13 research outputs found
Experimental and Numerical Assessment of Crashworthiness Properties of Composite Materials: A Review
No full textCrashworthiness is a critical property that enables aerospace structures to minimise injuries and equipment damage during impact scenarios. This review examines the current state of crashworthiness research, with a focus on regulatory frameworks, experimental testing, and numerical modelling techniques. Stringent safety standards set by the Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA) guide the design and certification protocols for aeronautical structures. Experimental crash testing, which includes both full-scale and subscale impact tests, provides essential data for validating material behaviour and energy absorption capabilities under both quasi-static and dynamic loading conditions. Advanced numerical modelling tools offer significant insights into crash behaviour, enabling optimisation of structural designs whilst reducing reliance on costly physical testing. This review highlights the integration of regulations, empirical data, and computational tools in advancing crashworthiness research, with an emphasis on developing safer, more efficient, and sustainable aerospace designs. Future directions should prioritise the use of sustainable materials and optimise crashworthy designs through artificial intelligence (AI) and advanced numerical models to enhance structural performance and safety
The nematode assemblage of a coastal lagoon (Lake Varano, southern Italy): ecology and biodiversity patterns
No full textThis study was conducted in Lake Varano (southern Italy) in order to determine the environmental parameters that influence nematode taxonomic and functional diversity and how they influence them, and to classify for the first time the ecological quality status of a transitional environment. The general composition and level of taxonomic diversity were comparable with those reported for transitional environments worldwide. Principal component analysis revealed that the main environmental factors controlling the assemblages in terms of both composition and biological traits were grain size, organic matter, pollution load index and, only secondarily, salinity. Molgolaimus allgeni, Terschellingia longicaudata and Leptolaimus luridus showed higher values in relation to silt, organic matter and pollution load index, while Axonolaimus caudostriatus, Odontophora wieseri, Paramonhystera pellucida and Paracanthonchus longicaudatus showed higher values in relation to the redox potential and sand percentage. Salinity was detected as an influencing parameter only secondarily and particularly for Calomicrolaimus honestus, Daptonema normandicum, Thalassomonhystera parva and Sabatieria pulchra. With respect to functional traits, the trophic groups seemed to be mainly related to sediment type, which is in turn reflected by the nature of the available food. The maturity index, as well as c-p classes, did not always permit a clear interpretation of the interaction between anthropogenic and natural factors. However, the greater influence of the San Antonino and San Francesco Canals was perfectly revealed by the nematode assemblage. In accordance with the current ecological quality classes, Lake Varano can mainly be classified as having good to poor ecological quality status
Experimental and Numerical Assessment of Sheet Molding Compound Composite Crushing Behavior
No full textThis study investigates the crashworthiness properties of carbon fiber sheet molding compound (CF-SMC) material, highlighting its potential for applications requiring effective energy absorption. While CF-SMC exhibits promising specific energy absorption values, further optimization of both the material and its geometrical design is necessary to enhance performance. Notably, CF-SMC's manufacturing advantages, including faster production and the capability to integrate recycled fibers, make it a cost-effective and sustainable option for industries prioritizing efficiency and environmental responsibility. The short-fiber material model implemented within the ESI-VPS software was calibrated by means of tensile and compressive test simulations, and it was validated through crash simulations. The results indicate a strong correlation between experimental data and numerical predictions, confirming the effectiveness of the modeling approach
Analysis of the Crushing Behavior of Flat Composite Plates Produced by Sheet Molding Compound
No full textSMC composites, comprising chopped fiber bundles within a matrix
material, offer the potential to create lightweight structures with high strength and
stiffness, serving as viable substitutes for heavier metal components. The complex
task of designing SMC composites with optimized performance characteristics is
compounded by their inherently localized anisotropic behavior and the presence of
various interacting forms of damage. Consequently, simulating the performance of
SMC in crash-worthy applications necessitates a comprehensive characterization
of the material’s mechanical properties through tailored experimental tests. In this
study, an experimental study has been conducted on a commercial SMC mate-
rial, with the primary objective of comprehensively comprehending its behavior
and deriving specific parameters essential for numerical simulations. Employing
ESI-VPS, the crashworthiness of flat components was simulated and successfully
achieved a favorable correlation between the obtained results and the experimental
data
Harpacticoid copepod assemblages associated to hard substrates of the marine protected area of Portofino.
No full textCaratterizzazione di materiali compositi tramite prove di compressione di lastre piane
No full textLo scopo della tesi è stato trovare parametri geometrici atti all'ottenimento di risultati conformi per la fixture, studiando il variare dei risultati al variare di parametri, quali layup, trigger, luce e velocità della provacr.
La fixture viene utilizzata per caratterizzare materiali compositi tramite prove di compressione per lastre piane
THE FORGOTTEN POSIDONIA OCEANICA (L.) DELILE DETRITAL HABITAT: NEMATODE COMMUNITY AND TWO NEW SPECIES OF ECHINODERES (KINORHYNCHA: ECHINODERIDAE) INHABITING THIS NEGLECTED ENVIRONMENT
No full textSeagrass beds are among the most important and studied marine vegetated habitats worldwide,
Recently, the supra-littoral deposits of leaf litter (i.e., banquettes), have been investigated as part of
the seagrass life cycle, in terms of their nutrients, biomass and associated community. Nevertheless,
an overlooked fraction of the seagrass detritus never reaches the shore and sinks far away to deeper
seafloor, but the destiny of the leaves transported to deep subtidal habitats remains unknown, even if
they might host organisms consuming and processing seagrass carbon far away from the donor bed.
Meiofauna is the most abundant and ubiquitous component of the benthos, which could be a useful
tool to answer several ecological questions, since plays a key role enhancing energy flow from the
microbial community to the entire food web. A huge issue related to meiofaunal research is the lack
of information on both taxonomy and community structure, and despite recently this trend is
changing, several habitats remain unexplored, such as the deep macerating P. oceanica detritus. This
study investigated for the first time the meiofaunal community inhabiting sediments characterized by
P. oceanica detritus in a deposit located at 65-80 m depth off Ischia Island (Gulf of Naples, Italy) in
the zone D of the MPA “Regno di Nettuno”. The results show that the meiofaunal community appears
highly diversified and strongly dominated by nematodes (from 85% to 93%). The nematode
community revealed a very high biodiversity (number of families and genera: 31 and 104,
respectively), with a clear prevalence of selective and non-selective deposit feeders that suggest the
key role of this habitat in the benthic detrital food web.
Additionally, two new species of Echinoderes are described: Echinoderes semprucciae sp. nov. and
Echinoderes sandullii sp. nov. Both species can be easily distinguished from their congeners by their
unique arrangement of cuticular structures and represent the first record of kinorhynchs inhabiting a
macerating P. oceanica detrital habitat. This study will possibly draw attention to this peculiar
environment that deserves to be deeply investigated given the strong connection to the much betterknown
living seagrass beds, which support incredibly diverse community, from tiny invertebrates to
large fishes, providing important services to people as well, especially in the Mediterranean Sea
Fibre riciclate per materiali compositi sostenibili
No full textL'industria aeronautica rappresenta uno dei settori più avanzati e tecnologicamente complessi al mondo, con un ruolo fondamentale nello sviluppo economico globale. Tuttavia, essa è anche una delle più impegnative dal punto di vista ambientale, contribuendo significativamente alle emissioni di gas serra e al consumo di risorse naturali. Negli ultimi anni, la crescente pressione per ridurre l'impatto ambientale del settore ha stimolato la ricerca e lo sviluppo di soluzioni innovative, sostenibili ed efficienti, tra cui l'adozione di materiali compositi leggeri e ad alte prestazioni.
In questo contesto, l'impiego di fibre riciclate nei materiali compositi si presenta come una strategia promettente per coniugare le esigenze di sostenibilità con le prestazioni tecniche richieste dal settore aeronautico. Tuttavia, la loro applicazione nell'industria aeronautica è ancora in una fase emergente, con diverse sfide da affrontare.
L’obiettivo di questa tesi è esplorare il potenziale utilizzo di fibre riciclate per la produzione di materiali compositi sostenibili nell'industria aeronautica. Attraverso un'analisi delle tecnologie disponibili, delle proprietà dei materiali e delle implicazioni ambientali, si intende fornire una panoramica completa delle opportunità e delle sfide associate a questa soluzione innovativa
Influenza della temperatura sulla crashworthiness di materiali compositi CFRP
No full textLa necessità di realizzare mezzi di trasporto più sicuri ed efficienti ha portato i progettisti a studiare nuovi materiali che avessero un miglior comportamento a crashworthiness, cioè con un’elevata capacità di assorbire l’energia durante un urto, e che fossero più leggeri. I materiali compositi, rinforzati con fibra di carbonio (CFRP), grazie alle loro eccellenti proprietà meccaniche come la leggerezza e il rapporto rigidezza/peso, stanno svolgendo un ruolo fondamentale nello sviluppo di nuove soluzioni tecniche. Questo ha portato i compositi a essere utilizzati anche in ambienti con temperatura elevata. Questa tesi, basata su una ricerca bibliografica, si pone l’obiettivo di analizzare come le variazioni di temperatura influenzino il comportamento dei CFRP a crash, in particolare la capacità di assorbire energia e i relativi meccanismi di rottura
Studio della permeabilità delle fibre naturali nei materiali compositi
No full textL’industria dei materiali compositi ha recentemente mostrato interesse per le fibre naturali, come alternativa sostenibile alle tradizionali fibre sintetiche. Questa tendenza è guidata dalla necessità di ridurre l’impatto ambientale, mantenendo elevate prestazioni meccaniche e garantendo l’affidabilità dei processi di produzione.
Tuttavia, l’impiego delle fibre naturali come rinforzo nei materiali compositi comporta nuove problematiche tecniche, dovute alla variabilità delle proprietà del rinforzo, alla sensibilità all’umidità e, in particolare, alla difficoltà nella determinazione del parametro di permeabilità. La permeabilità è il parametro critico nella fabbricazione di componenti mediante i processi produttivi LCM (Liquid Composite Molding). Se non determinato correttamente, l’oggetto finale presenterà difetti che incideranno sulle proprietà meccaniche, rendendolo inutilizzabile.
Lo scopo di questa tesi è analizzare la permeabilità delle fibre naturali, identificando i principali parametri che la influenzano e i modelli analitici per la sua previsione e analisi, basandosi su una ricerca bibliografica che esamina le metodologie e i modelli proposti nella letteratura scientifica
