CIB affairs

The development of a new lightweight military shelter system is based on an unusual composite structural system utilizing the innovative use of pultrusion production techniques for plastic. The authors report on the combined development of both the structural system and the components which are made from linear pultruded sections of reinforced plastic and an anticlastic stressed membrane The shelter comprises a ‘kit’ of purpose designed components which are used to fulfil the multiple reuirements of the shelter brief. This has resulted in a smaller number of component parts, less weight and enhanced ease of fabrication and assembly. Some of the techniques used in the design of components and parts indicate an alternative approach to the use of plastics in building construction.

Le développement de ce nouvel abri militaire léger repose sur un systéme structurel composite original qui fait appel á l'utilisation de techniques novatrices de transformation des matiéres plastiques par pultrusion (extrusion par étirage). Les auteurs décrivent le développement combiné du système structurel et des éléments constitutifs qui sont fabriqués à partir de profilés pultrudés linéaires en matière plastique renforcée et d'une membrane qui rèsiste aux tensions. L'abri se présente sous la forme d'un ensemble d'éléments de structure spécifiquement concus permettant de répondre aux multiples conditions du cahier des charges. Le nombre de pièces est ainsi réduit, l'ensemble est plus léger et plus facile à fabriquer et à assembler. Certaines des techniques utilisées pour la conception des éléments de structure et des pièces font envisager une autre méthode d'utilisation des plastiques dans le secteur de la construction.     

Developing a new military shelter system: a case study in innovation

A lightweight, rapid-erect shelter system using a new combination of composite materials and fabric diaphragms in a truss support system has been developed in response to changes in military requirements. This paper outlines the background to the project and the reasons for its inception; it follows the development of the design from initial conceptual idea to eventual solution. Decisions influencing the overall design, structure, materials, prototyping and manufacturing techniques are discussed in relation to performance criteria and client capabilities. The authors focus on the problems encountered in the development programme and the innovation process, highlight how these problems were overcome and detail the benefits which were created. In particular, the resulting tent incorporates lightweight sprung glass reinforced composite beams, post-tensioned by a fabric diaphragm. The new shelter uses a minimum number of these lightweight, rigid components and consequently achieves a reduction in weight, erect and strike times and packed bulk through its innovations. Pour repondre a l'evolution des besoins des forces armees, on a developpe un nouvel abri leger, a montage rapide, qui utilise une nouvelle combinaison de materiaux composites et de diaphragmes en toile dans un systeme a bati-support. Cet article rappelle les grandes lignes du projet et les raisons de sa mise en oeuvre; il decrit l'avancement du concept, de la conception initiale jusqu'a solution definitive. Les decisions qui ont une influence sur la conception generale, la structure, les materiaux, les prototypes et les techniques de fabrication sont examinees par rapport aux criteres de performance et aux capacites de l'utilisateur. Les auteurs se penchant notamment sur les problemes rencontres dans le cadre du programme de developpement et au niveau de l'innovation; ils expliquent clairement comment ces problemes ont ete resolus et exposent en detail les avantages qui en decoulent. En particulier, la tente qui est nee de cette idee est realisee avec des poutres composites renforcees a la fibre de verre elastique legere, qui sont post-tensionnees par un diaphragme en toile. Ce nouvel abri utilise un nombre minimal de ces composants rigides et legers. Ce concept permet donc de reduire le poids ainsi que les temps de montage et de demontage; en outre, ces tentes peuvent etre emballees en quantites grace a toutes ces innovations.     

Thermal comfort and clothing insulation of resting tent occupants at high altitude

Thirty-nine males and 18 females, in six groups, participated in six high altitude treks (each lasting 3–4 weeks and climbing up to 5500 m) in the Himalaya and Karakoram. Inverse relationships between mean overnight total insulation (sleeping bag plus clothing) and air temperature in tents were recorded for all treks. Average overnight thermal sensations varied little with air temperature as the subjects modified their clothing insulation to maintain thermal sensations warmer than ‘neutral’ for all treks. For combined treks, subjects adjusted their mean overnight total insulation up to 7 clo for thermal sensations of between 0 (‘neutral’) and +1 (‘slightly warm’) on average, measured on the standard seven-point thermal sensation scale developed for everyday low-altitude conditions. Very few subjects (3% of all daily responses, on average) reported ‘cool’ or ‘cold’ sensations. General tent discomfort increased with altitude suggesting that subjects interpreted tent comfort predominantly in terms of thermal outdoor conditions.