Durability of flax-basalt hybrid composites for marine applications

2015

The aim of the present work is to evaluate the influence of external layers of mat basalt on the durability behaviour and performances of flax/epoxy laminates. To this scope, long-term aging tests were performed to evaluate the durability of the two different laminates in critical environmental conditions. In particular, Flax composites were constituted by ten layers of bidirectional flax fabric whereas hybrid laminates (i.e. Flax-Basalt) were produced by replacing four external layers of bidirectional flax with four layers of basalt mat. Both laminates had a total average thickness equal to 3 mm. The samples were exposed to critical environmental conditions following the ASTM B 117 standar…

Failure mechanisms of flax/epoxy laminates with open hole: a failure map

2017

Aim of this paper is the investigation of the pin/hole contact stress and failure mechanisms of flax/epoxy composite laminates underwent to tensile bearing tests. In particular, the maximum loads and failure modes are evaluated at varying joint geometry. In order to optimize the use of composite materials in structural applications, an experimental failure map, identifying main failure modes of mechanically fastened joints, is obtained by evaluating failure modes (i.e., net tension, shear out, cleavage and bearing) as a function of the pin diameter and the position of the hole from the free edge of the laminate. Main goal of this paper is give a simple experimental methodology to support th…

ANALISI E SVILUPPO DI UN SETUP SPERIMENTALE PER LA DETERMINAZIONE DELLA TENACITÀ A FRATTURA A MODO II NEI MATERIALI COMPOSITI E IBRIDI

Il presente lavoro di Tesi si propone a compimento del percorso previsto dal Ciclo XXVI del corso di Dottorato di Ricerca in Ingegneria Civile e Ambientale – Indirizzo Materiali – seguito durante il triennio Gennaio 2013- Dicembre 2015 presso l’Università degli Studi di Palermo. L’elaborato si sviluppa in due principali sezioni. Dopo un’introduzione all’argomento affrontato, nella prima parte del lavoro, viene analizzato, sia sperimentalmente che numericamente, un setup tipicamente utilizzato nell’industria aeronautica per la caratterizzazione delle delaminazione a MODO II nei materiali compositi (Transverse Crack Tensile test – TCT-test). A partire dai risultati ottenuti dalle analisi prel…

Effect of NaOH Treatment on Properties of Phoenix Sp. Fiber

2016

The aim of this paper is to investigate the effect of an alkali treatment on physical, chemical, mechanical, and morphological properties of Phoenix Sp. fibers. The use of natural fibers as reinforcement in polymer composites requires a deep investigation to understand their behavior and which treatment is more appropriate to improve the quality of the untreated material. For this reason, fibers were extracted from the petioles of the Phoenix Sp. plant and they were treated with NaOH solution in different weight concentrations (5%, 10%, and 15%). The mechanical behavior was investigated through tensile test on single fiber at different gauge length (20 mm, 30 mm, 40 mm, 50 mm, and 60 mm). C…

The assessment over time of the performance of jute-basalt hybrid composites for cladding panels

2017

The technology of dry assembly to produce multi-layer panels is an efficient alternative to traditional systems. Eco-sustainable systems are increasingly studied, particularly fiber reinforced composites for external cladding, based on natural fibers. Nevertheless, durability data on these composites are still lacking, being this is a really actual theme, especially for their potential use in outdoor applications. In this way, hybridization of natural fibers with mineral fibers as basalt ones appears promising. In the present paper, the performance of jute-reinforced laminate was compared with those of two jute/basalt reinforced hybrid laminates. The laminates were manufactured by means of …

Durability of basalt/hemp hybrid composites

2017

This study focused on the performance of injection-molded short hemp fibre and hemp/basalt fibre hybrid high density polyethylene composites. Results showed that hybridization with basalt fibre enhanced the performance properties. Analysis of fiber length distribution in the composite and fracture surface was performed to study the fiber breakage and fracture mechanism. Prolonged moisture absorption and accelerated ageing of short hemp fibre and hemp-basalt hybrid reinforced thermoplastic composites was addressed. Ageing in water did not result in a reduction of the strength of the composite samples, while it was found to decrease stiffness of hemp fibre reinforced composites. Mechanical pr…