Search results for "bending"

Self-Cleaning ZnO Nanosheets for Piezoelectric Sensors

2022

The design of wearable sensors coupling versatile analytical detection to self-cleaning is a highly desired combination, tackling the need of smart devices in response to the recent virus pandemics. To this aim, this work shows ZnO nanostructures obtained by a mild wet-chemistry approach onto ITO/PET flexible supports, resulting in wearable piezoelectric sensors exhibiting photocatalytic activity. ITO surfaces are treated with 0.5 mM KMnO4 aqueous solution (20 minutes, 90°C); ZnO growth is subsequently carried out by a previously shown wet-chemistry method [1]. SEM analysis shows the presence of a good surface coverage of ZnO nanosheets (NSs) (about 1.5 NSs/μm2) in the case of treated ITO, …

Strength and ductility of confined concrete columns under axial load and biaxial bending

2012

The behaviour of prismatic reinforced concrete columns under increasing eccentric compression load was experimentally investigated and analytically modelled. Columns with distributed longitudinal reinforcement and closely spaced transverse reinforcement were tested up to failure, considering different values and directions of eccentricity. Preliminary tests were carried out under concentric compression in order to validate the choice of the stress-strain laws adopted for the confined concrete and the longitudinal steel bars in compression. In the paper, closed form expressions able to approximate the experimental results in the case of uniaxial bending are presented. Finally, a fibre numeri…

A closed form procedure for the design of longitudinal bars in RC sections subjected to axial load and biaxial bending

2020

This paper presents an analytical procedure for the design of the longitudinal reinforcement in reinforced concrete rectangular sections subjected to axial load and biaxial bending moment. The integration of the equilibrium equations is performed in analytical form for the case of uniaxial moment, including the effect of the reinforcement placed on the sides of the section and adopting code-based constitutive laws for steel and concrete. The strength domain of the section is calculated in closed form for the case of only main steel and in simplified form when including the reinforcement disposed on the side. Additionally, a formulation is proposed for the interaction domain of the two compo…

On bottom steel plate to concrete anchorage in hybrid steel trussed concrete beams

2012

A semi-precast hybrid steel trussed-concrete beam typology is considered. Beams are made up of a steel truss encased in a concrete beam. The steel to concrete stress transferring mechanism is analyzed by experimental tests on six specimens of the beam. Four point bending tests on three slab thick beams and three full thick beams have been carried out. The instrumentation allowed to measure global and local response. The global response was monitored in terms of load vs. midspan-deflection curves and the local response was recorded by strain-gauges placed both on the bottom steel plate and at the top concrete surface of the beam in order to investigate the stress transfer mechanism between s…

Dependence of geometrical configuration on mechanical behaviour of GFRP composite sandwiches

2008

Buckling of Elastic Beam Under Unilateral Constraint

1988

ABSTRACT A criterion is proposed to calculate the critical load of a continuous beam under unilateral constraint. The beam is assumed to be built in at the ends and to rest on equally spaced elastic supports, that have equal stiffness. The problem is solved by determining the length of the half-wave of the buckled shape, the number of supports involved, and their position with respect to the end of the half-wave. The analysis model thus defined is determined in relation to the geometry of the beam and to the ratio between the stiffness of the supports and the shearing stiffness of the generic span. It is shown that there exists a limiting value of this ratio, below which the critical load i…

Changes in surface stress, morphology and chemical composition of silica and silicon nitride surfaces during the etching by gaseous HF acid

2007

Abstract HF acid attack of SiO2 and Si3N4 substrates is analyzed to improve the sensitivity of a sensor based on microcantilever. Ex situ analysis of the etching using XPS, SIMS and AFM show significant changes in the anisotropy and the rate of the etching of the oxides on SiO2 and Si3N4 surface. Those differences influence the kinetic evolution of the plastic bending deflection of the cantilever coated with SiO2 and Si3N4 layer, respectively. The linear dependence between the HF concentration and the Si3N4 cantilever bending corresponds to a deep attack of the layer whereas the non-linear behavior observed for SiO2 layer can be explained by a combination of deep and lateral etching. The ca…

Thermodynamic and kinetic properties of water–oil–surfactant mixtures

1998

Abstract We present experimental data on thermodynamic and kinetic properties of the emulsification failure of a droplet-phase microemulsion, and model them by a bending free energy. In contrast to most other models used to describe water–oil–surfactant mixtures no entropic contributions are included in the present description. Still, there is quantitative agreement between theory and measurements, even though there are no free parameters in our model – only experimentally accessible material constants appear.

Influence of Heat Treatment on Fatigue Crack Growth in Ti-6Al-4V Alloy

2011

The paper contains the results of experimental work carried out in order to analyse the initiation and propagation of fatigue cracks in Ti-6Al-4V titanium alloy. The tests were performed on plane specimens with the stress concentrators in form of one-sided sharp notches. The tested specimens were made of the oxygenated Ti-6Al-4V subjected to various variants of heat treatment.

On the analysis of Catalan thin vaults

2010

This paper is concerned with the identification, modelling and analysis of thin layered vaults, typical in the Catalan constructions of the XIX century. These special structures, also known as bovedas tabicadas, are characterized by very low thickness with respect to the medium surface dimensions and by the presence of different superimposed layers of bricks tied with mortar, are studied in order to individuate a coherent mechanical model for describing the material behaviour, to recognize the structural response utilizing as comparison adequate experimental results, and to extend the obtained results for the analysis of new vaults or for the restoration design of existing vaults. Firstly, …