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The passive safety in aircraft concerns all measures able to protect the passengers and crew in the event of an accident or emergency. In this context, an important role is played by the design adopted for components inside the passengers' cabin, such as the seats and the interior lining. An effective approach in design of passive safety system is provided by anthropomorphic test devices. In this work, a new design of the interior lining of the fuselage wall has been introduced and its crashworthiness features have been studied through a side impact of an unbelted window‐side passenger. The new proposed interior lining is made with a hybrid sandwich‐based design with a polypropylene honeycomb core able to ensure passive safety for passengers and thermal and acoustic insulation. [ABSTRACT FROM AUTHOR]

Increasing the impact resistance properties of any transport vehicle is a real engineering challenge. This challenge is addressed in this paper by proposing a high-performing structural solution. Hence, the performance, in terms of improvement of the energy absorbing characteristics and the reduction of the peak accelerations, of highly efficient shock absorbers integrated in key locations of a minibus chassis have been assessed by means of numerical crash simulations. The high efficiency of the proposed damping system has been achieved by improving the current design and manufacturing process of the state-of-the-art shock absorbers. Indeed, the proposed passive safety system is composed of additive manufactured, hybrid polymer/composite (Polypropylene/Composite Fibres Reinforced Polymers—PP/CFRP) shock absorbers. The resulting hybrid component combines the high stiffness-to-mass and strength-to-mass ratios characteristic of the composites with the capability of the PP to dissipate energy by plastic deformation. Moreover, thanks to the Additive Manufacturing (AM) technique, low-mass and low-volume highly-efficient shock-absorbing sandwich structures can be designed and manufactured. The use of high-efficiency additively manufactured sandwich shock absorbers has been demonstrated as an effective way to improve the passive safety of passengers, achieving a reduction in the peak of the reaction force and energy absorbed in the safety cage of the chassis' structure, respectively, up to up to 30 kN and 25%. [ABSTRACT FROM AUTHOR]

the passive safety of aircraft passengers is such an important aspect in the design of aircraft structures as strength and fatigue concerns. The development of methods and devices to prevent passenger injuries is the subject of continuous efforts. The mission is to minimize stresses and accelerations on passengers during a crash. Over the years, studies on crash phenomena have been focused on experimental tests, using full-scale structures and Anthropomorphic Test Devices (ATDs) to assess the consequences of impact phenomena on the human body. However, due to the high costs of experimental campaigns and the difficulty of controlling all relevant parameters, the need of efficient numerical models capable of validating experimental data has increased. This is specifically relevant for tests on ATDs. In the frame of this work, the side-impact of an aircraft passenger have been numerically investigated positioned on a window-side seat of an aluminium commercial aircraft fuselage a World SID-based dummy. An attempt to increase the aircraft crashworthiness was made placing in correspondence with the head and the shoulders of the dummy hybrid sandwich shock absorbers. In order to validate the considered dummy model, a lateral impact against a flat barrier has been carried out. The obtained numerical results have been cross-compared with literature experimental data. Then, the side-impact behaviour of the dummy within a fuselage section has been investigated, with the aim to verify the absorption capability of the shock absorbers and to quantify their effect on the safety of the dummy. The employment of the shock absorbers allowed to reduce the acceleration peaks experienced by the dummy's head up to 50%. [ABSTRACT FROM AUTHOR]

Increasing transportation safety can be observed as one of the biggest engineering challenges. This challenge often needs to be combined with the need to deliver engineering solutions that are able to lower the environmental impact of transportation, by reducing fuel consumption. Consequentially, these topics have attracted considerable research efforts. The present work aims to address the previously cited challenges by maximizing the energy absorption capabilities of hybrid aluminum/composite shock absorbers with minimal thickness and mass. This engineering solution makes it possible to lighten vehicles and reduce fuel consumption, without compromising safety, in terms of crashworthiness capabilities. A numerical sensitivity study is presented, where the absorbed energy/mass (AE/m) and the absorbed energy/total panel thickness (AE/Htot) ratios, as a consequence of low-velocity impact simulations performed on six different shock absorbers, are compared. These hybrid shock absorbers have been numerically designed by modifying the core thickness of two basic absorbers' configurations, characterized, respectively, by a metallic lattice core, intended to be produced through additive manufacturing, and a standard metallic honeycomb core. This work provides interesting information for the development of shock absorbers, which should be further developed with an experimental approach. Indeed, it demonstrates that, by integrating composite skins with a very light core producible, by means of additive manufacturing capabilities, it is possible to design shock absorbers with excellent performance, even for very thin configurations with 6 mm thickness, and to provide a significant increase in AE/m ratios when compared to the respective equal volume standard honeycomb core configurations. This difference between the AE/m ratios of configurations with different core designs increases with the growth in volume. In detail, for configurations with a total thickness of 6 mm, the AE/m increases in additive manufacturing configurations by approximately 93%; for those with a total thickness of 10 mm, the increase is 175%, and, finally, for those with a total thickness of 14 mm, the increase is 220%. [ABSTRACT FROM AUTHOR]

The increasing use of composite materials in the aviation industry for the manufacture of higher performance components required the introduction of efficient optimisation methods for the design of composite laminates. Metal-replacement with composites provided the first step in the design of higher performance aviation structures. Nowadays, the additional step is to optimise these structures to make them even more performing and lighter. Mass reduction drives the optimization with number and orientation of plies as main parameters. In this perspective, the Double-Double (DD) laminates approach provided an effective method to optimise composite structures for weight reduction and strength purposes, without restrictions on symmetry and orientation angles. Especially for optimized components, crashworthiness remains a key aspect in evaluating the performance of composite aircraft structures, such as for fuselages. In this work, the crashworthiness features and the dynamic response of a regional fuselage barrel section in a vertical drop test has been numerically investigated performing a comparison between a configuration with conventional composite skin and a configuration with optimized and lightened skin through the Double-Double (DD) approach. The comparison proved that the configuration with the optimised skin has been characterised by adequate performance in terms of crashworthiness and passive safety for passengers, when compared to the conventional configuration. The effectiveness of Double-Double method in designing crashworthy composite components has been demonstrated, while simultaneously reducing the structure's total mass and enabling compliance with restrictive fuel consumption and emission regulations. The employment of optimized skin resulted in a total mass reduction for the whole structure up to 34%, due to mass reduction of the skin of 69.8% with respect to conventional configuration. [ABSTRACT FROM AUTHOR]