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In recent decades, composite materials have been widely used in several fields. The challenge in recent years has been to find an effective and automatable repair technique for these materials. Low-speed impact tests were carried out on panels made from prepregs in carbon fibre and epoxy resin. An innovative repair technique has been tested by injecting resin into the delamination due to the impact event. After the first impact, some panels were repaired and re-impacted, while others were impacted twice consecutively. The data analysis and damage detection by an ultrasound technique demonstrate that the absorbed energy of the twice-impacted panels is lower than that of the repaired ones, demonstrating a configuration similar to that of the panels impacted only once. The results of this research have demonstrated the effectiveness of the repairs. [ABSTRACT FROM AUTHOR]

The transport industry is one of the most important for society and its economic growth. In Europe, this is especially true for road transport, which is an essential pillar for employment, trade, and economic development. The challenge is to minimize energy and cost and maximize efficiency while ensuring comfort and safety. This is the driving force behind technological progress that with social changes (such as, changing consumer preferences, greater environmental awareness) and political changes is revolutionizing the way people and goods move. Nevertheless, the selection of lightweight materials is negligible; it could involve new manufacturing technologies and joining techniques. Jaguar Land Rover (JLR) has been one of the prominent car producers employing aluminum alloys since 2003. A typical JLR monocoque is characterized by 90% aluminum stampings components made of 5xxx and 6xxx series aluminum alloys. Audi Space Frame (ASF) represents an alternative interpretation of improved lightweight frame architecture, and it is characterized by aluminum for more than 80% with the residual parts in CFRP used for rear panels, tunnel and the components useful to higher torsional stiffness. A 30% weight decrease is reached with respect to traditional steel corresponding elements. This review shows an overview of the challenges and opportunities for automotive body structures in the coming years while maintaining the goal of reducing mass and improving sustainability without increasing costs and impacting safety. This manuscript first evaluates how we can reduce mass in vehicles minimizing the carbon footprint and developing recyclable structures. The potential of new materials will be shown in light of the design constraints and the choice of technology used. The final remarks will discuss opportunities for engineering innovation dictated by this period of great changes and needs. [ABSTRACT FROM AUTHOR]

In this work, carbon fiber-reinforced composites (CFRP), respectively, based on a vynilester and epoxy resin were loaded under low-velocity impact condition to highlight the influences of different matrices and temperature on their dynamic response. In particular, measurements were performed at room and the low temperature of -25[degrees]C on samples simply supported by air to exactly simulate the incidental impact during the structure service and having the same thickness. Impact tests were carried out at penetration to obtain the complete load-displacement curve and to measure the penetration energy, and at different energy levels, 5, 10, and 20 J, to investigate the influence of the matrix on the damage start and propagation. After the impact tests, the specimens were nondestructively investigated by the ultrasound technique to measure the delamination. The interesting results obtained on carbon fiber laminates impacted at room and lower temperature are here reported and compared. In general, better behavior was noted for vinyl ester-based composites, extensively used in the naval field, thanks to their low absorption for humidity., INTRODUCTION Carbon fiber-reinforced composites (CFRP) materials are widely used to replace traditional ones in several fields, recently in naval and aerospace in particular, thanks to their functional and structural properties. [...]

The rheology of the polymer matrix plays a crucial role in determining the quality of thermoplastic laminates. To highlight this aspect, we prepared laminates based on polyamide 11 (PA11), a bio-based matrix with tricky rheology, and basalt fiber fabrics. The PA11 viscosity rapidly increases over time due to degradation phenomena. Samples were prepared by two procedures differing in terms of duration and intensity of the hot compaction step. Morphological analyses revealed that the fast procedure ensures a better impregnation of the fabrics, with a substantial reduction of the volume of voids (1%, against 9% of the slow procedure). This reflects in considerable increases of the flexural modulus (ca. + 20%) and strength (ca. + 60%) and a significant reduction the extent of impact damage. This study provides useful guidelines for a correct selection of the processing parameters based on the knowledge of the rheological behavior of the polymer matrix. [ABSTRACT FROM AUTHOR]

The complexity of the damage behavior of composite materials due to the simultaneous evolution of different mechanisms involving matrixes, reinforcements and interfaces is a topic which, despite decades of knowledge, still requires specific insights and is the subject of a multitude of researches. Recently, with the attention increasingly directed towards biobased raw materials, these aspects have shown a renewed interest, prompting the need for further contributions. In this context, this experimental research work aims to investigate the damage behavior of laminate structures based on a commercial polyamide obtained from castor oil, reinforced with woven basalt fibers. The focus was on samples obtained by hot compaction using two different pressure profiles and subjected to low velocity impacts with different impact energies. Damage analysis was performed on impacted specimens using ultrasonic phased array inspections and pulsed thermography. The non-destructive analysis supported low velocity impact test results, confirming the different contribution of the damage mechanisms involved, as expected from the different level of compaction of the materials, in turn due to diverse manufacturing conditions. This research has emphasized the complementarity and effectiveness of these two nondestructive characterization techniques, providing potentially useable results for the optimal design and manufacturing of biocomposite systems. [ABSTRACT FROM AUTHOR]