Finite element software is best known for the colorful images of simulated strain patterns on 3D model -- ranging from blue (no problems, mate!) to red (danger, danger). This software finds weak points where the model might break -- or where the manufacturer can ensure the product breaks to generate repeat sales, for the cynically inclined.
Anyhow, material science engineers (generically called "scientists" by C|Net's Candace Lombardi) at University of Illinois have moved FEA from software simulation right into products. As she describes in Color-changing materials react to force, Bend or stretch the item and it begins to turn orange -- and progresses to red close to its breaking point. Or, it turns purple while being compressed. Once the stress is removed, the color changes back to normal.
Next step: self-healing parts.