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In the last decades, the demand and use of renewable energies have been increasing. The increase in renewable energies, particularly wind energy, leads to the development and innovation of powerful wind energy converters as well as increased production requirements. Hence, a higher supporting structure is required to achieve higher wind speed with less turbulence. To date, the onshore wind towers with tubular connections are the most used. The maximum diameter of this type of tower is limited by transportation logistics. The purpose of this paper is to propose an alternative wind turbine lattice structure based on half-pipe steel connections.

In this study, a new concept of steel hybrid tower has been proposed. The focus of this work is the development of a lattice structure. Therefore, the geometry of the lattice part of the tower is assessed to decrease the number of joints and bolts. The sections used in the lattice structure are constructed in a polygonal shape. The elements are obtained by cold forming and bolted along the length. The members are connected by gusset plates and preloaded bolts. A numerical investigation of joints is carried out using the finite element (FE) software ABAQUS.

Based on the proposed study, the six “legs” solution with K braces under 45° angle and height/spread ratio of 4/1 and 5/1 provides the most suitable balance between the weight of the supporting structure, number of bolts in joints and reaction forces in the foundations, when compared with four “legs” solution.

In this investigation, the failure modes of elements and joints of an alternative wind turbine lattice structures, as well as the rotation stiffness of the joints, are determined. The FE results show good agreement with the analytical calculation proposed by EC3-1-8 standard.

The aim of the paper is to provide an economically viable solution for the blade repair process. There is a continual increase in the repair market, which requires an increased level of specialised technology to reduce the repair cost and to increase productivity of the process.Design/methodology/approach – This paper introduces the aerospace component defects to be repaired. Current repair technologies including building‐up and machining technology are reviewed. Through the analysis of these available technologies, this paper proposes an integrated repair strategy through information integration and processes concentration.Findings – Provides detailed description and discussion for the repair system, including 3D digitising system, repair inspection, reverse engineering‐based polygonal modelling, and adaptive laser cladding and adaptive machining process.Originality/value – This paper describes a 3D non‐contact measurement‐based repair integration system, and provides a solution to create an individual blade‐oriented nominal model to achieve adaptive repair process (laser cladding/machining) and automated inspection.

IT is a comparatively simple matter to settle down to the quantity production of an aeroplane in a brand new factory where expense is no object when considering the purchase of new machines and the ordering of tools, but it is far different when the factory already exists and has to be adapted to produce a much greater number of machines than had ever been contemplated by its original constructors and when the cost of the original design has to be added to that of tooling and overheads. The production of the Hawker Hurricane 1 affords a striking example of the successful solution of this problem. No one with any knowledge of the Kingston works can do anything but admit that they are not ideal. The buildings are old and at no time has work been slack enough to permit the closing of any one section for its complete rebuilding. Another handicapping feature was the lack of space in the immediate vicinity to allow for expansion. It is these facts that must be understood and appreciated for the true realisation of the work described in the following pages.

A fitting for the attachment of struts, tension members, etc., to spars or like structural members of the type comprising a boom wholly or partly of circular or polygonal cross section and with its edges lying wholly or partly on a circular are, is adapted to be rotated about the axis of the boom and to be fixed in any position within a given range to suit the inclination of the struts, tension members and the like. As applied to a spar comprising a circular boom a, Fig. 1, joined to another boom by a web a1 the fitting comprises a U‐shaped piece b which fits closely to the boom over an are of 180 deg. and is extended downward by parallel arms b1, b2 to form seatings b3, b4 for a iixing bolt c. The side edges of the fitting converge as shown in Fig. 2. Integral lugs d1, d2 are formed with their sides parallel to a radius of the boom and serve for attachment of a strut. Bolt c is passed through a sleeve g of the type described in Specification 352,767 and serves to secure link plates f1, f2, connected by a yoke piece f3 to which a tension member f is attached. The hole for bolt c is formed after the fitting has been assembled and adjusted to correct alignment with the strut and tension member. A similar fitting is described for a polygonal boom, the bolt c being located perpendicular to a diametrally opposed pair of polygonal boom faces. If the lines of force of strut and tension members are not at right‐angles to the bolt c the fitting may be aligned with the strut and the tension member offset on the yoke f3 the links 1, f2 being then made stiffcr. The tension members may be attached to bolt c2 securing a strut c or to bolts in similar lugs. The bolt c in this case passes through a compression member i such as is shown in Fig. 5, and which may extend for some distance along the boom. In a further modification the fitting a embraces the boom over a greater are than 180 deg. and is therefore made in two halves with a division between the lugs d1, d2. In a still further modification, Fig. 5, the fitting b is similarly shaped to the foregoing but is of sufficient internal diameter to slip over the boom on which it is located by shaped packing pieces h1, h2 and by bolt c. Bracing members may be attached to the boom by angle brackets having a part j fixed to the outer side of the fitting b and having a radially extending arm j1 to which a member such as k is fixed.

In the two short sections which close Chapter VII, an improved ring programme is developed which allows i.a. for the application of externally applied moments on the ring vertices and a preliminary and tentative extension of the analysis takes into account the bending stiffness of some of the flanges. The final chapter returns to the subject of the uniform, circular section fuselage and develops the theory for the polygonized cross‐section in analytical form. Standard expressions are given for the elements of the D,, matrix and application of the analysis to a simple example suggests that the effect of the polygonization on the accuracy of the stress distribution is insignificant.

The purpose of this paper is to propose and demonstrate a new additive manufacturing approach that breaks the layer-based point scanning limitations to increase fabrication speed, obtain better surface finish, achieve material flexibility and reduce equipment costs.

The freeform additive manufacturing approach conceptually views a 3D article as an assembly of freeform elements distributed spatially following a flexible 3D assembly structure, which conforms to the surface of the article and physically builds the article by sequentially forming the freeform elements by a vari-directional vari-dimensional capable material deposition mechanism. Vari-directional building along tangential directions of part surface gives surface smoothness. Vari-dimensional deposition maximizes material output to increase build rate wherever allowed and minimizes deposition sizes for resolution whenever needed.

Process steps based on geometric and data processing considerations were described. Dispensing and forming of basic vari-directional and vari-dimensional freeform elements and basic operations of joining them were developed using thermoplastics. Forming of 3D articles at build rates of 2-5 times the fused deposition modeling (FDM) rate was demonstrated and improvement over ten times was shown to be feasible. FDM compatible operations using 0.7 mm wire depositions from a variable exit-dispensing unit were demonstrated. Preliminary tests of a surface finishing process showed a result of 0.8-1.9 um Ra. Initial results of dispensing wax, tin alloy and steel were also shown.

This is the first time that both vari-directional and vari-dimensional material depositions are combined in a new freeform building method, which has potential impact on the FDM and other additive manufacturing methods.

Power‐operated spherical gun turrets are mounted at the nose and tail ends of an aeroplane fuselage 12. The turret shown in the figure is formed of a spherical frame covered with bulletproof glass and enclosing the gun and gunner. During elevation and depression the gun barrel sweeps through a longitudinal slot 15 giving a large are of fire extending upwardly and downwardly.

The purpose of this paper is to present a new method for representing heterogeneous materials using nested STL shells, based, in particular, on the density distributions of human bones.

Nested STL shells, called Matryoshka models, are described, based on their namesake Russian nesting dolls. In this approach, polygonal models, such as STL shells, are “stacked” inside one another to represent different material regions. The Matryoshka model addresses the challenge of representing different densities and different types of bone when reverse engineering from medical images. The Matryoshka model is generated via an iterative process of thresholding the Hounsfield Unit (HU) data using computed tomography (CT), thereby delineating regions of progressively increasing bone density. These nested shells can represent regions starting with the medullary (bone marrow) canal, up through and including the outer surface of the bone.

The Matryoshka approach introduced can be used to generate accurate models of heterogeneous materials in an automated fashion, avoiding the challenge of hand-creating an assembly model for input to multi-material additive or subtractive manufacturing.

This paper presents a new method for describing heterogeneous materials: in this case, the density distribution in a human bone. The authors show how the Matryoshka model can be used to plan harvesting locations for creating custom rapid allograft bone implants from donor bone. An implementation of a proposed harvesting method is demonstrated, followed by a case study using subtractive rapid prototyping to harvest a bone implant from a human tibia surrogate.

IT was not until the Battle of Britain that Hawker Aircraft Ltd. found, like so many other aircraft firms, that pre‐war repair methods were unsuitable for dealing with the variety and quantity of work which resulted from large‐scale engagements in the air. They discovered that not only were new types of repairs needed but also that more attention had to be paid to the speedy distribution of repair information.

The purpose of this paper is to present a new index of social vulnerability (SV), based on local level data [statistical blocks (SBs)]. This same methodology was applied before at the municipal level, which is a level of analysis that under-evaluates local spots of high SV, by one side, and generalizes the coverage of support capacity equipment and infrastructure. The geographical level of detail of the input data allows to overcome those limitations and better inform infra-municipal risk practitioners and planners.

The assessment of SV in this paper adopts an inductive approach. The research context of this conceptual and methodological proposal derived from the need to operationalize the concept of SV as a planning tool. This approach required to distinguish between the components of criticality and support capability, as their assessment provides knowledge with distinct applications in risk management. The statistical procedure is based on principal components analysis, using the SB as the unit of analysis.

Support capability acts as a counter-weight of criticality. This understanding is well illustrated in the mapping of each component and the final score of SV. The methodological approach allowed to identify the drivers of criticality and support capability in each SB, aiding decision-makers and risk practitioners in finding the vulnerability forcers that require more attention (public or private social equipment, housing policies, emergency anticipatory measures, etc.).

An original approach to SV assessments is the consideration of the components of criticality and support capability. The results allow for the definition of adapted and specific strategies of risk mitigation and civil protection measures to distinct types of risk groups and by different stakeholders and risk practitioners. By predicting the impact and the recovery capacity of communities, the results have applicability in several fields of risk governance as, for example, risk communication and involvement, social intervention (health, education and housing), emergency response, contingency planning, early warning and spatial planning.