Progress in Aerospace Sciences最新文献

This paper reviews the development and state-of-the-art research of attitude control technologies for launch vehicles, as well as the application evaluations of the responsive tolerant control (RTC) technology. First, the control theories and methods related to launch vehicles are classified and surveyed. Although studies in this field are still active, many new methods have not exhibited impressive advantages over a well-tuned gain scheduling-based traditional solution when dealing with a complete rigid–flexible-sloshing model, and few have been adopted for in-flight use. The conservatism in applications stems from the distinctive dynamical characteristics of launch vehicles, which are discussed in detail thereafter. However, as traditional methods also face challenges in meeting the increasing new requirements, an innovative solution, namely RTC, has gradually found its role in robust launch vehicle applications. The RTC differs from the concept of adaptive control in that it has no effect under most conventional operations but responds to certain scenarios in a timely manner, and these scenarios include unmodeled modes, unforeseen disturbances far beyond prescribed limits, and unexpected failures where the fundamental assumptions implied in the feedback control theories or design guidelines are violated. After introducing a practical architecture of RTC, three methods are reviewed and their limitations are analyzed: an adaptive gain and damping adjustment method to deal with unmodeled modes, an angular-acceleration-based active load-relief method to reduce bending moments, and online identification and reconstruction of the command mapping relationship to counter the polarity errors. The RTC introduced in the paper has been validated from an applied and computational domain by flights or simulations with high fidelity, thus effectively improving the robustness and the adaptability of launch vehicles.

Lattice structures, produced by repeated unit cells in the particular pattern, offer a high strength-to-weight ratio. The current advancement in Additive manufacturing (AM) technology, creating complex geometries like lattice structures has revolutionized production across various industries. While several reviews have focused on different specific aspects of lattice structures, a comprehensive overview of recent advancements of lattice in aerospace structural applications is lacking.

Therefore, a comprehensive review of lattice structures used in aerospace lightweight applications manufactured through AM is presented here. Basic classification of lattice structure is presented followed by detailed study of several factors influencing mechanical properties of lattice structures, crucial for aerospace lightweight application. Current trends in manufacturing technologies of lattice structures are analyzed in detail with identification of capabilities and limitations. Furthermore, detailed literature on the lattice structure optimization techniques is presented with current limitations. Furthermore, the engineering applications of lattice structures in aerospace lightweight, along with the fabrication processes involved, challenges in applications of lattice in aerospace applications and future research directions are reported.

By providing insights into current research trends and future directions, this review serves as a valuable resource for researchers and engineers involved in the design and development of lightweight aerospace lattice structures. It lays the groundwork for the exploration of new and innovative lattice structures tailored to meet the evolving needs of the aerospace industry.

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%.

Airplanes are inevitably subjected to various impact loading conditions in the event of emergency landing. An airplane crash scenario is a complex nonlinear impact event which involves large deformation, material fracture, structural failure, and dynamic contact. The impact response becomes more complicated due to the presence of composite materials, which are becoming the dominated choice for aircraft components. However, the impact damage and failure severity of composite fuselage sections can be effectively alleviated with optimized energy absorbing (EA) design. Accordingly, the crashworthy design of fuselage sections has always remained a top priority to prevent catastrophic structural failure and significant casualties. This paper presents a systematic literature review on the impact response and EA design of composite fuselage structures. Firstly, the typical composite materials such as composite tubes, corrugated composite plates, hybrid composite structures and bio-inspired composite materials are introduced to dissipate the impact kinetic energy during a crash. Then, the analytical models and finite element modeling methods of composite bolted joint structures are described to investigate their impact response and failure mode. The crashworthy design of typical composite fuselage structures including sub-cargo support struts, cabin floor support struts, fuselage frame and cabin floor/fuselage frame connection are described in this paper. Finally, an emphasis is placed on the evaluation criteria of the occupant crash safety and the crashworthy evaluation method of fuselage structures.

Crashworthiness is the ability of civil aircraft fuselage structure and internal systems to maximum protect the occupants’ safety in a crash or emergency landing event, and is an important embodiment of the civil aircraft safety, which can determine the occupant survivability to a certain extent. The crashworthiness is dominated by the crash response characteristics of typical fuselage section (including occupant/seat restraint system), and the crashworthiness evaluation mainly includes fuselage structural response evaluation and occupant injury evaluation. Firstly, the crashworthiness requirements are sorted out according to the Airworthiness Standards of transport category airplanes and Special Conditions, and the research work on drop tests and crashworthiness numerical simulation of fuselage section are gathered. Then, the failure of typical skin-stringer-frame structures and fuselage section are analyzed, and the crash safety evaluation criteria are summarized. After that, the impact tolerance of various parts of human (head, neck, thoracic, spine, abdomen, extremity) and the occupant injury evaluation criteria are summarized. In addition, the crashworthiness design principles and design methods of fuselage section are outlined for occupant survivability. Finally, the crashworthiness evaluation under different crash factors and conditions (impact velocity, impact ground, cargo loading and aircraft wing position) are summed up, and the aircraft crashworthiness is comprehensively evaluated through integrating the survivable volume, the retention strength, the occupant injury and the emergency evacuation, and the crashworthiness evaluation process is outlined. This article is intended as a comprehensive literature review of crashworthiness design and evaluation of fuselage structure for occupant survivability.

The crashworthiness of a structure is a measure of its protective capability under dynamic events by absorbing the crash energy in a controlled way. Fiber reinforced composite materials can represent a valid alternative to ductile metals as impact energy absorbers in a crashworthy structure. In fact, composites are characterized by high mechanical properties coupled with low weight, capability to be designed by tailoring the specific requirements and good energy absorption capabilities. However, the impact resistance and the damage modes of long fiber composites involve different factors (constituent materials, geometry, lay up, manufacturing process) and are difficult to predict. In addition, there are no standard experimental procedures to assess the crashworthiness of composite materials. Therefore, a large and proper experimental characterization on composites with different geometries can be useful to understand the failure mechanisms under dynamic loads.

In this work, three different kinds of carbon fiber epoxy composites have been realized by vacuum infusion process in order to investigate the effect of the width and the shape. In particular, two plane and one C-shaped composites have been manufactured and characterized with Charpy test at different impact velocity according to the three-point bending procedure. Further, in-plane compression tests on larger flat composites have been performed by using an anti-buckling fixture to evaluate the specific Energy Absorption (SEA). Results evidenced the effect of the impact velocity on the impact resistance, the greatest rigidity of the c-shaped composite and the damage modes.

One of the most critical air transportation issues is the passengers' protection during collision and impact events that must be absorbed in a controlled way in order to reduce damages. The capability of an aircraft to eliminate injuries in relatively mild impacts and to reduce severe effects on occupants in critical crashes is called crashworthiness. The crashworthiness is the ability of a structure to protect occupants during dynamic events. It is usually measured by the capacity of a structural system to dissipate kinetic impact energy by itself, by means of a controlled and predictable deformation aimed to minimize stresses and accelerations on passengers during a crash. In aeronautical applications, the crashworthiness is dominated by the crash response characteristics of typical fuselage sections (including occupant/seat restraint system), and the crashworthiness evaluation mainly includes fuselage structural response evaluation and occupants’ level of injury evaluation. This special issue consists of four papers, starting with a review of the crashworthiness design and evaluation aspects of civil aircraft fuselage structures, followed by a review of the impact response characteristics and the crashworthy design principles for composite fuselage structures. The third paper addresses the issue of the lack of standard experimental procedures to assess the crashworthiness of composite structures whereas the fourth paper describes a numerical model for the simulation of the side impact of an aircraft passenger.