The development of technology to fabricate “self-actuating” objects seems to be the next big thing in 3-D printing. However, realizing flat materials that transform through material forces into a desired 3-D object is a challenge. The range of objects has been limited to those with sharp edges and little, if any, curvature, and transformation methods have been based primarily on folding or processes that could not be controlled very precisely.
Now, computer scientists from the Institute of Science and Technology Austria have made it possible to create self-actuating, smooth, free-form objects. The development relies on an ingenious material design and a new method of self-transformation, forming the CurveUps technique. The researchers also developed the computational tools to take a user-provided 3-D model and automatically create a 2-D flattened template that, upon release, transforms into the original 3-D version.
CurveUps are made up of tiny tiles sandwiched between pre-stretched latex layers. During the transformation process, the tension in the latex pulls the tiles together joining them into a continuous shell.
In creating the 2-D templates for printing, the program takes a user-supplied 3-D form and automatically generates a 2-D tile layout, including the orientation, location and shape of each tile and connecting pins. As even small models will have hundreds or thousands of individual tiles, this poses an optimization problem of tremendous proportions — one infeasible on any personal computer. The team then implemented a two-step optimization procedure, which first gives an approximate solution, then performs local refinements before producing a final template.