ME 472 Demonstration: Seeing stress!

You might see stress when you look in the mirror, but in a material that is just flexing a little (elastically), you can’t see the stress. You have to go back to TAM 251 (Solid Mechanics) and ME 330 (Materials) to derive the definitions and apply with confidence. But in ME 472 this week, we’re going to visualize the stresses in a photoelastic material through a polariscope in the Mechanical Testing Instructional Laboratory (MTIL), located in Talbot Lab. A photoelastic material refracts the light based on the local stress state, in our case the difference between stresses in the vertical and horizontal directions. Each fringe of light represents a constant stress difference! Check out one of our images here — the stresses get high when the contour lines are very close together near where the pieces touch. Stress is not so bad after all!