A radio frequency strain monitor includes a voltage controlled oscillator for generating an oscillating signal that is input into a propagation path. The propagation path is preferably bonded to the surface of a structure to be monitored and produces a propagated signal. A phase difference between the oscillating and propagated signals is detected and maintained at a substantially constant value which is preferably a multiple of 90 DEG by changing the frequency of the oscillating signal. Any change in frequency of the oscillating signal provides an indication of strain in the structure to which the propagation path is bonded.
申请公布号
US4843346(A)
申请公布日期
1989.06.27
申请号
US19880203177
申请日期
1988.06.07
申请人
ADMINISTRATOR, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
发明人
HEYMAN, JOSEPH S.;ROGOWSKI, ROBERT S.;HOLBEN, JR., MILFORD S.