Folded plate structures made of cementitious composites

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The folding technique exploiting principles of origami is becoming increasingly popular in engineering disciplines and opens up new opportunities also in the field of folded structures with load-carrying function. In combination with novel cement-based composites continuously reinforced with flexible textile fabrics, the folding technique provides an innovative method for design and manufacturing of light-weight structures based on the principle of form follows force. Due to the high adaptivity of the manufacturing process the method lends itself to mass-customization as it complies with the requirements on high variability and economic production. In the first project period, basic components of the design and manufacturing methodology for cement-based folded structures have been developed. New algorithms for the simulation of the folding process and for geometrically based form-finding methods have been mathematically formulated and implemented as plug-ins in the simulation toolkit called oricrete. Based on the conducted simulations, devices controlling the folding process have been developed and validated for singly curved shells based on the Yoshimura crease pattern. The target configuration has been fixed by grout in the crease lines. The mechanical properties of the grouted crease lines have been tested for bending, tensile, transverse and shear loadings. The load-carrying behavior has been analyzed using a finite element model automatically generated by the oricrete toolkit. The goal of the second project period is the extension of the design and production methodology with efficient statically based form-finding algorithms and manufacturing strategies combining several folding approaches. The feasibility of the proposed concepts is to be evaluated on behalf of demonstrator objects. In particular, form-finding methods reflecting the crease line stiffness properties shall be developed and implemented in the oricrete toolkit. This development will address the general need for efficient form-finding methods reflecting the mechanical properties and foldability constraints. The developed methods and algorithms for a geometrically and statically based form-finding will be employed to analyze the formability and static performance of several know crease patterns. The form-finding methods will be validated by geometrically and physically nonlinear analysis of the load-carrying behavior. The developed manufacturing strategies will be used to produce several thin folded specimens for the experimental validation of the simulation results. As a final goal of the project a folded roof structure consisting of several folded segments will be built as a demonstrator of the developed methodology.