The present disclosure relates to detecting strain in polymers.  More particularly, the present disclosure relates to composite structures in which strain is detectable upon visual inspection. 
Measurement of strain in materials is typically done with instrumentation.  Very few examples exist of materials that can give a visual measure of strain.  One example is a liquid crystal system, which is very dependent on thickness, and is a costly option.  There is a need for low cost visual indicators of strain in polymeric materials.