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The purpose of this paper is to present experimental investigations on the structural behaviour of composite sandwich panels for civil engineering applications. The performance of two different core materials – rigid plastic polyurethane (PU) foam and polypropylene (PP) honeycomb – combined with glass fibre reinforced polymer (GFRP) skins, and the effect of using GFRP ribs along the longitudinal edges of the panels were investigated.

The experimental campaign first included flatwise tensile tests on the GFRP skins; edgewise and flatwise compressive tests; flatwise tensile tests on small‐scale sandwich specimens; and shear tests on the core materials. Subsequently, flexural static and dynamic tests were carried out in full‐scale sandwich panels (2.50×0.50×0.10 m³) in order to evaluate their service and failure behaviour. Linear elastic analytical and numerical models of the tested sandwich panels were developed in order to confirm the effects of varying the core material and of introducing GFRP ribs.

Tests confirmed the considerable influence of the core, namely of its stiffness and strength, on the performance of the unstrengthened panels; in addition, tests showed that the introduction of lateral reinforcements significantly increases the stiffness and strength of the panels, with the shear behaviour of strengthened panels being governed by the ribs. The unstrengthened panels collapsed due to core shear failure, while the strengthened panels failed due to face skin delamination followed by crushing of the skins. The models, validated with the experimental results, allowed simulating the serviceability behaviour of the sandwich panels with a good accuracy.

The present study confirmed that composite sandwich panels made of GFRP skins and PU rigid foam or PP honeycomb cores have significant potential for a wide range of structural applications, presenting significant stiffness and strength, particularly when strengthened with lateral GFRP ribs.

The purpose of this paper is to discuss the application of THz spectroscopy for the inspection and evaluation of the internal structure of complex samples with honeycomb fillers.

Three complex samples with honeycomb fillers are investigated using THz spectrometer in order to determine the applicability of chosen non-destructive method for the analysis of internal structure of structural components. The first analysed sample has aluminium honeycomb filler with some cells filled with water. The aim of the analysis is to distinguish empty and full cells. The other two sandwich samples are made of different non-metallic components and for them the possibility of THz spectroscopy application is analysed.

The empty and full cells in metal honeycomb filler were easily distinguished due to different absorption coefficients of electromagnetic waves in THz range for air and water. It was especially visible for frequency domain. The THz spectroscopy was able to inspect the non-metallic samples internal structures and distinguish skins (with layers), honeycomb fillers and adhesive layers between them. It was also possible to detect, localise and determine the size of a local damage of honeycomb walls due to impact influence.

The present study is an original research work. There are very limited literature papers which present analyses of internal structures of sandwich elements using THz spectroscopy and investigate utility of the method for mechanical damage and contamination (water) detection and localisation.

The purpose of this paper is to provide an overview of the design and experimental work of compliant wing and wingtip morphing devices conducted within the EU FP7 project NOVEMOR and to demonstrate that the optimization tools developed can be used to synthesize compliant morphing devices.

The compliant morphing devices were “designed-through-optimization”, with the optimization algorithms including Simplex optimization for composite compliant skin design, aerodynamic shape optimization able to take into account the structural behaviour of the morphing skin, continuum-based and load path representation topology optimization methods and multi-objective optimization coupled with genetic algorithm for compliant internal substructure design. Low-speed subsonic wind tunnel testing was performed as an effective means of demonstrating proof-of-concept.

It was found that the optimization tools could be successfully implemented in the manufacture and testing stage. Preliminary insight into the performance of the compliant structure has been made during the first wind tunnel tests.

The tools in this work further the development of morphing structures, which when implemented in aircraft have potential implications to environmentally friendlier aircrafts.

The key innovations in this paper include the development of a composite skin optimization tool for the design of highly 3D morphing wings and its ensuing manufacture process; the development of a continuum-based topology optimization tool for shape control design of compliant mechanisms considering the stiffness and displacement functions; the use of a superelastic material for the compliant mechanism; and wind tunnel validation of morphing wing devices based on compliant structure technology.

Aircraft wings, one of the most important parts of an aircraft, have seen changes in its topological and design arrangement of both the internal structures and external shape during the past decades. This study, a numerical, aims to minimize the weight of multilaminate composite aerospace structures using multiobjective optimization.

The methodology started with the determination of the requirements, both imposed by the certifying authority and those inherent to the light, aerobatic, simple, economic and robust (LASER) project. After defining the requirements, the loads that the aircraft would be subjected to during its operation were defined from the flight envelope considering finite element analysis. The design vector consists of material choice for each laminate of the structure (20 in total), ply number and lay-up sequence (respecting the manufacturing rules) and main spar position to obtain a lightweight and cheap structure, respecting the restrictions of stress, margins of safety, displacements and buckling.

The results obtained indicated a predominance of the use of carbon fiber. The predominant orientation found on the main spar flange was 0° with its location at 28% of the local chord, in the secondary and main web were ±45°, the skins also had the main orientation at ±45°.

The key innovations in this paper include the evaluation, development and optimization of a laminated composite structure applied to a LASER aircraft wings considering both structural performance and manufacturing costs in multiobjetive optimization. This paper is one of the most advanced investigations performed to composite LASER aircraft.

The systems aspects of an uninhabited tactical aircraft (UTA) preliminary design are detailed. The study, performed at the post‐graduate level at Cranfield University, looks to investigate the feasibility of unmanned combat aircraft in a number of roles to reduce the risk to pilots and reduce life cycle costs (LCC). The scope of the work includes stealth, vulnerability, mission effectiveness, avionics, landing gear, secondary power, fuel systems, propulsion, performance and cost. The unusual depth to which the design work progressed enables insights to be gained that far exceed those available at the conceptual design phase. A Northrop Grumman concept of near‐identical configuration has subsequently reached the public domain.

Aircraft structure mass estimation is a very important issue in aerospace. Multiple methods of different fidelity are available, which give results with varying accuracy. Sometimes these methods are giving a high discrepancy of estimated mass compared to the real mass of the structure. The discrepancy is especially noticeable in the case of small aircraft with a composite structure. Their mass properties highly depend not only on the material but also on technology and the human factor. Moreover, methods of mass estimation for unmanned aerial vehicle (UAV) platforms are even less established and examined. The purpose of this paper is to present and discuss various methods of mass estimation.

The paper presents different procedures of mass estimation for small UAVs with a composite structure. Beginning from the simplest one, where mass is estimated basing on a single equation and finishing with a mass estimation based on finite element method model and three-dimensional computer-aided design model. The results from all methods are compared with the airworthy aircraft and conclusions are discussed.

Mass of flying aircraft was estimated with different methods and compared. It revealed levels of accuracy of the investigated methods. Moreover, the influence on structure mass of human factor, glueing and painting is underlined.

Mass of the structure is a key factor in aerospace, which influences the performance of the aircraft. Thorough knowledge about the accuracy of the mass estimation methods and possible sources of discrepancies in mass analyses provides an essential tool for designers, which can be used with confidence and allows for the development of new cutting-edge constructions.

There are very few comparisons of mass estimation methods with an actual mass of manufactured and functional airframes. Additionally, mass estimation inaccuracies based on technological issues are presented, which is seldom done.