1,721,073 research outputs found
Evaluation of aging behavior under salt-fog spray conditions of green sandwich structures
Full text linkIn this paper, the aging resistance of sandwich structures made with cork agglomerate as core and flax-reinforced polymeric laminates as face sheets was investigated for the first time. In order to evaluate their durability in a hostile environment, a sandwich plate was manufactured by vacuum bagging technique and aged under salt-fog spray conditions, according to ASTM B 117 standard. The evolution of the sandwich mechanical properties during the aging exposition was analyzed by carrying out quasi-static flexural tests and Charpy impact tests both on unaged specimens and on specimens aged for 10, 25, and 60 days, respectively. The quasi-static experimental results showed that despite the salt-fog exposition leads to clear decrements in both maximum strength and modulus, the deformation capability of the sandwich structure evidences a noticeable improvement. According to this last result, it was found that the impact strength of the sandwich specimens was clearly increased after the salt-fog exposition evidencing that the studied green sandwich maintains good toughness properties in a hostile environment such as marine
Structural and Mechanical Modification Induced by Water Content in Giant Wild Reed (A. donax L.)
Full text linkGiant wild reed Arundo donax L. is an aggressive agricultural species with remarkable features such as fast-growing, untapped economic potential, eco-friendliness, and high specific properties (e.g., high strength/weight and modulus/weight ratios). Here, the bending properties of giant reed were studied at a molecular level to evaluate the effect of the conditions used during the preparation for their applications (also referred to as treatment conditions). The aim was to achieve new information potentially useful to suggest new possible applications of A. donax L. for structural applications in modern buildings. In this study, green reeds collected in a Sicilian plantation were dried for 2000 h in a climatic chamber under humidity-temperature-controlled conditions, then fully dried in an oven and finally re-moistened through two different procedures. The combination of different analytical techniques (such as calorimetry and fast field cycling NMR relaxometry) revealed that giant reed bending properties are strongly affected by the presence of bound water. In particular, it has been evidenced that a progressive enhancement of bending characteristics is obtained when the interactions between residual water and A. donax L. fibers become progressively stronger. For this reason, it can be suggested that fibers having different plasticity can be produced by modulate the heating treatment to regulate the amount of bound water inside A. donax L. fibers
Failure maps to assess bearing performances of glass composite laminates
Full text linkAim of this article is the assessment of the bearing mechanical performances of pin-loaded glass laminates as function of their geometrical configuration. To this concern, 32 specimens having different hole diameter (D), laminate width (W), and hole center to laminate free edge distance (E) have been tested under bearing conditions. The maximum bearing stress and the stress-displacement curves were analyzed as function both of hole to laminate free edge distance E and hole diameter D. Moreover, an experimental 2D failure map was created by placing the experimental results (i.e., the kind of failure mechanism occurred for each geometrical configuration) in the plane E/D versus W/D ratios. In order to identify a simplified methodology able to design mechanically fastened joints in an easy and effective way, a simplified theoretical failure map on E/D and W/D axes was proposed. The theoretical model showed a good matching with the experimental results validating the proposed approach. In particular, the proposed simplified failure map highlighted that woven glass fiber composite laminates fastened joints should have E/D and W/D ratios higher than 1.6 and 2.1, respectively, in order to stimulate a progressive bearing failure mechanism and achieve the full laminate strength. Finally, another goal of this article was to assess failure mechanisms evolution by drawing a 3D plot (i.e., at varying E/D and W/D geometrical ratios) of the failure index evaluated for each failure mechanism according to the maximum stress criterion
Experimental Analysis and Numerical Modelling of the Mechanical Behavior of a Sisal-Fiber-Reinforced Geopolymer
Full text linkThe present paper is devoted to the proposal of appropriate numerical modelling able to provide a suitable description of the mechanical behavior of a composite geopolymer. Reference is made to a natural sisal-fiber-reinforced geopolymer. The study is based on the results of appropriate experimental investigations for compressive, flexural and splitting loadings, taking into account different weight percentages of fibers to evidence their role in the mechanical behavior. The main objective of the paper is to calibrate the microplane constitutive model, available in ANSYS software version 18.1, where the numerical analyses are performed. Therefore, the present study is structured in two different steps. Firstly, the mechanical behavior of geopolymers reinforced with sisal fibers is experimentally investigated, and subsequently, the gathered test data are interpreted and utilized to calibrate the relevant constitutive model to be used in the numerical stage. The obtained results are compared with experimental data, yielding good correlations. The paper's results supply the parameters required to obtain an affordable numerical model of the reinforced geopolymer for different percentages of fibers to be adopted for material design with assigned mechanical properties
Materiali e Tecniche Innovative per l'Edilizia Sostenibile
Full text linkIl cambiamento climatico e la necessità di ridurre il consumo energetico degli edifici sono argomenti
chiave del dibattito politico, scientifico, economico e culturale. Un dibattito al quale si è voluto dare il
proprio contributo sin dall’anno accademico 2010-2011 con la prima edizione del Master in Materiali e Tecniche Innovative per l’Edilizia Sostenibile (MeTIES) dell’Università degli Studi di Palermo insieme al Consorzio Universitario per l’Ateneo della Sicilia Occidentale e del Bacino del Mediterraneo (UNISOM), perseguendo il preciso obiettivo di formare una generazione di professionisti che sappiano padroneggiare le nuove tecnologie per ripensare il modo di “costruire”.
Tutti gli studenti che hanno seguito il master, nelle diverse edizioni, hanno avuto modo di mettere a frutto le competenze acquisite durante il corso in un ambito lavorativo. Si è voluto contribuire al dibattito sulle possibili strade da perseguire per lo sviluppo sostenibile attraverso la formazione di “operatori” che abbiano la capacità di individuare, sviluppare e proporre soluzioni possibili e concrete per l’efficientamento energetico degli edifici. Il libro contiene alcune risposte operative alle necessità di un settore che sarà sempre di più al centro delle scelte economiche e politiche dei prossimi
decenni.Climate change and the need to reduce energy consumption in buildings are key topics in the political, scientific, economic and cultural debate. Since the academic year, 2010-2011, we wanted to make a debate and also our contribution with the first edition of the Master in Materials and Innovative Techniques for Sustainable Construction (MeTIES) University of Palermo together with the University Consortium for the University of Western Sicily and the Mediterranean Basin (UNISOM). The main objective of this Master is to form a professional generation who knows how to master new technologies and to rethink the way to "build".
All the students of the master, in different editions, have had the opportunity to improve skills acquired during the course in workplace. The aim was to contribute to the debate on possible ways to pursue sustainable development through the training of "operators" who have the ability to identify, develop and propose possible and concrete solutions for the energy efficiency of buildings. The book contains some solutions to the needs of a sector that will be increasingly at the center of the economic and political choices of the coming decades
Thermal Behaviour of Blends of Polycarbonate and Liquid-Crystal Polymers: A D.S.C. Study
No full text
- …
