Structural membranes are wide-span lightweight textile structures that can be built in a variety of in-teresting and appealing shapes. Since textiles can only carry loads through tension, the combination ofprestress and curvature is essential and necessitates the so-called design cycle including formfinding,structural analysis and cutting pattern generation. All three steps are highly nonlinear and iterative anal-yses with a result that influences the structural behaviour as well as the appearance. Formfinding needsto be perfomed to attain a functioning structure under prestress. Once a formfound shape is set, structuralanalysis ensures a structure’s safety. Finally the cutting pattern generation provides the flat patterns, i.e.fabric stripes, which can be raised to the desired threedimensional shape. This presents a challenge sincethe double curved surfaces cannot be developed into plane ones without compromise.Due to the interactive nature of the design cycle analyses, working with a single model holds a substantialadvantage for the designer. With Isogeometric B-Rep Analysis (IBRA), it is possible to design andanalyse these free-form shapes without leaving the CAD environment. As IBRA uses the NURBS-based CAD models for analysis, the geometry can be represented in a far better way than is possiblewith classical FEM meshes. It thus leads to more accurate results with regard to both the shape andthe stresses, because the curvature’s influence on the structural behaviour is accounted for appropriately.IBRA accesses the full B-Rep description of a geometry. This means that CAD functionalities whichare fundamental for the construction of geometries, e.g. trimming, can be used without compromisingthe analysis model. Especially with regard to the cutting pattern generation it is beneficial to modelthe pattern stripes by simply applying trimming operations to the formfound shape and performing theanalysis on the trimmed patches.The design cycle of membrane structures with IBRA will be presented in this paper on an exemplarystructure. An emphasis will be put on the cutting pattern generation, where CAD-integrated analysiswith IBRA holds the most advantages.
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Structural membranes are wide-span lightweight textile structures that can be built in a variety of in-teresting and appealing shapes. Since textiles can only carry loads through tension, the combination ofprestress and curvature is essential and necessitates the so-called design cycle including formfinding,structural analysis and cutting pattern generation. All three steps are highly nonlinear and iterative anal-yses with a result that influences the structural behaviour as well as the appeara...
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