Search results for "Fatigue."

Changes in the Association between European Workers’ Employment Conditions and Employee Well-Being in 2005, 2010 and 2015

2020

[EN] The aim of this paper is to study whether there is a change in the association between employment conditions and European employees' well-being at three different time points (the years 2005, 2010 and 2015), characterized by different socio-economic contexts. We based our study on the European Working Conditions Survey. Logistic regressions were performed by adjusting for gender, age, level of education, seniority, occupation, establishment size, activity sector and economic activity. Adjusted odds ratios (ORadj) and 95% confidence intervals (95% CI) are reported. In general, the association between employment conditions (type of employment contract, supervising, weekly working hours, …

Understanding mental fatigue and perception of effort to understand endurance performance

2015

Lettre à l'éditeur ("Journal of Applied physiology" vol.118, no.10). Fait partie de : "Commentaries on Viewpoint: The two-hour marathon: what's the equivalent for women?". http://jap.physiology.org/content/118/10/1324#ref-list-2

Characterization of rubberized asphalt for railway sub-ballast. Improvements in the mix-design, performance features and rational methodology of HMA_…

2018

(STR) can be incorporated into asphalt mixtures in two different methods, which are referred to as the wet-dry process. The blending of recycled rubber (CRM) with asphalt has been used for years, and several manufacturing processes have been developed in Europe as well as in the USA. The use of a bituminous sub-ballast layer has been pointed out as an exciting alternative to the granular sub-ballast design traditionally applied in most railroad tracks. Frequently, unbound granular materials are replaced by bituminous sub-ballast that provide additional benefits to the subgrade protection. Much research has been conducted on finding other alternative material to be used as a modifier in asph…

CHARACTERIZATION OF RUBBERIZED ASPHALT FOR RAILWAY SUB-BALLASTS

Tesi di dottorato sotto la supervisione del professore Gaetano di Mino del Dipartimento di Ingegneria Civile di Palermo), come borsista Marie-Curie all'interno del progetto SUPRITN 2013/2017. Il mio lavoro e la linea della ricerca riguarda i conglomerati bituminosi con granulato di gomma per lo strato di sub-ballast nelle linee ferroviarie. L’attività di ricerca comprende il mix-design dell’asfalto con aggiunta di gomma, la caratterizzazione e le prestazioni per la ferrovia in termini di comportamento meccanico e lo smorzamento delle vibrazioni. In particolare con l’avvento dell’alta velocità, diversi studi hanno evidenziato ottime caratteristiche fisico-meccaniche per ciò che riguarda il c…

Static strength and fatigue life of optimized hybrid single lap aluminum–CFRP structural joints

2017

Hybrid bolted/bonded joints are used to assemble structural components, commonly made by carbon fiber reinforced plastics (CFRP), with aluminum frames. Hence, they have become common solutions in a number of modern structural applications in the industrial fields, as well as civil constructions. Unfortunately, due to the lack of understanding of the relationships between the multiple parameters of influence that characterize their mechanical performance, only limited improvement have been achieved so far over classical bonding approaches, in terms of static and fatigue strength. As a result, further studies are needed in order to better exploit the potential of hybrid bolted/bonded joints a…

Infrared Thermography assisted evaluation of static and fatigue Mode II fracture toughness in FRP composites

2019

Abstract The work proposes the combined use of a Modified Transverse Crack Tension (MTCT) test coupon and Infrared Thermography, to evaluate the static and fatigue behaviour of Fibre Reinforced Polymer composites under Mode II delamination. Artificial delaminations starters are added to the TCT coupon, whose effects on the Strain Energy Release Rate are discussed. Infrared Thermography and Thermoelastic Stress Analysis are implemented to investigate stresses and delaminations growths on two FRP materials: a pre-preg IM7/8552 carbon fibre-epoxy and a glass-fibre reinforced epoxy laminates. The thermographic, thermoelastic and second harmonic signals have been obtained and used to monitor the…

Thermoelastic Stress Analysis of modified Transverse Cut Tensile composite specimens under pure Mode II fatigue delamination

2018

The present work investigates the behaviour of a Transvers Crack Tensile (TCT) specimen undergoing fatigue loading, by means of a Thermoelastic Stress Analysis (TSA) experimental setup. The TCT is a tensile composite specimen where a number of internal layers are cut through the beam width. The presence of such transverse notch favours the formation of interlaminar Mode II delaminations, starting from the notch tips and propagating between the cut and continuous plies. In this work, a modification is adopted to the classic TCT specimen, where insert films, mimicking artificial delaminations, are laid across the notch tips. This is done with the purpose to favour a pure Mode II and a symmetr…

Fatigue and Healing Properties of Low Environmental Impact Rubberized Bitumen for Asphalt Pavement

2017

The addition of recycled tyre rubber as a modifier to enhance the mechanical properties of bitumen has proven to provide asphalt mixtures with better mechanical performance. However the rubberised bitumen presents the limitation of requiring higher manufacturing and compaction temperatures. This could be solved by subjecting the tyre rubber to sort of pre-treatments such as: Adding warm-mix additives and/or using partial devulcanisation. These solutions have the potential of lowering the overall environmental impact of the asphalt pavement, however it is still not clear whether these can be detrimental for the rubberized asphalt binder mechanical properties. This paper investigates the effe…

Thermo-rheological analysis of WMA-additive modified binders

2020

AbstractThermo-rheological characteristics of unmodified and modified bitumen have significant impacts on the mechanical response of asphalt. This study investigates the impacts of an organic and a chemical Warm Mix Asphalt additive on bitumen thermo-rheological and mechanical characteristics. Modified binders with different concentrations of each additive were studied and analysed comparatively to a 40/60 penetration grade bitumen. Frequency sweep tests were performed at different ageing levels to characterise the Linear Viscoelastic properties. The multiple stress creep and recovery, linear amplitude sweep (LAS) and low temperature creep stiffness tests, together with the Glover–Rowe (G–R…

Fatigue crack initiation and subsequent crack growth in fillet welded steel joints

2019

Abstract The fatigue damage evolution in fillet welded steel joints where cracks are emanating from the weld toe is investigated. Based on existing experimental data for as-welded joints including crack depth measurements of the early crack growth it is proposed to make a distinction between the crack initiation phase and the subsequent crack growth phase. The welded detail in question is an F class detail with plate thickness 25 mm made of medium strength carbon steel. It is found that the crack initiation phase defined at a crack depth of 0.1 mm is close to 25% of the fatigue life even at a relatively high constant stress range of 150 MPa. At lower stress ranges it is concluded that the i…