Publications associées à The investigation of stress in freestanding GaN crystals grown from Si substrates by HVPE

Influence of fiber orientation on the tensile behavior of UHPFRC and reinforced UHPFRC under static and fatigue loadings

Ultra-high performance fiber reinforced cementitious composite (UHPFRC) is a modern class of cementitious building materials. Because of its superior mechanical properties and durability, it is increasingly used globally to rehabilitate, strengthen and mod ...

EPFL2024

Strain engineering and strain measurement by spring tethers on suspended epitaxial GaN-on-Si photonic crystal devices

Romuald Houdré, Jun Wang

Suspended epitaxial gallium nitride (GaN) on silicon (Si) photonic crystal devices suffer from large residual tensile strain, especially for long waveguides, because fine structures tend to crack due to large stress. By introducing spring-like tethers, des ...

Iop Publishing Ltd2024

Short-term behavior of glass fiber-polymer composite bending-active elastica beam under service load application

Thomas Keller, Landolf-Giosef-Anastasios Rhode-Barbarigos, Tara Habibi

Bending-active elastica beam is a structural configuration that is based on the elastic deformation of an initially straight beam. This deformation occurs when horizontal displacements are applied to a sliding support, causing the beam to bend into an arch ...

2024

Instabilities in Elastic and Magneto-Elastic Beams and Shells: from Shell Buckling to the Design of a Programmable Braille Reader

Arefeh Abbasi

In this thesis, we conduct a comprehensive investigation into structural instabilities of both elastic and magneto-elastic beams and shells, resulting in a creative proposal to design a programmable braille reader. Methodologically, we combine numerical si ...

EPFL2024

Experimental and ab initio derivation of interface stress in nanomultilayered coatings: Application to immiscible Cu/W system with variable in-plane stress

Claudia Cancellieri, Pandula Manura Liyanage, Giacomo Lorenzin

Interface stress is a fundamental descriptor for interphase boundaries and is defined in strict relation to the interface energy. In nanomultilayers with their intrinsically high interface density, the functional properties are dictated by the interface st ...

Elsevier2024

Influence of model uncertainty and long term deformations in action effects calculation in reinforced concrete structures

Xhemsi Malja

Most codes of practice adopt a semi probabilistic design approach for the dimensioning and assessment of structures. Accordingly, structural safety is ensured by performing limit state verifications using design values determined with adequately calibrated ...

EPFL2024

Proliferation-driven mechanical compression induces signalling centre formation during mammalian organ development

Pengfei Xu, Sangwoo Kim

Localized sources of morphogens, called signalling centres, play a fundamental role in coordinating tissue growth and cell fate specification during organogenesis. However, how these signalling centres are established in tissues during embryonic developmen ...

Nature Portfolio2024

Frictional weakening leads to unconventional singularities during dynamic rupture propagation

Marie Estelle Solange Violay, François Xavier Thibault Passelègue, Federica Paglialunga, Mathias Alexandre David Lebihain

Earthquakes i.e. frictional ruptures, are commonly described by singular solutions of shear crack motions. These solutions assume a square root singularity order around the rupture tip and a constant shear stress value behind it, implying scale-independent ...

2024

Computational Homogenization for Inverse Design of Surface-based Inflatables

Mark Pauly, Francis Julian Panetta, Uday Kusupati, Yingying Ren, Florin Isvoranu, Seiichi Eduardo Suzuki Erazo

Surface-based inflatables are composed of two thin layers of nearly inextensible sheet material joined together along carefully selected fusing curves. During inflation, pressure forces separate the two sheets to maximize the enclosed volume. The fusing c ...

2024

Shear and steel-fibre reinforcement for the punching resistance of flat slabs at internal and edge columns

Diego Hernández Fraile

Reinforced concrete flat slabs consist of a continuous, thin concrete plate that rests on a grid of columns. The supporting surface of the columns is very small compared to the floor plan dimensions, leading to concentrations of shear forces near the colum ...

EPFL2024

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

Thomas Keller, Abdolvahid Movahedirad, Lulu Liu

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

Experimental and analytical investigation of shear-reinforced concrete and dowel action

Marko Pejatovic

Codes of practice can be overly conservative, particularly for the shear resistance of reinforced concrete beams with shear reinforcement when large loads act close to supports. This thesis addresses the topic by proposing a refined design approach based o ...

EPFL2024

A global framework for data-informed bridge examination

Eugen Brühwiler, Philippe Schiltz, Numa Joy Bertola

Examining the performance of an existing bridge requires information on several aspects, such as design choices, material properties, and ongoing degradation processes. It often happens that some critical information is not available. The traditional appro ...

2024

Evaluation of Interface and Residual Strain of NiTi Layer Deposited on NiTiX Substrate by Laser Powder Bed Fusion

Elyas Ghafoori, Christian Leinenbach, Irene Ferretto, Mahbod Golrang, Mahshid Memarian

This study investigates the microstructure and properties of functionally graded NiTi alloy bilayers. The NiTi layer is printed by laser powder bed fusion on a NiTiX (where X is Hf or Cu) substrate prepared by vacuum arc remelting. Specimens produced with ...

Wiley-V C H Verlag Gmbh2024

Mapping orthorhombic domains with geometrical phase analysis in rare-earth nickelate heterostructures

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Bernat Mundet

Most perovskite oxides belong to the Pbnm space group, composed of an anisotropic unit cell, A-site antipolar displacements, and oxygen octahedral tilts. Mapping the orientation of the orthorhombic unit cell in epitaxial heterostructures that consist of at ...

Aip Publishing2024

Long live(d) CsPbBr3 superlattices: colloidal atomic layer deposition for structural stability

Raffaella Buonsanti, Alexander Nicolas Chen, Philippe Benjamin Green, Victoria Lapointe

Superlattice formation afforded by metal halide perovskite nanocrystals has been a phenomenon of interest due to the high structural order induced in these self-assemblies, an order that is influenced by the surface chemistry and particle morphology of the ...

Royal Soc Chemistry2024

Crack tip kinematics reveal the process zone structure in brittle fracture

John Martin Kolinski, Chenzhuo Li, Xinyue Wei

When brittle hydrogels fail, several mechanisms conspire to alter the state of stress near the tip of a crack, and it is challenging to identify which mechanism is dominant. In the fracture of brittle solids, a sufficient far-field stress results in the co ...

PERGAMON-ELSEVIER SCIENCE LTD2023

Experimental Evaluation and Modeling of Residual Stress Distributions for Hot-Rolled Wide Flange Steel Members

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Andronikos Skiadopoulos

Local and member instability modes in structural steel members are influenced by initial geometric imperfections and residual stresses among other parameters. The robustness of stability-related design provisions and finite element modeling procedures of s ...

2023

Single-Well Pore Pressure Preconditioning for Enhanced Geothermal System Stimulation

Marie Estelle Solange Violay, Barnaby Padraig Fryer, Mathias Alexandre David Lebihain

The stress state is an important parameter in terms of both earthquake nucleation and rupture. Here, a new stimulation technique is proposed for Enhanced Geothermal Systems (EGSs), which have previously been burdened with a number of high-profile incidence ...

2023

Nanomechanical Modeling of the Bending Response of Silicon Nanowires

Yusuf Leblebici, Zuhal Tasdemir, Mustafa Yilmaz, Mohammad Nasr Esfahani

Understanding the mechanical behavior of silicon nanowiresis essentialfor the implementation of advanced nanoscale devices. Although bendingtests are predominantly used for this purpose, their findings shouldbe properly interpreted through modeling. Variou ...

AMER CHEMICAL SOC2023