Structure and deformation mechanisms in UHMWPE-fibres

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Compliant mechanisms achieve motion through elastic deformation rather than contact surfaces, eliminating friction, wear, and lubrication requirements. Historically, conventional manufacturing processes have constrained both the design and adoption of these mechanisms in cryogenic and space applications. This work exploits the design freedom of Laser Powder Bed Fusion (LPBF) to propose a streamlined Design for Additive Manufacturing (DfAM) workflow for optimizing and customizing a flexure pivot operating at

We investigate the influence of AlN buffer thickness on the structural, electrical, and thermal properties of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on semi-insulating SiC substrates by metal-organic chemical vapor deposition. X-ray diffraction and atomic force microscopy reveal that while thin AlN layers (120 nm) exhibit compressive strain and smooth step-flow surfaces, thicker single-layer buffers (550 nm) develop tensile strain and increased surface roughness. Multi-layer buffer struc

In a previous study, it was shown that the incorporation of calcium aluminates-based accelerators is an effective solution to improve the early age strength of LC3. The higher early age strength was linked to the ettringite formation during the first hours of hydration [1]. Late age strength results (up to 1 year) of LC3 incorporating calcium aluminates-based accelerators were higher than PC and LC3. This study focuses on understanding the late age strength of LC3 boosted with calcium aluminates-based accel

This paper proposes a new model for simulating the inelastic behavior of steel beam-columns exhibiting softening. A novel rate-independent multiaxial metal plasticity model is formulated to mimic nonlinear geometric effects (local buckling) through material softening. The governing equations that define the yield surface are presented. The evolution rules of the model at various loading paths are established. Asymmetric responses between tensile and compressive loading are explicitly considered. Prior to in

Complex, nonlinear, and transient phenomena are at the heart of modern research in mechanics of materials. For example, the buildup and release of elastic energy at geological fault is what causes earthquakes, and the intricate details of the slip zone, the propagation of slip fronts and waves radiated through the various geological media are still active areas of research (Kammer et al., 2012, 2014; Roch et al., 2022). Similarly, understanding fracture in heterogeneous materials such as concrete, masonry o

We investigate the effect of shear dilatancy of a permeable fault on the diffusion of pore pressure and the occurrence of dynamic slip. Starting from the results of Garagash & Germanovich (2012), we include the effect of both inelastic changes of material porosity and hydraulic aperture with slip on the nucleation and arrest of dynamic slip. Locally elevated pore pressure associated with fluid injection leads to a reduction of the fault frictional resistance which may eventually falls below the background s

This paper explores the system of laminated annealed glass beams post-tensioned through stainless steel tendons bonded to the lower glass edge. The tendons are first pre-tensioned and then adhesively bonded to the glass. The compressive pre-stress applied by the tendon increases the fracture strength of the beam; in case of glass fracture, the steel tendon provides ductility enhancing the post-fracture behaviour of the beam. In order to explore the optimal adhesive properties for such application, three typ

The article descirbes briefly the EPSF method and gives example of solutions obtained with the method as well as a solution with the RPSF method and comparison between the two methods.

Refractive index changes up to 2.5 × 10-3 were demonstrated in H2-loaded germanium free Bi-Al-doped silica fibers using both ArF excimer and cw-Ar+-244 nm lasers. Tensile stress changes indicate clear contribution of compaction to the total index change.

In this paper, we demonstrate the integration of local oxidation and metal-gate strain technologies to induce 3.3%/5.6 GPa uniaxial tensile strain/stress in 2 μm long suspended Si nanowire MOSFETs, the highest process-based stress record in MOSFETs until now, by elastic local buckling. Significant stress level modulation in the channel from 1.2 to 5.6 GPa on a single wafer is demonstrated for the first time by varying the NW width. The GAA Si NW MOSFET with 5.6 GPa uniaxial tensile stress is characterized a

The fabrication procedure changes when changing the size of the structural components. For the weldments, the change of the welding procedure leads to the change in residual stresses which consequently affects the fatigue life of the structure. The weld size and number of welding passes are important factors which have considerable impact on the values and distribution of the welding residual stresses. This technological size effect is investigated in this study by simulating the welding process for tubular

This project aims to analyze, fabricate and characterize a mechanical hydrogen sensor. The potential of hydrogen gas detection using beam resonators is investigated. The beams consist mainly of Si3N4, providing a tensile stress to prevent buckling. Pd expands in the presence of hydrogen gas, but as it is constrained in the longitudinal direction, a compressive stress is generated. Similar to a guitar string being tuned, the stress change will change the resonance frequency of the beam. Pt layer beams are al

Multiscale modeling, including molecular dynamics (MD) and discrete dislocation dynamics (DDD) methods, appears as a significant tool for the description of plasticity and mechanical properties of materials. This research concerns the influence of irradiation on the plasticity of pure Fe and focuses on the interaction of a single dislocation with a spherical void at various geometries. MD simulation shows that the void strengthening is proportional to the interaction area. Stress field around the void influ

Particle Reinforced Metal Matrix Composites (PRMMCs) are produced by high-pressure infiltration of ceramic particle beds. Matrix materials are either pure Al or Al-4,5%Cu, and the reinforcement is made either of angular or of polygonal alumina particles. The resulting composites feature a high volume fraction (40-60%) of uniformly distributed reinforcement. These materials accumulate damage during deformation, in the form of particle cracking or matrix voiding; localization of damage induces final failure.

The endeavour to develop nanodevices demands for patterning methods in the nanoscale. To bring nanodevices to the market, there is a need for fast, low-cost replication nanopatterning methods. In addition, an increased flexibility of the nanopatterning methods is important for the engineering of multimaterial and multifunctional nano/micro-electro-mechanical systems (NEMS/MEMS), such as polymer-based electronic and sensor devices, 3D microfluidic systems, and bio-analytical systems. A series of alternative,

In anticipation of the introduction of high modulus materials in the Swiss standards, a research project has been carried out for the evaluation of these bituminous mixtures. These mixtures make possible to reduce rut in base courses. With a temperature of 50°C, three test sections (two with high modulus and one with a reference material for base layer), were built in a building for ALT and were submitted to traffic loads corresponding to those of heavy vehicles. The behaviour of the test sections correspon

By using synchrotron radiation phase sensitive radiography we have examined the reactions of screw superdislocations or micropipes in silicon carbide single crystals: bundling, twisting, and splitting. To understand the nature of these reactions, a model of micropipe motion during crystal growth has been proposed. Based on this model, a computer simulation of the evolution of a random micropipe ensemble has been performed. The simulation demonstrates that the coalescence of micropipes with opposite-sign Bur

The mechanical properties of extruded films of isotactic polypropylene (iPP) and ethylene-propylene rubber toughened iPP (iPP/EPR) have been analyzed in terms of the specific essential and non-essential work of fracture using high speed tensile test apparatus modified for quasi-static testing in the range 0.0001 to 3 ms.1. Three iPP/EPR grades with modifier contents of 15, 21 and 30 vol% were investigated. As the deformation rate increased, relatively uniform necking of the whole ligament and extensive plas

Micropipe bundling and twisting in SiC crystals was revealed using synchrotron x-ray phase sensitive radiography. The computer simulation of micropipe evolution during the crystal growth suggests that the bundled and twisted micropipes arise under the influence of stress fields from other neighboring micropipes. The annihilation of twisted dipoles is attributed to their transformation into semiloops. Reactions of micropipe coalescence lead to the generation of micropipes and/or the annihilation of initial m

Uniaxial fragmentation tests were carried out in situ in a scanning electron microscope (SEM) on 10-nm-thick silicon oxide coatings deposited by plasma enhanced chemical vapor deposition on poly(ethylene terephthalate). In order to prevent charging effects due to the isolating nature of the oxide surface, an additional conductive gold layer was sputtered onto the coating prior to its tensile loading in the SEM chamber. The gold layer was shown not to affect initiation of tensile failure of the oxide coating

Structure and deformation mechanisms in UHMWPE-fibres

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Design for additive manufacturing of cryogenic flexible pivot enabling on-demand customization, and reducing failure risks

Impact of AlN buffer thickness on electrical and thermal characteristics of AlGaN/GaN/AlN HEMTs

Understanding the Late Age Strength of Low CO2 Binders Incorporating Calcium Aluminates-Based Accelerators

A MULTIAXIAL PLASTICITY MODEL WITH SOFTENING FOR FIBER-BASED STEEL BEAM-COLUMNS

Akantu: an HPC finite-element library for contact and dynamic fracture simulations

Modelling of fluid injection into a frictional weakening dilatant fault

Comparative Study of Post-tensioned Glass Beams with Bonded Tendons

Verification of details of existing structures with the elastic-plastic stress field method

Fabrication/Characterization of Fiber Gratings and Photosensitivity in Ge-Free Bi-Al-Silica Fibers

Local stressors to accommodate 1.2 to 5.6 GPa uniaxial tensile stress in suspended gate-all-around Si nanowire nMOSFETs by elastic local buckling

Investigation of technological size effects of welding on the residual stresses and fatigue life of tubular joints made of structural steels S355 and S690

Mechanical Hydrogen Sensing

Dislocation-void interaction in Fe: a comparison between molecular dynamics and dislocation dynamics

Damage and fracture of particle-reinforced metal matrix composites

Advancing towards well-controlled full-wafer nanostencil lithography

Assessment of Resistance to Rutting of High Modulus Bituminous Mixtures Using Full-Scale Accelerated Loading Tests.

Synchrotron radiographic study and computer simulation of reactions between micropipes in silicon carbide

Essential work of fracture of polypropylene and polypropylene blends over a wide range of test speeds

Micropipe evolution in silicon carbide

Mechanical analysis of ultrathin oxide coatings on polymer substrates in-situ in a scanning electron microscope