...

ELSEVIER SCI LTD2020

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

Thomas Keller, Anastasios Vassilopoulos, Chao Wu, 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

Two-dimensional quasi-static debonding in GFRP/balsa sandwich panels

Thomas Keller, Anastasios Vassilopoulos, Aida Cameselle Molares

The two-dimensional (2D) debonding behavior of GFRP/balsa sandwich panels presenting embedded circular disbonds at the face sheet/core interface was experimentally investigated. The bottom of the panels was fixed and out-of-plane quasi-static tensile loads ...

2019

Two-dimensional crack growth in FRP laminates and sandwich panels

Aida Cameselle Molares

Fiber-reinforced polymer (FRP) composite materials are currently being selected for the design of lightweight and efficient structural members in a wide number of engineering applications. Sandwich panels with glass fiber-reinforced polymer (GFRP) face she ...

EPFL2019

Modular exoskeleton for example for spinal cord injured patients

Mohamed Bouri, Tristan Hubert Vouga, Paul Bertusi

The invention concerns an exoskeleton made of elements combined or attached together, said elements being adjustable or not and said elements being made in a sandwich construction. The invention also concerns a method to manufacture such an exoskeleton. ...

2018

Thermo-mechanical stability of lightweight glass-free photovoltaic modules based on a composite substrate

Christophe Ballif, Alessandro Francesco Aldo Virtuani, Valentin Chapuis, Hengyu Li, Laure-Emmanuelle Perret Aebi, Ana Cristina Oliveira Martins

Lightweight PV modules are attractive for building-integrated photovoltaic (BIPV) applications, especially for renovated buildings, where the additional load bearing capacity is limited. This work focuses on the development of a lightweight, glass-free pho ...

ELSEVIER SCIENCE BV2018

Hypervelocity impact testing on stochastic and structured open porosity cast Al-Si cellular structures for space applications

Andreas Mortensen

A hypervelocity (6.7–7.0 km/s) impact testing campaign was conducted using Ø 2 mm, 95% Al projectiles onto A357 aluminium alloy stochastic foams with 4–5 mm typical pore dimensions, or alternatively diamond cubic periodic structures of cast AlSi12 with a 6 ...

2018

Local structural effects in fiber-reinforced polymer web-core sandwich structures

Sonia Yanes Armas

Glass fiber-reinforced polymer (GFRP) pultruded decks and sandwich panels currently represent two of the most extensive applications of FRP materials for load-bearing structural components in the bridge and building domains. Based on the state of the art, ...

EPFL2017

Creep of Sandwich Panels with Longitudinal Reinforcement Ribs for Civil Engineering Applications: Experiments and Composite Creep Modeling

Thomas Keller, Mário Alexandre De Jesus Garrido

Composite sandwich panels with reinforcement ribs or webs are being increasingly considered for structural applications in civil engineering. Such panels are prone to creep when subjected to significant permanent loads and therefore the effects of this phe ...

American Society of Civil Engineers2017

Studies on Traction Separation Relations in Fracture of Layered Composites : Experiments and Modeling

Georgios Pappas

Layered fiber reinforced composite materials are prone to fracture in planes parallel to the direction of fibers leading to extensive delamination or intralaminar fracture. This phenomenon of crack propagation is frequently accompanied by significant incre ...

EPFL2017

Connection systems between composite sandwich floor panels and load-bearing walls for building rehabilitation

Thomas Keller, Mário Alexandre De Jesus Garrido

The use of advanced composites for building rehabilitation presents several advantages when compared with traditional construction materials. When degraded building floors need to be replaced, composite sandwich panels are a potentially interesting solutio ...

Elsevier2016

System transverse in-plane shear stiffness of pultruded GFRP bridge decks

Thomas Keller, Julia De Castro San Roman Fest, Sonia Yanes Armas

The static transverse behavior of two pultruded GFRP deck systems with trapezoidal (DS) and triangular (AS) cell cross-sectional geometry was experimentally investigated in order to study their transverse in-plane shear stiffness. Symmetric three-point ben ...

Elsevier2016

Post-wrinkling behavior of webs in GFRP cell-core sandwich structures

Thomas Keller, Anastasios Vassilopoulos, Behzad Dehghan Manshadi

Similarly to the post-buckling behavior of steel girder webs, the post-wrinkling behavior of glass fiber reinforced polymer (GFRP) cell-core sandwich webs can increase their ultimate shear strength. Post wrinkling is, however, different from post-buckling ...

Elsevier2016

Effect of service temperature on the flexural creep of vacuum infused GFRP laminates used in sandwich floor panels

Thomas Keller, Mário Alexandre De Jesus Garrido

This paper presents an experimental and analytical study about the effect of temperature on the flexural creep of GFRP laminates produced by vacuum infusion. Such laminates are considered for use in the faces of sandwich panels for building floor applicati ...

Elsevier2016