The secret of wrinkling, folding, and creasing
The process of wrinkle formation is familiar to anyone who has ever sat in a bathtub a little too long. But exactly why layered materials sometimes form one kind of wrinkly pattern or another — or even other variations, such as creases, folds, or delaminated buckles — has now been explained at a fundamental level by researchers at MIT. The underlying process is the same in all of these cases: Layers of material with slightly different properties — whether skin tissue or multilayer materials created in the lab — tend to form patterned surfaces when they shrink or stretch in ways that affect the layers differently. But the new analysis, for the first time, creates a unified model that shows exactly how the properties of the individual layers, and how they are bonded to each other, determines the exact form of the resulting texture. MIT associate professor of mechanical engineering Xuanhe Zhao...