The structural health monitoring method of the present invention utilizes a sensor system to determine information about deformation, stress and/or damage in structural elements. The sensor system and the method employ at least one sensor which comprises a material having fully-reversible nonlinear elasticity. The method comprises associating at least one sensor including a material having fully-reversible nonlinear elasticity with a structural element in a manner whereby stress is transferred from said structural element to said sensor, propagating ultrasound through a portion of the sensor, receiving the ultrasound which has been propagated through at least a portion of the sensor and determining information about the structural element from attenuation and/or time of flight of said received ultrasound.