Search results for "CFR"

Robotic geometric and volumetric inspection of high value and large scale aircraft wings

2019

Increased demands in performance and production rates require a radical new approach to the design and manufacturing of aircraft wings. Performance of modern robotic manipulators has enabled research and development of fast automated non-destructive testing (NDT) systems for complex geometries. This paper presents recent outcomes of work aimed at removing the bottleneck due to data acquisition rates, to fully exploit the scanning speed of modern 6-DoF manipulators. The geometric assessment of the parts is carried out with a robotised dynamic laser scanner encoded through an absolute laser tracker. This method allows scanning speeds up to 330mm/s at 1mm pitch. State of the art ultrasonic ins…

Fast ultrasonic phased array inspection of complex geometries delivered through robotic manipulators and high speed data acquisition instrumentation

2016

Performance of modern robotic manipulators has enabled research and development of fast automated non-destructive testing (NDT) systems for complex geometries. This paper presents recent outcomes of work aimed at removing the bottleneck due to data acquisition rates, to fully exploit the scanning speed of modern 6-DoF manipulators. State of the art ultrasonic instrumentation has been integrated into a large robot cell to enable fast data acquisition, high scan resolutions and accurate positional encoding. A fibre optic connection between the ultrasonic instrument and the server computer enables data transfer rates up to 1.6GB/s. Multiple data collection methods are compared. Performance of …

Tensile behaviour of anti-symmetric CFRP composite

2011

Abstract This paper addresses the response of a 17-ply anti-symmetric carbon/epoxy composite subjected to uniaxial tensile loading. Hashin ply damage model is adopted to describe the damage behaviour of the plies, whereas damage initiation and progression of the interfaces are characterised by mixed-mode cohesive damage model. Force-displacement curves obtained numerically and experimentally show good agreement. Results show that all laminae and interfaces experience the damage except laminae with 0o fibre. In addition, damage is concentrated at the tab and central regions of the tensile specimen. Edge delamination is observed in all interfaces.

TENACITÀ ALLA FRATTURA INTERLAMINARE DI COMPOSITI CFRP SOTTOPOSTI A PROCESSI DI INVECCHIAMENTO IDROTERMICO

2011

In questo lavoro si è condotto uno studio degli effetti dell’invecchiamento idrotermico sulla tenacità alla frattura interlaminare in Modo I di laminati in composito CFRP con lay-up unidirezionale. I pannelli realizzati impiegano una resina epossidica DGEBA. Provini DCB sono stati ricavati in accordo con la norma ASTM D5528. Prove dinamico meccaniche DMTA sono state condotte per analizzare l’influenza dell’invecchiamento sulla temperatura di transizione vetrosa, e quindi sul grado di fragilità della matrice. Il lavoro descrive il set-up sperimentale per la determinazione delle Curve R, evidenziando l’influenza della morfologia del tessuto in carbonio. I valori di GIC di innesco e di propaga…

Numerical and Experimental Analysis of the Frictional Effects on 4ENF Delamination Tests Performed on Unidirectional CFRP

2015

Abstract Progressive delamination in composite materials under static or fatigue loading condition are, in many structures, one of the predominant cause of failure. In the paper, an accurate study of quasi-static delamination growth under mode II loading condition is conducted. Several experimental tests are performed on composite laminates consisting of unidirectional carbon/epoxy layers. Four-point end-notched flexure (4ENF) test is employed in order to characterize the mode II interlaminar fracture toughness. The R-curve is obtained by means of optical and numerical determination of crack tip position. The energy release rate and the crack length are calculated through experimental deter…

Analysis of the Combustion Process in a Hydrogen-Fueled CFR Engine

2023

Green hydrogen, produced using renewable energy, is nowadays one of the most promising alternatives to fossil fuels for reducing pollutant emissions and in turn global warming. In particular, the use of hydrogen as fuel for internal combustion engines has been widely analyzed over the past few years. In this paper, the authors show the results of some experimental tests performed on a hydrogen-fueled CFR (Cooperative Fuel Research) engine, with particular reference to the combustion. Both the air/fuel (A/F) ratio and the engine compression ratio (CR) were varied in order to evaluate the influence of the two parameters on the combustion process. The combustion duration was divided in two par…

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets

2017

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly adva…

Effetti di ecfrasi nei canti XVI e XVIII della Gerusalemme liberata. Una proposta didattica

2019

The essay analyzes particular scenes of the poem by Tasso (XVI and XVIII) where the symbolic meaning of the places and scenes depicted by the characters is more explicit. It traces the long pictorial, artistic and musical reception of Gerusalemme Liberata to reflect on the transformative effects of ecfrases in the development of epic events

Vedute d'incantesimo: l'ekphrasis di opere d'arte immaginarie al servizio dell'osservazione microscopica

2012

Numerical and Experimental Study of Defects Evolution in a Composites Wing Box Under Compressive Loads

2013

Due to their high specific strength and stiffness, Carbon Fibres Reinforced Plastics (CFRP) are commonly considered suitable for aerospace structural applications. However, their failure mechanisms are not completely predictable and this is the main reason why the CFRP integration in the aerospace industry has been generally slow in the last twenty years. Indeed, the lack of robust numerical tools, able to take into account the damage tolerance of composite structures, has led to over-conservative designs, not fully realising the promised economic benefits of composites materials. The Project MACMES (Damage Management of Aircraft Composite Structures Monitored by Embedded Sensors), funded b…