Keywords: stretchable electronics, flexible electronics, conductive inks, printed electronics, nanomaterials, carbon nanotubes, graphene, silver nanowires, wearable sensors, soft electronics, polymer substrates, TPU, PDMS, electromechanical reliability, mechanical testing, fracture mechanics, finite element modeling, FEA, multiaxial strain, thin film cracking, additive manufacturing, direct ink writing, printed multilayer circuits, printed vias, in-space manufacturing, NASA electronics, mechanical modeling, structural health monitoring, soft robotics, biomedical electronics, aerospace electronics, Radial Stretch Tester, electromechanical fatigue, stretchable circuit design