The Petrofina company showcased new textile construction technologies when, as part of its 75th anniversary celebration, it used stressed textile roofs in their service station development at Wanlin in Belgium. These bold and elegant forms, each covering an area of 44 by 54 metres, have met with widespread approval, receiving several prestigious design awards. With the textile machinery industry paying particular attention to this market segment, new, more specialised equipment is now being developed which is better suited to producing the required high-quality lightweight technical fabrics. Higher production speeds mean lower costs and an increased capacity to respond rapidly to market needs.

No easy task

The design of such structures is another question. We needn't look far to find otherwise daring and intrepid young architects cringing at the mention of industrial textiles in their designs. Even for the simplest textile structures like ropes, cables and belts, there has been very little attempt to develop predictive models to assist with design optimisation. The industry has had to rely on experience coupled with trial and error in its attempts to develop new techniques. Designs for larger and more complex structures like the roofs at Wanlin have traditionally been tested using hand-built models, a largely outmoded practice now increasingly seen as downright primitive among many young designers, and all of this without the help of any of the specialised Computer-Aided Design (CAD) software packages so prevalent today in all kinds of design areas.
The objective of this project was to develop integrated CAD software for the design of surface-stressed architectural textile structures. Dubbed ISIMEM, the system represents a unique approach to structural textile design and has already resulted in significantly improved quality and productivity for many progressive architects. Designed for use within a variety of operating systems, ISIMEM is targeted at architects and structural engineers working with lightweight buildings and civil engineering constructions. A training program provides an introduction to membrane building structures, including basic knowledge of membrane materials and properties, guidelines for design and other fundamental information.

The real thing

The 'meat' of the system consists of a newly developed formfinder design tool called CADISI which allows the user to design funicular structures like stressed textile roofs or cable nets. This means, first of all, the determination of suitable doubly curved surface forms using a force-equilibrant form-finding strategy. A variety of algorithms can be used to determine suitable forms. From there, geometrically non-linear analysis software for static structural analyses allows verification of the behaviour of lightweight structures under applied loads. Finally, a rendering system generates high quality realistic images of textile structure designs for client review.
The CADISI formfinder is supported by several existing software tools, providing a complete and easy-to-use low-cost CAD system covering the entire design process from building conception to design, force analysis, cost analysis and presentation of results. Complex manual calculations and cumbersome and costly hand-built models are done away with, leaving more time for the real creative design work.
CADISI is an excellent tool for presenting ideas and proposals not only to clients, but also to other architects, designers and engineers who can then take the construction process forward. Subsequent steps like pattern generation, the selection and cutting of textile materials and the construction itself are all made easier.

Partnership and market success

The ISIMEM project was carried out by a consortium consisting exclusively of SMEs. The resulting CAD system is now being successfully marketed by Technet GmbH with strong promotional and marketing support from France's Serge Ferrari S.A. Additional industrial partners include raw materials and textile manufacturing companies, all of whom stand to gain from the increased acceptance of lightweight textile building structures among both architects and clients.
ISIMEM software has generated significant positive feedback from users worldwide and its popularity is still growing. Partners say that their common clearly defined goal of exploiting the results both internally and commercially was a major factor in the successful completion of the project.