'Winning While Losing:' Borneo Headquarters and the End of Confrontation, June-November 1966

From 1963 to 1966 Britain fought an undeclared war against Indonesia in the jungles of Borneo. Existing accounts of the tactical outcomes of this campaign take at face value the comments produced after the event by such key individuals as Sir Walter Walker, until March 1965 the British Director of Borneo Operations, who regarded the campaign as ‘a complete success’. This article demonstrates that this narrative is a retrospective judgement and that senior British officers at the time regarded the conclusion of the campaign as a success for Indonesia. </jats:p

Valorisation of lignin by depolymerisation and fractionation using supercritical fluids and conventional solvents

A procedure for Lignosulphonate valorisation is investigated. An attempt has been made to obtain diverse value-added products maximizing the atom economy. This procedure is carried in sequential steps starting with an oxidative depolymerization in supercritical water. Next, the reaction mixture is fractionated according to its solubility in water and in ethyl acetate. Several analytical methods - CHN elemental analysis, aqueous GPC and 31P-NMR - were used to determine the composition of these fractions and to assess their suitability for different applications. Water-insoluble fractions were converted to a lignin-derived hydrochar for the synthesis of active carbon of superior quality. Monomers were recovered from bio-oil fraction by supercritical carbon dioxide extraction and the remaining oil is proposed as a potential starting material for the synthesis of polyurethane foams

The pivotal role of rapid manufacturing in the production of cost effective customised products

The concept of Rapid Manufacturing (RM) is emerging from the so-called Rapid Prototyping technologies where additive rather than subtractive techniques will be used to make parts or even completed assemblies. As no tooling is required, one of the main benefits of RM will be the ability to make cost-effective custom products that could all be entirely individualised to a particular consumer or user. Thus, Rapid Manufacturing is the enabling technology for true, cost effective custom manufacturing and has the potential to revolutionise the design and manufacturing worlds. This paper will introduce results from a current research project that is being undertaken at Loughborough University looking into the effects that will occur to the logistics and supply chain infrastructure with the advent of RM

An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

A method using experimental nanoindentation and inverse finite-element analysis (FEA) has been developed that enables the spatial variation of material constitutive properties to be accurately determined. The method was used to measure property variation in a three-dimensional printed (3DP) polymeric material. The accuracy of the method is dependent on the applicability of the constitutive model used in the inverse FEA, hence four potential material models: viscoelastic, viscoelastic–viscoplastic, nonlinear viscoelastic and nonlinear viscoelastic–viscoplastic were evaluated, with the latter enabling the best fit to experimental data. Significant changes in material properties were seen in the depth direction of the 3DP sample, which could be linked to the degree of cross-linking within the material, a feature inherent in a UV-cured layer-by-layer construction method. It is proposed that the method is a powerful tool in the analysis of manufacturing processes with potential spatial property variation that will also enable the accurate prediction of final manufactured part performance

Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V

Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V

Microstructure of Ti-6Al-4V produced by selective laser melting

Ti-6Al-4V is the most widely used titanium alloy. Manufacturing of Ti-6Al-4V components using novel additive processing techniques such as selective laser melting is of great interest. This study focuses on the microstructure characterisation of Ti-6Al-4V components produced by selective laser melting (SLM) with full (Ti-6Al-4V base plate) and partial (Ti-6Al-4V needle-shaped bed) support. The starting material, a plasma atomised powder, and the component products are studied using various microscopy techniques including optical, scanning electron and transmission electron microscopy and electron backscattered diffraction (EBSD). Powder particles are fully dense, possess a spherical shape and are composed of acicular α phase. The as-built material shows oriented acicular martensitic phase with well defined columnar grains. The morphology of martensitic phase and microstructural evolution will be discussed in relation to the SLM processing parameters employed and the different cooling rates experienced by the components

Reducing porosity in AlSi10Mg parts processed by selective laser melting

Selective laser melting (SLM) is widely gaining popularity as an alternative manufacturing technique for complex and customized parts. SLM is a near net shape process with minimal post processing machining required dependent upon final application. The fact that SLM produces little waste and enables more optimal designs also raises opportunities for environmental advantages. The use of aluminium (Al) alloys in SLM is still quite limited due to difficulties in processing that result in parts with high degrees of porosity. However, Al alloys are favoured in many high-end applications for their exceptional strength and stiffness to weight ratio meaning that they are extensively used in the automotive and aerospace industries. This study investigates the windows of parameters required to produce high density parts from AlSi10Mg alloy using selective laser melting. A compromise between the different parameters and scan strategies was achieved and used to produce parts achieving a density of 99.8%