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This paper's aim is to focus on the design, manufacture and test of a stiffened panel in composite material with integrated longitudinal foam‐filled stiffeners, spar and rib caps, using one‐shot liquid infusion (LI) process, reducing weight and number of subparts respect to metallic reference baseline P180 Avanti vertical fin.

Extensive activities in computational applications in order to improve the efficiency of the design process finite element analysis/structural sizing codes have led to an optimised engineering design process that resulted in a successful stiffened carbon fibre reinforced polymer panel design in terms of weight and number of parts with respect to the metallic baseline.

The composite panel has fulfilled all the design requirements (reduction of mass and number of parts with respect to the metallic reference baseline) overcoming the certification static test, and confirming the reliability of the theoretical analyses.

The composite aircraft components, conceived as unitized structure by one‐shot process, guarantee not only a mass reduction, compared to aluminium components, but assure also the reduction of the number of subparts and of the assembly process cycle time. On the other hand, the LI technology implies the development of more specific and advanced techniques to control the manufacturing and the weight.

The stiffened panel is the most used component in the aircraft structures; the solution shown in this work can find applications in many parts of an aircraft.

The results obtained in this work can be useful to those who work in aeronautical structural departments with the aim to reduce weight and subparts of the airframe.

A conceptual design method for composite material stiffened panels used in aircraft tail structures and unmanned aircraft has been developed to bear compression and shear loads.

The method is based on classical laminated theory to fulfil the requirement of building a fast design tool, necessary for this preliminary stage. The design criterion is local and global buckling happen at the same time. In addition, it is considered that the panel does not fail due to crippling, stiffeners column buckling or other manufacturing restrictions. The final geometry is determined by minimising the area and, consequently, the weight of the panel.

The results obtained are compared with a classical method for sizing stiffened panels in aluminium. The weight prediction is validated by weight reductions in aircraft structures when comparing composite and aluminium alloys.

The work is framed in conceptual design field, so hypotheses like material or stiffeners geometry shall be taken a priori. These hypotheses can be modified if it is necessary, but even so, the methodology continues being applicable.

The procedure presented in this paper allows designers to know composite structure weight of aircraft tails in commercial aviation or any lifting surface in unmanned aircraft field, even for unconventional configurations, in early stages of the design, which is an aid for them.

The contribution of this paper is the development of a new rapid methodology for conceptual design of composite panels and the feasible application to aircraft tails and also to unmanned aircraft.

Regarding the assembly of the fuselage panel, this paper aims to illustrate a design of pre-assembly tooling of the fuselage panel for the automatic drilling riveting machine. This new prototype of pre-assembly tooling can be used for different types and sizes of fuselage panels. Also, apply to the automated drilling and riveting machine of the fuselage panels.

Based on the different structures of the fuselage panel, the position of the preassembly tooling components, location of the clamp and position of the fuselage panel are determined. After that, the overall structure of the preassembly tooling is designed, including the movable frame and the cardboard. The cardboard positioning module and the clamping module formulate a detailed design scheme of preassembly tooling for the fuselage panel. The structure of the pre-assembled tooling is optimized by static analysis. The result of the overall design is optimized by using MATLAB and CATIA-V5 software, and the results meet the condition of the design requirements.

The traditional assembly process of the fuselage is to install the fuselage panel on the preassembly tooling for positioning the hole and then install it on the automated drilling and riveting tooling for secondary tooling. Secondary tooling can consume assembly errors of the fuselage panel. The new prototype of flexible tooling design for the fuselage panel not only avoids the secondary tooling error of the fuselage panel but also meets the preassembly of different types of fuselage panels.

The further development of the flexible tooling design of the fuselage panel is to reduce the error of sliding tooling due to friction of the sliding components. Because if the assembly cycle is increased, the sliding parts will lose material due to corrosion. As a result, the repeated friction force is the root cause of the positioning error of sliding parts. Therefore, it is necessary to engage less corrosive material. Also, the lubricant may be used to reduce the corrosion in minimizing the positioning error of the sliding tool components. In addition, it is important to calculate the number of assembly cycles for efficient fuselage panel assembly.

According to the structure and assembly process characteristics of the fuselage panel, the fuselage panel preassembly tooling can optimize the assembly process of the fuselage panel and have certain practical application values.

Describes preliminary structural design work on a notional uninhabited tactical aircraft (UTA), carried out at Cranfield University. UTAs are seen as an important future element of military fleets. A notional baseline requirement was derived, leading to the evolution of a design solution. The basic requirements for such a UTA are naturally highly classified but, although industry has been hesitant to comment, the baseline requirements and design solution developed herein are believed to be reasonable.

Purpose — This study proposes an optimal survey design method for multi-day and multi-period panels that maximizes the statistical power of the parameter of interest under the conditions that non-linear changes in response to a policy intervention over time can be expected.

Design/methodology/approach — The proposed method addresses balances among sample size, survey duration for each wave and frequency of observation. Higher-order polynomial changes in the parameter are also addressed, allowing us to calculate optimal sampling designs for non-linear changes in response to a given policy intervention.

Findings — One of the most important findings is that variation structure in the behaviour of interest strongly influences how surveys are designed to maximize statistical power, while the type of policy to be evaluated does not influence it so much. Empirical results done by using German Mobility Panel data indicate that not only are more data collection waves needed, but longer multi-day periods of behavioural observations per wave are needed as well, with the increase in the non-linearity of the changes in response to a policy intervention.

Originality/value — This study extends previous studies on sampling designs for travel diary survey by dealing with statistical relations between sample size, survey duration for each wave, and frequency of observation, and provides the numerical and empirical results to show how the proposed method works.

Although vacuum insulation panels (VIPs) are thermal insulators that combine high thermal performance with limited thickness, application in the building sector is still rare due to lack of scientific knowledge on the behaviour of these panels applied in building constructions. This paper, therefore, seeks to give an overview of the requirements for and the behaviour of VIPs integrated into building components and constructions. Moreover, the interaction between different requirements on and properties of these integrated components are discussed in detail, since a desired high quality of the finished product demands an integral approach regarding all properties and requirements, especially during the design phase. Therefore, the importance of an integral design approach to application of VIPs is shown and emphasized in this paper.

To achieve this objective, the legally and technically required properties of VIPs and especially their interrelationships have been studied, resulting in a relationship diagram. Based on these investigations of thermal‐ , service life‐ and structural‐properties have been selected to be studied more elaborately using experimental set‐up for structural testing and simulation software for thermal and hygrothermal testing.

Two relationships between requirements or properties were found to be of principal importance for the design of façade components in which VIPs are integrated. First, thermal performance requirements strongly interact with structural performance, principally through the edge spacer of this façade component. A high thermal performance requires minimization of the thermal edge effect, in most cases reducing the structural performance of the entire panel. Second, an important relationship between thermal performance and service life has been recognised. The operating phenomenon mainly governing this interaction is thermal conductivity aging.

Most research in the field of vacuum insulation until now has been directed towards gaining knowledge on specific properties of the product, especially on thermal and hygrothermal properties. The relationships and interactions between these properties and the structural behaviour, however, have been neglected. This paper, therefore, addresses the need for an integral design (and study) approach for the application of VIPs in architectural constructions.

A new approach to the problem of minimum‐weight design of stiffened compression panels is presented. It is predominantly based on the plate instability mode in which the sheet and stiffeners, having been stressed to the same degree, simultaneously buckle over a long wavelength with the length of a buckle equal to the pin‐ended length of a panel. Charts to determine the buckling stresses of the modes required for the minimum‐weight design are given. Formulae and charts are presented to compute the effective moment of inertia of a stiffener, a most important quantity, over a wide range of panel proportions, for Z‐section and integrally machined unflanged stiffeners. The principles of minimum‐weight design are discussed and illustrated by the lightest Z‐stiffener panels selected from extensive test data. Comparison of the theoretical stresses of the optimum panels and many other panels of different proportions with those obtained by tests shows good agreement. The principle of dimensional similarity, which is implicit in the buckling mode referred to above, eliminates the effects of size. Results obtained either from theory or tests can therefore be applied to different size panels of like proportions.

Material-based computation has been recently introduced in architectural education, where parameters and rules related to materials are integrated into algorithmic thinking. The authors aim to identify affordances of material-based computation in terms of supporting the understanding of parametric design, informing the process of parametric form finding in an educational setup and augmenting student learning outcomes.

The authors propose a material-informed holistic systems design framework for parametric form finding. The authors develop a pedagogical approach that employs material-based computation focusing on the interplay between the physical and the digital in a parametrically driven façade design exercise. The approach comprises two phases: (1) enabling physical exploration with different materials to arrive at the design logic of a panel prototype and (2) deducing embedded and controlled parameters, based on the interplay of materials and deriving strategies for pattern propagation of the panel on a façade composition using variation and complexity.

The results confirmed the initial hypothesis, where the more explicit the material exploration and identification of physical rules and relations, the more nuanced the parametrically driven process, where students expressed a clear goal oriented generative logic and utilized parametric design to inform form finding as a bottom-up approach.

Most precedent approaches developed to teach parametric design concepts in architectural education have focused on universal strategies that often result in fixating students on following standard blindly followed scripts and procedures, thus defying the purpose of a bottom-up form finding framework. The approach expands the pedagogical strategies employed to address parametric design as a form finding process.

Real flight is cognitively demanding; accordingly, both indicators and display panel layout should be user-friendly to improve pilot-aircraft interaction. Poor pilot-interface interactions in aircrafts could result in accidents. Although a general reason of accidents is improper displays, relatively few studies were conducted on interfaces. This study aims to present an optimization model to create intuitively integrated user-friendly cockpit interfaces.

Subjectivity within most usability evaluation techniques could bring about interface design problems. A priori information about indicator’s possible locations may be available or unavailable. Thus different analytical approaches must be applied for modifications and new interface designs. Relative layout design (RLD) model was developed and used in new interface designs to optimize locations of indicators. This model was based on layout optimization and constructed in accordance with design requirements, ergonomic considerations with the pilot preferences. RLD model optimizes interface design by deploying indicators to the best locations to improve usability of display panel, pilot-aircraft interaction and flight safety.

Optimum interfaces for two problem instances were gathered by RLD model in 15.77 CPU(s) with 10 indicators and 542.51 CPU(s) with 19 indicators. A comparison between relative and existing cockpit interfaces reveals that locations of six navigation and four mechanical system indicators are different. The differences may stem from pilots’ preferences and relativity constraints. Both interfaces are more similar for the central part of the display panel. The objective function value of relative interface design (Opt: 527938) is far better than existing interface (737100). The RLD model improved usability of existing interface (28.61 per cent considering decrease in the objective function values from 737100 to 527938.

Future cockpit and new helicopter interface designs may involve RLD model as an alternative interface design tool. Furthermore, other layout optimization problems, e.g. circuit boards, microchips and engines, etc. could be handled in a more realistic manner by RLD model.

Originality and impact of this study related to development and employment of a new optimization model (RLD) on cockpit interface design for the first time. Engineering requirements, human factors, ergonomics and pilots’ preferences are simultaneously considered in the RLD model. The subjectivity within usability evaluation techniques could be diminished in this way. The contributions of RLD model to classical facility layout models are relativity constraints with the physical constrictions and ergonomic objective function weights. Novelty of this paper is the development and employment of a new optimization model (RLD) to locate indicators.

The genetic algorithm (GA) technique is widely used for the optimization of stiffened composite panels. It is based on sequential execution of a number of specific operators, including the encoding of particular design variables. For instance, in the case of a stiffened composite panel, the design variables that need to be encoded are: the number of plies and their stacking sequences in the panel skin and stiffeners. This paper aims to present a novel, implicit, heuristic approach for encoding composite laminates and, through its use, demonstrates an improvement in the optimization process.

The stiffened panel optimization has been formulated as a constrained discrete minimum-weight design problem. GAs, which use both new encoding schemes and those previously described in the literature, have been used to find near-optimal solutions to the formulated problem. The influence of the new encoding scheme on the searching capabilities of the GA has been investigated using comparative analysis of the optimization results.

The new encoding scheme allows the definition of stacking sequences in composites using shorter symbolic representations as compared with standard encoding operators and, as a result of this, a reduction in the problem design space. According to numerical experiments performed in this work, this feature enables GA to obtain near-optimal designs using smaller population sizes than those required if standard encoding schemes are used.

The approach to encoding laminates presented in this paper is based on the original heuristics. In the context of GA-based optimization of stiffened composite panels, the use of the new approach rather than the standard encoding technique can lead to a significant reduction in computational time employed.