When you're just a child, there's nothing better than a clown and a few balloon animals to make your birthday party one to remember. There's just something unforgettable about experiencing a balloon twisting in action—the contortion of the balloon, that rubber smell, and the inevitable high-pitched squeakiness that fills the room until a bunny or giraffe appears.
But that clown might need to get a new act soon.
But how? If you create a balloon from a 3D model of a certain animal, when it's inflated the shape will become deformed. So, the team uses the 3D finished balloon shape, then works backwards, calculating what the empty balloon would need to be shaped like. They model the way the balloon stretches when blown up, then deflate it to find the shape that will most likely reproduce the intended inflated shape.
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Some shapes are easier to make then others. Shapes with flat surfaces or pointy regions tend to bulge, whereas rounded objects appear normal. Below are the results obtained with the team's method. The columns show target shapes, optimized balloons, simulated inflated balloons, fabricated optimized balloons, and fabricated balloons.
The team's goal is "to develop a method for designing balloons that, once fabricated, can be inflated into as complex shapes as foil balloons, but are as deformable and as easy to manufacture as conventional rubber balloons."
But if you prefer the precision of hands-on balloon animal making, learn some twisting skills.