Embedded NMR sensors for cure monitoring and control of composite structures

摘要

Methods and apparatus for monitoring and controlling cure cycles of composite structures utilize specialized NMR sensor (14) embedded into critical regions in the interior of composite structures (18) to provide in-situ cure state information. Signals developed by the NMR sensors (14) during the curing cycle are processed by an NMR spectrometer (30) to determine selected NMR parameters including T.sub.1, T.sub.2, T.sub.1D, and T.sub.2 * of the materials in the vicinity of the sensor, from which the rigidity of the materials are deduced. Experimental data show clear trends in values of particular NMR parameters taken as time series during cure cycles. Cure cycle control is accomplished using output data from an enhanced NMR spectrometer (30*) to drive temperature and pressure controllers (38, 42) of a curing oven (20*) for real time process control.