Search results for " Structures"

Effect of moisture uptake on flax-reinforced composite laminates: influence on dynamic and quasi-static properties

2016

International audience; This study proposes to investigate the effect of moisture uptake on a wide spectrum of mechanical behaviours of unidirectional flax fibre-reinforced epoxy laminates. It includes tensile monotonic and fatigue testing. Results show that UD flax-epoxy composites, whenexposed to hygrothermal conditioning at 70°C and 85% RH, exhibit a diffusion kinetic which follows a one dimensional Fickian behaviour. The mass uptake at equilibrium is approximately 3.3 % and the diffusion coefficient 6.5 10-6 m2.s-1. Water vapour sorption is shown to induce a significant change in the shape of the tensile stress-strain curve. Contrary to all expectations, water saturation does not degrad…

Modelling an Improved NOL Ring Test Using a Reduced Volume Method for the Characterisation of Composite Cylinders

2019

International audience

Temporal-range estimation of multiple objects: evidence for an early bottleneck.

2011

When making parallel time-to-contact (TTC) estimates of two approaching objects, the two respective TTC estimates interfere with one another in an asymmetric fashion. The TTC of the later-arriving object is systematically overestimated, while the estimated TTC for the first-arriving object is as accurate as in a condition presenting only a single object. This asymmetric interference points to a processing bottleneck that could be due to early (e.g., during the estimation of the TTC from the optic flow) or late (e.g., during the timing of the response or the motor execution) constraints in the TTC estimation process. We used a Sperling-like prediction-motion task to differentiate between the…

Modélisation numérique de structures composites réparées par collage de patchs externes en traction

2014

National audience; Request PDF on ResearchGate \textbar On Dec 30, 2014, Lingling Peng and others published Modélisation numérique de structures composites réparées par collage de patchs externes en traction

Analyse numérique de structures sandwichs viscoélastiques et modèle à dérivées fractionnaires

2019

The work deals with the free vibration problem of sandwich structures with a viscoelastic core. Zener model with fractional derivatives with four parameters is used to describe the viscoelastic behaviour. The fractional law is implemented in a numerical tool based on the Ritz method and a variable kinematics approach which is particularly adapted for sandwich plate modelling, the Sublaminate Generalized Unified Formulation (SGUF). The non-linear eigenvalue problem that arises from the frequency dependence of the viscoelastic properties is solved using an iterative algorithm. The approach is validated on several examples consisting of viscoelastic sandwich beam and plate structures, includin…

Who Controls the National Academic Promotion System: An Analysis of Power Distribution in Poland

2023

In studying the performance of academic systems, one often tries to find out—by inspecting some well-defined parameters—how specific changes in the legal system influence the volume and quality of desired outputs, such as publications, patents, or alumni. This mechanistic approach neglects the fact that the main actors in this spectacle are not passive, but have their own priorities, and actively self-organize in response to any changes in their professional environment. In this contribution, we investigate such collective social behavior using the data for academic promotions in Poland in the years 2011 to 2020. Focusing on degrees higher than the PhD, we analyzed over 12,500 habilitation …

Evaluation of the iridocorneal angle with accommodation using optical coherence tomography

2017

The changes in the iridocorneal angle structure during accommodation are assessed by means of anterior segment optical coherence tomography. Thirteen right eyes were included in the study. The device used for the measurement was the Visante® omni system. The stimuli were set up at different vergences (0.0 D, -1.5 D, and -3.0 D). The angle opening distance 500 and 750, the trabecular iris space area 500 and 750, and the scleral spur angle parameters were assessed at the nasal and temporal regions. The results in the iridotrabecular angle comparing the three accommodative states of the eye did not yield any statistically significant difference at nasal or temporal angle sections. In light of …

Structures, interactions and packing of filamin domains

2011

Development of Removable Visual Impact Indicator or Polymer Composite Materials

2021

The prototype of removable visual impact indicator for thermoset polymer composite materials is developed, and its characteristics are experimentally determined. The indicator is a fabric tape glued by epoxy to the surface of the polymer composite. The tape is impregnated with a composition that provides a visual response at the place of an impact on the composite surface. Ball-drop tests demonstrated the increase of the magnitude of the visual response with the impact energy at different substrate hardnesses. The shelf-life and mode of the tape storage until commissioning are determined. Peel tests showed the ability to remove a used indicator without damaging the surface of the composite.

Pull-off adhesion of hybrid glass-steel adhesive joints in salt fog environment

2016

The aim of this paper was to evaluate the durability behaviour of glass/steel adhesive joints exposed to salt fog environmental conditions for ten weeks, according to ASTM B117 standard. To this scope, pull-off mechanical tests were carried out in order to evaluate the performances evolution and damage phenomena of the adhesive joints during the ageing exposition. Two different types of adhesives were compared (i.e. epoxy and polyurethane ones). Moreover, the effects of the glass surface condition and the presence of a basalt mat layer within the adhesive thickness were evaluated. The mechanical performances were related with the occurred failure mechanisms. Epoxy-based joints showed higher…