1,721,038 research outputs found
Neural Network Predictions of the Impact Behaviour of GFRP Laminates
No full textComposite materials are widely used in aerospace, naval and automotive applications due to their high strength and stiffness to weight ratio. Nevertheless, damages related to low-velocity impacts can compromise composite materials’ performances. The paper investigates the low-velocity impact behaviour of glass fibre-reinforced plastic laminates with various thicknesses and under different working conditions. In detail, composite laminates were subject to low-velocity impact tests by changing
the temperature and the impact energy. The goal of these tests is to investigate some key features such as absorbed energy, maximum impact force, indentation depth, and delamination area. In addition, the experimental data allowed the training of artificial neural network-based models. The increase in the impact strength and the decrease in the specimens’ deflection confirmed greater rigid impact performance at low temperatures. This behaviour translates into a different onset and growth of damage, detecting lower indentation and delamination at the decrease in the temperature. Finally, the intelligent models can provide outstanding predictions, estimate complex nonlinear relationships between inputs and outputs, as well as signal the presence of anomalous data because of possible human error
Le finiture delle murature in laterizio nei cantieri religiosi del XII e XIII secolo. Ricerche in corso
No full textThe numerous Cistercian and Canonical abbeys of the twelfth and thirteenth centuries that are preserved in the north-west of Italy constitute an important heritage for the study of construction techniques, materials and surface finishes.
In this essay we present some results from the Staffarda, Morimondo and Vercelli abbeys, in which the masonry textures, mortar joints and surface finishes demonstrate solutions of great interest.
From the researches emerges the operative process related to the qualification of the masonry, that defines a strong interrelation between the construction components, the architectonic elements and the decorative apparatus, made through the surface treatments of materials. The study of the constructive choices that specifically concern the finishing treatments, although not always fully preserved, also allows to identify the organization, management and origin of masters of work active in the different construction site
Influence of the Heated-Bed Material on PLA Mechanical Properties and Energy Consumption in the FDM Process
Get PDFUltrasonic damage investigation on woven jute/poly (lactic acid) composites subjected to low velocity impact
No full textn the present contribution, particular attention is devoted to the fabrication and characterization of fully bio laminated structures based on a commercial poly (lactic acid) (PLA) including a jute fabric as reinforcements, even because of the limited availability of the reference literature. An ultrasonic technique is used to investigate the delamination caused by low velocity impact tests, on plates obtained by typical film stacking and compression molding techniques. The square specimens, 100*100 mm, were impacted by a falling dart machine at five increasing impact energy values of 2 J, 5 J, 10 J, 12 J, and 15 J. The delamination is investigated by the very commonly used Ultra Sound technique employing a linear phased array probe. The delaminated area is correlated with both the impact energy and the measured indentation depth. The results showed a threshold energy for the beginning of the internal damage. Moreover, a linear relationship between the delaminated area, the energy and the indentation depth was found. © 2016 Elsevier Lt
Influence of the Manufacturing Technology on Impact and Flexural Properties of GF/PP Commingled Twill Fabric Laminates
No full textThe purpose of this work is to evaluate the influence of the manufacturing technology on the mechanical behaviour of composite laminates from commingled fabrics consisting of glass and polypropylene fibers. In this regard, non-isothermal and isothermal moulding technologies were used for manufacturing flat laminates with different thicknesses and stacking sequences. The laminates were characterized by flex and impact tests up to complete penetration; the data of penetration energy were also used to estimate the goodness of fit of a prediction model present in literature. The results obtained from the mechanical tests show the effectiveness of the isothermal moulding technology compared to the non-isothermal one, which is extremely important considering that the preheating phase is avoided with the first technology, saving on equipment and processing times
Conoscenza e conservazione del patrimonio architettonico rurale della Valchiusella e di Rueglio (Piemonte). Lo studio dell’abitato storico e il recupero di Ka’ D-Mezanis
No full textRestoration work on a stately home (Ka’ D-Mezanis) in Rueglio, a settlement in the Valchiusella area between Ivrea and the southern part of the Valle d’Aosta, prompted a research project on rural and mountain architecture conducted in recent years by a research group from the Politecnico di Torino, under the scientific direction of Silvia Beltramo.
The restoration works on Ka’ D-Mezanis were completed in 2018 and were carried out by applying a careful and conservative approach that made it possible to recover the constructive and decorative elements of the house. The works also offered the chance to reflect on the cultural heritage of the area, for both the local community and the public administration.
It became clear that there was a need for an in-depth study of the historical tissue of the settlement, in order to appraise the feasibility of undertaking careful and sustainable renovation, in the light of the available economic resources and the architecture that was preserved.
The research project covered the following main topics: a critical analysis of the building techniques and materials used at Ka’ D-Mezanis, to constitute a reference case study; a detailed survey of the masonry through stratigraphic analysis of the architecture; a study of other buildings with similar constructive and formal solutions in the territory of Valchiusella; and cataloguing of the historical urban landscape of the municipality of Rueglio by investigating functions and construction techniques with the definition of an abacus of masonry.
The results of the ongoing research are presented to the scientific community as a starting point for shared reflections that can direct further development of the study and open up international collaborations
Thermoplastic polyurethane/glass fabric composite laminates: Low velocity impact behavior under extreme temperature conditions
No full textThis paper reports the low velocity impact behavior of thermoplastic laminated structures based on thermoplastic polyurethane reinforced with woven glass fiber highlighting effects related to sample thickness and test temperature with the aim to verify their potential applications. Plaques obtained by film stacking and compression molding technologies are tested using an instrumented falling dart machine at room temperature, −25 °C and −50 °C. Impact results are reported in terms of typical load-deflection and energy-time curves, but also discussed with reference to the well known ductility index (DI) parameter. As expected, the cooling is reflected in an increased stiffness of tested specimens and their higher propensity to the damage. Increases of plate thickness and reductions of the test temperature lead to enhanced friction phenomena at the material-dart contact, responsible of significant deviations from well established semi-empirical models about the Hertz contact force and the penetration energy. Finally, no delamination phenomena seem to be verified for all investigated samples as supported by visual inspections of front and rear impacted areas
Fused filament fabrication of polylactic acid/flax composites: Effects of infill strategy on dynamic and static behavior and energy consumption
No full textFused Filament Fabrication (FFF) is one of the most widely used Additive Manufacturing (AM) techniques, employing thermoplastic filament to create components. Among its many process parameters, the infill pattern plays a crucial role in determining both the mechanical performance and environmental footprint of printed parts, particularly in energy dissipation and damage behavior under impact. In this context, Natural Fiber Composites (NFCs), such as PLA reinforced with flax, are gaining interest due to their renewable origin, yet their low-velocity impact response and overall process sustainability remain underexplored. This study addresses these gaps by investigating the influence of infill pattern on the flexural and impact behavior of FFF-printed flax-reinforced PLA, while also assessing energy consumption during printing through a gate-to-gate Life Cycle Assessment (LCA). Results show that reducing the infill density of the Solid pattern by 20% leads to a 7.52% reduction in printing energy under constant conditions. Among all tested patterns at 80% infill, the Triangular pattern emerged as the most balanced option, offering favorable mechanical performance with a relatively low environmental impact. These insights aim to support more sustainable design strategies for prototyping and non-structural applications involving biocomposites produced by FFF
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